Effect Of SOD3 Overexpression On Growth And Proliferation Of Gastric Cancer MGC803 Cells

Objectives: The superoxide dismutase(SOD3) protein of down-regulation expression in gastric mucosa carcinogenesis was identified by early study using quantitative proteomics.The role and mechanism of SOD3 protein will be clarified in the proliferation of gastric cancer cells,and it will provide the basis for elucidating the molecular mechanism of gastric cancer.Methods: 1.The pCDNA3.1-SOD3 eukaryotic expression vector was transfected into gastric cancer MGC803 cells(pCDNA3.1 as vector contrast).After screening by G418,MGC803 cell line with stable and overexpression of SOD3,was established and nameed MGC803-SOD3 cell line(MGC803-pCDNA3.1 as vector control cell).The expression of SOD3 protein was detected with immunofluorescence and Western-blot in MGC803-SOD3 cells.2.The the growth and proliferation of MGC803 cells of SOD3 overexpression were observed by cell growth curve,plate cloning,soft agar colony forming assay and flow cytometry.3.The expression of JAK3,STAT3 and its phosphorylated protein was detected by Western-blot in MGC803-SOD3 cells.Results:1.The results of cell growth curve showed that the growth of MGC803-SOD3 cells was slower than that of MGC803 and MGC803-pCDNA3.1 cells(P< 0.01).2.The results of plate cloning showed that the clones of MGC803,MGC803-pCDNA3.1 and MGC803-SOD3 were respectively 262.32±29.34,250.43±27.26 and 86.52±12.43.The number and the clonal volume of MGC803 cells were significantly decreased after SOD3 overexpression compared with the MGC803 and MGC803-pCDNA3.1 cells(P< 0.01).The results showed that the proliferation ability of MGC803 cells decreased after SOD3 overexpression.3.The results of soft agar colony assay showed that the colony of MGC803,MGC803-pCDNA3.1 and MGC803-SOD3 cells were respectively326.42±35.24,314.13±32.25 and 128.21±21.42.The number and the volume of colony formation of MGC803 cells were significantly decreased after SOD3 overexpression compared with MGC803 and MGC803-pCDNA3.1 cells(P < 0.01).The results also showed that the proliferation of MGC803 cells decreased after SOD3 overexpression.4.The S-phase ratios of MGC 803,MGC 803-pCDNA3.1 and MGC 803-SOD3 cells were respectively 46.26±2.38,42.34±2.45 and 31.26±2.34.The G1-phase ratios were 46.12±2.52,8.22±2.64 and 61.73±3.12,and the cell proliferation indices were respectively 53.88,51.77 and 38.27.The results showed that the proportion of S phase,G1 phase and the proliferation index in MGC803 cells were decreased after SOD3 overexpression(P< 0.01).In addition,the apoptotic rates of MGC803,MGC803-pCDNA3.1 and MGC803-SOD3 cells were respectively 9.67±1.24,10.02±1.32 and 28.95±3.26.The results showed that the apoptosis rate of MGC803 cells was increased after SOD3 overexpression(P<0.01).5.Western blot showed that the expression of JAK3 and STAT3 proteins was' t significantly different in MGC803-SOD3 cells,but the phosphorylation level of JAK3 and STAT3 proteins was lower than that in MGC803 and MGC803-pCDNA3.1 cells(P< 0.01).Conclusions: The overexpression of SOD3 reduces cell growth and proliferation and promotes apoptosis in MGC803 cells,which probably related to its inhibit of JAK3-STAT3 pathway activation.