目的 研究人参皂苷Rg₃对小鼠非小细胞肺癌Lewis细胞（LLC）中免疫检查点程序性死亡分子1配体（PD-L1）的调节作用及其作用机制。方法 通过MTT法及细胞长时程动态监测法观察人参皂苷Rg₃对LLC增殖的影响；20 ng/mL γ干扰素（IFN-γ）处理LLC制备PD-L1高表达体外模型，采用人参皂苷Rg₃进行干预，流式细胞术及免疫荧光检测人参皂苷Rg₃对PD-L1表达的影响；采用Western blotting法验证人参皂苷Rg₃对PI3K/蛋白激酶B（Akt）/哺乳动物雷帕霉素靶蛋白（mTOR）通路相关蛋白表达的影响。结果 人参皂苷Rg₃ 16、32、64、128 μmol/L能够显著抑制LLC增殖（P<0.01）及减少IFN-γ诱导的PD-L1表达（P<0.05）；人参皂苷Rg₃ 32、64 μmol/L能够降低PI3K、mTOR蛋白的表达水平（P<0.01）；人参皂苷Rg₃ 16、32、64 μmol/L能够抑制Akt蛋白的磷酸化（P<0.05）。结论 人参皂苷Rg₃能够显著抑制LLC中PD-L1表达，通过抑制PI3K/Akt/mTOR通路，阻断PD-L1介导的肿瘤细胞免疫逃逸，增强T细胞的免疫应答作用，抑制LLC生长。

Objective To investigate the effect of ginsenoside Rg₃ on immune checkpoint PD-L1 in Lewis cells (LLC) and to explore the related mechanism.Methods The effects of ginsenoside Rg₃ on the proliferation of LLC were observed by MTT assay and cell long-term dynamic monitoring. LLC cells treated with 20 ng/mL IFN-γ were used to construct experimental model with high expression of PD-L1 in vitro. The effect of ginsenoside Rg₃ on expression of PD-L1 was detected by flow cytometry and immunofluorescence. The effect of ginsenoside Rg₃ on the protein expression of PI3K/Akt/mTOR pathway was verified by Western blotting.Results Ginsenoside Rg₃ at 16, 32, 64, and 128 μmol/L significantly inhibited the proliferation of LLC (P < 0.01) and reduced the expression of PD-L1 induced by IFN-γ (P < 0.05). Ginsenoside Rg₃ at 32 and 64 μmol/L significantly decreased the protein expression of PI3K and mTOR (P < 0.01), and ginsenoside Rg₃ at 16, 32, and 64 μmol/L significantly inhibited the phosphorylation of Akt proteins (P < 0.05).Conclusion Ginsenoside Rg₃ significantly inhibited the expression of PD-L1 in LLC cells by inhibiting PI3K/Akt/mTOR pathway. Ginsenoside Rg₃ blocked the tumor cells escaping immune response by PD-L1 over-expression, enhanced the immune response of T cells, and inhibited the growth of non-small cell lung cancer cells.

国家自然科学基金资助项目（81403260）；国家自然科学基金资助项目（81673725）；国家自然科学基金资助项目（81573859）；国家自然科学基金资助项目（81673648）；国家自然科学基金资助项目（81703765）；江苏省研究生创新基金项目（KYCX18_1584）；江苏省研究生创新基金项目（KYCX18_1616）；江苏省研究生创新基金项目（KYCX17_1315）；江苏省自然科学基金项目（BK20151567）；江苏高校品牌专业建设工程资助项目（TAPP-PPZY2015A070）；江苏高校中药学优势学科建设工程资助项目（PAPD）[苏政办发（2014）37号文]；江苏省中医药领军人才项目（SLJ0229）