Category: Basic Science: Oncology
Introduction & Objective : To investigate the expression of SIRT7, its significance in renal cell carcinoma(RCC) and the effect of silencing SIRT7 expression on the biological characteristics of human 786-O renal cell carcinoma(RCC) cell lines by small interfering RNA in vitro.
Methods : A tissue microarray (TMA) containig specimens from 75 patients with ccRCC and 30 paracanerous tissues was constructed and then immunohistochemistry was used to examine the expression of SIRT7 protein. Expression of SIRT7 was examined in 20 fresh ccRCC tissues and paired adjacent normal renal tissues by real-time quantitative PCR and Western blotting. The blank control (Bank Control ), negative control (Negative Control) and siRNA interference (SIRT7-siRNA) groups were designed in this study. The small interfering RNA(siRNA) was synthesized and transfected into 786-O cell lines with Lipofectamin 2000 for silencing the expression of SIRT7. The expression levels of SIRT7 mRNA was detected by RT-PCR after transfected with 48h. After transfected，The cell proliferation was detected by MTT method. The cell apoptosis was detected by flow cytometry. The invasion and migration capabilities were evaluated by using Transwell chamber migration assay and scratch wound healing assay, respectively.
Results : Immunohistochemical results showed that the positive expression rate of SIRT7 was 78.7% in ccRCC specimens, and 10% in normal renal tissues.The difference was statistically significant (P0.001). QRT-PCR results showed that the expression of SIRT7 was upregulated in the 20 cases of ccRCC clinical tissue specimens compared with normal renal tissues (P<0.001). And so was Western blotting results. The expression of SIRT7 protein in 20 cases of ccRCC specimes and normal renal tissues were 0.4081±0.0234 and 0.1104±0.0108, respectively. The difference was statistically significant (P<0.001). The expression levels of SIRT7 mRNA in 786-0 cell lines were effectively downregulated by siRNA. The proliferative rate was decreased(P<0.001), the apoptosis rate was increased(P<0.001) , and the invasion and migration capabilities were both decreased significantly (P<0.001).
These results suggest that SIRT7 expression was upregulated in the ccRCC tissues, which is likely correlated with ccRCC development. SIRT7 can efficiently increase the capacities of proliferation, migration and invasion and decrease the capacities of apoptosis of 786-0 cell lines. SIRT7 maybe become a new potential target in the treatment of renal cancer.
Guoxi Zhang– No.23 Qingnian Road, Ganzhou,China, First affiliated hospital of Gannan medical university, Ganzhou, Jiangxi, China (People's Republic)