YWHAZ gene contributes to the radioresistance of oral squamous cell carcinoma cells

Objective To investigate the contribution of YWHAZ gene on the radioresistance and metastasis ability of oral squamous cell carcinoma (OSCC) cells. Methods The relationship between the expression level of YWHAZ gene and the survival of head and neck squamous cell carcinoma (HNSC) patients was analyzed using Gene Expression Profiling Interactive Analysis (GEPIA) database. A radioresistance cell line (CAL-27R) was constructed by irradiating CAL-27 cells with fractional doses. Cell survival was measured by colony formation assay. Cell migration and invasion were detected by transwell assay. The formation of γH2AX foci was detected by immunofluorescence assay. The protein expressions were detected by western blot assay. In some experiments, CAL-27R cells were effectively transferred with siRNA YWHAZ (siYWHAZ). Results GEPIA database showed that the expression level of YWHAZ in HNSC tumors was higher than that in adjacent normal tissues, and the HNSC patients with higher level of YWHAZ had a shorter survival. In vitro experiments demonstrated that the expression of YWHAZ protein in CAL-27 cells was lower than HSC-3 cells (t = 18.89, P﹤0.01) and radioresistant CAL-27R cells (t = 25.70, P﹤0.01). Knockdown of YWHAZ gene significantly increased radiation-induced cell killing effect, apoptosis induction, and γH2AX foci formation in CAL-27R and HSC-3 cells. Moreover, siRNA YWHAZ transfection also reduced the invasion and migration abilities of the irradiated CAL-27R [(t = 21.09, P﹤0.01 (migration); t = 6.16, P﹤0.05 (invasion)] and HSC-3 cells [(t = 34.53, P﹤0.001(migration); t = 4.92, P﹤0.05 (invasion)] and attenuated radiation-induced expressions of metastasis-related proteins. Conclusion YWHAZ contributes to the radioresistance of oral squamous cells and thus it may applicable to be a potential target for OSCC radiotherapy.