CYP2E1 plays a suppressive role in hepatocellular carcinoma by regulating Wnt/Dvl2/β-catenin signaling

Objective: Knowledge of the role of CYP2E1 in hepatocarcinogenesis is largely based on epidemiological and animal studies, with a primary focus on the role of CYP2E1 in metabolic activation of procarcinogens. Few studies have directly assessed the effects of CYP2E1 on HCC malignant phenotypes. Methods: The expression of CYP2E1 in HCC tissues was determined by qRT-PCR, western blotting and immunohistochemistry. Overexpression of CYP2E1 in HCC cell was achieved by lentivirus transfection. The function of CYP2E1 were detected by CCK-8, wound healing, transwell assays, xenograft models and pulmonary metastasis model. TOP/FOP-Flash reporter assay, western blotting, functional rescue experiments, Co-immunoprecipitation and reactive oxygen species detection were conducted to reveal the underlying mechanism of the tumor suppressive role of CYP2E1. Results: CYP2E1 expression is down-regulated in HCC tissues, and this downregulation was associated with large tumor diameter, vascular invasion, poor differentiation, and shortened patient survival time. Ectopic expression of CYP2E1 inhibits the proliferation, invasion and migration and epithelial-to-mesenchymal transition of HCC cells in vitro, and inhibits tumor formation and lung metastasis in nude mice. Mechanistic investigations show that CYP2E1 overexpression significantly inhibited Wnt/beta-catenin signaling activity and decreased Dvl2 expression in HCC cells. An increase in Dvl2 expression restored the malignant phenotype of HCC cells. Notably, CYP2E1 promoted the ubiquitinmediated degradation of Dvl2 by strengthening the interaction between Dvl2 and the E3 ubiquitin ligase KLHL12 in CYP2E1-stable HCC cells. CYP2E1-induced ROS accumulation was a critical upstream event in the Wnt/beta-Catenin pathway in CYP2E1-overexpressing HCC cells. Conclusions: These results provide novel insight into the role of CYP2E1 in HCC and the tumor suppressor role of CYP2E1 can be attributed to its ability to manipulate Wnt/Dvl2/beta-catenin pathway via inducing ROS accumulation, which provides a potential target for the prevention and treatment of HCC.