Oncogene UBE2I enhances cellular invasion, migration and proliferation abilities via autophagy-related pathway resulting in poor prognosis in hepatocellular carcinoma.

ABSTRACT

Hepatocellular carcinoma (HCC) is a worldwide malignancy with high morbidity and mortality. In this study, ubiquitin conjugating enzyme E2I (UBE2I), a small ubiquitin-like modifier E2 enzyme reportedly expressed in tumors, was examined for its potential effects in HCC. Bioinformatics analysis was performed based on HCCDB, TIMER, and Kaplan-Meier plotter databases to explore the clinical implications in HCC. An siRNA kit was used to downregulate UBE2I, and in vitro experiments-including migration, invasion and proliferation assays-were performed to examine UBE2I expression in HCC. Western blot (WB) was used to determine whether downregulated UBE2I expression influenced the prognosis of HCC via autophagy pathways. Finally, RNA-sequencing was performed to explore candidate molecular mechanisms underlying the effect of UBE2I. Bioinformatics analysis including stratification by alcohol ingestion and hepatitis status in HCC showed that highly expressed UBE2I was not only correlated with poor prognosis, but was also associated with immune infiltrates. In vitro experiments showed that high expression of UBE2I was associated with increased migration, invasion and proliferation of HCC cells. WB results indicated that downregulated expression of UBE2I was associated with higher levels of autophagy-related proteins including LC3A/B, Beclin-1 and ATG16L1. Moreover, RNA-sequencing results suggested that UBE2I was involved in hepatocarcinogenesis, non-alcohol fatty liver disease, steatohepatitis, liver fibrosis, inflammation, hepatoblastoma, tumor angiogenesis, type 2 mellitus diabetes, biliary tract disease and other diseases. We conclude that oncogene UBE2I is associated with poor prognosis of HCC via autophagy pathways and may be involved in hepatocarcinogenesis, tumor angiogenesis, non-alcohol fatty liver disease and inflammation.