Transcriptional and Posttranscriptional regulation of fibulin-1 by estrogens leads to differential induction of messenger ribonucleic acid variants in ovarian and breast cancer cells
Transcriptional and Posttranscriptional regulation of fibulin-1 by estrogens leads to differential induction of messenger ribonucleic acid variants in ovarian and breast cancer cells
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DOI：
10.1210/en.2004-1239
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发表时间：
2005-02-01
期刊：
影响因子：
4.8
通讯作者：
Pujol, P
中科院分区：
文献类型：
--
作者：
Bardin, A;Moll, F;Pujol, P
纤维蛋白-1是一种细胞外基质蛋白，在上皮性卵巢癌和乳腺癌中过度表达。在雌激素受体(ER)阳性的卵巢和乳腺癌细胞系中，雌激素显著增加了纤毛蛋白-1mRNA的水平。用纤维蛋白-1启动子载体进行的转染实验表明，17β-雌二醇(E_2)促进了纤维蛋白-1基因的转录，并且ERα比ERβ更有效地介导了转基因纤维蛋白-1启动子对E_2的调节。利用缺乏特异性蛋白1(Sp1)的SL2细胞和GC盒的定点突变，我们证明了E2的调节是通过近端的特异性蛋白1结合位点进行的。此外，我们还发现，两种主要的纤毛蛋白-1剪接变异体-1C和-1D的mRNAs是由雌二醇诱导的。这两种mRNAs变体的诱导都是直接的，并且不依赖于新合成的蛋白质中间体。有趣的是，放线菌素D追赶实验表明，E2处理选择性地缩短了纤维蛋白-1D mRNA的半衰期。这表明雌激素对纤毛蛋白-1变异体的稳定性有不同的影响，并可能解释了E2处理时纤毛蛋白-1D mRNA积累减少的原因。总之，我们的数据表明，雌激素通过ERpha，在转录和转录后水平上都是纤维蛋白-1表达的关键调节因子。在卵巢癌和乳腺癌中过度表达的纤毛蛋白-1C变异体的优先诱导，可能在雌激素促进的癌变过程中发挥重要作用。
Fibulin-1 is an extracellular matrix protein overexpressed in epithelial ovarian and breast cancers. In estrogen receptor (ER)-positive ovarian and breast cancer cell lines, fibulin-1 mRNA levels are markedly increased by estrogens. Transfection experiments using fibulin-1 promoter constructs indicate that 17beta-estradiol (E2) increases fibulin-1 gene transcription and that ERalpha is more potent than ERbeta to mediate E2 regulation of the transfected fibulin-1 promoter. Using SL2 cells devoid of specificity protein 1 (Sp1) and site-directed mutagenesis of GC boxes, we evidenced that the E2 regulation occurs through a proximal specificity protein 1 binding site. In addition, we show that fibulin-1C and -1D mRNAs, the two major fibulin-1 splicing variants, are differentially induced by E2. The induction of both mRNAs variants is direct and independent of a newly synthesized protein intermediate. Interestingly, actinomycin D chase experiments demonstrate that E2 treatment selectively shortens the fibulin-1D mRNA half-life. This indicates that estrogens affect differentially the stability of fibulin-1 variants and may explain the lower accumulation of fibulin-1D mRNA on E2 treatment. In conclusion, our data show that estrogens, via ERalpha, are key regulators of fibulin-1 expression at both the transcriptional and post-transcriptional levels. The preferential induction of the fibulin-1C variant, which is overexpressed in ovarian and breast cancer, might play an important role in estrogen-promoted carcinogenesis.