TRIM50 suppressed hepatocarcinoma progression through directly targeting SNAIL for ubiquitous degradation.

Tripartite motif-containing 50 (TRIM50) belongs to the tripartite motif (TRIM) protein family, which has been implicated in the pathogenesis of multiple cancers. However, the role of TRIM50 in hepatocellular carcinoma (HCC) remains to be clarified. Here we showed that TRIM50 expression was significantly decreased in liver cancer tissues compared with corresponding non-cancerous liver tissues, and its decreased expression was significantly correlated with advanced disease progression. Gain-of-function assay by exogenous overexpression of TRIM50 in HCC cells showed that proliferation, colony formation, migration and invasion of HCC cells were significantly inhibited, whereas loss-of-function assay by TRIM50 knockdown showed that these malignant behaviors of HCC cells were significantly increased. Further investigation showed that TRIM50 could directly bind with SNAIL and induced K-48 linked poly-ubiquitous degradation of SNAIL protein, which further reversed SNAIL-mediated epithelial-to-mesenchymal transition (EMT) process of HCC cells. In vivo assay by xenograft tumor model verified the antitumor effect of TRIM50 on HCC. Taken together, these results showed that TRIM50 acted as a tumor suppressor in HCC cells by directly targeting SNAIL and reversing EMT, which further indicated that positive modulation of TRIM50 might be a novel therapeutic strategy for SNAIL overexpressed HCC cells.