Therapeutic Effect On Gastric Cancer Of Targeted Inhibition Of Suv39H1 Gene By RNA Interference

【Objectives】To investigate the expression of Suv39H1(suppressor of variegation 3-9 homolog 1),and histone methylation of H3K9 and H3K4 in Gastric Carcinoma,we design a siRNA segment targeting Suv39H1 gene to study its effect on cell growth ,cell apoptosis and histone modification in gastric cancer MGC-803 cells line.【Methods】1.The expression of Suv39H1, histone methylation of H3K9 and H3K4 was detected by immunohistochemical method in gastric cancer, chronic superficial gastritis, atrophic gastritis and mediate to severe dysplasia. 2. Four siRNA segments targeting Suv39H1 gene were designed. Transfection into MGC-803 cells performed by Lipofectamine 2000. The optimal segment was screened by RT-PCR and Western blot. 3. Cell growth affected by Suv39H1 siRNA was determined by MTT. Cell apoptosis was measured by TUNEL assay. 4. The expression of BCL-2,pro-Caspase-9,pro-Caspase-3,P21 and C-myc and the expression of histone methylation of H3K9 and histone acetylation of H3, H4 were detected by Western blot.【Results】1.The expression rate of Suv39H1 in gastric cancer is 72.57﹪, which is significantly higher than that in other benign gastric disorders(p<0.05). It is correlated with degree of differentiation, depth of infiltration, lymphatic metastasis in gastric cancer compared to other benigh gastric disorder(p<0.05). The expression rate of histone methylation of H3k9 is 85.47﹪in gastric cancer, which is higher than that in others(p<0.05). It is correlated with degree of differentiation, depth of infiltration, lymphatic metastasis and TNM stages compared to others(p<0.05). 2. The optimal segment is screened out from four siRNA segments designed for Suv39H1. The sequence is sense 5'-CGUGGAUUGUCUCAGGGAATT-3',antisense 5'-UUCCCUGAGACAAUCC ACGTG -3'. 3. Suv39H1 siRNA upregulates P21 and surpresses the proliferation of MGC-803 cells. Suv39H1 siRNA depredates the BCL-2,pro-Caspase-9,pro-Caspase-3,C-myc and induces cell apoptosis. 4. Suv39H1 siRNA down-regulates the expression of histone methylated H3K9, and up-regulates histone acetylation of H3. The change of histone acetylation of H4 is not seen.【Conclusions】1. Suv39H1 and methyl-H3K9 could be a carcinogen. It plays an important role in tumor initiation, progression and metastasis in Gastric Cancer.2. Suv39H1 siRNA could significantly inhibit MGC803 cell growth, induce cell apoptosis, downregultes H3K9 methylation and upregulates histone-H3 acetylation. Suv39H1 gene might be an anti-cancer target.