Abstract: Objective To investigate the effect of interleukin-17A (IL-17A) on chemosensitivity of ovarian cancer cells to cisplatin (DDP) and explore the mechanism in light of autophagy regulation. Methods Ovarian cancer SKOV3 cells cultured in vitro were treated with different concentrations of DDP (1-20 μg/mL). MTT assay was used to observe the changes in proliferation of the treated cells and the effect of treatment with 100 ng/mL IL-17A for 24 h on DDP-induced apoptosis of SKOV3 cells. We then examined the expression of IL-17A receptor (IL-17RA) in SKOV3 cells using flow cytometry. Annexin V-FITC/PI double staining was used to detect the cell apoptosis rate, and early apoptosis of the cells was detected with JC-1 assay. A neutralizing monoclonal antibody (mAb) against IL-17RA was used to block IL-17RA. We also observed the effects of IL-17RA silencing mediated by a siRNA targeting IL-17RA (siRNA-IL-17RA) and treatment with 3-methyladenine (3-MA) for inhibiting autophagy on DDP-induced apoptosis of SKOV3 cells. The expressions of apoptosis-related proteins (Bcl-2, Bax, and cleaved caspase-3) and autophagy-related proteins (P62 and Beclin-1) in the treated cells were detected using Western blotting. Results DDP increased the expression of IL-17RA in ovarian cancer SKOV3 cells. Treatment with IL-17A significantly reduced the susceptibility of SKOV3 cells to cisplatin-induced apoptosis (P<0.05). DDP obviously augmented the expression of Beclin-1 and reduced the autophagy degradation substrate P62 protein in the cells (P<0.05). IL-17A/IL-17RA strongly enhanced the DDPinducted autophagy of the cells (P<0.05). Blocking autophagy with 3-MA significantly increased DDP- induced apoptosis of SKOV3 cells with IL-17RA silencing, lowered the expression of Bcl-2 and enhanced Bax expression in the cells (P<0.05). Conclusion IL-17A/IL-17RA can decrease chemosensitivity of SKOV3 cells to DDP by upregulating DDP-induced autophagy

Key words: ovarian cancer, interleukin-17A, cisplatin, autophagy, drug resistance