Regulation of tumor promotion by RasGRP1

RasGRP1 对肿瘤促进的调节

• 批准号: 6931008
• 负责人: PATRICIA S LORENZO
• 金额: $ 27.29万
• 依托单位: UNIVERSITY OF HAWAII AT MANOA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-02 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6931008
• 关键词: SDS polyacrylamide gel electrophoresis; apoptosis; biological signal transduction; cell differentiation; cell growth regulation; chemical carcinogenesis; flow cytometry; gene expression; gene targeting; genetically modified animals; guanine nucleotide binding protein; immunocytochemistry; keratinocyte; laboratory mouse; phorbols; polymerase chain reaction; protein kinase C; skin neoplasms; tissue /cell culture; tumor promoters; western blottings

DESCRIPTION (provided by applicant): Tumor promotion is a reversible and non-genotoxic stage in carcinogenesis and, as a consequence, the various components of this process are central targets for the development of mechanism-based anticancer and chemopreventive drugs. In the mouse skin model of chemical-induced carcinogenesis, tumor promotion is achieved by exposure of carcinogen-treated epidermis to phorbol esters, which induce the clonal expansion of those keratinocytes carrying the carcinogen-induced activating mutation in the H-Ras gene. The nature of the interaction between phorbol esters and Ras signaling in tumor promotion has not been defined yet. Although protein kinase C (PKC) has historically been considered responsible for all phorbol ester actions, the discovery of non-PKC receptors casts doubts on the assumption of an exclusive PKC-mediated effect. We have recently characterized the novel Ras activator RasGRP1 as a high affinity receptor for phorbol esters, and our preliminary data indicate that RasGRP1 is expressed in the epidermal keratinocyte, the target cell in chemical carcinogenesis. These data suggest that RasGRP1 may represent a novel and direct link between Ras and phorbol ester signaling in the epidermis. The present proposal will address this possibility. We hypothesize that phorbol esters can modulate RasGRP1 activity in keratinocytes, and that this modulation contributes to the mechanisms activated by tumor promotion during cancer formation. The specific aims to test the hypothesis are: (1) to define the functional role of RasGRP1 on the responses induced by phorbol esters in keratinocytes, including growth arrest, differentiation, and apoptosis; (2) to determine if RasGRP1 signaling is altered in initiated (H-Ras-mutated) keratinocytes, either by changes in the level of expression of RasGRP1, changes in substrate affinity, or both; and (3) to establish in vivo models to investigate the role of RasGRP1 in skin carcinogenesis and tumor promotion (knockout and transgenic animals for RasGRP1). Taken together, the results of this study have the potential to unravel a new molecular target for the transmission of phorbol ester-signals involved in carcinogenesis. This information could lead to future approaches for developing novel chemopreventive compounds targeted to tumor promotion events.

描述（由申请人提供）：肿瘤促进是致癌过程中的可逆和非遗传毒性阶段，因此，该过程的各种组分是开发基于机制的抗癌和化学预防药物的中心靶点。在化学诱导的致癌作用的小鼠皮肤模型中，通过将致癌物处理的表皮暴露于佛波醇酯来实现肿瘤促进，佛波醇酯诱导那些在H-Ras基因中携带致癌物诱导的活化突变的角质形成细胞的克隆扩增。佛波醇酯和Ras信号在肿瘤促进中的相互作用的性质尚未确定。虽然蛋白激酶C（PKC）历来被认为是负责所有佛波酯的行动，非PKC受体的发现投下了怀疑的假设，一个排他性的PKC介导的效果。我们最近的特点是新的Ras激活剂RasGRP 1作为佛波酯的高亲和力受体，我们的初步数据表明，RasGRP 1在表皮角质形成细胞，化学致癌作用的靶细胞中表达。这些数据表明，RasGRP 1可能代表了一种新的和直接的联系Ras和佛波酯信号在表皮。本提案将处理这一可能性。我们假设佛波醇酯可以调节角质形成细胞中的RasGRP 1活性，并且这种调节有助于在癌症形成期间通过肿瘤促进激活的机制。验证这一假设的具体目的是：（1）确定RasGRP 1在由佛波醇酯诱导的角质形成细胞反应中的功能作用，包括生长停滞、分化和凋亡;（2）确定RasGRP 1信号传导是否在引发角质形成细胞凋亡中改变。（H-Ras突变的）角质形成细胞，通过RasGRP 1表达水平的变化、底物亲和力的变化或两者;以及（3）建立体内模型以研究RasGRP 1在皮肤癌发生和肿瘤促进中的作用（RasGRP 1的敲除和转基因动物）。总之，这项研究的结果有可能解开一个新的分子靶点的佛波酯参与致癌信号的传输。这些信息可能会导致未来的方法，开发新的化学预防化合物针对肿瘤促进事件。