Transfer of E2F-1 to human glioma cells results in transcriptional up-regulation of Bcl-2.
Transfer of E2F-1 to human glioma cells results in transcriptional up-regulation of Bcl-2.
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发表时间：
2001-09
期刊：
影响因子：
11.2
通讯作者：
C. Gomez-Manzano;P. Mitlianga;J. Fueyo;Ho Young Lee;Min Hu;K. Spurgers;T. Glass;D. Koul;T. Liu;T. McDonnell;W. Yung
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文献类型：
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作者：
C. Gomez-Manzano;P. Mitlianga;J. Fueyo;Ho Young Lee;Min Hu;K. Spurgers;T. Glass;D. Koul;T. Liu;T. McDonnell;W. Yung
强有力的证据支持这样的原则，即E2 F转录因子的激活，通过改变p16-细胞周期蛋白D-Rb途径，是一个关键事件，在大多数人类恶性胶质瘤的恶性进展。E2 F的致癌能力与E2 F介导的几种正调节细胞增殖的蛋白质的上调有关。然而，E2 F可能通过激活抗凋亡分子间接增强增殖。在这项工作中，我们试图确定E2 F-1介导的事件是否涉及抗凋亡分子Bcl-2的上调。Western印迹分析显示，在E2 F-1转移后24小时，Bcl-2上调，但Bcl-x（L）未上调。北方杂交结果显示E2 F-1的转染也能上调Bcl-2 RNA表达。为了支持这些发现和E2 F-1在Bcl-2的诱导中具有直接作用的概念，我们在Bcl-2序列内发现了推定的E2 F结合位点。随后涉及bcl-2启动子中CTCCGCGC位点的凝胶迁移率移动和超移动实验表明，E2 F-1结合Bcl-2。反式激活实验一致表明，异位E2 F-1激活位于bcl-2基因P1启动子区-1448/-1441区域的应答元件。正如预期的那样，E2 F家族的其他成员如E2 F-2和E2 F-4也反式激活bcl-2启动子。我们的研究结果表明，E2 F-1调节抗凋亡分子Bcl-2的表达，并建议Bcl-2的上调可能有利于E2 F-1和E2 F家族转录因子的其他成员的致癌作用。
Strong evidence exists to support the tenet that activation of E2F transcription factors, via alterations in the p16-cyclin D-Rb pathway, is a key event in the malignant progression of most human malignant gliomas. The oncogenic ability of E2F has been related to the E2F-mediated up-regulation of several proteins that positively regulate cell proliferation. However, E2F may indirectly enhance proliferation by activating antiapoptotic molecules. In this work, we sought to ascertain whether E2F-1-mediated events involve the up-regulation of the antiapoptotic molecule Bcl-2. Western blot analyses showed up-regulation of Bcl-2 but not of Bcl-x(L) by 24 h after the transfer of E2F-1. Northern blot studies showed that transfer of E2F-1 also up-regulated Bcl-2 RNA. In support of these findings and the concept that E2F-1 has a direct effect in the induction of Bcl-2, we found a putative E2F binding site within the Bcl-2 sequence. Subsequent gel-mobility shift and supershift experiments involving the CTCCGCGC site in the bcl-2 promoter showed that E2F-1 bound Bcl-2. Transactivation experiments consistently showed that ectopic E2F-1 activated responsive elements located in the -1448/-1441 region in the P1 promoter region of the bcl-2 gene. As expected, other members of the E2F family of transcription factors such as E2F-2 and E2F-4 also transactivated the bcl-2 promoter. Our results demonstrate that E2F-1 modulates the expression of the antiapoptotic molecule Bcl-2 and suggest that up-regulation of Bcl-2 may favor the oncogenic role of E2F-1 and other members of the E2F family of transcription factors.