Tricuspid regurgitation (TR) is a highly prevalent valvular heart disease that has been long overlooked, but lately its independent association with adverse cardiovascular outcomes was recognized. The time point to intervene and repair the tricuspid valve is defined by the right ventricular (RV) dilation and dysfunction that comes up at a later stage. While guidelines favor tricuspid valve repair before severe RV dysfunction ensues, the definition of RV dysfunction in a universal manner remains vague. As a result, the candidates for transcatheter or surgical TR procedures are often referred late, when advanced RV dysfunction is established, and any derived procedural survival benefit is attenuated. Thus, it is of paramount importance to establish a universal means of RV function assessment in patients with TR. Conventional echocardiographic indices of RV function routinely applied have fundamental flaws that limit the precise characterization of RV performance. More recently, novel echocardiographic indices such as strain via speckle-tracking have emerged, demonstrating promising results in the identification of early RV damage. Additionally, evidence of the role of alternative imaging modalities such as cardiac computed tomography and cardiac magnetic resonance, for RV functional assessment in TR, has recently arisen. This review provides a systematic appraisal of traditional and novel multimodality indices of RV function in severe TR and aims to refine RV function assessment, designate future directions, and ultimately, to improve the outcome of patients suffering from severe TR. Clinically significant tricuspid regurgitation (TR) is a common valvular heart disease affecting 0.55% of the general population, with functional TR accounting for the most severe TR cases ,2. DespiSignificant TR has a deleterious impact on right ventricular (RV) size and function; TR will progressively induce tricuspid annular dilation and tricuspid leaflet tethering due to RV remodeling, while retaining normal RV function at the compensating phase. When the point of RV adaptation to volume overload is surpassed, patients suffer RV functional compromise and enter a vicious cycle of recurrent heart failure admissions, further aggravating their prognosis  7]. In . In 7]. The current review aims to enlighten the assessment of RV dysfunction in the presence of severe TR by addressing the merits of novel imaging modalities in echocardiography, cardiac computed tomography (CCT), and cardiac magnetic resonance (CMR). It ultimately endeavors to provide a guide for multiparametric assessment of RV function that will enable well-timed therapeutic decision making in TR.Challenges in the evaluation of RV performance stem mostly from its complex anatomy. The RV is a crescent-shaped structure including an outlet, apex, and inlet portion. Hence, incorporating the contractile force of all three components with the measurement of one single index is practically impossible . ConventTricuspid annular plane systolic excursion (TAPSE) evaluates the distance of systolic excursion of the RV annular segment along its longitudinal plane, while S’ measures the peak systolic annular velocity via Doppler tissue imaging at the tricuspid annulus level. Both are widely established indices, recommended for RV function assessment with a suggested cutoff value of 17 mm and 9.5 cm/s, respectively . In contDespite their widespread use, evidence of the prognostic value of those indices is contradictory in severe TR. In the study by Karam et al., which included 249 high-risk patients with severe TR undergoing transcatheter repair, neither TAPSE nor FAC assessed pre-intervention could elicit long-term prognostic information . ConversKwon et al. associated reduced preoperative S’ with unfavorable outcomes in patients with severe functional TR, with previous mitral valve surgery having isolated tricuspid valve surgery, but their study was small and underpowered . For surTAPSE and S’ are simplified estimates of RV function and subjects to significant limitations in the setting of severe TR. Both indices are angle and load dependent and they assume that the displacement of a single point of the tricuspid annulus represents the overall function of the complex, three-dimensional structure of the RV . TherefoLeft ventricular EF by two-dimensional Simpson’s biplane method is the main echocardiographic parameter implemented to evaluate ventricular function for left-sided valvular heart disease in clinical practice. Simpson’s biplane method cannot be applied for the RV, which can only be assessed from a single plane in an apical RV-focused view via two-dimensional echocardiography. However, echocardiography allows the estimation of RV EF with the use of two-dimensional imaging that allows real RV full-volume capture and it is not dependent on the image plane orientation of the two-dimensional imaging.Three-dimensional echocardiography has shown less volume underestimation than two-dimensional echocardiography and acceptable performance for volume quantification, comparable to CMR . A head-Despite the benefits of three-dimensional echocardiography, the use of RV EF can markedly overestimate RV function for patients with severe TR, as it does not account for the relationship between contractility and afterload, but only describes the percentage of volume change per cardiac cycle . Three-dIn patients with severe TR presenting with RV volume overload, the contraction of subendocardial longitudinal fibers might be the first to be insulted indicating an early phase of ventricular damage, while contractility of the mid-circumferential RV layers can still be preserved or even augmented to compensate for the loss of longitudinal force  24]. Wh. Wh24]. For over two decades, two-dimensional speckle-tracking echocardiography has emerged as a novel imaging technique assessing intrinsic myocardial function. Despite being initially utilized for the left ventricle, its applicability has recently been extended to the RV. RV global longitudinal strain (RVGLS) and RV free-wall longitudinal strain (RVFWLS) are the two main indices of speckle-tracking echocardiography for the assessment of RV performance, with a strong correlation to CMR-derived RV EF . These iRV longitudinal strain has provided evidence of refined risk stratification for TR patients. Prihadi et al. studied a large cohort of 896 patients with moderate or severe functional TR and disclosed that RV FWLS identified a higher number of patients with abnormal RV function compared to the traditional TAPSE and FAC . This obApart from the ability to detect RV dysfunction in advance of the conventional parameters, RV longitudinal strain provides prognostic information for patients with severe TR treated conservatively. Prihadi et al. demonstrated that RV FWLS is associated, over and above TAPSE and FAC, with long-term outcomes . In the RV strain could serve as a tool to select appropriate surgical candidates for TR repair at an early stage of the disease, before irreversible RV damage ensues, to optimize outcomes. Kim et al. indicated in a cohort of 115 patients with severe functional TR undergoing isolated tricuspid valve surgery that a pre-operative RV FWLS > −24% could independently predict dismal post-operative outcomes . FurtherRV longitudinal strain provides information on the myocardial contraction beyond a mere description of volumetric RV changes. As such, it appears to be superior to other RV indices and could potentially refine risk stratification and optimal thresholds for intervention in TR. Although RV function assessment is paramount in severe TR, it fails to account for the subtending RV afterload, which may vary substantially between patients. Besides RV dysfunction, the prognostic role of pulmonary hypertension, which is a common hemodynamic complication of long-standing heart failure and TR, has been recognized . RV-pulmTAPSE/PASP ratio has demonstrated good correlation with the invasive pressure-volume loop-derived end-systolic/arterial elastance, which is the gold-standard measure of RV-PA coupling . This inWhile TAPSE/PASP could play a role to select appropriate candidates for percunatenous tricuspid valve interventions with severe TR, its utility is questionable for cases with greater than severe  TR. In such cases, TAPSE/PASP may overestimate the true coupling of the RV-PA circuit, as echocardiographic PASP is underestimated and correlates poorly with the respective invasive PASPs. In a cohort of 126 patients with greater than severe TR undergoing transcatheter repair, only the TAPSE/PASP using the invasive PASP could provide prognostic information, whereas the echocardiographic TAPSE/PASP could not .CCT use in patients with significant TR is advocated for use in pre-procedural planning of the transcatheter repair. CCT has a high spatial resolution and provides three-dimensional cardiac data. This enables the precise assessment of the tricuspid annular morphology and the sub valvular anatomy, the characterization of surrounding structures, the determination of pacing lead location, the definition of optimal fluoroscopic angulations, and vascular access root planning .Beyond the value of CCT for anatomical assessment, its role in RV function evaluation has recently been explored. Due to its optimal spatial resolution, CCT enables excellent endocardial–blood pool interface definition  and concCurrently, CCT is not implemented in everyday clinical practice for the RV EF evaluation, due to a lack of availability, radiation exposure, and the need for an iodinated contrast, making the available data scarce. However, RV EF assessment should be encouraged in all the patients with TR undergoing a CCT for any reason, such as coronary artery disease evaluation or pre-procedural planning of valvular repair or replacement.CMR is considered the gold-standard modality for volumetric quantification of the RV. CMR derived RV EF bypasses any potential geometrical assumptions of the RV shape and is based on the real RV volumes in end-diastole and end-systole . This inPark et al. identified RV EF as an independent predictor of cardiac death and major postoperative cardiac events in 75 consecutive patients undergoing corrective surgery for severe functional TR . In a coDespite its excellent accuracy in volume quantification, CMR-derived RV EF still relies on a mere description of RV volumetric changes in a cardiac cycle, potentially overestimating RV function for patients with a severe TR background. Even the effective RV EF that accounts for the regurgitant volume does not providing any information about the myocardial RV function per se, and is considered to be impaired in an advanced stage of RV dysfunction. However, earlier signs of RV decompensation might be of stronger clinical relevance to drive the interventional decisions on TR.Most available evidence of longitudinal strain in TR stems from speckle-tracking echocardiography which, however, is limited by the two-dimensional nature of this modality for a complex three-dimensional structure. Recently, CMR has allowed the estimation of strain using standard cine images, without the need for separate pulse sequences . A multiA unique advantage of CMR is the myocardial tissue characterization which has been studied for the left ventricle in cases of left-sided valve disease ,64, but In an attempt to monitor the trajectory of severe TR and apply timely intervention, the approach to RV function assessment should be holistic. The assessment of imaging indices should be complemented by biochemical biomarkers in clinical practice. Elevated B-type natriuretic peptide levels before intervention may connote advanced disease and have been associated with poor post-operative course in severe TR . OverallIn patients with severe TR and right heart failure, physical signs of overt tissue oedema resulting from long-standing intravascular and interstitial fluid volume expansion is the prevailing symptom. Carbohydrate antigen 125 is a reliable surrogate of congestion in heart failure and is independent of renal function, age, and weight. Particularly in the setting of severe TR, carbohydrate antigen 125 has demonstrated stronger association with mortality compared to natriuretic peptides, which may not reflect the contribution of functional TR towards the disease pathophysiology . MoreoveEarly intervention for left-sided valve diseases to prevent irreversible left ventricular damage is an established practice applied in everyday clinical practice. However, a long way has to be made to achieve an early intervention on the tricuspid valve in case of TR to avoid RV dysfunction. The high operative morbidity and mortality documented for the surgical treatment of TR is largely attributable to the lack of universally established indices of RV dysfunction and accepted cutoff values, leading to inconsistent practices regarding the right time for intervention . This miAccording to the ESC and ACC/AHA guidelines, severe TR should be treated interventionally/surgically when RV failure symptoms arise, and for the asymptomatic patients intervention is recommended in the presence of progressive RV dilatation or systolic dysfunction. No recommendations are available for patients with severe asymptomatic functional TR ,9. HowevPromising evidence has emerged on the role of strain imaging via speckle-tracking echocardiography, which is an index of early RV damage associated with outcome in asymptomatic patients with severe TR ,35,37,38In the current era of the new TR classification and the accompanied phenotypes of RV remodeling, the implementation of different cutoff values for RV dysfunction might be necessary . For insSince RV function should dictate the timing of tricuspid valve repair in severe TR, it has to be assessed in a universal, easily accessible, and widely available manner that can detect even subtle RV dysfunction. RV strain imaging seems to be the key in revealing in advance the anticipated RV decompensation. RV longitudinal strain via speckle-tracking echocardiography has considerable strengths compared to traditional simplified parameters of RV function in describing early RV damage. Moreover, CMR-derived feature-tracking strain has arisen, showing additive value over the gold-standard measure of RV EF. Although evidence is promising, further prospective research is crucial before strain-driven patient management in TR can be advocated.


The pathophysiology of skin cancer is complex, with multiple factors contributing to its development. The proactive treatment of skin cancer has been investigated in the form of chemoprevention of cutaneous malignancies in clinical trials. Chemoprevention is the use of natural or pharmacologic agents that prevent or reverse skin cancer development. Multiple trials have arisen over the past decades to explore the efficacy of specific agents to halt the progression of UV radiation damage. This comprehensive review article aims to assess clinical trials performed with chemopreventive agents for melanoma and nonmelanoma skin cancers. The following compounds were most often used in these trials: nicotinamide, retinoids, polyphenolic antioxidants, COX-2 selective inhibitors, non-steroidal anti-inflammatory drugs, difluoromethylornithine, and 5-fluorouracil. Many agents show promise in their ability to prevent nonmelanoma skin cancer formation, with few melanoma trials demonstrating efficacy. The chemoprevention efforts aimed at skin cancer are complex; current and future trials will be instrumental in identifying therapeutic agents that pose efficacy in halting cancer development and assessing whether long-term administration is tolerable. The American Academy of Dermatology estimates that one in five Americans will develop skin cancer in their lifetime,2. These cancers are subdivided into two broad categories: malignant melanomas and nonmelanoma skin cancers (NMSC). Malignant melanomas are the most frequent cause of skin cancer-related death, and it is estimated that about 7650 people are expected to die of melanoma in the U.S. in 2022. The NMSC category is further delineated into two major subtypes: basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) and it is estimated that 2–3 million cases occur each year in the world. Environmental exposures such as ultraviolet radiation (UVR) are highly correlated with skin cancer development. Educational initiatives to prevent exposure to risk factors for skin cancer and timely detection of these lesions are essential for preventing cutaneous malignancies and their progression.Skin cancer is the most prominent malignancy worldwide, affecting every ethnicity, socioeconomic background, demographic cohort, geographic region, and age group. These rays mediate DNA damage by mutating tumor suppressor genes necessary for the maintenance of cellular homeostasis and a regulated life cycle. They also cause immunosuppression, inflammatory responses, and oxidative stress, leading to the dysregulation of skin cells and the development of malignancies. These various cell damage mechanisms possess many routes that lead to homeostatic disruption in skin cells, making this type of cancer challenging to prevent and treat.The pathophysiology of skin cancer is complex and multiple factors contribute to the development of precancerous and cancerous lesions. With both melanoma and NMSC, the most common underlying etiology of malignancy formation is UVR-induced damage from sunlight exposure. UVA plays a role in carcinogenesis of the skin’s stem cells, while UVB radiation induces keratinocyte DNA damage, upregulation of inflammatory pathways, and tumor formation,6. Dysregulated DNA repair processes lead to inhibition of apoptosis, expansion of mutated keratinocytes, and initiation of skin malignancies,5. Chronic exposure to UVR is the most influential risk factor for developing actinic keratoses, cancer precursors. Additionally, more than one severe sunburn in childhood from sunlight and UVR exposure results in a 2-fold increase in melanoma risk,8.UVR can be subdivided into ultraviolet A (UVA) rays and ultraviolet B (UVB) rays, which exist along different wavelengths. These types of waves most frequently reach the earth’s surface in the form of UVA, with only 1%-10% of them existing as UVB,9. Due to impaired homeostatic functions in skin immunity, tumor formation has been associated with pro-inflammatory reactions via the arachidonic acid pathway. Upregulation of prostanoid production and cyclooxygenase 2 (COX-2) expression has been shown to increase mouse and human skin carcinogenesis, where these levels are low and maintained in normal skin. Immunosuppression leading to skin cancer formation via other mechanisms has also been observed, such as in transplant patients who receive immunosuppressive therapies, allowing immune susceptibility to cutaneous malignancy formation. Ultimately, multiple factors contribute to the development of skin cancer via mechanisms of free radical formation, DNA damage, alteration of homeostatic genes, and dysregulation of immune function, leaving the skin susceptible to the growth of malignancies.Immunosuppression induced via UVR is a contributing factor to carcinogenesis, frequently resulting in the development of skin cancers. Tumor formation occurs by diminishing antigen-presenting cell function, inducing immunosuppressive cytokine production, and altering delayed-type hypersensitivity reactionsSkin cancers often are not identified until their progression to solid tumors that are visible to the naked eye. While most are caught in early stages prior to metastasis, some aggressive forms of skin cancer such as melanoma may have already invaded the lymphatics or other parts of the body when a patient presents with a visible lesion. Thus, there has been a growing interest in recent years in the development of prophylactic agents to prevent skin cancer formation in patients believed to be at high risk for developing these malignancies. Many clinical trials have aimed to identify whether these chemopreventive agents are efficacious in halting malignancy formation and progression. In this review, we seek to provide an updated summary of chemopreventive agents that have emerged in recent decades through various trials and studies, as well as highlight future horizons in skin cancer treatment. This review was conducted via literature search using PubMed and included relevant articles using the search terms “chemoprevention”, “squamous cell carcinoma”, “basal cell carcinoma”, “melanoma”, and “skin cancer”. Pertinent trials and studies related to chemopreventive mechanisms and potential efficacious agents were included for discussion in this review.,12. With UVR exposure over a lifetime, prevention efforts are limited in that people of all ages can be at risk for sun damage accumulated early in life that may not present in the form of visible cutaneous malignancies until decades later. There has been a demonstrated need for developing interventions that are used in the time period following damaging UVR exposure and before the development of skin cancers.Skin cancer most typically manifests in the later stages of life. The median ages for the presentation of melanoma, BCC, and SCC are 65, 69, and 75 years of age, respectively. Chemopreventive agents that pose promising effects often target pathways brought upon by UV radiation-induced tumorigenesis. Molecular targets in these transduction mechanisms include inflammatory cytokines, cyclooxygenase-2, prostanoids, melanocortin one receptors, oxidative stress contributors, and many others,13,14. Benefits to these specific targeting mechanisms include low toxicity and directed action towards malignant proliferating cells. Many agents involved in regulating UVR signal transduction to halt skin cancer progression have been tested in clinical trials. The major compounds assessed in these trials include nicotinamide (NAM), retinoids, difluoromethylornithine (DFMO), polyphenolic antioxidants from green tea extracts, 5-fluorouracil (5-FU), COX-2 inhibitors such as celecoxib, and non-steroidal anti-inflammatory drugs (NSAIDs),12,15. Trials have aimed to assess the efficacy of oral and topical formulations in their potential to halt tumor formation pathways while maintaining low rates of adverse effects. Other agents that also pose benefits for chemoprevention have been investigated in cellular and animal studies, but have not yet been developed in the context of human trials. A summary of the chemopreventive agents and the pathways these compounds target during skin cancer development can be found in Chemoprevention has been posed as a solution and is defined as using natural or pharmacologic agents that prevent or reverse skin cancer genesis. Criteria for risks of cutaneous malignancy formation include lesion location, size, borders, de novo vs. recurrent disease, underlying immunosuppression, prior radiation, and pathologic subtypes.These treatments are plausible for populations considered medium to high risk for developing skin malignancies. This includes patients with a history of high amounts of sun exposure, pre-malignant skin markers such as actinic keratoses, numerous or invasive previous skin cancers, immunosuppression history, and organ transplant recipients. Immune function impairment in OTRs following chronic use of immunosuppressive medications causes an inability to eradicate cells with precancerous changes in addition to direct carcinogenic effects of these agents on cancer-initiated cells. A few successful chemopreventive agents that have been used in OTR patients who are at high risk for the development of skin cancer include retinoids, cyclooxygenase inhibitors, and ornithine decarboxylase (ODC) inhibitors such as DFMO.Skin cancer accounts for a significant cause of morbidity in people who have considerable immunosuppression. Populations especially at risk for the development of skin cancer include immunosuppressed organ transplant recipients (OTRs). This group’s risk for developing NMSCs is increased by approximately 10–250 fold. While surgical removal is the mainstay of initial treatment for skin cancers without distant metastatic disease, patients become more vulnerable to surgical interventions with age. Skin cancer is most prominent in the elderly population, and with aging comes increased rates of comorbidities, functional losses, cognitive impairment and decreased wound healing ability. A recent study in 2022 found that hypofractionated radiation therapy is a safe and efficient treatment for elderly patients with SCC. It has been shown that SCC has overexpression of the epidermal growth factor receptor pathway, suggesting this pathway is a possible treatment target in the future. Regarding basal cell carcinomas, dysregulation of the sonic hedgehog pathway is seen in these tumor types and emerging inhibitors such as Vismodegib and Sonidegib show promise. Recent advancements have tremendously increased recurrence-free and overall survival in patients with melanoma through the relatively new monoclonal antibody immune checkpoint inhibitors and targeted therapies (BRAF/MEK inhibitors). For example, ipilimumab (CTLA-4 inhibitor) and pembrolizumab (PD-1 inhibitor) have significantly reduced the risk of recurrences in trials and increased overall survival benefits in their use as adjuvant therapies in patients who completed surgical resection of melanoma lesions. However, systemic therapies also pose a risk for toxicities which elderly patients are more susceptible to. While recent advances in treatment modalities have instrumentally improved skin cancer outcomes, there still lies a need for prophylactic agents to prevent their development to avoid invasive interventions. It has been estimated that approximately 60% of people with a history of developing one NMSC will be diagnosed with a second within ten years. With high skin cancer recurrence rates, new chemoprevention modalities pave a new horizon in treating patients at high risk for malignancy development and recurrence.Treatment intervention for skin cancer lesions varies in the form of surgical removal, radiation therapies, and systemic therapies such as immune checkpoint inhibitors. Studies examining the chemopreventive activity of agents tested in trials have shown varying results, warranting current and future trials to establish which agents are safe and efficacious. Carefully selected target populations and identifying biomarkers with prognostic and predictive value are necessary to evaluate these therapeutics. Limiting factors of clinical trial investigation include the rarity of cancer endpoints in populations, the large population sizes required for data reliability, length of time for carcinogenic progression, sun exposure, and subject compliance to long-term treatments with frequent and high dosing regimens. Feasibility of the dietary and pharmacologic agents used in chemoprevention is difficult and accounts for significant challenges in past and future trials. The controversies surrounding the subject of chemoprevention are largely based on these clinical trial limitations and speculation of proven efficacy. Trials and studies that have most recently been discussed in the literature include the following agents: nicotinamide, COX-2 inhibitors/NSAIDs, retinoids, DFMO, and 5-FU. The following sections describe these agents in detail and highlight clinical trials and studies related to their chemopreventive abilities. A summary of the main chemopreventive trials mentioned in this review can be found in Chemopreventive agents that have shown promise in vitro and UV mouse models have been explored in humans through clinical trials. Potential new agents are selected from leads of basic science and epidemiology. Compounds with approved preclinical toxicology profiles advance to phase I and phase IIa clinical trials. After this, larger phase IIb and multicenter phase III trials are performed before final approval of efficacious agents in human populations. High NAD+ suppresses reactive oxygen species production and promotes mitochondrial homeostasis and cell survival. Centrally involved in DNA repair mechanisms, NAM is a substrate for the DNA repair enzyme poly(ADP)ribose polymerase that acts to repair UV-mediated nucleotide damage. NAM also possesses anti-inflammatory roles by decreasing the expression of NF-kB, a well-known pro-inflammatory transcription factor.Nicotinamide (NAM) is a water-soluble form of Vitamin B3 (niacin) that also serves as a precursor for many cellular metabolism pathways in the form of nicotinamide adenine dinucleotide (NAD+). Evaluation of its use in animal models also lends promise to its ability to combat immunosuppression by UV radiation. In one of the first studies to investigate NAM in chemoprevention, Gensler et al. treated UV-irradiated mice with nicotinamide twice weekly and saw prevention of immunosuppression and skin tumor induction by reducing tumor incidence from 75% to 42.5%. Overall, NAM increased NAD+ levels circulating in the blood, reduced immunosuppression in cutaneous areas of UV damage, and reduced inflammation in both cancerous and precancerous lesions,26.Studies have demonstrated nicotinamide’s therapeutic action for inflammatory skin conditions such as bullous pemphigoid and acne vulgarisOver the past few decades, there has been a rise in evidence that NAM administration in humans might play a role in preventing cancer pathogenesis. NAM has been investigated in multiple phase III clinical trials of skin cancer prevention, which lend efficacy towards its use as a chemopreventive agent. It also has beneficial potential in its safety against toxicity, and cost-effectiveness and has been well tolerated in trials.. Furthermore, NAM has notably expressed clinical value in a 2015 phase III randomized trial of NAM by Chen et al., commonly referred to in the literature as the ONTRAC trial. This trial was conducted in a cohort of 386 subjects labeled as high-risk patients due to the inclusion criterion of having at least 2 NMSCs in the previous five years. Those given 500 mg of nicotinamide twice daily for twelve months had the rate of new NMSCs decline by 23% compared to the placebo group. Specifically, the new BCC rate decreased by 20%, the new SCC rate decreased by 30%, and actinic keratoses decreased by 11%. The results of this trial support the notion that oral NAM is safe and effective in reducing the recurrence of AKs, BCCs, and SCCs. Neurocognitive function was also assessed in this trial but yielded no significant findings. Upon cessation of NAM usage after a six-month follow-up period, there was no significant decrease in recurrence rates, suggesting that NAM administration is effective only on a daily regimen, without long-term effects after discontinuation. Thus, the argument arises of whether all chemopreventive agents must be used continuously for optimal efficacy. For each individual therapeutic, oral and topical agents warrant thorough investigation to assess for long-term adverse effects from their continual administration.In 2012, a phase II clinical trial brought attention to nicotinamide’s ability to treat pre-cancerous lesions. Oral administration of NAM significantly reduced the incidence of actinic keratoses (AK) in high-risk individuals compared to placeboet al. also conducted a phase II-controlled chemoprevention trial in renal transplant patients in 2016. With the same treatment of 500 mg oral NAM, there was a 16% reduction in AKs and a 35% reduction in NMSCs. However, results were not significant due to a small sample size of 22. The limitations of clinical trial abundance and reliability are especially prominent in this population of patients who have received solid organ transplants due to difficulty in the recruitment of large cohorts. A recent case-control study administered oral nicotinamide to a group of 38 patients who received either a kidney or liver transplant, and NAM was found to be effective in reducing rates of NMSCs and AKs compared to controls. Of the 18 treated patients with a significant decrease in AK size, 42% showed complete clinical regression. This further supports NAM’s value in chemoprevention for halting the development of NMSCs.The usefulness of NAM has also been investigated recently in trials specific to immunosuppressed populations. Chen . In the ONTRAC study mentioned previously, six in situ and four invasive melanomas were reported during the NAM intervention period between both treated and control groups. There were no significant differences between the thickness and invasiveness of lesions between the groups, suggesting limitations to the chemopreventive effects of NAM in melanoma reduction,28. However, individuals were recruited based on the incidence of NMSCs, and patients with a history of melanoma in the previous five years were excluded,28. Thus, to accurately assess NAM’s role in melanoma prevention, a group of high-risk for melanoma would need to be treated in trials. Overall, the ONTRAC trial and other clinical studies suggest chemoprevention with nicotinamide clinical trials is warranted for high-risk melanoma individuals. A summary of NAM trials can be found in While nicotinamide reduces incidences of nonmelanoma skin cancers and actinic keratoses, no trials have been conducted on its use for melanoma chemoprevention. It has been hypothesized that the photoprotective effects of NAM against melanoma induction pathways, such as DNA damage and UV-mediated immunosuppression, suggest potential in its usefulness for treatment, similar to results gathered from NMSC trials. Some NSAIDs inhibit COX-1 and COX-2 enzymes, leading to toxicity from loss of COX-1 action. Thus selective COX-2 inhibitors pose as better candidates for chemopreventive agents. Studies have reported that an increase in COX-2 enzyme and, therefore, prostaglandin E2 levels are correlated strongly with cancer development and metastases,33. Regarding the skin, expression of COX-2 has been observed to be stimulated by UVB radiation, increasing the incidence of cutaneous inflammatory pathways,34,35.Cyclooxygenase (COX) inhibitors, commonly used as anti-inflammatory agents, have demonstrated promise in their potential as chemopreventive agents. The enzyme cyclooxygenase is central to prostaglandin production and inflammatory pathways in the body. Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit this enzyme and are known for their analgesic, antipyretic, and platelet-inhibiting properties,36. Other mouse model studies have proven celecoxib to reduce UV-induced tumorigenesis, prostaglandin synthesis in the epidermis, tumor yield, and skin tumor formation in mice,13,37. COX-2 is upregulated in tumors and suggests that the arachidonic acid/COX-2/eicosanoid pathway has a significant role in photocarcinogenesis,37. Treatment of squamous cancer cells in vitro with COX-2 inhibitors inhibits cell growth,38.Studies in mice models have suggested a relationship between COX-2 inhibition and decreasing cancer pathogenesis. Compared to controls, one leading COX-2 inhibitor, celecoxib, decreases multiplicity and increases tumor latency in UVR-exposed mice. It is effective in both low and high doses, converted to human dosages as 200 mg and 400 mg, respectively. While fewer AK lesions were present in the celecoxib group, the lack of significant data suggested that celecoxib may effectively prevent SCCs and BCCs. Applying topical NSAIDs to areas of the skin at risk for the development of AKs and NMSCs is a point of interest. COX inhibitor diclofenac is an established treatment by the Food and Drug Administration (FDA) for actinic keratoses, lesions prominently associated with squamous cell carcinoma development. Randomized placebo-controlled trials have affirmed its efficacy and demonstrated that topical diclofenac gel could induce a 60%-80% complete response in AK lesion clearance.When applied to humans, the effectiveness of oral celecoxib as a chemopreventive agent has been investigated in both oral and topical formulations. A double-blind, placebo-controlled, randomized clinical trial evaluated 240 subjects with a previous history of 10–40 AKs. After receiving 200 mg of oral celecoxib or placebo twice daily for nine months, no significant differences were found in the number of new AKs between the two study arms,41. In vitro studies have found at least a 3-fold increase in COX-2 levels in different melanoma cell lines. Additionally, a recent study analyzed COX-2 levels in lymph nodes with melanoma metastases and found that high COX-2 expression (> 10%) reduced progression-free survival by almost three years. One trial for patients with metastatic melanoma treated subjects with autologous dendritic cells, human telomerase reverse transcriptase, and tumor lysate to generate an immune response on a vaccine basis. Meanwhile, these patients were also treated with cyclophosphamide, IL-2, and celecoxib. The overall survival rate of patients increased compared to a previous trial without cyclophosphamide and celecoxib; however, results cannot be solely attributed to the action of celecoxib. Additionally, a case series of 27 patients with incurable metastatic melanoma who received celecoxib treatment obtained spontaneous regression.Regarding melanoma, COX-2 is expressed in malignant melanomas and is correlated with its development and progression. The primary outcome of this study found that 52.2% of participants at 12 weeks confirmed complete response (CR) or partial response (PR) of melanoma per the Response Evaluation Criteria in Solid Tumors (RECIST).A recent phase II clinical trial evaluated the antiproliferative potential of oral aspirin associated with programmed cell death protein 1 (PD-1) or pembrolizumab and cytotoxic T-lymphocyte-associated protein 4 (CTLA4) or ipilimumab inhibitors in patients with unresectable stage III or stage IV melanoma2 (PGE2) and activates adenosine monophosphate-activated protein kinase (AMPK) to inhibit colony formation, cell motility, and pigmentation while also reducing growth in some melanoma tumors in vivo. Clinical trials are warranted, which evaluate the ability of COX-2 inhibitors and NSAIDs as the sole therapeutic in order to determine their chemopreventive value in human subjects with both NMSCs and melanoma.Aspirin is a nonselective NSAID that suppresses prostaglandin EThe use of COX-2 inhibitors in immunosuppressed OTR populations poses potential risks regarding their negative effect on kidney graft and cardiovascular functions. Still, topical preparations of COX-2 inhibitors may be beneficial with no risk. Further research is warranted on cyclooxygenase chemoprevention in these populations. A summary of COX-2 trials can be found in . Concerning cancer development, retinoids act at the nuclear level to cause growth arrest and apoptosis in rapidly dividing tumor cells. They also promote immune surveillance and are involved in the maturation of keratinocytes, and topical administration generates thickening of the skin. One derivative of retinol, tretinoin, has been used topically for the treatment of AK. Studies have found significant decreases in AK lesions and sizes of lesions upon treatment with retinol,48.Retinol, also known as Vitamin A, is a fat-soluble vitamin essential to many biological processes. Its use in skin aging is prominent as its topical application promotes dermal collagen synthesis, prevents the degradation of collagen, and inhibits UV-induced matrix metalloproteinases, which are enzymes that mediate extracellular matrix degradation.It has been suggested that isotretinoin, a retinoid derivative commonly used to treat cystic acne, is the most effective retinoid for preventing NMSC in high-risk patients in clinical trials,49. Another study of 719 subjects with BCC or SCC were administered retinol, isotretinoin, or placebo, and no differences in new NMSC development or tumor multiplicity were found. A multicenter clinical trial on subjects with two or more BCCs was administered low doses of isotretinoin and also yielded no significant results. In this trial, not only was isotretinoin ineffective in reducing the number of BCCs, but treatment was also correlated with significant systemic adverse effects. It has been suggested that these studies indicate that retinoids are more effective in the early stages of skin carcinogenesis, rather than in high-risk patients with multiple previous NMSCs or more progressed diseases. However, when patients with the inherited disease xeroderma pigmentosum were administered isotretinoin, a rapid and significant reduction in the incidence of new skin cancers was observed.A positive chemoprevention trial on NMSCs involving retinol administration was conducted with 2297 subjects with moderate to severe AKs. Administration of oral retinol  significantly reduced squamous cell carcinomas but not basal cell carcinomas. Subjects were randomized to a placebo or acitretin 25 mg orally five days/week with outcomes of the rate of new NMSC development. The resulting data did not have a statistically significant reduction in the rate of new primary NMSCs of treated subjects. However, umbrella testing indicated a significant trend favoring acitretin for the incidence of new NMSC, time to new NMSC, and total NMSC counts. These results were suggested to have been the result of low statistical power.Acitretin, another vitamin A derivative, has been proposed for chemoprevention. A prospective, randomized, double-blind trial tested skin cancer prevention effects of a 2-year treatment with acitretin on 70 patients with a history of more than 2 NMSCs within five years of trial onset. Systemic retinoid use has reduced the appearance of AKs and SCC development risk in the immunocompetent population. Similar studies in transplant subjects have yielded reductions in AKs, but there is no clear consensus on whether it prevents SCC development. Multiple trials have generated contrasting results on whether different retinoid therapeutics significantly affect incidences of SCC in transplant populations–56. However, the use of retinoids as chemopreventive agents after transplantation is recommended in those at high risk for NMSC development, as there have been multiple trials and studies supporting the notion that retinoids such as acitretin and etretinate show favorable results for chemoprevention in high-risk organ transplant recipients (OTRs). An open randomized crossover trial evaluating the efficacy of acitretin for NMSC chemoprevention in renal allograft recipients was performed on a cohort of 23 patients. After the first year of drug-free evaluation, subjects were given 25 mg of acitretin daily for one year and the number of SCCs in patients while on acitretin was significantly reduced compared to the drug-free period. A similar trend was exhibited in BCCs; however, it was not significant. Of note is the toleration of this medication for this trial in that 9 of the participants withdrew from the trial due to adverse effects from this medication. Further evaluation is needed to assess the plausibility of long-term, frequent dosing regimens with these derivatives and whether alternating days of dosage or drug holidays could yield higher tolerability.In special populations of solid organ transplant recipients, retinoids have been identified to be protective in the development of NMSC. Adverse effects reported from long-term administration of certain derivatives include increased mucositis and skin toxicities. Additionally, a rebound effect has been observed in the frequency of skin cancers upon discontinuation of systemic retinoids, thus necessitating long-term treatment with strict adherence. A summary of retinoid trials can be found in Drawbacks to retinoid use include teratogenicity and the necessity for long-term treatment. These agents are highly teratogenic because women must wait up to two years after discontinuing certain oral retinoid medications before considering pregnancy. Polyamines are crucial to cell growth, proliferation, and tumor promotion when dysregulated. Epithelial carcinogenesis of skin, breast, and colon tissue has been linked to levels of polyamines. Further, studies show that many tumor promoters increase ODC activity and a number of preneoplastic conditions and tumor samples show high levels of ODC, suggesting that ODC may act as an oncogene. Under this rationale, DFMO has been reported as a possible chemopreventive agent due to its inhibition of this enzyme.DFMO is an irreversible inhibitor of ODC, an enzyme essential in polyamine biosynthesis and the production of amino acids. ODC activity increases in UV-medicated skin carcinogenesis observed in vitro. Multiple studies have proven ODC to be a molecular target for the chemoprevention of both SCCs and BCCs in experimental animals,63. Adverse effects of these medications include their associations with dose-dependent hearing loss, although a clinical trial found it to be well tolerated with evidence of mild ototoxicity,65.DFMO effectively reduces actinic keratoses and basal cell carcinomas in immunocompetent populations. In Another phase II trial, topical DFMO reduced AK number, suppressed polyamines, and reduced p53 proteins. The combination of topical diclofenac, an NSAID, and topical DFMO has demonstrated efficacy in chemoprevention ability for SCCs.Multiple clinical trials have been performed, supporting the validity of DFMO as one of the leading agents for chemoprevention. A randomized, placebo-controlled phase IIb trial found DFMO to reduce skin polyamine concentrations by 21%, as well as the total number of AKs on the forearms of patients with at least ten distinct AKs. 291 participants with a history of NMSCs were randomized to placebo or oral DFMO for 4–5 years. The primary endpoint, new NMSCs, was not significantly different between subjects taking DFMO and placebo. While there were no significant differences in squamous cell carcinomas between groups, there was a substantial decrease in new basal cell carcinomas among the treated arm. These results may be because the Hedgehog signaling pathway is essential to basal cell carcinogenesis. DFMO also reduces mRNA expression of sonic hedgehog and glioma-associated transcription factors,65. Conclusions of this trial lend interest to the plausibility that sensitivities to ODC inhibition vary between squamous and basal cell carcinogenesis.In 2010, subjects with a history of skin cancer were enrolled in a phase III clinical trial with daily administration of oral DFMO. Polyamine levels did not vary significantly between the groups or from levels before the study. COX-2 expression did decrease over time, but did not vary significantly between the groups. The results of this study hypothesized that diclofenac and DFMO might also affect COX-2 levels with cross-talk between the polyamine and COX-2 pathways. This trial was limited in its lack of a placebo arm. The combination of DFMO and NSAIDs are effective in cancer prevention at other sites, such as colonic adenomas, and further trials are warranted to address the efficacy of this combination,68.One clinical trial enrolled 159 subjects and randomized them to 90 days of topical DFMO, topical diclofenac (an NSAID), or both medicationset al. conducted a phase I trial of 18 subjects to investigate DFMO on skin polyamine levels and TPA-induced ODC toxicity. Significant inhibition of ODC activity was achieved, and polyamine levels were suppressed, suggesting that DFMO might be an effective chemopreventive agent in skin cancer for transplant recipients. However, trials in these populations are needed to further explore its safety and efficacy. A summary of DFMO trials can be found in In OTR populations, Carbone . Epigallocatechin-3-gallate (EGCG) is an active antioxidant, serving as the most abundant polyphenol. With its anti-inflammatory potential, EGCG has also been correlated with suppression of the COX and lipoxygenase pathway, commonly targeted by other chemopreventive agents.The transcription factor activated protein-1 (AP-1) is another important player in pathways of skin cancer development, and its activation leads to UV-induced tumor production. Compounds that target this transduction pathway have been tested as chemopreventive agents, such as green tea polyphenols. These formulations have antioxidant properties, and epidemiologic studies have illustrated associations between green tea consumption and decreased risk of cancer developmentIn vivo mice, studies of topical application with this compound found significant reductions in the multiplicity and volume of UV-induced skin tumors with no visible toxicity or loss of UV-induced immunosuppression. Regarding the AP-1 pathway, investigations have observed that EGCG significantly inhibits AP-1 transcriptional activation in HCL14 keratinocytes. Similar results in human keratinocyte cell lines showed EGCG inhibition of UVB-induced activation of AP-1. It has also been hypothesized that EGCG downregulates inflammasome and nuclear factor (NF)-kB activity and even abolishes tumor necrosis factor receptor-associated factor 6 (TRAF6) activity in melanoma by preventing migration and invasion of cells,75.Inhibition of human tumor cell line growth has been demonstrated by EGCG, even in melanoma. . However, a recent single-blind clinical trial of 50 healthy adults who had supplementation of oral green tea extract with vitamin C did not have a significant reduction in skin erythema or leukocyte infiltration. An area of disagreement arises when assessing the efficacy of oral versus topical EGCG. Outcomes in mice have shown that tumor-reducing outcomes were obtained by topical EGCG, but oral formulations were ineffective. Hypotheses for this result are due to inadequate EGCG supplies in the skin following oral ingestion. Clinical trials have been tested using EGCG as a chemopreventive agent. In a double-blind phase II clinical trial, 51 volunteers with AK were given topical EGCG for a 12-week period. No significant differences among treatment and placebo groups were found for the prevention of NMSCs, possibly due to poor bioavailability and lack of activity in the formulation.Few clinical trials have assessed the therapeutic chemopreventive abilities of EGCG. One study in human subjects found that topical green tea polyphenols confirmed their protective activities against UV-induced erythema. In addition to EGCG, they include (6)-gingerol, caffeic acid phenethyl ester, capsaicin, curcumin, eugenol, caffeic acid, genistein, luteolin, silymarin/silibinin, resveratrol, ursolic acid, allyl sulfides, and indole-3-carbinol. Their targets include various pathways leading to tumor formation, including oncogenes, oxidative stress, and UV radiation damage. Another naturally occurring agent in soil called selenium has antioxidant properties and has shown chemoprotective effects when used in mice with UV-induced melanoma. Similar to polyphenol efficacy in skin cancer prevention via the UVB/AP-1 signal transduction pathway, a monoterpene derived from fruits and vegetables called perillyl alcohol blocks it as well. This compound inhibits UVB-induced AP-1 transcriptional activation and tumorigenesis when applied topically to mice. Other agents exerting effects on the AP-1 signaling pathway include salicylates blocking the MAPK cascade, and several synthetic retinoids.Many other phytochemicals have been studied in vitro and pose potential benefits for application to human skin cancer models. These agents are biologically active compounds derived from herbal products and plants, are highly tolerated, and are cost-effective. While no clinical trials have been completed on these remaining compounds in humans with skin cancer, they provide a promising outlook for the future of chemoprevention. A summary of phytochemical trials can be found in Recognized limitations to phytochemicals in skin cancer include formulation and delivery for optimal bioavailability, adverse effects, and lack of evidence for the recommendation for their use in preventing cutaneous malignancies5-FU is an antimetabolite drug widely used for cancer treatments, particularly colorectal cancer. Thymidylate synthase is an active enzyme in forming thymidine nucleotides in cancer cell DNA. 5-FU exerts its effects via thymidylate synthase inhibition and incorporation of its metabolites into RNA and DNA. 5-FU has been suggested to treat actinic keratosis and types of basal cell carcinomas. However, for chemoprevention purposes, a large clinical trial demonstrated the ability of 5-FU to prevent the development of squamous cell carcinomas.. This trial was a randomized, double-blind, placebo-controlled trial of topical fluorouracil for chemoprevention of keratinocyte carcinomas (KC), also known as NMSC, in 932 subjects with a history of at least 2 KCs in the past five years. Application of fluorouracil (5%) or vehicle control cream on the face and ears twice daily for 2–4 weeks was assigned upon randomization. No difference was found between treatment groups in time to a first keratinocyte, basal cell, or squamous cell carcinoma. However, during the first year of the study, 5 participants (1%) in the fluorouracil group developed squamous cell carcinoma vs. 20 (4%) in the control group, yielding a 75% risk reduction. There were no significant effects on basal cell carcinoma risk reduction or keratinocyte carcinoma risks. Conclusions of this study lend rationale that fluorouracil substantially reduces surgery for squamous cell carcinomas for one year on the face and ears, and a reduction in KC was observed.The Veterans Affairs Keratinocyte Carcinoma chemoprevention Trial is a high-impact trial that has frequently been referred to in the literature. Topical administration consisting of 0.005% calcipotriol ointment and 5% 5-FU cream was found to suppress skin cancer development and reduce the number of AKs by 87.7% in the treatment group versus 26.3% in the control group. This trial concluded that this combination optimally activated CD4+ T cell-mediated immunity against actinic keratoses and, potentially, skin cancer.Synergistic effects of calcipotriol, a topical thymic stromal lymphopoietin inducer, and 5-FU were assessed in a randomized, double-blind trial with 131 subjects. A summary of 5-FU trials can be found in In immunosuppressed populations, capecitabine, a pro-drug for 5-FU, was tested at low doses in solid transplant recipients and found incidences of SCCs and AKs to be significantly reduced with manageable toxicityRecent advances in clinical trials and investigations lend interest to the efficacy of chemopreventive interventions as future pharmaceuticals for the prevention of skin cancer in high-risk populations. With the increased understanding of the pathophysiology of cutaneous malignancy development, molecular markers continue to be identified as targets in these pathways. Limitations to this review include the possibility that our literature search did not encompass all relevant trials and studies related to chemoprevention in skin cancer in recent years. Clinical trial identification numbers were not available for all trials mentioned in the review as some were international studies, older trials, or we could not locate the trial number. Additionally, data from ongoing or recently completed clinical trials are not yet available and may yield new findings that are not reported in this review. The lack of concrete evidence for chemopreventive abilities of many proposed agents hinders the ability to draw strong conclusions about their efficacy.The chemoprevention efforts aimed at skin cancer are complex; future trials will be instrumental in identifying therapeutic agents that pose efficacy in halting cancer development while also being tolerable for long-term administration. There have been limited trials assessing chemoprevention in both melanoma and skin cancer in solid organ transplant immunosuppressed patients, and more are needed in this cohort to prevent skin cancer mortality in these populations.


The decellularized extracellular matrix (dECM) is capable of promoting stem cell proliferation, migration, adhesion, and differentiation. It is a promising biomaterial for application and clinical translation in the field of periodontal tissue engineering as it most effectively preserves the complex array of ECM components as they are in native tissue, providing ideal cues for regeneration and repair of damaged periodontal tissue. dECMs of different origins have different advantages and characteristics in promoting the regeneration of periodontal tissue. dECM can be used directly or dissolved in liquid for better flowability. Multiple ways were developed to improve the mechanical strength of dECM, such as functionalized scaffolds with cells that harvest scaffold-supported dECM through decellularization or crosslinked soluble dECM that can form injectable hydrogels for periodontal tissue repair. dECM has found recent success in many periodontal regeneration and repair therapies. This review focuses on the repairing effect of dECM in periodontal tissue engineering, with variations in cell/tissue sources, and specifically discusses the future trend of periodontal regeneration and the future role of soluble dECM in entire periodontal tissue regeneration. Decellularized extracellular matrix (dECM) is a promising biomaterial for repairing periodontal defects since dECM maximizes the retention of complex protein arrays, glycosaminoglycans, proteoglycans, and many other matrix components found in natural tissues . TherefoPeriodontal defects caused by periodontitis, trauma, and tumors often result in the destruction of alveolar bone, periodontal membrane, and cementum. The current clinical treatment methods include basic treatment of periodontal disease, periodontal surgery, and guiding tissue regeneration, but their efficacy is often not ideal, and the orderly structure and the height of alveolar bone cannot be regenerated . SeveralTo the contrary, natural ECM contains useful structural and biochemical information, providing sufficient bioactive cues to trigger cell functions needed for tissue regeneration. The decellularized scaffold derived from naturally occurring tissues or cultured cells maintains a natural 3D network structure and can serve as a natural scaffold. Moreover, a dECM scaffold conserves natural ECM components such as glycosaminoglycans, proteoglycans, and growth factors and could, in return, moderate immune reactions, modulate inflammatory processes, impact periodontal-related stem cell behaviors and fates, and promote periodontal regeneration. Since the complexity of periodontal tissue and tissue-specific ECM with biological cues aimed at regeneration of certain tissue , it is important to provide different regenerative niches for the recruitment and modulation of endogenous stem cells for both cementum, periodontium, and alveolar bone tissue regeneration . Nevertheless, advanced manufacturing techniques such as 3D printing and electrospinning have been applied to fabricate dECM-based materials/scaffolds that could mimic the unique features of periodontal tissues recently. Consequently, the dECM application form is broadened, and the clinical translation of dECM-based materials is promoted in the field of periodontal regeneration. Therefore, dECM is a vital source of bioactive material for triggering the repair of periodontal tissue and regeneration of the periodontium.As a promising biomaterial, dECM has been widely applied in periodontal tissue engineering. Natural ECM generated from decellularized ECM (dECM) can be divided into two groups as decellularized cells/cell sheets (C-dECM) or decellularized tissue-specific ECM (T-dECM) according to the origins.Significant efforts have been made to improve the quality and efficiency of the generation of cell-derived ECM with 3D structure. Part of these works involve harvesting cell-derived dECM membranes and then fabricating a 3D scaffold using various physical and chemical techniques . As showIn recent years, scientists have applied certain decellularized cell sheets to periodontal regeneration. Decellularized cell sheet techniques refer to the effective removal of cellular and nuclear components of the cell sheet, especially DNA and RNA, while retaining the basic components, biological activity, and mechanical integrity of the extracellular matrix (dECM) of the sheet. Due to the lack of cells and major tissue structure, the foreign body reaction and immune rejection are significantly reduced or even absent in the cell sheet-derived dECM material, while the original three-dimensional structure, mechanical integrity, biological activity, and good biocompatibility are well preserved. Therefore, the use of decellularized sheets in regenerative medicine is increasing. Moreover, decellularized membrane sheets combined with cytokines or new materials to achieve better tissue regeneration effects have been used in many tissue regeneration processes, such as dental tissue regeneration , bone re(1)Periodontal ligament (stem) cell sheetsThe biological properties of human periodontal membranes were evaluated in vitro by Jiang et al. . Decellu(2)BMC/BMSC sheet:The 14-day BMSC sheets cultured in vitro significantly promoted osteogenesis of bone marrow stem cells compared with counterparts by Xu et al. Proteomic analysis showed that the extracellular matrix components of the cell sheet varied over time. Type IV collagen chains in 14-day dECM were higher than those in other membranes and more able to promote osteogenic differentiation of BMSCs . Type IV(3)Urogenic mesenchymal (stem) cell sheets:Yang et al. found that the conditioned medium of hUMSC contained components that could promote cementum differentiation . Xiong eMany studies have raised the question of whether dECM derived from different cell types has different effects on cell growth. Hoshiba et al. studied dECM extracted chemically or enzymatically from chondrocytes produced from chondrocytes, fibroblasts, and bone marrow mesenchymal stem cells and investigated their effects on articular chondrocyte behavior . ECM derThe C-dECM, with several unique benefits, has attracted considerable interest . C-dECMsAlthough C-dECMs could help to provide a microenvironment with the help of omplicated manufacturing for relative tissue regeneration, reconstructing the natural 3D architecture of the whole organ or tissue in the laboratory is now unrealistic . Therefore, C-dECM couldn’t perfectly mimic the sophisticated ECM structure and interior architecture, such as the porous structure and the collagen fiber arrangement, which might have an effect on cell adhesion, proliferation, and differentiation . FurtherDespite the similar ECM composition between different tissues and organs, subtle differences in function, proportion, structure, and stiffness of the ECM can influence the interaction of cells in determining cell fate . Tissue (1)Dental -related human tissues derived dECMTo achieve the goal of complete periodontal regeneration, many studies have evaluated the effectiveness of decellularized tissue derived from human tooth-related tissue for tissue engineering. Hyoju Son et al.  applied The human tooth dECM has also been demonstrated to promote the differentiation of PDLSC, as proved by Ik-Hwan Kim et al. . The cemAs for the complicated composition of different human-derived tissues dECM and the related functions, they vary from type to type. Dental tissue engineering approaches make it easier to solve this problem with dECM constructs generated from tissues derived from the same origin as extraembryonic mesoderm, which are believed to have more bioactive molecules naturally. Dental-derived tissue dECM has been widely used to promote dental tissue repair and has achieved great success ,33,34.(2)Non-dental-related tissue-derived dECMa.Human amnion dECMDecellularized human amnion has been adopted as a soft tissue replacement and a delivery system for stem cells. Dilcele Silva Moreira Dziedzic et al. applied the decellularized amnion infiltrated by adipose mesenchymal stem cells (ADSCs) with mineralized extracellular matrix to a rat periodontal root bifurcation lesion model . After bb.Human umbilical vein dECMAllogenic “scaffolds” derived from the human umbilical veins (HUVs) were fabricated, and the biological and mechanical properties during early remodeling events were examined. Human umbilical vein-derived dECM harvested by the osmotic lysis method displayed increased cellular proliferation and reduced metabolic activity compared to HUVs treated with surfactant. Biomechanical properties were largely preserved and similar when subjected to different treatments, and the results suggest that by optimizing processing conditions, biological events associated with remodeling can be modulated to tailor function for specific clinical applications. 3D dECM derived from the HUVs has potential for functioning as a regenerative matrix for tissue regeneration with ideal biomechanical properties . Allogen(1)Heterogenous dental -related tissues derived from dECMa.Decellularized porcine dental matrixHan et al.  treated b.Decellularized matrix of dog periodontal ligamentThe effect of dog periodontal acellular matrix on periodontal healing was evaluated by Lee et al. . The manc.Decellularized rat mandible matrixNaoko Nakamura et al.  prepared(2)Heterogenous, non-dental-related tissue-derived dECMSolid dECM from non-dental-related tissue sources has recently been studied for periodontal defect regeneration due to its rich resources, economic benefit, massive production, and usually harvesting from discarded tissue, such as treated porcine small intestinal submucosa (SIS) and the extracellular matrix of amnion and pericardium.a.SIS SIS is one of the most commonly used decellularized tissues, with good potential for soft tissue repair and regeneration, but it lacks sufficient mechanical properties to guide bone tissue regeneration unless properly modified. Gu et al. used the pig small intestinal submucosal tissue as a biological collagen membrane for guiding tissue regeneration . In the b.Decellularized AmnionDecellularized Amnion is of great biocompatibility and can maintain original tissue structure, support cell attachment, cell infiltration, bone deposition, and periodontal regeneration . The amnc.Decellularized pericardiumSerena Bianchi et al. introduced the decellularized bovine pericardium as a membrane material loading PDLSCs . The decThe porcine pericardium ,50 is ald.To sum up, decellularization of natural tissues to produce extracellular matrix is a promising method for 3D scaffolding and for investigating cell-ECM interaction during regeneration of target tissue . The fatCurrently, there are many studies using different types of dECM for periodontal treatment, including solid-state dECM for the treatment of periodontal defects and soluble dECM-derived materials such as injectable dECM hydrogels. Solid-state dECM has the advantage of accessibility, mechanical strength, preservation of ECM structure and components, and ease of handling compared with soluble dECM. While soluble dECM material is easier to modify into different shapes adapted to the defect area, such as through 3D printing, and could be used in minimal injury treatment such as hydrogel injection. Previous studies used to focus on the application of solid-state C-dECM and T-dECM, and solid tissue has a natural advantage in the recellularization of cell seeds with more well-preserved dECM components, while dECM bioink with ideal flowability and viscosity makes it applicable to encapsulate seed cells directly. Therefore, the adoption of dECM in different states of periodontal tissue depends on the purpose and characteristics needed.Solid-state dECM functioned as a “scaffold” that underwent decellularization and was used directly as a biomaterial without further disrupting the dECM microstructure. Solid-state dECMs can be classified according to the mode of application. These include acellular membrane sheets, dECM patches/sheets, and the whole periodontal tissue. Soluble dECM is a material that has been decellularized; it then takes additional steps to resolve the extracellular matrix structure and dissolve the dECM into a liquid form. Soluble materials can be classified according to recombinant or application methods, including powders, microdroplets, injectable hydrogels, 2D and 3D hydrogels, and periodontal regeneration modules consisting of soluble dECM and other biomaterials. This review will focus on the different types of dECM in the context of periodontal regenerative applications with tissue and species sources and discuss in detail advances in the development, in vitro studies, in vivo implementation, and clinical translation of solid and soluble dECM.This section focuses on solid-state dECM stents, which do not dissolve into dECM powder or liquid and are used directly after decellularization. This approach preserves the native tissue architecture in the process of expressing the dECM component at its tissue-specific location. Therapies using this solid decellularization approach focus on either directly using the material as a solid-state module or membrane material or on trying to recellularize the dECM and develop into functionalized tissue .To evaluate the effects of dECMs with different physiochemical characteristics and biological components on cell behavior and tissue repair in periodontal regeneration, many researchers have applied dECMs to promote the regeneration of periodontal tissue. In addition to the direct application of the above cell- and tissue-derived ECM, it is common to combine solid decellularized extracellular matrix with biomaterials, chemicals, cytokines, and other biological cues to improve their physicochemical properties. dECM has been constructed in vitro or harvested from decellularized tissue, and it has been combined with various modification methods to establish tissue engineering constructs that meet the needs for periodontal regeneration.(1)Direct application of pure dECMCell- and tissue-derived dECM, with the ideal composition, structure, and mechanical properties of the extracellular matrix after cellular components are removed, is usually in a sheet-shape or block mass and has been directly used to fill the periodontal defect area in the application practices of periodontium reconstruction, cementum regeneration, and bone tissue engineering.Cell-derived dECM could be harvested from rich cell types and could easily get a great amount of dECM satisfying the application need. Pre-osteoblast (MC3T3-E1 cell sheet)-derived matrix was found to exhibit considerable chemotactic effect and osteogenic induction capability to bone marrow mesenchymal stem cells (BMSCs) . MoreoveIn addition, the further treatment of decellularized tissue to make it meet the application needs of periodontal tissue engineering is also a problem that scientists try to solve. The most commonly used decellularized tissue in periodontal regeneration is decellularized bone ,58. BoneOther shapes of 3D cell-derived dECMs with spatial structure that depend on polymers such as poly (lactic-hydroxylactic acid) (PLGA) and polylactic acid (PLA) as expendable templates have also been developed. In these cases, cells are directly seeded onto the template surface, which in turn stimulates ECM deposition to form a cell-ECM-template structure. Decellularized methods are being used, and the polymer template will be removed by chemical reagents, leaving only cell-derived dECM scaffolds with three-dimensional shapes. With a spatially structured cell-derived dECM-laden scaffold, exhibiting a mild host immune response and good biocompatibility when in vivo.(2)dECM-based hybrid scaffoldSimilar to three-dimensional cell-derived dECM scaffolds with specific spatial structures, a novel cell-derived ECM hybrid scaffold was generated by covering the template surface with cell-derived ECM and then retaining the template, making these templates biologically active. The surface bioactivity of the mixed scaffolds provides greater control of cell fate for more beneficial interactions between cells and biomaterials. Furthermore, cell-derived ECM hybrid scaffolds with stronger mechanical properties than tissue or cell-derived ECM products lessen the applications of dECM quantity and improve efficacy in tissue engineering, particularly those associated with bone tissue engineering, which are believed to have a strong correlation of extracellular stiffness.Farag et al. constructed tissue-engineered composite constructs by loading PDLSCs on a polycaprolactone scaffold and then decellularizing them. The effects of tissue-engineered constructs on differentiation of allogeneic PDLSCs and other MSCs were assessed by gene expression of bone markers and periodontal ligament markers after cell seeding, confirming that the decellularized hybrid tissue-engineered constructs were able to induce cell differentiation in vitro . PolycapGu et al. modified the porcine SIS by EGCG crosslinking, which increased the SIS to four layers, greatly improving its mechanical strength. The EGCG crosslinking significantly improved the mechanical properties and hydrophilicity of the submucosa of decellularized SIS while maintaining good cell affinity. In contrast to decellularized pig small intestinal submucosa, EGCG cross-linked decellularized pig small intestinal submucosa enhances adhesion of fibroblasts and pre-osteoblast cells and promotes osteogenic differentiation of MC3T3-E1 cells. In the rat cranial defect model, the crosslinked material had a better occlusion effect and accelerated bone regeneration, acting as a promising guiding tissue regeneration membrane material .At present, there are many studies to modify dECM-based materials combined with other cytokines, immune regulators, anti-inflammatory components, and antibacterial materials to construct a tissue-engineered periodontal regeneration module. For example, deoxyprostaglandin nanoparticles were found to be anti-inflammatory and improve regeneration by Jiang et al. . Cytokin® supported by an acellular amniotic membrane induced more CM and PDL than the polymer scaffold group, according to Khorsand et al. [Recellularization/stem cell homing promoted or mediated by dECM-based materials count for a great deal in periodontal tissue repair. On the one hand, dECM with biological cues serves as a tissue engineering construct that could promote stem cell homing. On the other hand, dECM-based material serves as a vehicle laden with a great amount of tailored stem cells to provide the defect area with a greater amount of stem cells and a more active cell-ECM reaction in periodontal tissue regeneration in the first place . For exad et al. .To sum up, there has been established a shared set of rules for solid state decellularized material in periodontology. The methodology of dECM materials relies on application need and has seen great success in promoting periodontal tissue repair and reconstruction. However, with the development of advanced manufacturing techniques, more and more scientists focus on the integration , cell-laden ability (flowability and solubility), and minimally invasive effect (injectable and phase change) of tissue engineering constructs for periodontal regeneration. Therefore, some scientists found a solution to improving the properties of dECM with the invention of soluble dECM.This section focuses on soluble dECMs, which prepares solid dECM into dECM powder or dissolved into a liquid. This approach both retains the natural ECM structure and increases its flowability. Treatments using this dECM method for periodontal tissue engineering mainly include minimally invasive hydrogel injection therapy, light-curing hydrogel synthesis, and 3D-printed bioink manufacturing.The lysis method is based on porcine SIS dECM, which was first developed by Freytes et al. in 2008 and shortly followed by dissolved dECM ,38 by SiSoluble dECM is usually used in dental-derived dECM, such as porcine pulp dECM, dog periodontal membrane dECM, and even human dental capsule dECM. However, non-dental dECM, such as porcine SIS, acellular amnion, etc., needs to increase additional biological signals to promote periodontal regeneration, such as fibroblast growth factor , platele(1)Grinded dECM powder/granuleGrinded and partially dissolved dECM has been used directly for tissue engineering applications. This may be due to the fact that granular dECM could contain more repair components than fully dissolved dECM. Grinded dECM powder can be partially dissolved in solution or resuspended to form a suspension for the injection without complete dissolution ,68, whicThese methods rely on direct injection of partially dissolved dECM powder or dECM microparticles. For example, partially digested adipose tissue dECM powder has been used as an injectable material for adipose tissue engineering. In in vitro studies, dECM powder can very effectively promote cell attachment and proliferation . Thus, h(2)Nanoparticles/microdropletsGrinding particles vary greatly in size and cannot be fully dissolved, which affects the homogeneity of dECM materials and impacts the therapeutic effect. To obtain dECM particles with more bioactive characteristics as nanomaterials while preserving the regenerative effect, the dECM solution could be electrosprayed into nanoparticles. A method for homogeneous dECM nanoparticles was developed by Link et al. . The gro(3)HydrogelECM-derived hydrogels remove cellular components and DNA, retain sGAG and other ECM proteins, such as collagen, gel at physiological temperature and pH, and have nanofiber structure .a.2D coating and hydrogelThe platform of dECM-based scaffolds via 2D coating or hydrogel systems provides an excellent method to assess cellular responses to different dECM, allowing high-throughput analysis and evaluation of rare or inaccessible pathological parameters of dECM ,78. TissHere, we expect that the use of extracellular matrix hydrogels derived from decellularized tissues/cells can provide an environment capable of directing cell growth. These gels have biochemical features of the tissue-specific extracellular matrix and have the potential for clinical translation. For example, hydrogels from the porcine SIS dECM can enable the formation and growth of endoderm-derived human organs, such as the stomach, liver, and pancreas ,54,70. Fb.3D hydrogelIn clinical practice, cells are exposed to a 3D environment. Hydrogels with a specific spatial structure may significantly alter the cell properties and the repairing potential compared to a 2D model. In the application of 3D bio-printed tissue engineering modules to promote periodontal regeneration, compared to purely injectable dECM materials, preparing spatially-stable dECM hydrogel is challenging due to its soft mechanical properties and process difficulties. 3D printing technology is a useful method, and Seung Hyeon Hwang et al. prepared scaffolds with a three-layer dECM hydrogel patch with spatial segmentation, providing controlled release of multiple growth factors and inducing good neovascularization for tissue regeneration .Extruded 3D bioprinting relies on structurally supported bioink layers stacking on each other, requiring high-viscosity solutions for proper printing and scaffold fabrication . At the Moreover, 3D hydrogel could support 3D printing of periodontal regeneration constructs . Yang etTherefore, 3D ECM hydrogel has been viewed as a customized scaffold with promising characteristics  for threEntire periodontal tissue engineering has been a shared goal of scientists aiming for periodontal regeneration. However, most of the research addressing the periodontal defect focuses on alveolar bone regeneration , even foWith the development of soluble dECM, 3D printing and other advanced fabrication techniques have helped improve the fidelity and strength of dECM-based 3D scaffolds , focusinTo sum up , given tIt has been shown that dECM is a complex material composed of a variety of key components associated with regeneration that can regulate cellular responses and thereby activate the body’s process of tissue repair. The combination of dECM materials and tissue engineering methods plays an important role in the treatment of periodontal defects regeneration caused by periodontal diseases. The fabrication and in vitro analysis of dECM (solid dECM and soluble dECM) of various tissue origins are prerequisites for applications. The dECM can be generated and improved by a variety of methods, and complex periodontal regeneration modules based on the dECM were recently developed ,48,55,87In vitro and in vivo studies on the treatment of periodontal defects have shown that both solid and injectable dECM therapies have a regenerative effect, and dECM materials such as decellularized bone powder  have entered clinical use for the treatment of human periodontal diseases. Various other therapies using dECM materials and their derivative materials, stem cells, and/or cytokines also attract great attention. Periodontal treatment based on dECM is not limited to solid state dECM as periodontal guide tissue regeneration (membrane) material, but more focuses on the role of solid or soluble dECM as a potential tissue engineering scaffold to simulate the in vivo microenvironment, determine stem cell fate, and promote tissue regeneration. Over the past decade, as dECM hydrogels are gradually developed, more and more studies have overcome defects in nature’s dECM physical properties, clarified the biological effects of dECM, and are going to guide the next generation of periodontal regeneration.Complete periodontal tissue regeneration was the ultimate purpose of periodontal regeneration. However, there remain challenges in achieving complete periodontal regeneration with dECM application due to the shrinkage, distortion, collapse, and lack of strength of dECM . The preRecently, a large number of scientists focused on the spatiotemporal stability of degradable scaffolds with controlled degradation speeds, which was of great interest ,105. MorHowever, although the past few decades have witnessed substantial progress in dECM developments, there remain challenges in understanding the accurate and specific key ECM proteins and the ratio of these molecules for cell proliferation and targeted cell differentiation for 3D organoid culture and tissue repair. Thus, further basic research and preclinical testing are necessary before clinical translation to better understand how the network system exerts a positive effect on stem cells and cell-ECM interaction.Moreover, given that ECM is an essential part of body tissue, cell/tissue-derived dECM preserving its structures and properties is critical for developing 3D microenvironments for tissue regeneration models for cell therapy or cell-free therapy in periodontal regeneration. Macromolecular materials such as collagen, Matrigel, and electrospun polymer membranes mimicking natural ECM structure are generic products widely used in periodontal tissue engineering. However, tissue engineering constructs for complicated periodontal tissues  need to be developed, and specialized dECM is required to be tailored for either C, P, or AB. Since different tissues have different preferences for porosity, permeability, mechanical properties, and, more importantly, biological cues of different dECMs, it is necessary to generalize the natural origin of the ECM of specific tissues of periodontal tissue or tailor an ECM with a biological effect on specific stem cells that proved to play a key role in promoting relative tissue  regeneration.


This necessitates the exploration of new approaches in drug development for central nervous system (CNS) disorders. Developing efficient CNS drugs has been recognized as highly challenging due to several reasons, including the difficulty in predicting brain penetration of drug candidates, their molecular binding to targets, and the resulting functional activation. In this context, functional neuroimaging emerges as a promising method to address these challenges by monitoring brain activity and its changes following drug administration. Technological advancements over the years have enabled the probing of brain activity at multiple spatiotemporal scales, providing valuable insights into drug effects in both living animals and humans. Functional neuroimaging offers a way to identify the most promising compounds and improve our understanding of drug mechanisms of action in pathological contexts. These contributions are illustrated by the articles selected for this Research Topic, in which pharmacological questions are addressed using different in vivo imaging at a molecular level is well-established. However, in preclinical small-animal imaging, fully quantitative PET imaging to access ligand concentration or receptor occupancy can be challenging due to limited access to radiopharmaceuticals and methodological constraints related to radiopharmacology and radioactive metabolites. Radiolabeled fluorodeoxyglucose (18F-FDG) offers a solution to these issues and provides insights into the metabolic profile and potential mode of action of pharmacological agents. Two papers in this Research Topic investigated the use of 18F-FDG as a “surrogate treatment response” marker for buprenorphine and ketamine. Soyer et al. showed that regions with the highest post-buprenorphine decrease in normalized 18F-FDG signal coincided with the regions with the highest buprenorphine binding. This study opens possibilities for detecting longitudinal and intrasubject variability in responses to opioids by measuring changes in regional brain glucose metabolism. The second paper by Chaib et al. explored longitudinal changes in 18F-FDG uptake following a single injection of a subanesthetic dose of ketamine and suggested a potential “biosignature” of ketamine-like antidepressants.PET is a highly translatable, non-invasive imaging method widely used in pharmacological research for target engagement, biodistribution, and biomarker measurements. Despite its relatively high cost, PET's contribution to neuropharmacology through Brems et al. evaluated the effects of a positive allosteric modulator of α7 nicotinic receptors, at three doses in awake rats. The authors showed a non-linear effect of the drug with maximal size of BOLD changes in numerous regions at the intermediate dose and a global decrease of functional connectivity, shedding new light on the drug's action mechanism.In a complementary manner, fMRI has been utilized for many years as a tool for deciphering the impact of drugs on brain activity. Using a drug directly as a stimulus to induce hemodynamic changes, known as “pharmaco-MRI,” allows for easy exploration of changes in the whole brain with a temporal resolution in the order of seconds. Recent advancements in fMRI have enabled imaging of awake, restrained animals, eliminating the confounding variable of anesthesia. Ionescu et al. utilized fUS to study changes in functional connectivity patterns occurring in different frequency bands after the administration of ketamine. The authors demonstrated that ketamine induced transient increases in connectivity in all frequency ranges, except for the fastest frequencies, which displayed decreased functional connectivity in corticostriatal areas. This specific effect persisted for 9 days after the beginning of the treatment.A recent neuroimaging technique, functional ultrasound imaging (fUS), relies on hemodynamics and allows the measurement of cerebral blood volume changes at high spatiotemporal resolution. Several proof-of-concept studies demonstrated its value for neuropharmacological applications. Nasretdinov et al. conducted large-scale multi-structure microelectrode local field potential (LFP) recordings in freely-moving rats treated with LSD, ketamine, or the non-hallucinogenic amphetamine. The authors primarily focused on the aperiodic part of LFP, associated with asynchronous spiking rather than synchronized currents and linked to the fMRI signal. Their findings revealed distinct brain activation patterns induced by the compounds: ketamine resulted in a substantial increase in spectral power, while LSD predominantly triggered an increase in the excitation/inhibition balance.Intracerebral electrophysiological recordings, despite being invasive and limited in their field of view, provide direct insights into the electrical activity of neurons, which are crucial for understanding psychoactive compounds. Finally, this Research Topic illustrates the dynamism of research in psychopharmacology which is evolving through the use of revisited psychotropic molecules and the integration of new exploration dimensions and experimental paradigms brought about by neuroimaging technologies. Neuroimaging, including PET, fMRI, fUS, and intracerebral electrophysiological recordings, provides valuable tools for advancing pharmacology in the CNS and improving the development of drugs for neuropsychiatric diseases.BV: Writing—original draft. LZ: Writing—review and editing.


Recent advances in the field of proteomics have allowed extensive insights into the molecular regulations of the cell proteome. Specifically, this allows researchers to dissect a multitude of signaling arrays while targeting for the discovery of novel protein signatures. These approaches based on data mining are becoming increasingly powerful for identifying both potential disease mechanisms as well as indicators for disease progression and overall survival predictive and prognostic molecular markers for cancer. Furthermore, mass spectrometry (MS) integrations satisfy the ongoing demand for in-depth biomarker validation. For the purpose of this review, we will highlight the current developments based on MS sensitivity, to place quantitative proteomics into clinical settings and provide a perspective to integrate proteomics data for future applications in cancer precision medicine. We will also discuss malignancies associated with oncogenic viruses such as Acquire Immunodeficiency Syndrome (AIDS) and suggest novel mechanisms behind this phenomenon. Human Immunodeficiency Virus type-1 (HIV-1) proteins are known to be oncogenic per se, to induce oxidative and endoplasmic reticulum stresses, and to be released from the infected or expressing cells. HIV-1 proteins can act alone or in collaboration with other known oncoproteins, which cause the bulk of malignancies in people living with HIV-1 on ART. The introduction of mass spectrometry (MS) has become more popular in recent years, making it an attractive approach to understanding the complexity of cancer-mediated signaling; as such, this has allowed the assessment of individual unique biosignature profiles ,2. SpeciProteome profiling studies have been granted the ability to reveal diverse molecular signatures and signaling pathways to monitor cancer progression and to assess the efficiency of therapeutic treatments ,5. A varLarge-scale datasets can be generated from a single proteomics analysis, which gives rise to detailed information about the biological events surrounding tumor vitality and aggressiveness ,8. HenceCancer biomarkers have transcended current treatments based on their validation and efficacy. In recent years, there have been promising advances in quantitative proteomics methodologies that play a major role in detecting novel cancer biomarkers. Quantitative proteomics operates under the principle that a signal response from any given analyte is related to its abundance within the mixture ,10. The A key aspect of the proteomics process is the preservation of the tissue samples. There are three main methods to preserve these: fresh frozen (FF) , formaliTo compare the sample effect between FF and FFPE, two studies will be discussed in which the researchers aimed to compare the performance of paired FF and FFPE tissues in both genomics and proteomics experiments, respectively. The objective of both studies was to determine which tissue type yielded better results in terms of genomic and proteomic analysis. The experiments involved obtaining paired FF and FFPE tissue samples from the same individuals to evaluate their performance. The first study to be discussed focused on examining protein retrieval in different types of kidney tissues from human biopsies . InitialIn terms of the genomic study, the researchers aimed to evaluate the feasibility and reliability of microarray studies analyzing transcriptome data from FF and FFPE tissues obtained from striatal areas of post-mortem rat brains and hippocampus biopsies from humans . The who15N and 13C labeling . Th. Th37]. Overall, tissue-based proteomics strategies have been successfully applied to many cancer types, including predominant forms such as breast, prostate, and lung . The tisProteomics-based analysis plays a fundamental role in tumor diagnostics and therapeutics by discovering potential biomarkers to detect early stages of cancer and inhibit carcinogenesis ,48. The Triple-negative breast cancer (TNBC): This is considered a more aggressive variant in comparison to other breast cancers as it lacks the expression of the usual estrogen receptors (ER), progesterone receptors (PR), or Her2/neu receptors that are usually targeted by chemotherapy treatment . W. W147]. Evidence from a growing number of studies suggests that TNBC stem cells promote metastasis by regulating the WNT, Nuclear Factor kappa B (NFκB), Notch, Signal Transducer and Activator of Transcription 3 (STAT3) and hedgehog (Hh) pathways to induce an epithelial-to-mesenchymal transitional change ,155,156.Healthy and malignant cells that are subjected to stress-inducing factors can result in the disruption of proteoforms and folding complexity. This can be attributed to endoplasmic reticulum (ER) stress . As a meCoriolus versicolor, has been known to possess anti-tumor properties as well as to modulate the immune response against patients suffering from breast and lung cancer [Interestingly, natural compounds targeting ER stress response have been designed to kill cancer cells, with molecules showing excellent curative effects See . Here, wg cancer . Particug cancer . Interesg cancer . It has g cancer . This reUltimately, we will discuss the cell cycle and its unchecked growth. Tumorigenic cells frequently suffer genomic instabilities in abnormal proliferative environments . This imAdvancements during recent decades have increasingly recognized that no two cancer types are shared within individuals. While two oncogenic disturbances may be classified clinically and pathologically as the same, the response and resistance to treatment can be completely different. Although chemotherapy and radiotherapy have been first in line in the treatment of various cancers, the complexity and heterogeneity of cancer have led to the need for a personalized and precise approach for treatment . By combWhen compared to genomics, proteomics has been advancing rapidly and with promising results, including the development of drugs that directly target pathologies at the protein level instead of the gene level, such as inhibitors of MAPK, PI3K, serine/threonine protein kinase, BRAF, VEGF, and EGFR . Drugs wQuantitative proteomic approaches coupled to personalized medicine have expanded the possibilities regarding integrating new emerging technologies that can positively impact the health modalities of the individual. Among these, nanotechnology has been shown to synergize with the use of MS-based approaches for disease progression . This isIn relation to non-AIDS-defining cancers include lung cancer, anal cancer, Hodgkin’s lymphoma, oropharyngeal cancer, hepatocellular carcinoma, vulvar cancer, penile cancer, and glioblastoma multiforme ,206,207.The signaling mechanisms pertaining to cancer progression have challenged novel integration for bioinformatic tools. As a result, cancer proteome databases have been extensively created to monitor and compile massive data for interpretation. This gives meaningful insight into cancer progression. Consequently, bioinformatics remains an indispensable tool for analyzing large-scale datasets in the most common form of protein and gene expressions. This has led to databases relating to amino acid sequences for a detailed study of the protein structures and mechanistic signaling components in cancer. In recent years, the advancements in bioinformatics have significantly increased as an integral tool for supporting therapeutic cancer treatments. Identifying new classes of molecular signatures such as alternative splicing reflects one of these advancements, which was previously unattainable . Newly sProteomics profiling is a continuously expanding field relying on the combination of current advances, both technological and analytical, to screen for and discover cancer-causing molecular signatures. These proteomics signatures and signaling including ER stress have been implicated in various cancers and provide, as such, the potential to develop effective therapies and bioinformatic resources for basic and translational research. Moreover, information on large-scale proteomics studies on clinical models with targetable approaches such as metastasis, metabolism, proliferation, cell cycle, and stress-induced responses  provide