Cell death caused by quinazolinone HMJ-38 challenge in oral carcinoma CAL 27 cells: dissections of endoplasmic reticulum stress, mitochondrial dysfunction and tumor xenografts.
BACKGROUND
This investigation clearly clarified the synthesized and antimitotic compound, 2-(3'-methoxyphenyl)-6-pyrrolidinyl-4-quinazolinone (HMJ-38), addressing its target and precise mechanism of action. We hypothesized that HMJ-38 might sensitize apoptotic death of human oral carcinoma CAL 27 cells in vitro and inhibit xenograft tumor growth in vivo.


METHODS
Cell viability was assessed utilizing MTT assay. HMJ-38-treated cells represented DNA fragmentation using agarose gel electrophoresis as further evidenced using TUNEL staining. Flow cytometric analyses, immunoblotting and quantitative RT-PCR were applied for protein and gene expression. Antitumor xenograft study was employed.


RESULTS
HMJ-38 concentration- and time-dependently reduced viability of CAL 27 cells. The effect of intrinsic molecules was signalized during HMJ-38 exposure with disruption of ΔΨm, MPT pore opening and the release of various events from mitochondria undergoing cell apoptosis. HMJ-38 also markedly facilitated G2/M phase arrest. HMJ-38 stimulated the activation of CDK1 activity that modulated phosphorylation on Ser70 of Bcl-2-mediated mitotic arrest and apoptosis. HMJ-38 triggered intracellular Ca(2+) release and activated related pivotal hallmarks of ER stress. HMJ-38 in nude mice bearing CAL 27 tumor xenografts decreased tumor growth. Furthermore, HMJ-38 enhanced caspase-3 gene expression and protein level in xenotransplanted tumors.


CONCLUSIONS
Early roles of mitotic arrest, unfolded protein response and mitochondria-dependent signaling contributed to apoptotic CAL 27 cell demise induced by HMJ-38. In in vivo experiments, HMJ-38 also efficaciously suppressed tumor volume in a xenotransplantation model.


GENERAL SIGNIFICANCE
This finding might fully support a critical event for HMJ-38 via induction of apoptotic machinery and ER stress against human oral cancer cells.
['Lu|Chi-Cheng|CC|', 'Yang|Jai-Sing|JS|', 'Chiang|Jo-Hua|JH|', 'Hour|Mann-Jen|MJ|', 'Lin|Kuei-Li|KL|', 'Lee|Tsung-Han|TH|', 'Chung|Jing-Gung|JG|']
D000818:Animals D002277:Carcinoma D016923:Cell Death D045744:Cell Line, Tumor D002470:Cell Survival D059865:Endoplasmic Reticulum Stress D064593:Heterografts D006801:Humans D051379:Mice D008928:Mitochondria D009062:Mouth Neoplasms D052999:Quinazolinones D017382:Reactive Oxygen Species D015398:Signal Transduction
HMJ-38 Endoplasmic reticulum stress Mitochondrial dysfunction Tumor xenografts Human oral carcinoma cells