589. SENP1 Knockdown Inhibits Hepatocyte Growth Factor-Induced Migration and Epithelial-Mesenchymal Transition of Hepatocellular Carcinoma

The hepatocyte growth factor (HGF)/c-Met signaling aberrations are implicated in the pathogenesis and progress of hepatocellular carcinoma (HCC). However, the epigenetic regulators and their roles in modulating HGF-induced epithelial-mesenchymal transition (EMT), invasion and metastasis of HCC cells are less explored. SUMO/sentrin specific protease 1 (SENP1) is the cysteine protease that regulates SUMO pathways by deconjugating sumoylated proteins. Using real-time PCR we identified increased expression of SENP1 and c-Met in HCC tumors compared to adjacent noncancerous tissues (pu003c0.05, n=20). We further demonstrated that SENP1 overexpression is associated with HGF/c-Met signals in HCC. Treatment of HCC cells with HGF results in upregulation of SENP1 in a stat5 dependent manner. To explore the role of SENP1 in regulation of characteristics of HCC cells, we knocked down SENP1 in HCC cells lines using lentiviral vectors pLKO. 1-GFP-Senp1-shRNA. HCC-LM3 cells transduced with this vector demonstrated 77% decreased expression of SENP1 compared to cells transduced with a control vector. Lentivirus-mediated SENP1 knockdown triggers apoptosis (from control with 7.68% to Senp1 shRNA with 20.4%), cell cycle arrest and inhibits proliferation (80.6% inhibition, pu003c0.01) of HCC cells. SENP1 silence reduces HGF-induced migration of HCC cells (66.7% inhibition, pu003c0.01). Importantly, SENP1 inhibition increases E-cadherin and ZO-1 expression, and decrease fibronectin and N-cadherin expression in HCC cells. A series of transcription factors are involved in regulation of EMT processes. Zeb1 is a zinc finger transcription factor which induces an EMT and confers a metastatic phenotype on carcinomas. We predicted the sumoylation sites of Zeb1 by using a site-specific predictor of SUMOsp 2.0. This prediction was further validated by using Zeb-1 immunoprecipitation and Sumo2 antibody blot. HGF treatment also induced the expression of zeb1. SENP1 knockdown increased Zeb1 desumoylation, leading to reduce its protein level in HCC cells.Our results indicate that SENP1 is frequently over-expressed and associated with HGF/C-met in HCC. SENP1 plays a key role in HGF-induced proliferation, migration and epithelial-mesenchymal transition, suggesting it may be a potential new therapeutic target for HCC.