RNF126 contributes to stem cell-like properties and metastasis in hepatocellular carcinoma through ubiquitination and degradation of LKB1.

Hepatocellular carcinoma (HCC) is one of the malignant tumors with the worst prognosis, and tumor recurrence and metastasis are the main factors leading to poor prognosis of HCC patients. Accumulating studies show that RNF126, ring finger protein 126, is involved in the pathological process of many tumors. However, the biological function and exact molecular mechanism of RNF126 in HCC remain unclear. In this study, we investigated the role of RNF126 in the pathogenesis of HCC. By analyzing database and verifying with our clinical specimens, it was found that RNF126 was highly expressed in HCC tissues, which is associated with shorter overall survival and higher recurrence rate. Overexpressed RNF126 can significantly promote the proliferation, migration, invasion and angiogenesis of HCC cells, whereas knockdown RNF126 can reverse this effect. Mechanically, RNF126 down-regulates liver kinase B1 (LKB1) expression by ubiquitination of LKB1 to weaken its stability, thereby significantly promoting stem-cell-like activity, migration, and angiogenesis of HCC. Notably, consistent with in vitro results, RNF126 was stably transformed in Hep3B and subcutaneously injected into nude mice. In established mouse xenograft models, tumor growth can be effectively inhibited and the occurrence of lung metastasis is reduced. In HCC, RNF126 may down-regulate LKB1 through ubiquitination, thus becoming a powerful prognostic biomarker and a recognized tumor suppressor. Therefore, our study may provide a promising new therapeutic strategy for targeting RNF126 for HCC patients.