Hormonal regulation of p53 activity in mammary tissue

描述(申请人提供)：在携带P53基因缺陷的妇女中患乳腺癌的风险极高，这揭示了P53在乳腺癌易感性中的特殊重要性。我们的实验室已经证明，乳腺上皮细胞中P53抑癌蛋白的活性受到激素的调节。具体地说，未分娩小鼠的乳房上皮中的P53活性受到损害，但对内分泌治疗有反应，内分泌治疗已被证明使乳房上皮对癌变具有抵抗力。初步数据表明，对于乳腺上皮细胞DNA损伤的P53依赖反应，需要雌激素和孕激素(E-P)的共同治疗。我们认为，在乳腺发育的特定时期，由于P53活性受损，乳腺上皮变得对癌变敏感，但特定的内分泌刺激有助于激活P53功能，并减轻这种风险。这项提案中概述的实验将确定E-P治疗调节乳腺中P53功能的途径。目的1：通过确定启动级联反应的受体(Aim 1.1)、转导信号的E P的转录靶标(Aim 1.2)以及作用于P53蛋白以使其对DNA损伤诱导的应激信号作出反应的酶(Aim 1.3)，来研究介导E P对P53活性影响的途径。目的：通过移植不同P53状态的乳腺上皮(BALB/c-TrP53/-vs BALB/c-TrP53-/-)小鼠，研究荷尔蒙治疗是否通过P53依赖机制抑制乳腺肿瘤。目的：使用药物抑制剂和来自基因敲除小鼠的乳腺组织，在全器官培养中研究依赖E-P激活P53所需的途径，以确定特定的靶点。乳腺上皮细胞系将被用来提供更高分辨率的分子机制分析。根据初步数据，将强调维甲酸代谢和转化生长因子-β信号转导的影响。这一结果将有助于确定调控乳腺上皮中P53功能的细胞机制。这些途径将为乳腺癌的治疗和预防提供新的靶点。

DESCRIPTION (provided by applicant): The extreme risk of breast cancer among women bearing genetic deficiencies in the p53 pathway reveals the particular importance of p53 in breast cancer susceptibility. Our laboratory has demonstrated that the activity of the p53 tumor suppressor protein in the mammary epithelium is subject to hormonal regulation. Specifically, p53 activity is compromised in mammary epithelium of nulliparous mice, but is responsive to endocrine treatments that have been shown to render the mammary epithelium resistant to carcinogenesis. Preliminary data demonstrate that treatment with both estrogen and progesterone (E+P) are required for p53-dependent responses to DNA damage in the mammary epithelium. We propose that the mammary epithelium is rendered susceptible to carcinogenesis due to impaired p53 activity during specific periods of mammary gland development, but that specific endocrine stimuli serve to activate p53 function and mitigate this risk. The experiments outlined in this proposal will define the pathways by which treatment with E+P regulate p53 function in the mammary gland. Aim 1: The pathways that mediate the effects of E+P on p53 activity will be examined by determining the receptors that initiate the cascade (Aim 1.1), the transcriptional targets of E+P that transduce the signal (Aim 1.2), and the enzymes that act on p53 protein to render it responsive to DNA damage-induced stress signals (Aim 1.3). Aim 2: Mice bearing transplants of mammary epithelium that vary in p53 status (BALB/c-Trp53+/- vs BALB/c-Trp53-/-) will be used to determine whether hormonal treatments inhibit mammary tumors by p53-dependent mechanisms. Aim 3: The pathways necessary for E+P-dependent activation of p53 will be examined in whole organ cultures using drug inhibitors and mammary tissue from knockout mice to identify specific targets. Breast epithelial cell lines will be used to provide higher resolution analysis of the molecular mechanisms. Based on preliminary data, the effects of retinoic acid metabolism and TGF-beta signaling will be emphasized. The results will lead to identification of cellular mechanisms that regulate p53 function in the mammary epithelium. These pathways will provide novel targets for both treatment and prevention of breast cancer.