MiR-23a-3p Mediates Sorafenib Resistance in Human Hepatocellular Carcinoma: Study on The Regulatory Mechanisms and Potential Natural Suppressor from Chinese Herbal Medicine

Hepatocellular carcinoma (HCC) is the most histotye of liver cancer, which has brought great concern to global health due to the high incidence and mortality. Due to the poor diagnosis of HCC, patients are often diagnosed at late stages and have to adopt systemic therapies for the rest of their lives. Until now, although various agents have been developed since sorafenib first came out, the efficiency of these agents did not get much better improvement. Drug resistance is the main hindrance for HCC patients to benefit from these drugs. Current studies have demonstrated the mechanisms of sorafenib resistance in HCC are involved in drug transporter systems, regulated cell death (RCD), cancer stem-like features, and so on. They can be subject to epigenetic modifications, especially microRNAs (miRNAs). 

In this study, the identification of deregulated miRNA, miR-23a-3p, was through weighted correlation network analysis (WGCNA) on the miRNA expression profile in a sorafenib-treated patients’ cohort and the correlation analysis on the clinical relevance. The role of miR-23a-3p in facilitating sorafenib resistance in HCC was confirmed by establishing an in vivo generated sorafenib resistant (IV-SR) HCC cell line and conducting loss-of-function (LOF) experiments in orthotopic HCC mouse models. In the mechanism studies, proteomic analysis was performed to figure out the key upstream regulator and the essential downstream signalling. It was found that the ETS Proto-Oncogene 1 (ETS1) was the transcription factor (TF) that directly activated miR-23a-3p transcription upon sorafenib treatment, and ferroptosis was the core downstream signalling suppressed by miR-23a-3p overexpression. Specifically, Acyl-CoA synthetase long chain family member 4 (ACSL4) was proved to be the target of miR-23a-3p, which is responsible for catalysing the polyunsaturated fatty acid-containing phospholipid synthesis, an important prerequisite for ferroptosis activation. 

Given the clinical significance and the regulatory mechanisms of miR-23a-3p in sorafenib-treated HCC, miR-23a-3p was suggested as a target to enhance sorafenib efficacy in anti-HCC activity. Then a screening approach to look for a miR-23a-3p-targeted Chinese compound was conducted and identified that fangchinoline and HL23 could prevent sorafenib-induced miR-23a-3p transcription. HL23 showed better cytotoxicity on HCC than fangchinoline and showed a synergistic effect with sorafenib. The combination treatment of HL23 and sorafenib in the orthotopic HCC mouse model indicated that HL23 could remarkably enhance sorafenib efficacy.

In conclusion, this study demonstrated that miR-23a-3p contributed to sorafenib resistance by targeting ACSL4-mediated ferroptosis in HCC and could be a target by HL23 to enhance the anti-HCC activity of sorafenib.