Role of YB-1 in EGFR regulation and breast cancer

YB-1 在 EGFR 调节和乳腺癌中的作用

• 批准号: 7267699
• 负责人: ISABELLE M BERQUIN
• 金额: $ 24.03万
• 依托单位: WAKE FOREST UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7267699
• 关键词: Anchorage-Independent Growth; Apoptosis; Binding; Binding Sites; Biological Assay; Boxing; Breast; Breast Cancer Cell; Breast Cancer Treatment; Cell Cycle Arrest; Cell Cycle Regulation; Cell Proliferation; Cellular Stress; Chromosomal Instability; Cyclin A; Cyclin-Dependent Kinase Inhibitor; DNA binding protein B; EGF gene; Enhancers; Epidermal Growth Factor Receptor; Epithelial Cells; Feedback; Fibroblasts; Genes; Genetic; Genetic Screening; Genetic Transcription; Growth; Human; In Vitro; Indium; Introns; Knockout Mice; Lead; Lesion; Ligands; Mammary Neoplasms; Mammary gland; Mediating; Messenger RNA; Mutation; Neoplasm Metastasis; Nuclear; Nuclear Translocation; Outcome; Patients; Phenotype; Phosphorylation; Promoter Regions; Protein Overexpression; Proteins; Receptor Signaling; Regulation; Reporter; Repression; Research Personnel; Role; Sampling; Serine; Signal Pathway; Sum; Transcriptional Regulation; Transgenic Mice; Translations; Work; base; c-erbB-1 Proto-Oncogenes; cell growth; chromatin immunoprecipitation; expression cloning; in vivo; malignant breast neoplasm; mouse model; outcome forecast; programs; promoter; receptor; receptor expression; senescence; tumor; tumor growth; tumor initiation; tumorigenic

DESCRIPTION (provided by applicant): Aberrant expression of the epidermal growth factor receptor (EGFR) is an indicator of poor prognosis in breast cancer. However, the mechanism by which EGFR becomes elevated is unclear. In a genetic screen to identify genes that mediate EGF-independent proliferation of breast cancer cells, we isolated YB-1 (Y-box binding protein 1), a multifunctional regulator of gene transcription and translation. We found that YB-1 overexpression in immortal human mammary epithelial cells (HMECs) conferred EGF independence and increased EGFR levels. YB 1 binds to the EGFR gene control regions, and elevated YB-1 levels in breast cancer samples correlate with EGFR expression and with poor patient outcome. Moreover, YB 1 transgenic mice develop mammary tumors. Interestingly, Akt phosphorylates YB-1 on Ser102, a residue necessary for YB-1 nuclear localization, EGFR induction, and growth stimulation. We hypothesize that YB-1 and EGFR are part of a positive feedback loop whereby EGFR signaling increases YB-1 nuclear localization; nuclear YB-1 binds to promoter regions to regulate transcription of EGFR and other genes controlling proliferation, which contributes to breast cancer formation. We propose the following Specific Aims: 1) Investigate the transcriptional regulation of EGFR by YB-1 in HMECs. We will analyze functional YB-1 binding elements in the EGFR gene that mediate induction by YB-1 using chromatin immunoprecipitation, reporter assays, and electrophoretic mobility assays. 2) Investigate the mechanism by which YB-1 stimulates EGF-independent cell growth. We will determine if (a) YB-1-induced EGF independence of breast epithelial cells requires YB-1 Ser102 phosphorylation and nuclear translocation; (b) YB-1 activates EGFR signaling pathways; (c) knockdown of YB-1 in HMECs reverses EGF independence and triggers cell cycle arrest, senescence or apoptosis; (d) YB-1-induced EGF independence requires both induction of EGFR and repression of negative growth regulators. 3) Examine the role of YB-1 and EGFR in tumor formation. We will determine if targeting YB-1 and/or EGFR in human breast cancer cells reduces their anchorage-independent growth in vitro and their tumorigenic and metastatic potential in an orthotopic nude mouse model. The proposed studies will deepen our understanding of the way breast cancer develops. Most importantly, this work will examine whether targeting YB-1 and EGFR in tumors represents a viable strategy for therapy in a subset of breast cancer where treatment options are currently limited.

描述（由申请人提供）：表皮生长因子受体（EGFR）的异常表达是乳腺癌预后不良的一个指标。然而，EGFR升高的机制尚不清楚。为了鉴定介导不依赖egf的乳腺癌细胞增殖的基因，我们分离了YB-1 (Y-box结合蛋白1)，这是一种基因转录和翻译的多功能调节因子。我们发现，YB-1在不朽的人乳腺上皮细胞（HMECs）中的过表达赋予了EGF独立性，并增加了EGFR水平。YB-1与EGFR基因控制区结合，乳腺癌样本中YB-1水平升高与EGFR表达相关，并与患者预后不良相关。此外，yb1转基因小鼠还会发生乳腺肿瘤。有趣的是，Akt磷酸化YB-1的Ser102，这是YB-1核定位、EGFR诱导和生长刺激所必需的残基。我们假设YB-1和EGFR是EGFR信号增加YB-1核定位的正反馈回路的一部分；细胞核YB-1与启动子区域结合，调控EGFR和其他控制增殖的基因的转录，促进乳腺癌的形成。我们提出以下具体目标：1)研究YB-1在hmec中对EGFR的转录调控。我们将使用染色质免疫沉淀、报告者测定和电泳迁移率测定分析EGFR基因中介导YB-1诱导的功能性YB-1结合元件。2)研究YB-1刺激不依赖egf的细胞生长的机制。我们将确定(a) YB-1诱导的乳腺上皮细胞的EGF独立性是否需要YB-1 Ser102磷酸化和核易位；(b) YB-1激活EGFR信号通路；(c) HMECs中YB-1的敲低逆转EGF独立性，引发细胞周期阻滞、衰老或凋亡；(d) yb -1诱导的EGF独立性需要同时诱导EGFR和抑制负生长调节因子。3)探讨YB-1和EGFR在肿瘤形成中的作用。我们将确定在人乳腺癌细胞中靶向YB-1和/或EGFR是否会降低其体外非锚定生长及其在原位裸鼠模型中的致瘤性和转移潜力。拟议的研究将加深我们对乳腺癌发展方式的理解。最重要的是，这项工作将检验肿瘤中靶向YB-1和EGFR是否代表了目前治疗选择有限的乳腺癌亚群的可行治疗策略。