中文摘要：

NGX6基因是新克隆的候选抑瘤基因，研究表明NGX6重表达可抑制结肠癌细胞的增殖．为进一步研究NGX6对细胞周期的影响，采用流式细胞仪检测NGX6重表达对结肠癌细胞HT-29细胞周期的影响，发现NGX6重表达可增加HT-29细胞在G0／G1期的分布比例，减少了S，G2，M期细胞数．利用蛋白质印迹和流式细胞术分析NGX6转染前后HT-29细胞周期素（cyclins）和细胞周期素依赖性蛋白激酶抑制物（cyclin-dependent kinase inhibitor，CKI）的表达变化，发现NGX6可下调HT-29细胞中cyclin E、cyclin D1的表达及上调p27的表达，对cyclin A和cyclin B的表达无明显影响，p16在三组结肠癌细胞中均无表达．研究结果表明，NGX6在HT-29细胞中通过下调cyclin E、cyclin D1和上调p27的表达，阻滞细胞周期于G0／G1期，从而发挥其在结肠癌中的抑瘤作用．

英文摘要：

NGX6, a candidate of tumor suppressor genes, can inhibit the proliferation of colon cancer in vivo and in vitro. The uncontrolled proliferation of tumor cell closely related with the dysfunction of the cell cycle. Flow cytometry and Western blot were used to explore effects of NGX6 on cell cycle progression and the expression of cyclins, CKI（p27,p 16） in colon cancer cell line HT-29. Flow cytometry （FCM） showed that the overexpression of NGX6 increased the proportion of HT-29 cells at G0/G1 phase and decreased that at S, G2 and M phase. Western blot and FCM indicated that NGX6 could down-regulate the expression ofcyclin E, cyclin D1 and increase the p27 expression,while NGX6 has no significant effect on expression of cyclin A and cyclin B. The expression of p16 was not detected in all groups. These results demonstrated that NGX6 arrested cell cycle progression at G0/G1 phase by down-regulating the expression of cyclin E, cyclin D1 and up-regulating that of p27 to inhibit the proliferation of HT-29 cells.