Amphiregulin Signaling in Human Breast Cancer

描述(申请人提供)：我们已经发现，大约一半的基底类型乳腺癌有证据表明，双调节蛋白(AREG)自分泌激活了EGFR。此外，我们的数据表明，当AREG是EGFR的激活配体时，受体的运输和下游信号显著改变，导致建立了涉及NF-β和IL-1的正反馈环，表达了独特的转录谱，并获得了运动和侵袭能力。本申请中提出的工作的总体目标是阐明AREG如何从根本上改变人类乳腺癌细胞的生物学并有助于侵袭性人类乳腺癌表型的表达，并检验AREG的作用是通过激活核因子-β和IL-1介导的假设。本项目的具体目的是：1)验证这样一种假说，即在AREG刺激的细胞而不是EGF刺激的细胞中，EGFR在细胞表面的积聚是导致NF-β活化和IL-1表达的EGFR信号改变的最近的机制；2)确定AREG刺激的细胞中EGFR信号体的组成，阐明AREG激活的EGFR到核积聚的信号通路，并分析这一通路在基础乳腺癌细胞侵袭性生长表型表达中的作用。3)通过影响针对EGFR的酪氨酸磷酸酶和/或酪氨酸激酶的活性，确定IL-1信号如何通过AREG/EGFR自分泌环调节乳腺癌细胞和乳腺上皮细胞的EGFR酪氨酸磷酸化；以及4)确定在具有AREG/EGFR自分泌环的乳腺癌中，抑制EGFR是否导致IL-1下调和核因子-βB的核丢失。AREG激活EGFR从根本上改变HME细胞的生物学特性，并诱导高侵袭性和耐药的乳腺癌细胞表达表型。了解这种差异的机制基础，并了解AREG介导的EGFR激活的下游后果将提高我们对乳腺癌这一特别侵袭性亚类的生物学的理解，对于这种亚类乳腺癌，除了标准化疗之外，没有其他治疗选择。 公共卫生相关性：这项拨款申请中提出的研究旨在了解一种特定类型的人类乳腺癌侵袭性生长的机制基础，这种癌症往往发生在年轻女性中，而且预后非常差。提高我们对导致这种疾病的途径的理解将影响我们为这种类型的乳腺癌患者设计新的靶向治疗的能力。鉴于目前针对这些癌症类型的治疗形式无效，开发新的策略以更有效地治疗最具侵袭性的乳腺癌患者将对公众健康产生积极影响。

DESCRIPTION (provided by applicant): We have found that approximately half of basal type breast cancers show evidence for autocrine activation of the EGFR by amphiregulin (AREG). Furthermore, our data indicate that when AREG is the activating ligand for EGFR, receptor trafficking and down stream signaling is dramatically altered resulting in the establishment of a positive feedback loop involving NF-?B and IL-1, the expression of a distinctive transcription profile, and the acquisition of motile and invasive capacity. The over arching goal of the work proposed in this application is to elucidate how AREG fundamentally alters the biology of human breast cancer cells and contributes to the expression of phenotypes characteristic of aggressive human breast cancer, and to test the hypothesis that AREG's effects are mediated via activation of NF-?B and IL-1. The specific aims of this project are: 1) To test the hypothesis that accumulation of EGFR at the cell surface, which occurs in AREG stimulated cells and not EGF-stimulated cells, is the proximate mechanism for the altered EGFR signaling that results in activation of NF-?B and expression of IL-1, 2) To determine the components of the EGFR signalosome in AREG stimulated cells, to elucidate the signaling pathway from AREG-activated EGFR to the nuclear accumulation of NF-?B, and to analyze the role of this pathway in the expression of aggressive growth phenotypes of basal breast cancer cells, 3) To determine how IL-1 signaling modulates EGFR tyrosine phosphorylation in breast cancer cells and mammary epithelial cells with an AREG/EGFR autocrine loop by influencing the activity of tyrosine phosphatases and/or tyrosine kinases that target EGFR, and 4) to determine if EGFR-inhibition in breast cancers with AREG/EGFR autocrine loops results in down-regulation of IL-1, and loss of nuclear of NF-?B. AREG activation of EGFR fundamentally alters the biology of HME cells and induces phenotypes expressed by highly aggressive and drug-resistant breast cancer cells. Understanding the mechanistic basis for this difference, and understanding the downstream consequences of AREG mediated activation of the EGFR will improve our understanding of the biology of a particularly aggressive subclass of breast cancer for which there are no therapeutic options beyond standard chemotherapy. PUBLIC HEALTH RELEVANCE: The research that is proposed in this grant application is aimed at understanding the mechanistic basis for the aggressive growth of a particular type of human breast cancer that tends to occur in younger women and which carries a very poor prognosis. Improving our understanding of the pathways that drive this disease will impact our ability to design novel targeted therapies for patients with this type of breast cancer. Given that current forms of therapy for these cancer types are ineffective, developing novel strategies to more effectively treat patients with the most aggressive type of breast cancer will have a positive impact on public health.