Abstract: Objective To investigate expression of DNA methyltransferase 2 (DNMT2) protein in gastric cancer and to study proliferation of SGC-7901 (gastric cancer cell) with DNMT2 inhibition treatment (RNA interference technique). Methods Immunohistochemistry was used to detect DNMT2 expression in 60 pairs of gastric cancer and corresponding non-cancerous tissues. Immunofluorescence was used to detect DNMT2 in SGC-7901. Three siRNA (DNMT2-siRNA-1, DNMT2-siRNA-2, DNMT2-siRNA-3) targeting DNMT2 were designed. And LipofectamineTM2000 was used to transfect DNMT2-siRNA to SGC-7901. RT-PCR and western blotting were used to evaluate the effect of DNMT2 inhibition. MTT assay was carried on for SGC-7901 with DNMT2 inhibition treatment. Results Expression rate of DNMT2 in gastric cancer tissues (43.3%) was lower than that in corresponding non-cancerous tissues (93.3%), P＜0.05. And DNMT2 expression was significantly lower in late-stage and poor-differentiated cancerous tissues than in early-stage and good-differentiated cancerous tissues (P＜0.05). DNMT2 was distributed in nucleus of gastric cancer cell. DNMT2-siRNA could be transfect to SGC-7901 perfectly, and DNMT2-siRNA-3 could inhibit DNMT2 mRNA and protein best. At last, 96 h and 120h after DNMT2-siRNA-3 transfection, cell growth rate of SGC-7901 increased compared with control (1.138±0.110 and 1.078±0.060 vs 1, P＜0.05). Conclusion Gastric cancer expressed lower DNMT2 protein than non-cancerous tissues did. Inhibition of DNMT2 could promote proliferation of gastric cancer cell more or less.

Key words: DNMT2, gastric cancer, RNA interference, epigenetics