Epigenetic Regulation of Cutaneous Tumorigenesis

项目摘要/摘要： 这份提案描述了一项为期五年的职业发展计划，旨在支持一名学术、医生- 科学家生涯。拟议的研究项目将利用以下网址提供的专门知识和资源 华盛顿大学医学院，它有着培养内科科学家的深厚传统。Dr。 蒂莫西·莱伊，癌症基因组学和表观遗传学专家，多次获得导师奖 将在全国和华盛顿大学担任主要研究导师。的最终目标是 候选人将成为学术医学中心的独立研究员，研究表观遗传控制 皮肤癌的发生、皮肤恶性肿瘤患者的护理。 这项研究的长期目标是确定表皮表观遗传状态的变化。 正常衰老过程中出现的角质形成细胞及其在产生与年龄相关的易感性中的作用 皮肤癌。年龄增加和紫外线暴露是两个最突出的流行病学危险因素 皮肤白皙人群中皮肤癌的发展。最近的研究已经确定了克隆性扩张 临床正常皮肤中含有致癌基因突变的细胞，表明额外的遗传或表观遗传学 转化为皮肤癌需要一些事件。衰老和紫外线照射不仅会导致DNA 损伤和突变，也已被证明会导致皮肤DNA甲基化的变化 人类患者；这些变化是否与皮肤癌的发病机制有关目前尚不清楚。我们的 初步数据表明，表皮细胞的DNA甲基化状态经历了程序性变化 随着小鼠年龄的增长，基因表达的刻板印象变化也会导致 一组细胞的发育，我们将其命名为“基础老化标志性角质形成细胞”(BASKS)。我们 将探索与年龄相关的表观遗传变化，包括DNA甲基化，可能会增加这一假说 对皮肤癌的易感性有以下具体目标：目标1：我们将定义表观遗传学 小鼠表皮中由正常衰老引起的事件，将它们与功能变化联系起来，并评估它们的 在皮肤癌的发展中起着重要作用。我们将定义BASK细胞的表观遗传变化，定义 生物标志物，允许净化这一群体，并测试老化皮肤对KrasG12D的易感性- 介导皮肤肿瘤发生和UVB诱导的、突变的TrP53克隆岛在皮肤中的发展。 目标2：我们将确定个体DNA甲基转移酶在年龄依赖性疾病发生中的作用 甲基化状态和皮肤的肿瘤性转化。使用Dnmt1条件缺陷的小鼠， DNMT3A和/或DNMT3B，我们将确定这些酶是否对年龄相关 BASK表型的发展及其缺陷是否与KrasG12D介导的皮肤相关 肿瘤发生学。如果成功，从这项工作中获得的见解可能允许创造新的治疗性或 角质形成细胞癌、基底细胞癌和鳞状细胞癌的预防方法。

Project Summary/Abstract: This proposal describes a five-year career development program designed to support an academic, physician- scientist career. The proposed research project will capitalize on the expertise and resources available at Washington University School of Medicine, which has a strong tradition of developing physician-scientists. Dr. Timothy Ley, an expert in cancer genomics and epigenetics, and a recipient of multiple mentorship awards nationally and at Washington University, will serve as the primary research mentor. The ultimate goal of the candidate is to be an independent investigator in an academic medical center, studying epigenetic control of cutaneous carcinogenesis, and caring for patients with cutaneous malignancies. The long-term goal of this study is to define alterations in the epigenetic “state” of epidermal keratinocytes that arise during normal aging and their roles in creating age-related susceptibilities for skin cancer. Increasing age and UV light exposure are the two most prominent epidemiologic risk factors for the development of skin cancer in fair skinned populations. Recent studies have identified clonal expansions of cells harboring oncogenic mutations from clinically normal skin, suggesting that additional genetic or epigenetic events are required for transformation to skin cancer. Aging and UV light exposure not only cause DNA damage and mutations, but also have been demonstrated to cause DNA methylation changes in the skin of human patients; whether these alterations are relevant for skin cancer pathogenesis is currently unknown. Our preliminary data suggests that the DNA methylation state of epidermal cells undergoes a programmed change at specific loci in mice as they age, as do stereotypical changes in gene expression resulting in the development of a population of cells that we have named “basal aging-signature keratinocytes” (BASKs). We will explore the hypothesis that age-related epigenetic changes, including DNA methylation, may increase susceptibility to skin cancer development with the following specific aims: Aim 1: We will define the epigenetic events in murine epidermis that result from normal aging, relate them to functional changes, and assess their roles in the development of skin cancers. We will define the epigenetic changes in BASK cells, define biomarkers that allow for the purification of this population, and test the susceptibility of aged skin to KRASG12D- mediated skin tumorigenesis and the development of UVB-induced, mutated Trp53 clonal islands in the skin. Aim 2: We will define the roles of individual DNA methyltransferases for the development of age-dependent methylation states and for the neoplastic transformation of skin. Using mice conditionally deficient in Dnmt1, Dnmt3a, and/or Dnmt3b in epidermal cells, we will determine whether these enzymes contribute to age-related development of the BASK phenotype, and whether their deficiencies are relevant for KRASG12D-mediated skin tumorigenesis. If successful, insights gained from this work may allow for the creation of novel therapeutic or preventative approaches for the keratinocyte cancers, basal cell and squamous cell carcinoma.