Lentivirus mediated silencing of ubiquitin specific peptidase 39 inhibits cell proliferation of human hepatocellular carcinoma cells in vitro.

Ubiquitin Specific Peptidase 39 (USP39) is a 65 kDa SR-related protein involved in RNA splicing. Previous studies showed that USP39 is related with tumorigenesis of human breast cancer cells. In the present study, we investigated the functions of USP39 in human hepatocellular carcinoma (HCC) cell line SMMC-7721. We knocked down the expression of USP39 through lentivirus mediated RNA interference. The results of qRT-PCR and western blotting assay showed that both the mRNA and protein levels were suppressed efficiently after USP39 specific shRNA was delivered into SMMC-7721 cells. Cell growth was significantly inhibited as determined by MTT assay. Crystal violet staining indicated that colony numbers and sizes were both reduced after knock-down of USP39. Furthermore, suppression of USP39 arrested cell cycle progression at G2/M phase in SMMC-7721cells. In addition, Annexin V showed that downregulation of USP39 significantly increased the population of apoptotic cells. All our results suggest that USP39 is important for HCC cell proliferation and is a potential target for molecular therapy of HCC.