MicroRNA-17-5p Regulation of Apoptosis-Related Protein Expressions in Oral Squam ous Cell Ca rcinoma Cells Is Related to Betel Quid Chewing

Background and purpose : Betel nut chewing is associated with oral cavity cancer in Taiwan. Radiotherapy is one of the therapeutic approaches. Our previous study demonstrated that microRNA (miR)-17-5p (one of the miR-17-92 polycistronic miRNAs) was enhanced in the irradiated OC3 cancer cell line (which was established from oral squamous cell carcinoma in a long-term betel nut chewer who did not smoke), and miR-17-5p was also found to inhibit downstream protein p21 expression and induce radiosensitivity. In this study, we used a human apoptosis protein array to clarify which apoptosis-related proteins are modulated by miR-17-5p. Materials and Methods : Total cell lysates from OC3 cells with control small interfering (si)RNA or miR-17-5p were used to analyze apoptosis-related proteins. A specific miR- 17-5p effector apoptosis-related protein was confirmed by Western blotting. To confirm the role of p53 in irradiated OC-3 cells, OC3 cells without or with a p53-overexpressing clone were irradiated and examined by propidium iodide staining and flow cytometry. Results : Using a human apoptosis protein array analysis (R&D Systems; catalog # ARY009), we simultaneously detected the relative expressions of 35 apoptosis-related proteins in OC3 cells that were treated with an miR-17-5p antisense oligonucleotide (AS-ODN) or a control ODN. Several proteins, including p21, p53, TNF RI, FADD, cIAP-1, HIF-1α, and TRAIL R1, were found to be up- or downregulated by miR-17-5p in OC3 cells; their expression patterns were also confirmed by Western blotting. We further clarified the role of p53 in irradiated OC3 cells, using a p53 overexpression strategy, and results revealed that enhancement of p53 expression significantly enhanced radiation-induced G2/M arrest of OC3 cells. Conclusions : miR-17-5p regulated the apoptosis-related proteins of p21, p53, TNF RI, FADD, cIAP-1, HIF-1α, and TRAIL R1 in OC3 cells; interestingly, its effect on p53 protein expression contributed to modulating the cell cycle arrest of OC3 cells.