[DeSUMOylation of protein kinase B1 inhibits cell proliferation and metastasis of hepatocellular carcinoma]

Objective: To investigate the effect of AKT1 deSUMOylation induced by Ubc9 silencing on the proliferation and metastasis of hepatocellular carcinoma (HCC) cells. Methods: The Ubc9 gene was silenced using RNA interference, and the expression levels of Ubc9, SUMO1 and AKT1 protein were detected by Western blot. Cell proliferation and cell cycle was analyzed by MTT and flow cytometry. Wound healing and transwell assays were used to detect the cell migration ability. Furthermore, the xenograft model was established, and tumor growth curves were drawn. The in situ apoptotic rates was measured using TUNEL Apoptosis Assay. The expression of proliferating cell nuclear antigen (PCNA), matrix metalloproteinase (MMP)-2 and MMP-9 were evaluated by immunohistochemical staining. Results: Knockdown of Ubc9 gene significantly decreased the protein expression levels of Ubc9, conjugated SUMO1, free SUMO1 and AKT1 in HCC cells (P<0.05 for all). In control, siR-neg and siR-Ubc9 groups, the cell proliferation indexes were 53.19%, 54.25% and 39.17%, respectively. Moreover, cell migration distance and migrating cells per low power field for all these three groups were (59.47±4.66) μm and 89.44±8.36, (56.56±5.37) μm and 93.84±8.79, as well as (34.57±6.61) μm and 41.67±5.39, respectively. In the xenograft model, the weights of subcutaneous tumors for these three groups were (3.78±0.69) g, (3.72±0.72) g and (2.09±0.61) g, respectively. The corresponding apoptotic cell rates were (7.79±2.21)%, (6.45±2.48)% and (33.59±5.44)%, respectively. The expression levels of PCNA, MMP-2 and MMP-9 protein were significantly decreased in siR-Ubc9 group (P<0.05). Conclusions: Ubc9 silencing in HCC cells induces AKT1 deSUMOylation, and then inhibits the proliferation and metastasis. These results provide a new therapeutic strategy for liver cancer in the future.

Role of small ubiquitin-related modifier-1 in the pathogenesis of hepatic fibrosis in rats

AIM: To observe the changes in the expression of small ubiquitin-related modifier-1 (SUMO-1) during the formation of hepatic fibrosis in rats and to investigate the role of SUMO-1 in the pathogenesis of hepatic fibrosis.

METHODS: Ninety male Sprague-Dawley rats were divided into two groups: model group and control group. The model group was subcutaneously injected with 40% carbon tetrachloride at a dose of 0.3 mL/100 g of body weight, while the control group was given equivalent volume of normal saline. Liver tissue samples were taken at weeks 2, 4, 6, 8, 10 and 12 after carbon tetrachloride injection. Hepatic fibrosis was pathologically evaluated. The expression of SUMO-1 mRNA and protein in liver tissue was detected by RT-PCR and Western blot, respectively.

RESULTS: During the formation of hepatic fibrosis, the expression of SUMO-1 mRNA was gradually up-regulated from week 2 to 12 (0.725 ± 0.017, 0.786 ± 0.018, 0.803 ± 0.023, 0.831 ± 0.020, 0.863 ± 0.016 and 0.892 ± 0.008, respectively; P < 0.01). Similarly, SUMO-1 protein expression was also gradually up-regulated from week 2 to 12 (0.810 ± 0.059, 0.873 ± 0.049, 0.923 ± 0.055, 0.959 ± 0.032, 0.988 ± 0.011 and 0.998 ± 0.004, respectively; P < 0.01).

CONCLUSION: The expression of both SUMO-1 mRNA and protein is gradually up-regulated during the formation of hepatic fibrosis, suggesting an important role of SUMO-1 in the pathogenesis of hepatic fibrosis.