Escin inhibits PD-L1 expression by suppressing the p38 MAPK/ERK signalling pathways and synergistically enhances PD-1 inhibitor efficacy in hepatocellular carcinoma

Abstract

Objective Treatment with immune checkpoint inhibitors (ICIs) currently has limited efficacy in hepatocellular carcinoma (HCC). Combining ICIs could achieve optimal immunotherapy. We investigated the anti-tumour effects of escin in HCC, focusing on its impact on PD-L1 expression and the enhancement of anti-tumour immunity of HCC when used in conjunction with ICIs. Methods The anti-tumour efficacy of escin was assessed in vitro using EdU staining, cell viability assays, flow cytometry, and transwell migration assays. The in vivo efficacy of escin was assessed using an orthotopic HCC mouse model. Transcriptome sequencing, network pharmacology, and bioinformatics analyses were performed to investigate the underlying mechanisms. The synergistic effect of escin was further evaluated in combination with an anti-PD-1 antibody in HCC-bearing mice. Results Escin exhibited promising anti-HCC efficacy in both in vitro and in vivo. It inhibited tumour proliferation and induced apoptosis by modulating the p38 MAPK and ERK signalling pathways. Furthermore, escin downregulated HCC-derived PD-L1 expression and reshaped the immunosuppressive state of an orthotopic murine HCC model. The combination of escin with anti-PD-1 therapy remarkably reduced the infiltration of CD206 + M2 tumour-associated macrophages and promoted the infiltration and activation of CD8 + T cells and dendritic cells (DCs) in liver tumours, exhibiting significantly enhanced antitumour activity. Conclusion This study provides novel insights into the mechanism of action of escin in inhibiting HCC and confirms the potential of escin in conjunction with ICIs as a therapeutic approach to impede HCC progression.