Regulation of epithelial-mesenchymal transition and stem cell activity by PTEN in breast cancer

PTEN 对乳腺癌上皮间质转化和干细胞活性的调节

• 批准号: 9250104
• 负责人: Shaohua Li
• 金额: $ 16.45万
• 依托单位: RBHS-ROBERT WOOD JOHNSON MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9250104
• 关键词: Actins; Address; Alleles; Animals; Area; BRCA1 gene; Binding Sites; Breast Cancer Cell; Breast Epithelial Cells; Breast cancer metastasis; Cancer Prognosis; Cellular biology; Chromatin Remodeling Factor; Clinical Trials; Complex; Epithelial; Event; FRAP1 gene; Fatty acid glycerol esters; Foundations; Gene Expression Regulation; Generations; Genes; Goals; Gray unit of radiation dose; Growth; Human; Immunoprecipitation; Knockout Mice; Light; Link; Lipids; Malignant Neoplasms; Mammary Neoplasms; Mammary gland; Maps; Mass Spectrum Analysis; Mediating; Mesenchymal; Modeling; Molecular; Morphogenesis; Mus; Mutation; Neoplasm Metastasis; PTEN gene; Pathway interactions; Penetrance; Phenotype; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Phosphotransferases; Phosphotyrosine; Predictive Value; Process; Protein Dephosphorylation; Protein p53; Protein phosphatase; Proteins; Regulation; Relapse; Reporting; Resistance; Role; SWI/SNF Family Complex; Signal Pathway; Signal Transduction; Site-Directed Mutagenesis; Specificity; Stem cells; Susceptibility Gene; TP53 gene; Testing; Therapeutic; Time; Transitional Cell; Tumor Suppression; Tumor Suppressor Proteins; Tumorigenicity; Xenograft procedure; base; cancer recurrence; cancer risk; cancer stem cell; cell growth; chromatin remodeling; clinically relevant; conventional therapy; drug discovery; early onset; epigenetic regulation; genetic analysis; inhibitor/antagonist; insight; knock-down; loss of function; mTOR Inhibitor; malignant breast neoplasm; mammary gland development; migration; mutant; new therapeutic target; novel; overexpression; promoter; public health relevance; reconstitution; transcription factor; tumor; tumor progression; tumorigenesis

 DESCRIPTION (provided by applicant): Epithelial-mesenchymal transition (EMT) has been implicated in promoting breast cancer invasion and metastasis. Recent studies have shown that this important process is also responsible for the generation of breast cancer stem cells (CSCs), which are resistant to conventional therapy and contribute to tumor metastasis and relapse. Independent of these findings, mutations in BRCA1/2, TP53 and PTEN have emerged as high- penetrance susceptibility genes and are clinically relevant for the determination of breast cancer risk and prognosis. Among these genes, PTEN inactivation promotes both EMT and CSC enrichment. However, the underlying molecular mechanisms behind these activities are largely unknown. In our genetic analysis of PTEN functions in epithelial morphogenesis, we have identified Abi1, a key component of the WAVE regulatory complex (WRC), as a new substrate for PTEN. Protein interaction studies have further demonstrated a novel interaction between Abi1 and Smarcc1 of the SWI/SNF chromatin remodeling complex, which links PTEN to SWI/SNF-mediated epigenetic regulation of cancer. PTEN dephosphorylates Abi1 and consequently downregulates Abi1 and Smarcc1. Overexpression of Abi1 or Smarcc1 in human mammary epithelial cells promotes EMT and enhances stem cell activity. Based on these findings, we hypothesize that PTEN loss induces EMT and CSC enrichment through Abi1 and Smarcc1 in breast cancer. To test this hypothesis, we propose two specific aims. In Aim 1, the role of Abi1 in PTEN loss-induced EMT, CSC enrichment, tumorigenicity and metastasis will be analyzed by gain- and loss-of-function approaches in breast cancer cells and a mouse xenograft mammary fat pad model. In addition, we will delete one or both Abi1 alleles in PTEN- null mouse mammary glands to determine if Abi1 elevation mediates PTEN loss-induced breast tumor formation. To elucidate the signaling events downstream of PTEN-Abi1, we will focus on the interaction of Abi1 with WRC components and Abl kinase and their role in the EMT and CSC enrichment. In Aim 2, we will map the binding sites that mediate the Abi1-Smarcc1 interaction by site-directed mutagenesis. We will then analyze the functional consequences of the Abi1-Smarcc1 interaction in SWI/SNF complex assembly and chromatin remodeling activity at the promoters of the EMT-inducing transcription factors. The impact on EMT and CSC activity will be analyzed both in breast cancer cells and mouse xenografts. Furthermore, we will test the hypothesis that elevated Smarcc1 competes with Smarcc2 in the SWI/SNF complex and thus induces EMT and CSC activity by overexpressing Smarcc2 and knocking down Smarcc1 in PTEN-deficient breast cancer cells. Successful completion of the proposed studies will lay the foundation for developing therapeutic strategies targeting EMT and CSCs in PTEN-deficient breast cancer. It will also shed light on the new PTEN- Abi1-Smarcc1 pathway.

 描述（由申请人提供）：上皮间质转化（EMT）与促进乳腺癌侵袭和转移有关，最近的研究表明，这一重要过程也与乳腺癌干细胞（CSC）的产生有关。与这些发现无关，BRCA1/2、TP53 和 PTEN 突变已成为高外显率易感基因。在这些基因中，PTEN 失活可促进 EMT 和 CSC 富集，但在我们对 PTEN 在上皮形态发生中的功能的遗传分析中，这些活性背后的分子机制在很大程度上尚不清楚。 ，我们确定了 WAVE 调节复合物 (WRC) 的关键成分 Abi1 作为 PTEN 的新底物。蛋白质相互作用研究进一步证明了 Abi1 和 Smarcc1 之间的新型相互作用。 SWI/SNF 染色质重塑复合体将 PTEN 与 SWI/SNF 介导的癌症表观遗传调控联系起来，从而下调 Abi1 和 Smarcc1 在人乳腺上皮细胞中的过度表达，促进 EMT 并增强干细胞活性。基于这些发现，我们发现 PTEN 缺失通过 Abi1 和 Smarcc1 诱导 EMT 和 CSC 富集为了检验这一假设，我们在目标 1 中提出了两个具体目标，将通过乳腺癌功能获得和丧失的方法来分析 Abi1 在 PTEN 缺失诱导的 EMT、CSC 富集、致瘤性和转移中的作用。癌细胞和小鼠异种移植乳腺脂肪垫模型 此外，我们将删除 PTEN 缺失小鼠乳腺中的一个或两个 Abi1 等位基因，以确定 Abi1 升高是否介导 PTEN。为了阐明 PTEN-Abi1 下游的信号转导事件，我们将重点关注 Abi1 与 WRC 成分和 Abl 激酶的相互作用及其在 EMT 和 CSC 富集中的作用。通过定点诱变介导 Abi1-Smarcc1 相互作用的结合位点然后我们将分析 SWI/SNF 复合物组装中 Abi1-Smarcc1 相互作用的功能后果。 EMT 诱导转录因子启动子处的染色质重塑活性将在乳腺癌细胞和小鼠异种移植物中分析对 EMT 和 CSC 活性的影响。此外，我们将测试 SWI/ 中升高的 Smarcc1 与 Smarcc2 竞争的假设。 SNF 复合物，从而通过在 PTEN 缺陷的乳腺癌细胞中过表达 Smarcc2 并敲除 Smarcc1 来诱导 EMT 和 CSC 活性，这将为拟议研究的成功完成奠定基础。该基金会正在开发针对 PTEN 缺陷乳腺癌的 EMT 和 CSC 治疗策略，该基金会还将阐明新的 PTEN-Abi1-Smarcc1 通路。