Identification of Novel Response and Predictive Biomarkers to Hsp90 Inhibitors Through Proteomic Profiling of Patient-derived Prostate Tumor Explants.
Inhibition of the heat shock protein 90 (Hsp90) chaperone is a promising therapeutic strategy to target expression of the androgen receptor (AR) and other oncogenic drivers in prostate cancer cells. However, identification of clinically-relevant responses and predictive biomarkers is essential to maximize efficacy and treatment personalization. Here, we combined mass spectrometry (MS)-based proteomic analyses with a unique patient-derived explant (PDE) model that retains the complex microenvironment of primary prostate tumors. Independent discovery and validation cohorts of PDEs (n = 16 and 30, respectively) were cultured in the absence or presence of Hsp90 inhibitors AUY922 or 17-AAG. PDEs were analyzed by LC-MS/MS with a hyper-reaction monitoring data independent acquisition (HRM-DIA) workflow, and differentially expressed proteins identified using repeated measure analysis of variance (ANOVA; raw p value <0.01). Using gene set enrichment, we found striking conservation of the most significantly AUY922-altered gene pathways between the discovery and validation cohorts, indicating that our experimental and analysis workflows were robust. Eight proteins were selectively altered across both cohorts by the most potent inhibitor, AUY922, including TIMP1, SERPINA3 and CYP51A (adjusted p < 0.01). The AUY922-mediated decrease in secretory TIMP1 was validated by ELISA of the PDE culture medium. We next exploited the heterogeneous response of PDEs to 17-AAG in order to detect predictive biomarkers of response and identified PCBP3 as a marker with increased expression in PDEs that had no response or increased in proliferation. Also, 17-AAG treatment led to increased expression of DNAJA1 in PDEs that exhibited a cytostatic response, revealing potential drug resistance mechanisms. This selective regulation of DNAJA1 was validated by Western blot analysis. Our study establishes "proof-of-principle" that proteomic profiling of drug-treated PDEs represents an effective and clinically-relevant strategy for identification of biomarkers that associate with certain tumor-specific responses.
['Nguyen|Elizabeth V|EV|', 'Centenera|Margaret M|MM|', 'Moldovan|Max|M|', 'Das|Rajdeep|R|', 'Irani|Swati|S|', 'Vincent|Andrew D|AD|', 'Chan|Howard|H|', 'Horvath|Lisa G|LG|', 'Lynn|David J|DJ|', 'Daly|Roger J|RJ|', 'Butler|Lisa M|LM|']
D016227:Benzoquinones D014408:Biomarkers, Tumor D049109:Cell Proliferation D015331:Cohort Studies D019008:Drug Resistance, Neoplasm D018841:HSP90 Heat-Shock Proteins D006801:Humans D007555:Isoxazoles D047029:Lactams, Macrocyclic D008297:Male D009363:Neoplasm Proteins D025341:Principal Component Analysis D011471:Prostatic Neoplasms D020543:Proteome D040901:Proteomics D015203:Reproducibility of Results D012118:Resorcinols
Hsp90 inhibitors patient-derived explants Biomarker: Diagnostic Biomarker: Prognostic Cancer therapeutics Patient cohorts Prostate cancer biomarkers Tumor microenvironment ex vivo