Berberine enhances the anti-hepatocellular carcinoma effect of NK92-MI cells through inhibiting IFN-gamma-mediated PD-L1 expression
Kunyuan Wang, Chengxin Gu, Ganxiang Yu, Jiaen Lin, Zhilei Wang, Qianting Lu, Yangzhi Xu, Dan Zhao, Xiaofeng Jiang, Weijian Mai, Shiming Liu, Hui Yang
Abstract
Berberine is one of the most promising clinically tested natural alkaloids, and immunotherapy using natural killer (NK) cells is a potentially effective treatment for hepatocellular carcinoma (HCC). This study aims to elucidate the effect of berberine on the anti-HCC effect of NK92-MI cells. Human HCC SMMC-7721 and Hep3B cells were co-incubated with NK92-MI cells, berberine (60 or 80 μmol/L), or their combination for 36 h. To evaluate the killing effect of NK92-MI cells on HCC cells, the release of lactate dehydrogenase (LDH) in HCC cells was measured. The anti-tumor effects of berberine, NK92-MI cells, and their combinations were evaluated by MTS, EdU, Tunel, and Western blot assays. A male BALB/c nude mouse subcutaneous tumor model was used to investigate the anti-HCC effect of berberine and NK92-MI cells in vivo. The LDH assay showed that berberine enhanced the cytotoxicity of NK92-MI cells on HCC cells. The combination of berberine and NK92-MI cells demonstrated more obvious anti-HCC effect than did the berberine or NK92-MI single treatment in inhibiting cell proliferation and inducing apoptosis both in vitro and in vivo. Mechanistically, the expression of programmed cell death-ligand 1 (PD-L1) in HCC cells was upregulated after co-culture with NK-92MI cells. PD-L1 expression was knocked down, thereby inhibiting the proliferation and promoting apoptosis of HCC cells, and inhibited by berberine that blocked the secretion of interferon gamma (IFN-γ), thereby enhancing the anti-tumor effect of NK92-MI cells. Current data show that the immunomodulatory role of berberine is to enhance the cytotoxic effect of NK92-MI cells and inhibit tumor immune escape by reducing the expression of PD-L1. Our study provides a rationale for the clinical application of berberine in combination with NK cells for the treatment of HCC.