大蒜素和亚硒酸钠对结肠癌细胞微卫星序列不稳定的抑制作用  

Inhibitory effect of diallytrisulfide and sodium selenite on microsatellite instability in a colon cancer cell line

作　　者：汪承亚[1] 周建伟[2] 倪黎[1] 丁小健[1] 赵红[1] 唐玲芳 

机构地区：[1]南京医科大学第一附属医院,江苏南京210029 [2]南京医科大学应用毒理研究所,江苏南京210029

出　　处：《癌症》2000年第4期300-303,共4页Chinese Journal of Cancer

基　　金：国家自然科学基金!(No 396 70 2 97)资助

摘　　要：目的 :以RER(replicationerror)表型的结肠癌细胞作靶细胞 ,研究大蒜素 (diallyltrisulfide ,DAT)和亚硒酸钠对肿瘤细胞微卫星序列 (microsatellitesequence,MS)突变的影响。方法 :将含有外源性MS ,(ca) 14,的穿梭质粒 pCMV CAR转染RER+ 或RER-结肠癌细胞株RKO或SW 480。外源性 (ca) 14 的突变可使质粒标记基因LacZ恢复正常读码 ,表达产生β 半乳糖核苷酶 ,后者使X gal变蓝。DAT及亚硒酸钠对MS突变的影响可直接通过X gal染色结果而判断出来。结果 :外源性 (ca) 14 的突变只发生于RKO细胞而不发生于SW 480细胞。使用DAT0 0 0 15 μg/ml及 0 0 15 μg/ml以及亚硒酸钠 5 μmol/L ,对细胞活力及增殖无影响 ,经作用 5天 ,均显示出对外源性(ca) 14 的突变有明显的抑制效应。但是低浓度亚硒酸钠 1μmol/L作用 5天 ,其抑制 (ca) 14 突变的作用不明显 ,延长作用时间到 5～ 6周 ,则又表现出对 (ca) 14 突变的明显抑制效应。结论 :外源性MS与内源性MS一样在RER+ 细胞中是不稳定的。DAT和亚硒酸钠能抑制RER+ 细胞中外源性 (ca) 14重复序列突变 ,提示它们对人癌细胞MS遗传不稳定有保护作用。Objective: Investigation of the effects of diallyltrisulfide (DAT) and sodium selenite on genetic instability of human tumor cells via their role in alteration of microsatellite sequence(MS) of replication error (RER) cells Methods: RER +and RER colon cancer cell lines, RKO and SW480, were used as hosts for lipofection with pCMV CAR in which a foreign (ca) 14 repeat was inserted in the coding sequence of lacZ reporter gene, resulting in misreading lacZ frame Any mutations which made the base number of (ca) 14 tract to be 3 fold resumed normal reading frame of lacZ, and lead to expression of β galactosidase Variable expression of lacZ in the transfectant cells resulted from DAT or selenite administration was measured by either blue cell counting or OD reading at λ410 after X gal staining Results: Mutations of the exogenous (ca) 14 were occurred and maintained in pCMV CAR transfectant RKO cells but not in SW480 cells DAT at 0 0015, 0 015 μg/ml and selenite at 5 μmol/L reduced markedly blue cells of RKO transfectant clones after incubation for 5 days Lower concentration of selenite at 1 μmol/L didn't show suppression of blue cell rate until cell's exposure to it for up to 5 weeks or more Conclusion: Foreign (ca) 14 repeat like endogenous MS was unstable in RER +cells Our data showed that DAT and selenite displayed an inhibitory effect on MS instability of cancer cells and thus demonstrated directly their beneficial role in stabilization of genomic DNA

关 键 词：大蒜素 亚硒酸钠 微卫星不稳定性 结肠肿瘤 

分 类 号：R735.35[医药卫生—肿瘤]