c-Src/EGF Receptors Interactions and Therapeutic Resistance in Breast Cancer

乳腺癌中的 c-Src/EGF 受体相互作用和治疗耐药

• 批准号: 7135324
• 负责人: SARAH J PARSONS
• 金额: $ 31.41万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7135324
• 关键词: breast neoplasms; cytochrome c; human; ligands; mitochondria; mutant; neoplasm /cancer; neoplastic cell; phosphorylation; receptor; role; xenotransplantation; breast neoplasms; cytochrome c; human; ligands; mitochondria; mutant; neoplasm /cancer; neoplastic cell; phosphorylation; receptor; role; xenotransplantation

DESCRIPTION (provided by applicant): The goals of this proposal are to determine in breast cancer patients the utilization of a novel signaling pathway emanating from the epidermal growth factor receptor (EGFR) that mediates resistance to drug therapy and to identify the downstream targets of this pathway. Our recent data suggest that ligand-activated EGFR may contribute to drug resistance by translocating to the mitochondria and binding to the mitochondrial enzyme, Cox II (cytochrome c oxidase II). Cox II is a key component of the electron transport chain that binds cytochrome c. It is postulated that binding of EGFR enhances Cox II activity and retention of cytochrome c in the mitochondria, thus reducing drug-induced apoptosis. Cox II binds phospho-Tyr 845 (pY845) of the EGFR, a novel site that is phosphorylated by c-Src following EGF treatment. The adaptor protein, p130Cas (Cas), may play a role in this process by activating c-Src and promoting phosphorylation of Y845 independently of ligand. Mutation of Y845 has no effect on the catalytic activity of the receptor but ablates EGF-induced DNA synthesis and EGF-mediated survival of breast cancer cells following drug treatment. It is not currently known how Cox II binding to pY845 affects Cox II activity or other properties of the mitochondria. The full array of therapeutic agents for which this mechanism applies is also not known. Three approaches will be taken to address these questions. First, we will examine selected breast cancer cell lines that inducibly or transiently express wt or mutant Y845F EGFR for their sensitivity to a panel of drugs that are currently in clinical use. It is expected that cells expressing the wt EGFR will exhibit enhanced resistance, while those expressing the mutant receptor will be more sensitive. Crosstalk between pathways emanating from pY845 and the estrogen receptor (ER) will also be examined in the context of these same cell lines. Second, we will measure alterations in mitochondrial components and functions following drug treatment in cells expressing either the wt or mutant EGFR. Finally, we will explore the possibility that, through its ability to activate c-Src, Cas can promote phosphorylation of Y845 independently of, or in concert with, EGF. In each case, findings from cultured cells and xenograft tumors will be compared to those of human breast cancer samples. Relevance: In spite of significant, recent advances in prevention and treatment of breast cancer, approximately 40,000 women succumb to metastatic or recurrent disease each year. Many fail therapy because their tumors are resistant to the action of cytotoxic or cytostatic drugs. The EGFR family plays an important role in resistance, and we hypothesize that survival signaling through pY845 on the EGFR is a key component of the process. Our studies aim to achieve a better understanding of which cancers demonstrate pY845-dependent resistance to therapy, so that we can target this pathway for intervention.

描述（由申请人提供）：该提案的目标是在乳腺癌患者中确定从表皮生长因子受体（EGFR）发出的新型信号通路的利用，该途径介导了对药物治疗的耐药性并鉴定该途径的下游靶标。我们最近的数据表明，配体激活的EGFR可能通过转移到线粒体并与线粒体酶Cox II（细胞色素C氧化酶II）结合而导致耐药性。 Cox II是结合细胞色素c的电子传输链的关键组成部分。据推测，EGFR的结合增强了COX II活性并在线粒体中的细胞色素C的保留，从而减少了药物诱导的细胞凋亡。 Cox II结合了EGFR的磷酸化磷酸-TYR 845（PY845），EGFR是一种新型位点，在EGF处理后通过C-SRC磷酸化。衔接蛋白P130CA（CAS）可以通过激活C-SRC并促进Y845的磷酸化来独立于配体，在此过程中起作用。 Y845的突变对受体的催化活性没有影响，但是在药物治疗后，EGF诱导的DNA合成和EGF介导的乳腺癌细胞的存活率没有影响。目前尚不知道Cox II与PY845的结合如何影响线粒体的Cox II活性或其他特性。该机制适用的全部治疗剂也尚不清楚。将采用三种方法来解决这些问题。首先，我们将检查选定的乳腺癌细胞系，这些细胞系有诱导或瞬时表达WT或突变体Y845F EGFR，以了解其对当前临床用途的一组药物的敏感性。预计表达WT EGFR的细胞将表现出增强的抗性，而表达突变受体的细胞将更敏感。从PY845发出的途径和雌激素受体（ER）之间的串扰也将在这些相同的细胞系的背景下进行检查。其次，我们将在表达WT或突变体EGFR的细胞中测量线粒体成分的改变和功能。最后，我们将探讨通过激活C-SRC的能力，CAS可以独立或与EGF协同促进Y845的磷酸化。在每种情况下，都会将培养细胞和异种移植肿瘤的发现与人类乳腺癌样品的发现进行比较。相关性：尽管在乳腺癌的预防和治疗方面取得了重大进展，但每年约有40,000名妇女屈服于转移性或经常性疾病。许多失败的治疗是因为它们的肿瘤对细胞毒性或细胞抑制药物的作用有抵抗力。 EGFR家族在阻力中起着重要的作用，我们假设EGFR上通过PY845的生存信号传导是该过程的关键组成部分。我们的研究旨在更好地了解哪些癌症证明PY845依赖于治疗的耐药性，以便我们可以针对这种干预途径。