Ginsenoside Rg3 attenuates cisplatin resistance in lung cancer by downregulating PD-L1 and resuming immune.

Programmed death ligand 1 (PD-L1) as one the most important immune checkpoint was verified to involve in chemotherapy resistance in non-small cell lung cancer (NSCLC). Ginsenoside Rg3 is isolated from Chinese herb-Panax ginseng which is recognized to boost immune and has anti-cancer activity against a majority of carcinomas including NSCLC. In this study, we aim to identify whether Rg3 could attenuate the PD-L1 expression induced by resistance to cisplatin and draw out the underlying mechanisms of PD-L1 in this process. Human lung cancer cell lines A549 and A549/DDP (cisplatin-resistance) were used. Cell viability was detected by MTT assay, the PD-L1, Akt and NF-κB p65 protein expression were detected using Western blot analysis, the T cells cytotoxity to tumor cells was detected by crystal violet staining living residual tumor cells after coculture of tumor cells and T cells. The results showed that Rg3 could inhibit the growth and alleviate the resistant to cisplatin of A549/DDP cells. PD-L1 was overexpression in A549/DDP cells than A549 cells. Rg3 could decrease the PD-L1 expression induced by chemoresistance and resume the T cells cytotoxity to cancer cells. NF-κB p65 and Akt were involved in the PD-L1 overexpression and restrained by Rg3. Therefore, Rg3 could be regarded as a new agent targeting PD-L1 in chemotherapy refractory NSCLC.