Naturally occurring dominant-negative Stat5 suppresses transcriptional activity of estrogen receptors and induces apoptosis in T47D breast cancer cells
Naturally occurring dominant-negative Stat5 suppresses transcriptional activity of estrogen receptors and induces apoptosis in T47D breast cancer cells
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DOI：
10.1038/sj.onc.1206277
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发表时间：
2003-03-20
期刊：
影响因子：
8
通讯作者：
Fujii, Y
中科院分区：
文献类型：
--
作者：
Yamashita, H;Iwase, H;Fujii, Y
信号转导子和转录激活子（Stat）5调节乳腺和造血细胞的生长、分化和存活。Stat 5在乳腺癌中的作用尚未确定，尽管Stat 5对某些造血系统恶性肿瘤至关重要。我们首次检测到Stat 5 b在人乳腺癌细胞系中被组成性激活，并使用Stat 5的显性阴性变体分析了Stat 5在雌激素受体（ER）阳性乳腺癌细胞系中的作用。产生了两种不同的羧基截短的Stat 5a衍生物。Stat 5aDelta 740对应于天然存在的可变剪接变体，Stat 5aDelta 713类似于核蛋白酶的80 kDa Stat 5a产物。Stat 5aDelta 740和Stat 5aDelta 713显示出相当的显性负性特性，并且同样良好地抑制野生型Stat 5a和Stat 5 b的转录活性。共转染实验显示，Stat 5aDelta 740完全阻断了T47 D和MCF 7细胞中内源性雌激素受体的转录活性，以及COS-7细胞中ER α和ER β的转录活性。选择Stat 5aDelta 740用于腺病毒递送，并且在感染的细胞中实现了酪氨酸磷酸化的Stat 5aDelta 740的高效表达。腺病毒介导的Stat 5aDelta 740在T47 D细胞中诱导凋亡，但在caspase-3阴性的MCF 7细胞中不诱导凋亡。目前的研究表明，Stat 5的显性负性变体的过表达抑制ER转录活性，并诱导雌激素反应性乳腺癌组织培养细胞的凋亡。
Signal transducer and activator of transcription (Stat) 5 regulates growth, differentiation, and survival of mammary and hematopoietic cells. The role of Stat5 in breast cancer has not been established, although Stat5 is critical for some hematopoietic malignancies. We detected for the first time that Stat5b is constitutively activated in human breast cancer cell lines, and analysed the role of Stat5 in estrogen receptor(ER)-positive breast cancer cell lines using dominant-negative variants of Stat5. Two distinct carboxyl-truncated Stat5a derivatives were generated. Stat5aDelta740 corresponded to a naturally occurring alternative splice variant, and Stat5aDelta713 was analogous to an 80 kDa Stat5a product of a nuclear protease. Stat5aDelta740 and Stat5aDelta713 displayed comparable dominant-negative properties and suppressed transcriptional activity of wildtype Stat5a and Stat5b equally well. Cotransfection experiments revealed that Stat5aDelta740 completely blocked transcriptional activity of endogenous estrogen receptor in T47D and MCF7 cells, and of both ERalpha and ERbeta in COS-7 cells. Stat5aDelta740 was selected for adenoviral delivery, and high-efficiency expression of tyrosine phosphorylated Stat5aDelta740 was achieved in infected cells. Adenoviral-mediated Stat5aDelta740 induced apoptosis in T47D cells but not in caspase-3-negative MCF7 cells. The present study indicates that overexpression of a dominant-negative variant of Stat5 suppresses ER transcriptional activity and induces apoptosis in estrogen-responsive breast cancer tissue culture cells.