Par-4 transcriptionally regulates bcl-2 through a WT1-binding site on the bcl-2 promoter
Par-4 transcriptionally regulates bcl-2 through a WT1-binding site on the bcl-2 promoter
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DOI：
10.1074/jbc.m205865200
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发表时间：
2003-05-30
影响因子：
4.8
通讯作者：
Lopez-Berestein, G
中科院分区：
文献类型：
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作者：
Cheema, SK;Mishra, SK;Lopez-Berestein, G
bcl-2原癌基因表达水平的升高与前列腺癌雄激素非依赖性的出现广泛相关。虽然bcl-2作为t（14：18）易位断裂点首次从人滤泡B细胞淋巴瘤中克隆，但由于基因结构没有明显改变，bcl-2过表达的机制在晚期前列腺癌中很大程度上不确定。我们研究了前列腺凋亡反应基因4（Par-4）和Wilms' tumor 1基因（WT 1）产物在前列腺癌细胞系中Bcl-2表达调控中的作用。我们观察到生长停滞和凋亡，在Bcl-2蛋白和转录的高Bcl-2表达，雄激素非依赖性前列腺癌细胞系，全反式维甲酸治疗（ATRA）后，但这并没有发生在雄激素依赖性细胞系表达低水平的Bcl-2。全反式维甲酸处理后Bcl-2蛋白和转录物的减少伴随着Par-4定位的变化和WT 1蛋白表达的诱导。在表达异位Par-4的稳定克隆和ATRA处理的细胞中，我们观察到Bcl-2蛋白和转录物减少。这伴随着WT 1表达的诱导。WT 1参与Par-4介导的Bcl-2下调进一步定义为阻断内源性WT 1表达，这导致Bcl-2表达增加。最后，我们检测到Par-4和WT 1蛋白结合到先前确定的WT 1结合位点上的bcl-2启动子在体外和体内导致从bcl-2启动子的转录减少。我们的结论是，Par-4通过Bcl-2启动子上的WT 1结合位点调节Bcl-2。这些数据还确定Par-4核定位作为ATRA介导的bcl-2调节的新机制。
Elevated expression levels of the bcl-2 proto-oncogene have been extensively correlated with the appearance of androgen independence in prostate cancer. Although bcl-2 was first cloned as the t(14:18) translocation breakpoint from human follicular B cell lymphoma, the mechanism of overexpression of bcl-2 is largely undefined for advanced prostate cancer because there are no gross alterations in the gene structure. We investigated the role of the product of the prostate apoptosis response gene-4 (Par-4) and the product of the Wilms' tumor 1 gene (WT1) in the regulation of Bcl-2 expression in prostate cancer cell lines. We observed growth arrest and apoptosis, upon decreasing Bcl-2 protein and transcript in the high Bcl-2-expressing, androgen-independent prostate cancer cell line, by all-trans-retinoic acid treatment (ATRA), but this did not occur in the androgen-dependent cell line expressing low levels of Bcl-2. The decrease in the Bcl-2 protein and transcript following all-trans-retinoic acid treatment was accompanied by changes in localization of Par-4 and an induction in the expression of WT1 protein. In stable clones expressing ectopic Par-4 and in ATRA-treated cells, we observed decreased Bcl-2 protein and transcript. This was accompanied by an induction in WT1 expression. The involvement of WT1 in the Par-4-mediated down-modulation of Bcl-2 was further defined by blocking endogenous WT1 expression, which resulted in an increase in Bcl-2 expression. Finally, we detected Par-4 and WT1 proteins binding to a previously identified WT1-binding site on the bcl-2 promoter both in vitro and in vivo leading to a decrease in transcription from the bcl-2 promoter. We conclude that Par-4 regulates Bcl-2 through a WT1-binding site on the bcl-2 promoter. These data also identify Par-4 nuclear localization as a novel mechanism for ATRA-mediated bcl-2 regulation.