Transcription factor ETV4 promotes the development of hepatocellular carcinoma by driving hepatic TNF-α signaling

Abstract

Background: Hepatic inflammation is the major risk factor of hepatocellular carcinoma (HCC). However, the underlying mechanism by which hepatic inflammation progresses to HCC is poorly understood. This study was designed to investigate the role of ETS translocation variant 4 (ETV4) in linking hepatic inflammation to HCC.

Methods: Quantitative real-time PCR and immunoblotting were used to detect the expression of ETV4 in HCC tissues and cell lines. RNA sequencing and luciferase reporter assays were performed to identify the target genes of ETV4. Hepatocyte-specific ETV4-knockout (ETV4^{fl/fl, alb-cre} ) and transgenic (ETV4^Hep-TG ) mice and diethylnitrosamine-carbon tetrachloride (DEN-CCL₄ ) treatment experiments were applied to investigate the function of ETV4 in vivo. The Cancer Genome Atlas (TCGA) database mining and pathological analysis were carried out to determine the correlation of ETV4 with tumor necrosis factor-alpha (TNF-α) and mitogen-activated protein kinase 11 (MAPK11).

Results: We revealed that ETV4 was highly expressed in HCC. High levels of ETV4 predicted a poor survival rate of HCC patients. Then we identified ETV4 as a transcription activator of TNF-α and MAPK11. ETV4 was positively correlated with TNF-α and MAPK11 in HCC patients. As expected, an increase in hepatic TNF-α secretion and macrophage accumulation were observed in the livers of ETV4^Hep-TG mice. The protein levels of TNF-α, MAPK11, and CD68 were significantly higher in the livers of ETV4^Hep-TG mice compared with wild type mice but lower in ETV4^{fl/fl, alb-cre} mice compared with ETV4^fl/fl mice as treated with DEN-CCL₄ , indicating that ETV4 functioned as a driver of TNF-α/MAPK11 expression and macrophage accumulation during hepatic inflammation. Hepatocyte-specific knockout of ETV4 significantly prevented development of DEN-CCL₄ -induced HCC, while transgenic expression of ETV4 promoted growth of HCC.

Conclusions: ETV4 promoted hepatic inflammation and HCC by activating transcription of TNF-α and MAPK11. Both the ETV4/TNF-α and ETV4/MAPK11 axes represented two potential therapeutic targets for highly associated hepatic inflammation and HCC. ETV4+TNF-α were potential prognostic markers for HCC patients.

Keywords: ETV4; MAPK11; TNF-α; hepatic inflammation; hepatocellular carcinoma; macrophage.