GSDME has prognostic and immunotherapeutic significance in residual hepatocellular carcinoma after insufficient radiofrequency ablation

Background: Heat stress can induce programmed cell death (PCD). Pyroptosis is a gasdermin-mediated PCD. This study hypothesized that insufficient radiofrequency ablation (IRFA) induced pyroptosis in hepatocellular carcinoma (HCC) and investigated its underlying mechanism and clinical significance. Methods: Thermostatic water bath was used to stimulate IRFA in vitro. Cell viability was assessed by MTT assay. IL-1 beta and HMGB1 were measured by ELISA assay. LDH level was measured by LDH cytotoxicity detection kit. Permeability of cell membrane was assessed by Hoechst33342/PI fluorescence staining. RNA expression was evaluated by qRT-PCR, and protein was assessed by Western Blotting or immunofluorescence or immunohistochemistry. Gene expression with clinicopathological characteristics from HCC patients treated by RFA were analyzed for associations between GSDME expression and prognosis. Results: Our study revealed that IRFA induced pyroptosis in HCCLM3 and HepG2 cells. GSDME, rather than GSDMD, was cleaved in heat stress-induced pyroptosis in HCCLM3 and HepG2 cells due to caspase-3 activation. However, GSDME overexpression promoted HCC growth in vivo and predicted poor PFS and OS in HCC patients treated by RFA. Heat stress modulated gene expression related to PD-L1 signaling and caspase inhibitors inhibited heat-induced PD-L1 expression in residual HCC after IRFA. Gsdme overexpression caused resistance to PD-L1 inhibitor in residual HCC after IRFA by increasing infiltrating of CD3+PD-1+ or CD3+CTLA-4+ exhausted T cells. Conclusions: This study indicated that GSDME could serve as a potential prognostic biomarker and help to prescribe personalized sequential immunotherapy for HCC patients receiving RFA.