Expression and role of programmed cell death ligand-1 in sorafenib-resistant hepatocellular carcinoma cells / 第二军医大学学报

ABSTRACT

Objective To explore the expression and role of programmed cell death ligand-1 (PD-L1) in sorafenib-resistant human hepatocellular carcinoma cells. Methods Sorafenib-resistant human hepatocellular carcinoma cell lines (Hep3B-SR, HepG2-SR) were established by the procedure of stepwise increase in sorafenib concentrations. CCK-8 assay was used to detect half inhibition concentration (IC50). The expressions of P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1) and PD-L1 were examined by Western blotting and qPCR. The expression of PD-L1 was silenced by transfecting siRNA into the drug-resistant cells, and the silencing efficiency was tested. After silencing the expression of PD-L1 in the drug-resistant cells, CCK-8 assay was used to detect IC50, the drug-resistance index was calculated, and the expressions of P-gp and MRP1 were examined. Then cell proliferation assay, wound healing assay, colony formation assay and flow cytometry were applied to examine cell proliferation, migration, clone formation and apoptosis, respectively. Results The drug-resistance indexes of Hep3B-SR and HepG2-SR were 5.4 and 5.2, respectively. The expressions of P-gp, MRP1 and PD-L1 in the drug-resistant cells were significantly up-regulated in comparison with the parental cells (all P0.01). After inhibiting the expression of PD-L1, the drug-resistance indexes of Hep3B-SR and HepG2-SR decreased to 1.8 and 1.5, respectively, and the expressions of P-gp and MRP1 were down-regulated (all P0.01). Silencing the PD-L1 expression could significantly inhibit the proliferation, migration and colony formation of drug-resistant cells, and could significantly promote the apoptosis (all P0.01); and these effects were strengthened by combining sorafenib. Conclusion PD-L1 is highly expressed in sorafenib-resistant hepatocellular carcinoma cells. Inhibition of PD-L1 expression can partially reverse the drug-resistance of the cells and significantly enhance the anticancer effect of sorafenib. Inhibiting the expression of PD-L1 can effectively repress the growth of sorafenib-resistant hepatocellular carcinoma cells, which is more if combining with sorafenib.