Role of p53 homologs in DNA repair in human keratinocytes

项目摘要/摘要 非黑色素瘤皮肤癌是美国普通人群中最常见的恶性肿瘤 在退伍军人中非常普遍。虽然通常不是致命的，但这些皮肤癌可能是一个主要的 疾病的来源，损害生活质量，并利用大量的卫生保健资源。累积DNA 表皮角质形成细胞的损伤，特别是太阳紫外线辐射，是导致皮肤角质形成细胞损伤的一个重要因素。 非黑色素瘤皮肤癌的发展。此外，其他皮肤病的某些治疗方法也使用DNA 会增加患皮肤癌风险的有害物质。巨大的、扭曲的DNA损伤通过 核苷酸切除修复过程，但对角质形成细胞DNA修复的调控知之甚少。 临床观察和最近的体外研究，包括来自PI实验室的研究表明，人类 角质形成细胞具有调节核苷酸切除修复的独特机制。肿瘤的丧失 非角质形成细胞类型中的抑制子P53通常会导致最丰富的UVR- 诱导出的光产物。然而，目前获奖期间的工作证明角质形成细胞 在修复受损之前，需要同时失去P53和家族的另一成员-P63。此外， PI实验室最近的研究表明，P53和P63的双重缺陷与受损有关 鳞癌的核苷酸切除修复可被利用来优先杀死这些 癌症。目前的提案试图了解p53和p63调节DNA的机制。 人角质形成细胞在正常生理过程中的修复，并确定它们在发生和发展中的作用 非黑色素瘤皮肤癌的行为。我们假设P53和P63协同调节细胞的修复。 UVR诱导的未分化角质形成细胞和终末分化角质形成细胞的主要DNA光产物， 这个过程的失调发生在鳞状细胞癌中，并提供了一种机制 突变和肿瘤进展，这可能是治疗上可利用的。这些假设将通过以下方式进行检验 具体目的如下：1)确定P53和P63调节修复蛋白的机制 角质形成细胞中的水平；2)确定p63在角质形成细胞核苷酸切除修复中的作用 3)评价核苷酸切除修复对角质形成细胞p63过度表达的反应； 4)建立、表征和纠正鳞状细胞癌中p63介导的修复失调。在… 其结论，该项目将阐明独特的光保护机制的分子基础。 表皮皮肤细胞，使我们能够了解这些机制是如何在皮肤过程中功能失调的 癌症的发生，并提出预防和治疗皮肤癌的新策略。

Project Summary/Abstract Non-melanoma skin cancers are the most common malignancies in the general population of the United States and are highly prevalent in the veteran population. While not usually fatal, these skin cancers can be a major source of morbidity, impair quality of life, and utilize significant health care resources. Cumulative DNA damage in epidermal keratinocytes, particularly from solar ultraviolet radiation, is an important factor in the development of non-melanoma skin cancers. In addition, certain therapies for other skin diseases utilize DNA damaging agents that increase the risk of skin cancer. Bulky, distorting DNA lesions are removed by the process of nucleotide excision repair, but little is known about the regulation of DNA repair in keratinocytes. Clinical observations and recent in vitro studies, including those from the PI's laboratory, indicate that human keratinocytes possess unique mechanisms for regulating nucleotide excision repair. Loss of the tumor suppressor, p53, in non-keratinocyte cell types typically results in a loss of repair of the most abundant UVR- induced photoproduct. However, work during the current award period has documented that keratinocytes require loss of both p53 and another member of the family-p63-before repair is compromised. Furthermore, recent work in the PI's laboratory suggests that a dual deficiency in p53 and p63 is associated with impaired nucleotide excision repair in squamous cell carcinomas that could be exploited to preferentially kill these cancers. The current proposal seeks to understand the mechanisms by which p53 and p63 regulate DNA repair in human keratinocytes during normal physiology, and to determine their role in the genesis and behavior of non-melanoma skin cancers. We hypothesize that p53 and p63 coordinately regulate repair of the major UVR-induced DNA photoproducts in both undifferentiated and terminally differentiating keratinocytes, and that dysregulation of this process occurs in squamous cell carcinomas and provides a mechanism for mutagenesis and tumor progression that may be therapeutically exploitable. The hypotheses will be tested by the following Specific Aims: 1) To determine the mechanisms by which p53 and p63 regulate repair protein levels in keratinocytes; 2) To determine the role of p63 in nucleotide excision repair during keratinocyte differentiation; 3) To assess the response of nucleotide excision repair to p63 over-expression in keratinocytes; and 4) To model, characterize and correct p63-mediated repair dysregulation in squamous cell carcinomas. At its conclusion, this project will elucidate the molecular basis of the unique photoprotective mechanisms of epidermal skin cells, allow us to understand how these mechanisms are dysfunctional during skin carcinogenesis, and suggest new strategies for preventing and treating skin cancers.