p63 and p73 Signaling in Cell Growth and Cancer

描述(申请人提供)：尽管p53在肿瘤抑制中的关键作用仍未受到挑战，但其家族成员p63和p73在正常细胞功能和肿瘤发生中的作用还远未确定。P53蛋白家族的结构相似和功能相似，在协同和拮抗相互作用中，通过相似的信号通路将它们连接起来；然而，体内模型表明，P63和P73在P53独立的发育和分化过程中都发挥作用。特别是，p63基因缺失的小鼠缺乏表皮和相关结构，如乳腺和前列腺癌。有趣的是，p63在皮肤、乳腺和前列腺等几种上皮组织的基底层都有表达，在许多鳞癌和基底样癌中过表达。有证据表明，p63在肿瘤中可能部分通过与p73的相互作用发挥作用，而p73在许多人类肿瘤中也过度表达。这些研究的目的是确定p63和p73在细胞代谢和存活以及上皮-间充质串扰和过渡中的作用，并发现这些作用在肿瘤发生过程中是如何被解除调控的。通过产生和整合广泛的染色质免疫沉淀和微阵列数据集，我们鉴定了许多新的p63和p73靶基因。基于我们的发现，我们提出了以下相互关联的假说：(I)p63和p73调控参与细胞代谢和存活以及上皮-间充质细胞相互作用和转变的独特或共享的靶基因的转录；以及(Ii)适当的p63和p73活性的丧失将导致细胞生存和功能的改变，导致发育异常或肿瘤发生，这取决于功能障碍的生物时间点。这些假说将通过以下具体目标来检验：(1)分析由p63和p73唯一或协同调控的新的靶基因。我们将使用器官模型系统确定这些靶基因在p63和p73信号下游生物相关端点中的作用；(2)分析p63和p73蛋白复合体以及新发现的与这些家族成员相互作用的蛋白质；以及(3)分析有条件的、组织特异性的p73基因敲除的小鼠。这些小鼠将在器官和代谢功能以及对压力的反应方面进行表征。将研究组织特异性p63、p73和p53基因敲除在乳腺中的单独或联合作用，以确定家族成员在成人组织功能和肿瘤易感性中的单独或协同作用。P53家族在人类肿瘤中的解除调控，以及对癌症中p63和p73信号轴的机械性理解将转化为癌症患者的治疗益处，突显了理解p63和p73调控和功能的重要性。

DESCRIPTION (provided by applicant): Although the pivotal role of p53 in tumor suppression remains unchallenged, the role of its family members, p63 and p73 in normal cell function and tumorigenesis is far from certain. Structural similarities and functions of the p53 family of proteins connect them in similar signaling pathways, in both collaborative and antagonistic interactions; however, in vivo models suggest a role for both p63 and p73 in p53-independent developmental and differentiation processes. In particular, p63-null mice lack an epidermis and related structures such as mammary and prostate glands. Interestingly, p63 is expressed in the basal layer of several epithelial tissues such as skin, breast and prostate, and is overexpressed in many squamous and basal-like carcinomas. Evidence suggests that p63 may function in tumors in part through interaction with p73, which is also overexpressed in many human tumors. The goal of the proposed studies is to determine the roles of p63 and p73 in cell metabolism and survival as well as epithelial-mesenchymal crosstalk and transition, and to discover how these roles are deregulated during tumorigenesis. Through generation and integration of comprehensive chromatin immunoprecipitation and microarray data sets, we identified numerous novel p63 and p73 target genes. Based on our findings, we propose the following interrelated hypotheses: (i) p63 and p73 regulate the transcription of unique or shared target genes involved in cell metabolism and survival as well as epithelial-mesenchymal cross-talk and transition; and, (ii) loss of proper p63 and p73 activity will lead to altered cell survival and function resulting in developmental abnormalities or tumorigenesis, depending on the biological time point of dysfunction. These hypotheses will be tested through the following Specific Aims: (1) To analyze select novel target genes uniquely or coordinately regulated by p63 and p73. We will determine the role of these target genes in biologically relevant endpoints downstream of p63 and p73 signaling using organotypic model systems; (2) To analyze p63 and p73 protein complexes and a newly identified protein that interacts with these family members; and (3) To analyze mice with conditional, tissue-specific knock-out of p73. The mice will be characterized in terms of organ and metabolic function and response to stress. The effect of tissue-specific knockout of p63, p73, and p53, alone or in combination, in the mammary gland will be studied to determine the separate or coordinate roles of the family members in adult tissue function, and susceptibility to tumorigenesis. The importance of understanding p63 and p73 regulation and function is underscored by the deregulation of the p53 family in human tumors and the expectation that a mechanistic understanding of the p63 and p73 signaling axes in cancer will translate to therapeutic benefit for cancer patients.