Regulatory factor X1 promotes sorafenib-induced ferroptosis in hepatocellular carcinoma by transcriptional regulation of BECN1.

BACKGROUND: Sorafenib is a commonly used first-line kinase-targeted drug for advanced hepatocellular carcinoma (HCC) patients suffering from limited efficacy. Emerging evidence indicates that sorafenib exerts anti-cancer activity through the induction of ferroptosis in HCC cells, but the underlying mechanism is still unclear. METHODS: The whole transcriptome sequencing and bioinformatics analysis were used to screen for target genes. The expression and subcellular localization of regulatory factor X1 (RFX1) were determined through immunohistochemistry, immunofluorescence, PCR and western blot analyses. The impact of RFX1 on HCC cell growth was assessed using CCK8, colony formation assays, cell death assays, and animal experiments. Glutathione measurement, iron assay and lipid peroxidation detection assays were performed to investigate ferroptosis of HCC cells. The regulatory mechanism of RFX1 in HCC was investigated by sgRFX1, co-IP, ChIP and luciferase experiments. Immunohistochemical and survival analyses were performed to examine the prognostic significance of RFX1 in HCC. RESULTS: In this study, we found that RFX1 promote ferroptosis in HCC cells. Further, we showed that sorafenib induces cell death through RFX1-mediated ferroptosis in HCC cells. The enhancing effect of RFX1 on HCC cell ferroptosis is largely dependent on inhibition of cystine/glutamate antiporter (system Xc-) activity through the BECN-SLC7A11 axis, where RFX1 directly binds to the promoter region of BECN1 and upregulates BECN1 expression. In addition, a STAT3-RFX1-BECN1 signalling loop was found to promote RFX1 expression in HCC cells. CONCLUSIONS: Our study reveals a novel mechanism underlying sorafenib-induced HCC cell death.