Loss of protein inhibitors of activated STAT-3 expression in glioblastoma multiforme tumors: implications for STAT-3 activation and gene expression.
Loss of protein inhibitors of activated STAT-3 expression in glioblastoma multiforme tumors: implications for STAT-3 activation and gene expression.
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DOI：
10.1158/1078-0432.ccr-08-0618
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发表时间：
2008-08-01
期刊：
影响因子：
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通讯作者：
Benveniste EN
中科院分区：
文献类型：
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作者：
Brantley EC;Nabors LB;Gillespie GY;Choi YH;Palmer CA;Harrison K;Roarty K;Benveniste EN
信号转导器和转录激活剂 (STAT) 响应多种细胞因子激活转录，控制增殖、基因表达和细胞凋亡。 STAT 蛋白（特别是 STAT-3）的异常激活通过促进细胞周期进展、刺激血管生成和损害肿瘤免疫监视，与包括多形性成胶质细胞瘤 (GBM) 在内的许多癌症的发病机制有关。人们对人类恶性肿瘤中的内源性 STAT 抑制剂（即激活 STAT 蛋白抑制剂 (PIAS) 蛋白）知之甚少。本研究的目的是检查来自对照和 GBM 大脑的人体组织样本中 STAT-3 及其负调节因子 PIAS3 的表达。通过免疫印迹和免疫组织化学分析对照和 GBM 人体组织，以确定 STAT-3 的激活状态和 PIAS3 蛋白的表达。通过检查细胞增殖、STAT-3转录活性和STAT-3靶基因表达来确定GBM细胞中siRNA或PIAS3过表达抑制PIAS3的功能结果。这是通过 3H-TdR 掺入、STAT-3 显性失活构建体、RT-PCR 和免疫印迹来完成的。通过酪氨酸和丝氨酸磷酸化评估，与对照组织相比，GBM 组织中的 STAT-3 激活升高。有趣的是，我们观察到对照组织中PIAS3的表达，而GBM组织中PIAS3蛋白的表达大大降低。 PIAS3 的抑制导致胶质母细胞瘤细胞增殖增强。相反，PIAS3 过表达抑制 STAT-3 转录活性、STAT-3 调节基因的表达和细胞增殖。我们认为 GBM 中 PIAS3 的缺失有助于增强 STAT-3 转录活性和随后的细胞增殖。
Signal Transducers and Activators of Transcription (STATs) activate transcription in response to numerous cytokines, controlling proliferation, gene expression and apoptosis. Aberrant activation of STAT proteins, particularly STAT-3, is implicated in the pathogenesis of many cancers, including Globlastoma Multiforme (GBM), by promoting cell cycle progression, stimulating angiogenesis, and impairing tumor immune surveillance. Little is known about the endogenous STAT inhibitors, the Protein Inhibitors of Activated STATs (PIAS) proteins, in human malignancies. The objective of this study was to examine the expression of STAT-3 and its negative regulator, PIAS3, in human tissue samples from control and GBM brains. Control and GBM human tissues were analyzed by immunoblotting and immunohistochemistry to determine the activation status of STAT-3 and expression of the PIAS3 protein. The functional consequence of PIAS3 inhibition by siRNA or PIAS3 over-expression in GBM cells was determined by examining cell proliferation, STAT-3 transcriptional activity and STAT-3 target gene expression. This was accomplished using 3H-TdR incorporation, STAT-3 dominant-negative constructs, RT-PCR and immunoblotting. STAT-3 activation, as assessed by tyrosine and serine phosphorylation, was elevated in GBM tissue compared to control tissue. Interestingly, we observed expression of PIAS3 in control tissue, while PIAS3 protein expression in GBM tissue was greatly reduced. Inhibition of PIAS3 resulted in enhanced glioblastoma cellular proliferation. Conversely, PIAS3 over-expression inhibited STAT-3 transcriptional activity, expression of STAT-3 regulated genes, and cell proliferation. We propose that the loss of PIAS3 in GBM contributes to enhanced STAT-3 transcriptional activity and subsequent cell proliferation.