Research On The Inhibitory Effect Of5-aza-2’-deoxytidine On Gastric Cancer Xenografts In Nude Mice

Objective:To study the inhibitory effect of5-Aza-CdR on gastric cancer xenografts in nude mice, then investigate the methylation status of promoter region CpG island of p16and the expression of p16mRNA and protein, analyze the demethylation effect of5-Aza-CdR in vivo.Methods:The xenograft cancer model was made by subcutaneous injection of BGC-823cell suspension with the concentration of1*107/ml, each nude mice was subcutaneous injected with0.1ml BGC-823cell suspension to the armpit of right forelimb. After about7days, when xenograft cancer growed to50-100mm3, the nude mice were randomly divided in to experimental group and control group. The nude mice in experimental group were dosed with5-Aza-CdR(lmg/kg) by intraperitoneal injection3times a week each sample. The nude mice in control group were dosed with saline solution of the same concentration by the same way. Diameter of the tumor was measured to calculate the volume and the inhibition rate. After28days, the samples were executed in order to extract DNA and RNA from tumor tissue. We selected3samples randomly from experimental group and control group for further detection. Then the methylation status of p16promoter region CpG island and the expression of p16mRNA and protein were investigated by MSP, RT-PCR and Western Blot.Results:Compared with samples in control group, the volume of tumor on nude mice in experimental group (intraperitoneal injection of1mg/kg5-Aza-CdR) shows a trend of decrease. The weight of tumor in experimental group is significantly lighter than that in control group. After samples were executed, DNA and RNA were extracted from tumor tissue for further detect. The result of MSP shows that samples of experimental group are in demethylation status, while two samples in control group are in methylation status and one sample in partially methylation status. The electrophoretogram of RT-PCR shows the expression of p16mRNA in experimental group are enhanced. The result of Western Blot shows that the expression of p16protein in experimental group are enhanced. The results are statistically significant.Conclusion:The inhibitory effect of5-Aza-CdR on gastric cancer xenografts in nude mice is proved to be statistically significant.5-Aza-CdR is proved to be an effective inhibitor of p16methylation in vivo. After treated with5-Aza-CdR, the expression of mRNA and protein are significantly enhanced, p16gene can be re-expressed. After further research,5-Aza-CdR can be potentially used for the clinical treatment of human gastric cancer.