RESUMO
Objective:To investigate the effects of bromodomain and extraterminal domain (BET) inhibitor JQ1 combined with siPD-L1 on the proliferation and apoptosis of oral squamous cell carcinoma (OSCC) Scc-25 cells and its mechanism.Methods:Scc-25 cells were cultured in vitro and treated with different concentrations of JQ1 (0, 0.2, 1, 5 μmol/L). Cell proliferation was detected by cell count kit-8 (CCK-8) assay; the expression levels of programmed cell death ligand 1(PD-L1) and forkhead box M1(FoxM1) protein were detected by Western blot. Appropriate concentration of JQ1 was selected for subsequent experiments. Scc-25 cells were divided into four groups: control group (without any treatment), siPD-L1 group (transfected with siPD-L1), JQ1 group (added JQ1 after transfected with non-specific siRNA), and combined treatment group (added JQ1 after transfected with siPD-L1). CCK-8 assay was used to detect the proliferation ability of Scc-25 cells in each group. Western blot was used to detect the expression levels of cleaved caspase-3, PD-L1 and FoxM1, and flow cytometry was used to detect the apoptosis rate of cells in each group. Results:With the increase of JQ1 concentration, the proliferation ability of SCC-25 cells and the expression levels of PD-L1 and FoxM1 decreased gradually (all P<0.01). JQ1 concentration of 1 μmol/L had obvious inhibitory effect on cell proliferation and the expression levels of PD-L1 and FoxM1, so JQ1 concentration of 1 μmol/L was selected for subsequent experiments. The proliferation ability of Scc-25 cells, the expression of PD-L1 and FoxM1 proteins in JQ1 group, siPD-L1 group and combination treatment group were significantly lower than those in the control group (all P<0.01), and the expression of cleaved caspase-3 protein and the rate of apoptosis were significantly higher than those in the control group (all P<0.01); Moreover, the effect of the combination treatment group was more significant than that of siPD-L1 group, JQ1 group (all P<0.01). Conclusions:The combination of JQ1 and siPD-L1 could effectively inhibit the proliferation and promotes the apoptosis of OSCC Scc-25 cells, and its mechanism may be related to the suppression of PD-L1 and FoxM1 signaling pathways.