Role of Cdc25A in breast cancer

Cdc25A 在乳腺癌中的作用

• 批准号: 6986965
• 负责人: HIROAKI KIYOKAWA
• 金额: $ 27.81万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6986965
• 关键词: RNA interference; apoptosis; biological signal transduction; breast neoplasms; cell cycle proteins; cell growth regulation; cell line; cyclins; enzyme activity; gene expression; genetically modified animals; human genetic material tag; laboratory mouse; mammary epithelium; molecular oncology; molecular pathology; neoplasm /cancer genetics; neoplastic cell; neoplastic process; neoplastic transformation; oncogenes; oxidative stress; phosphoprotein phosphatase; posttranslational modifications; protein degradation; transforming growth factors

DESCRIPTION (provided by applicant): Cdc25A, a dual-specific protein phosphatase, is frequently overexpressed in breast cancer, and associated with poor survival. The long-term goal of this program is to understand the exact role of Cdc25A in breast cancer and establish a scientific basis for anti-cancer therapies targeted on this protein. Cdc25A promotes cell cycle progression by activating cyclin E (A)/Cdk2 during G1 through S, and also cyclin B(A)/Cdk1 at the G2/M boundary. Ectopic expression of Cdc25A shortens the passage through G1 and cooperates with H-ras in transforming mouse embryonic fibroblasts, while silencing of Cdc25A results in arrest at both G1 and G2. We have shown that transforming growth factor-beta (TGFbeta), which is important for morphogenesis and tumor suppression of the mammary gland, downregulates Cdc25A in both transcriptional and posttranslational manners. These observations suggest that Cdc25A could be a critical oncogene in breast cancer, although it has not been demonstrated in vivo using animal models. This proposal is based on our following preliminary data: (i) Cdc25A-heterozygous knockout mice we generated show marked resistance to MMTV-ras induced mammary tumorigenesis; (ii) An MMTV-Cdc25A transgene synergistically cooperates with the MMTV-ras transgene in murine tumorigenesis; (iv) TGF-beta promotes Cdc25A protein degradation in a Smad3-dependent manner and this pathway could be defective in MCF7 and other human breast cancer cell lines; (iii) Cdc25A overexpression inhibits apoptosis signal-regulating kinase-1 (ASK1) and diminishes cellular sensitivity to oxidative stress-induced apoptosis. The central hypothesis evaluated in this proposal is that defective degradation of Cdc25A protein is rate-limiting for initiation and/or progression of breast cancer, causing deregulated control of cell cycle progression and apoptosis. The specific aims are: (1) Determine whether deregulated TGF-beta/Smad signaling is involved in Cdc25A stabilization in human breast cancer cell lines; (2) Determine how reduced Cdc25A expression or altered stability ofCdc25A affects cell cycle progression, cellular sensitivity to oxidative stress, and malignant transformation in response to ras and neu, using MCF-10a cells with Cdc25A siRNA and tetracycline-inducible expression ofCdc25A mutants; (3) Determine how altered Cdc25A expression affects breast tumorigenesis in mice with MMTV-neu, MMTV-myc or MMTV-Wnt-1 transgene, using our novel Cdc25A-knockout and MMTV-Cdc25A transgenic mouse lines. We expect that these studies will provide us with significant insight into the role of Cdc25A stabilization in breast cancer development and a molecular handle to develop effective therapies to target the oncogene.

描述（由申请人提供）：CDC25A是一种双特异性蛋白质磷酸酶，经常在乳腺癌中过表达，并且与生存不良有关。该计划的长期目标是了解CDC25A在乳腺癌中的确切作用，并为针对该蛋白质的抗癌疗法建立科学基础。 Cdc25a通过在G1至S期间激活细胞周期蛋白E（A）/CDK2以及在G2/M边界处激活Cyclin B（A）/CDK1来促进细胞周期的进程。 Cdc25a的异位表达缩短了通过G1的通道，并与H-RAS合作在转化小鼠胚胎成纤维细胞中，而Cdc25a的沉默会导致G1和G2的停滞。我们已经表明，转化生长因子β（TGFBETA），这对于乳腺的形态发生和肿瘤抑制很重要，在转录和翻译后的举止下都下调了Cdc25a。这些观察结果表明，CDC25A可能是乳腺癌中的关键癌基因，尽管使用动物模型在体内尚未证明它。该建议基于我们以下初步数据：（i）CDC25A杂合敲除小鼠我们产生的表明对MMTV-RAS诱导的乳腺肿瘤的抗性明显。 （ii）MMTV-CDC25A转基因在鼠肿瘤发生中与MMTV-RAS转基因协同合作； （iv）TGF-beta以Smad3依赖性的方式促进Cdc25a蛋白降解，并且该途径在MCF7和其他人类乳腺癌细胞系中可能有缺陷。 （iii）CDC25A的过表达抑制了凋亡信号调节激酶-1（ASK1），并降低细胞对氧化应激诱导的凋亡的敏感性。该提案中评估的中心假设是，Cdc25a蛋白的缺陷降解是乳腺癌的启动和/或进展的限制，导致对细胞周期进展和凋亡的控制控制。具体目的是：（1）确定在人类乳腺癌细胞系中CDC25A稳定中是否涉及放松管制的TGF-β/SMAD信号传导； （2）确定CDC25A表达降低或CDC25A的稳定性如何影响细胞周期的进展，对氧化应激的细胞敏感性以及对RAS和NEU的恶性转化，使用CDC25A和TetracyCline-siRNA和Tetracycline诱导的表达Cdc25a siRNA和Tetracycline sirna和NEU的恶性转化； （3）使用我们的新型CDC25A-KNOCKOUT和MMTV-CDC25A转基因小鼠系使用MMTV-NEU，MMTV-MYC或MMTV-WNT-1转基因的CDC25A表达如何影响小鼠的乳腺肿瘤发生。我们预计这些研究将为我们提供对CDC25A稳定在乳腺癌发育中的作用以及开发有效疗法以靶向癌基因的作用的重要见解。