The expression of DNA methyltransferase,demethylase and tumor-associated genes in human gastric cancer / 中华消化杂志

Objective To investigate the relationship of the expression of DNA methyltransferase,demethylase(mbd2) and tumor-associated genes in human gastric cancer. Methods Tissue samples of cancerous,para-cancerous and normal gastric mucosa were obtained surgically from 28 primary gastric cancer patients. The transcription level of DNA methyltransferase 1 (DNMT1),mbd2,methyl-CpG binding protein (MeCP2),p16 INK4A and c-myc were determined by using real-time RT-PCR and RT-PCR. The relationship between the expression of DNA methylation-associated genes and tumor-associated genes was analyzed. Results The mRNA level of DNMT1 was higher and the mRNA level of mbd2 gene was lower in cancerous tissue than that in normal tissue. The expression of c-myc instead of p16 INK4A and MeCP2 was increased in cancer tissues. The mRNA level of c-myc related negatively to mbd2 when gastric cancer developed. However,there was no any close relation between the transcription level of all above genes and tumor biological behavior in human gastric cancer. Conclusion This study indicates that MeCP2 but not DNMT1 may contribute to the regulation of tumor-associated genes expression in human gastric cancer.

Effect of recombinant DNA methylferase 1 plasmid on the expression of tumor-associated gene in human colon cancer cell line / 中华消化杂志

Objective To analyze the effect of eukaryotic expression vector containing sense and antisense DNA methyltransferase (DNMT1) gene on the transcript level of tumor associated genes in human colon cancer cell line. Methods Recombinant plasmid, including sense DNMT1 (HMT) and antisense DNMT1 (THM) gene, were constructed and transfected into SW1116 cell by using the lipofectamine. Then G418 filtration was performed. The expression of DNMT1 protein was examined by Western blotting. The transcription level of hMLH1, hMSH2, c myc and p16 INK4A genes were detected by RT PCR. Results The sense and antisense eukaryotic expression vectors were successfully constructed and then the constructed recombinant plasmids were transfected into SW1116 cell. The protein levels of DNMT1 have been up regulated and down regulated in SW1116 cells transfected with HMT and THM plasmids, respectively. The mRNA level of hMLH1, hMSH2, c myc gene were down regulated in the sense DNMT1 transfected cell. The mRNA level of hMSH2 was up regulated in the antisense DNMT1 transfected cell. However, the transcription level of p16 INK4A gene could not be associated with DNMT1 in SW1116 cell.Conclusion DNMT1 can regulate the expression of the tumor associated genes in human colon cancer cell line SW1116.

Construction of Eukaryotic Expression Vector for Tumor-Associated Gene SNC90 and Transfection into Cancer Cells / 中国肿瘤生物治疗杂志

Objective: To construct eukaryotic expression vector of tumor-associated gene SNC90 and transfect it into human colorectal cancer cell lines. Methods: A 1.5 kb tumor-associate gene SNC90 full length cDNA was inserted into a mammalian expression vector pREP9 to make recombinant vector pREP9-SNC90, which was then introduced into three kinds of colorectal cancer cell lines, SW1116, COL0205 and SW620, by lipofection or electroporation. The cells resistant to G418 drug were selected. Results: Cells transfected with pREP9-SNC90 showed fewer G418-resistant colonies than those transfected with void vector, the inhibitory rates are 72.2%, 74.2% and 59.7%, respectively. Conclusion : SNC90 may play a negative role in regulating growth of colorectal cancer cell.