The role of E1AF, an ets-oncogene family tranascription factor in cell cycle regulation.

E1 AF是ets癌基因家族转录因子的成员，并且E1 AF被证明与诱导多个MMP基因转录的MMP的启动子区结合。我们证明了Ad 12型E1 A能够通过使E1 AF表达失活来抑制癌细胞系的侵袭能力。建立了表达Ad 12 E1 A的口腔鳞癌细胞株。北方杂交结果显示，转染细胞E1 AF mRNA表达降低。在mRNA水平和蛋白质水平上都鉴定了MMPs的表达减少。CAT检测证实MMP基因转录活性降低。结果表明，Ad 12 E1 A通过下调E1 AF的表达，抑制癌细胞的侵袭能力，并通过下调MMP的表达来抑制癌细胞的侵袭能力。ZnCl刺激MT9.22细胞后，MMP-9和p21蛋白的表达协同增加，而E1 AF诱导MT9.22细胞后，MMP-9和p21蛋白的表达也同时增加，提示肿瘤细胞的侵袭性生长是在细胞周期的静止状态下进行的，E1 AF在这一过程中起着关键作用。使用不同量的E1 AF和p53表达载体沿着p21启动子荧光素酶报告质粒，证实了p21活性的增加。集落形成试验表明E1 AF具有与p53相似的肿瘤抑制作用。因此，这些结果表明，E1 AF能够与p53协同相互作用;因此，这种相互作用可以影响p21，导致其活性增强，并最终抑制肿瘤。

E1AF is a member of the ets-oncogene family transcription factor, and E1AF was shown to bind to the promoter region of MMPs that induce transcription from multiple MMP genes. We demonstrated that Ad type 12 E1A is able to suppress the invasion ability of a cancer cell line by inactivating E1AF expression. Ad12E1A expressing oral squamous cell carcinoma cell line was established. Northern blotting indicated that the expression of E1AF mRNA decreased in transfected cells. Reduced expression of MMPs was identified both in mRNA levels and in protein levels. Reduced transcriptional activity of MMP gene was confirmed by CAT assay. These results suggest that Ad12E1A downregulates E1AF which, in turn, restrains invasion ability of human cancer cells by way of downregulaton of MMP expression.Ca9.22 cells that manifest low levels of E1AF and MMP-1 and -9 expression were transfected with metallothionein inducible E1AF expression vector. MMP-9 and p21_<waf1/cipl> protein were synergistically increased in ZnCl stimulated MT9.22 cells, and MMP-9 and p21 protein were expressed in the same cells when E1AF was induced in MT9.22 cells.These results imply that invasive growth of tumor cells occur in static state of cell cycle and E1AF play key role of this phenomenon.Luciferase assays, using different amounts of E1AF and p53 expression vectors along with p2 1 promoter luciferase reporter plasmids, demonstrate an increase in the activity of p21. Colony formation assay indicates that E1AF is capable of tumor suppression similar to p53. These results, therefore, suggest that E1AF is able to interact synergistically with p53 ; in consequence, this interaction can influence p21 leading to an enhancement of its activity and eventually, tumor suppression.