TUMOR SUPPRESSOR ACTIVITIES OF ETS1 GENE PRODUCTS

我们异位表达了转录因子Ets！在两个不同的地方 高致瘤性人结肠癌细胞株DLD-1和HCT116， 不表达内源性ETS1蛋白，并已获得几个 独立克隆人。野生型ETS1蛋白在这些细胞中的表达 结肠癌细胞逆转转化表型和致瘤性 以剂量依赖的方式。相比之下，在DLD-1细胞中的表达 ETS1的一个变体，缺乏转录活性，没有改变 细胞的致瘤特性，表明细胞的减少 这些克隆的致瘤性是野生型ETS1所特有的 基因产品。DLD-1野生型ETS1转染体生长缓慢 无血清培养比表达突变ETS1蛋白的DLD-1细胞缺乏 转录活动。此外，DLD-1野生型ETS1 与DLD-1相比，转基因细胞在细胞周期的G0/G1期停留时间更长 突变型ETS1转染体。这些结果表明，ETS1蛋白在 适当的条件可能会干扰结肠癌细胞的生长。 鉴定ETS1与肿瘤抑制相关的功能结构域 函数，我们已经生成了ETS1的变体，其中缺少 转录活性或DNA结合活性。实验是 突变ETS1蛋白在结肠、乳腺和前列腺中的表达研究进展 以及确定“最小的ETS1区域”负责 用于抑制结肠癌细胞的致瘤性。

We have ectopically expressed transcription factor ETS! in two different highly tumorigenic human colon cancer cell lines, DLD-1 and HCT116, that do not express endogenous ETS1 protein and have obtained several independent clones. The expression of wild-type ETS1 protein in these colon cancer cells reverses the transformed phenotype and tumorigenicity in a dose-dependent manner. By contrast, expression in DLD-1 cells of a variant form of ETS1, lacking transcriptional activity, did not alter the tumorigenic properties of the cells, suggesting that the reduction in tumorigenicity in these clones was specific for the wild-type ETS1 gene products. DLD-1 wild-type ETS1 transfectants grow much slower in serum-free media than DLD-1 cells expressing mutant ETS1 proteins lacking transcriptional activities. Furthermore, DLD-1 wild-type ETS1 transfectants remain longer in G0/G1 stage of the cell cycle than DLD-1 mutant ETS1 transfectants. These results suggest that ETS1 protein under appropriate conditions may interfere with growth of colon cancer cells. To identify functional domains of ETS1 involved in tumor suppressor function, we have generated variant forms of ETS1 lacking either transcriptional activities or DNA binding activities. Experiments are in progress to express mutant ETS1 proteins in colon, breast and prostate cancer cells as well as to identify "minimum region of ETS1" responsible for suppression of tumorigenicity of colon cancer cells.