Erythropoietin receptors in breast cancer

描述(申请人提供)：本方案的目的是研究促红细胞生成素(EPO)及其受体(EPOR)在乳腺癌病理生物学中的表达和功能。EPO是一种低氧诱导的糖蛋白激素，是主要的造血细胞因子，通过与其特定的细胞表面受体EPOR结合来调节红细胞的产生，EPOR是I型细胞因子受体家族的成员。重组人促红细胞生成素被广泛用于癌症患者治疗或预防与化疗和放射治疗相关的贫血。我们实验室最近的研究表明，EPOR在乳腺癌细胞中有高水平的功能性表达。在人乳腺上皮细胞中观察到EPOR表达的诱导，对EpoRs结构的鉴定揭示了新的EPOR mRNA亚型在乳腺癌中的表达。EPOR及其配体EPO在肿瘤细胞中的共同表达提示有可能产生自分泌或旁分泌生长刺激环。在体外或体内抑制EPOR信号导致乳腺癌细胞增殖减少，这表明EPOR信号在乳腺癌的病理生物学中存在先前未知的功能作用。这项研究的目的是(1)研究EPO-EPOR的表达和信号在体内乳腺癌细胞增殖和诱导肿瘤血管生成中的作用；(2)研究EPOR介导的信号刺激原代人乳腺上皮细胞增殖的能力；(3)确定EPO-EPOR的过度表达是否与肿瘤缺氧有关，并作为乳腺癌患者的不良预后因素。我们建议研究EPO-EPOR在乳腺癌细胞中的表达和激活机制，并利用已建立的人乳腺癌异种移植和啮齿动物乳房窗原位乳腺癌研究EPO-EPOR在肿瘤生长和血管生成中的作用。我们将在原代人乳腺上皮细胞(HMECs)中过表达EPOR，以研究EPOR信号通路在HMECs中的激活及其对细胞增殖的影响。我们将表征肿瘤缺氧在EPO-EPOR过度表达中的作用，在用细胞缺氧标记的原发乳腺肿瘤中。我们将确定EPO-EPOR在原发肿瘤中的高水平共表达作为一个预后因素的效用，该因素可能与乳腺癌患者的不良无病生存和总生存率有关。预计这些研究的结果将有助于我们理解EPO和EPOR在乳腺癌病理生物学中的作用，并可能导致未来针对EPOR功能的新的治疗策略的制定。

DESCRIPTION (provided by applicant): The objective of this proposal is to investigate erythropoietin (EPO) and erythropoietin receptor (EpoR) expression and function in the pathobiology breast cancer. EPO is a hypoxia-inducible glycoprotein hormone that is the principal hematopoietic cytokine regulating the production of red blood cells by binding to its specific cell surface receptor EpoR, a member of the Type I cytokine receptor family. Recombinant human EPO is widely used in patients with cancer for treatment or prevention of anemia associated with chemotherapy and radiation therapy. Recent studies in our laboratory revealed high levels of functional EpoR expression in breast cancer cells. Induction of EpoR expression was observed in human mammary epithelial cells and characterization of the structure of EpoRs revealed the expression of novel EpoR mRNA isoforms in breast cancer. The co-expression of EpoR and its ligand EPO in tumor cells suggested the potential for generation of an autocrine or paracrine growth stimulatory loop. Inhibition of EpoR signaling in vitro or in vivo resulted in decreased proliferation of breast cancer cells suggesting the presence of a previously unknown, functional role for EpoR signaling in the pathobiology of breast cancer. The studies in this proposal will aim to (1) Characterize the role of EPO-EpoR expression and signaling in the proliferation of breast cancer cells and induction of tumor angiogenesis in vivo (2) Investigate the ability of EpoR-mediated signaling to stimulate the proliferation of primary human mammary epithelial cells and (3) Determine whether EPO-EpoR over-expression is coupled to tumor hypoxia and serves as an adverse prognostic factor in patients with breast cancer. We propose to study mechanisms of EPO-EpoR expression and activation in breast cancer cells and investigate the role of EPO-EpoR in tumor growth and angiogenesis using well-established human breast cancer xenografis and rodent mammary windows for orthotopic breast cancer. We will over-express EpoR in primary human mammary epithelial cells (HMECs) to investigate the activation of EpoR signaling pathways in HMECs and the effects on cellular proliferation in an experimental model of early mammary carcinogenesis. We will characterize the role of tumor hypoxia in EPO-EpoR over-expression in primary breast tumors pre-labeled with a cellular hypoxia marker. We shall determine the utility of high levels of EPO-EpoR co-expression in primary tumors as a prognostic factor that may be linked to an unfavorable disease-free and overall survival in patients with breast cancer. It is anticipated that the findings of these studies will contribute to our understanding of the role of EPO and EpoR in the pathobiology of breast cancer and may lead to the formulation of new therapeutic strategies targeted against EpoR function in the future.