E2F1 activates USP19 to affect the stability of c-Myc to facilitate the progression of hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is the most common malignant tumor worldwide with a high mortality rate. Herein, this study aims to explore the molecular mechanisms of E2F transcription factor 1 (E2F1), ubiquitin specific peptidase 19 (USP19) and c-Myc in regulating HCC progression. Methods: RT-qPCR and western blotting were utilized to assess mRNA and protein expression, respectively. The behavior of cells was examined through Methylthiazolyldiphenyl-tetrazolium bromide (MTT), flow cytometry, transwell, and cell sphere formation assays. Glycolysis-related indicators were detected by kits. The interaction between USP19 and c-Myc was measured by co-immunoprecipitation (Co-IP). Dual-luciferase reporter assay and Chromatin Immunoprecipitation (ChIP) assays were used to assess the binding of E2F1 and USP19 promoter. A mouse xenograft model was established for the purpose of analysis in vivo. Results: High level of c-Myc was observed in HCC tissues and cells. Silencing c-Myc results in the suppression of cell migration, invasion, proliferation, and glycolysis or promotion of apoptosis. USP19 directly bound to c-Myc, and maintained its stability by removing ubiquitination on c-Myc. Overexpression of c-Myc in HCC cells rescued the anti-tumor effect of USP19 deletion. E2F1 promoted USP19 transcription, and increased USP19 expression counteracts the effects of E2F1 depletion on cell behaviors. In vivo, USP19 knockdown controlled HCC growth by modulating c-Myc. Conclusion: E2F1 activated USP19 transcription, thereby stabilizing c-Myc via deubiquitination and accelerating HCC progression.