摘要目的 观察S-腺苷蛋氨酸(SAM)对体外培养的人胃癌细胞的细胞周期、凋亡以及侵袭力的影响,及对细胞中c-myc基因和尿激酶型纤溶酶原激活剂(uPA)基因甲基化状态及表达的影响.方法 用不同浓度(0、2、4 mmol/L)SAM处理体外培养的MKN-28、SGC-7901和MKN-45细胞72h,用流式细胞仪检测各组细胞周期分布和细胞凋亡率;Transwell法检测各组细胞侵袭力的改变;RT-PCR法检测各组细胞c-myc基因和uPA基因mRNA表达的变化;甲基化特异性PCR法检测各组细胞中c-myc基因和uPA基因的甲基化状态.结果随SAM浓度增加,3种细胞凋亡率均明显增加(P值均<0.01),侵袭力均受到明显抑制(P值均<0.01).与对照组相比,SGC-7901细胞G0/G1期细胞明显增加[(56.67±1.18)%比(74.53±2.49)%,P<0.01],细胞增殖指数(PI)明显降低[(43.33±1.18)%比(25.50±2.46)%,P<0.01].随SAM浓度增加,SGC-7901细胞c-myc和uPA基因及MKN-45细胞的uPA基因mRNA表达明显减弱(P值分别<0.05和<0.01),经SAM 4mmol/L处理的MKN-28细胞的uPA基因mRNA表达亦明显减弱(P<0.01).经SAM处理的SGC-7901细胞c-myc基因和3种细胞的uPA基因均部分甲基化或完全甲基化.结论 SAM可通过逆转SGC-7901细胞c-myc基因和3种细胞uPA基因的低甲基化状态,从而调控基因的表达,并可通过提供甲基,改善基因的低甲基化状态,达到抑制胃癌细胞生长、增殖和侵袭的作用.

abstractsObjective To investigate the impacts of S-ademetionine (SAM) on cell cycles,apoptosis and invasive capacity of gastric cancer cell lines,and its effects on methylation and expressions of c-myc and uPA.Methods MKN-28,SGC-7901 and MKN-45 cells were treated with gradient concentrations of SAM(0,2 and 4 mmol/L) for 72 hours.The changes of cell cycles and apoptosis were detected by flow eytometry,and invasion was detected by transwell assay.The expressions and methylations of c-myc and uPA were examined by RT-PCR and MSP,respectively.Results The cell apoptosis significantly increased and cell invasive capacity was restrained in three cell lines with increase of SAM concentration (all P values<0.01).In SGC-7901,the cell percentage of G0/G1 phase significantly increased [(74.53±2.49)% vs.(56.67±1.18)%,P<0.053,whereas the cell proliferation index (PI) decreased [(25.50±2.46)% vs.(43.33±1.18)%,P<0.05] in comparison with controls.The expressions of c-myc and uPA mRNA in SGC-7901,uPA mRNA in MKN-45 and in 4 mmol/L SAM treated MKN-28 significantly decreased.The methylations of c-myc gene in SGC-7901 and uPA gene in three cell lines were reversed after treated with SAM.Conclusions SAM reduces expressions of c-myc and uPA by reversing the methylations of c-myc in SGC-7901 and uPA in all three cell lines.However SAM,as methyl donor,can restrain the development and progression of tumor when hypomethylation widely presents in cancer.