RESUMO
<p><b>OBJECTIVE</b>To investigate the effects of silencing the expression of mutant p53 gene with RNA interference technique on biological behavior of gastric cancer SGC7901 cells.</p><p><b>METHODS</b>Recombinant plasmid of mutant p53 gene-targeting siRNA was transfected into gastric cancer SGC7901 cells by Lipofectamine(TM)2000. The expressions of mutant p53 gene mRNA and protein were identified by RT-PCR and Western blot assay. The proliferation of SGC7901 cells and changes of Oxaliplatin (OXA) drug sensitivity were detected by MTT assay. The cell cycle distribution and apoptosis rate were analyzed by flow cytometry. Changes in cell tumorigenicity ability were analyzed by colony formation assay and xenograft tumor formation in nude mice.</p><p><b>RESULTS</b>The expression of mutant p53 in SGC7901 cells was remarkable suppressed by mutant p53-siRNA. The cell growth curve of the transfected group turned to left compared to untransfected group and control group. The cell number of G(0)/G(1) phase of transfected group was decreased by 7.4% and 6.7% respectively, and that of S phase was increased both by 17.2% compared to control group and untransfected group, and the cell apoptosis rate induced by Oxaliplatin was remarkable decreased. The IC(50) of OXA in untransfected group, control group and transfected group were 15.88 μmol/L, 14.32 μmol/L and 20.34 μmol/L respectively. The colony formation rate and tumorigenicity ability in nude mice of transfected group increased remarkably.</p><p><b>CONCLUSION</b>Mutant p53-siRNA can significantly inhibit the expression of mutant p53 in SGC7901 cells, however, the use of RNA interference targeting mutant p53 gene in the treatment of gastric cancer is still uncertain.</p>