ABSTRACT
Objective To investigate the effects of Helicobacter priori (H.prlori) strains from the patient with gastric cancer on the expression of DNA mismatch repair (MMR) genes in AGS cells in vitro. Methods AGS cells were co-cultured with ten strains of H.prlori from five patients with gastric cancer and five patients with gastritis respectively.The expressions of DNA MMR genes (hMSH2 and hMLH1) in mRNA and protein levels were determined by RT-PCR and Western blot.The enteropathogenic E.coli served as a bacterial control.Results E.coli and H.priori strains from gastritis have no effects on the expression of hMSH2 and hMLH1 in both protein and mRNA levels on the whole,while all the H.prlori strains from gastric cancer reduced expression levels of hMSH2 and hMLH1.Conclusions There are different effects between H. prlori strains from gastric cancer and those from gastritis on DNA MMR in AGS cell line,indicating that infec- tion of some H.prlori strains might lead to the inhibition of DNA MMR,and that in turns increases the risk of gastric carcinogenesis during chronic H.prlori infection.
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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.
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Purpose:To investigate whether NSAIDs can induce apoptosis of gastric cancer cell lines,to observe the effect of different p53 genotype on NSAIDs induced apoptosis,to elucidate the regulation of NSAIDs on expression of apoptosis related genes. Methods:The anti-proliferative effect of NSAIDs was measured by MTT assay.Apoptosis was determined by acridine orange(AO) staining,Annexin-V/PI double staining,laser scanning cytometry(LSC) and flow cytometry (FCM).Alteration of bcl-2 and bax genes was detected by reverse transcription polymerase chain reaction (RT-PCR).Protein expression was determined by Western-blotting.Results: Indomethacin (Indo) and Aspirin (Asp) inhibited both AGS(wild-type p53)and MKN28(mutant p53) gastric cancer cell lines growth in a time/dose dependent manner.AGS cell line was more sensitive to NSAIDs,which apoptosis percentage was significantly higher than MKN28 under the same condition. The percentages of apoptosis of MKN28 were somewhat higher among NSAIDs treated groups compared with the normal control group,but these slight differences were not statistically significant. The bax mRNA kept increasing since NSAIDs treatment accompanied by a decrease of bcl-2 gene.The Bax protein increased after treatment while the Bcl-2 protein was undetectable, which tendency was more obvious during 6-24hs.Conclusion: Both Indo and Asp could induce apoptosis in gastric cancer cell lines,which adds further theoretical foundation to the anti-cancer use of NSAIDs.NSAIDs could not induce notable apoptosis of MKN28,which indicated the mutant p53 gene perhaps blocked NSAIDs induced apoptosis.One of the major pathways that mediated the anti-tumour response of NSAIDs in gastric cancer cells was through up-regulation of bax and down-regulation of bcl-2 genes and/or proteins.[