Regulation of tumor promotion by RasGRP1

RasGRP1 对肿瘤促进的调节

• 批准号: 6678116
• 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 2008-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6678116
• 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一个可逆且非基因毒性的阶段，因此，该过程的各个组成部分是开发基于机制的抗癌和化学预防药物的中心目标。在化学诱导致癌的小鼠皮肤模型中，通过将致癌物处理的表皮暴露于佛波酯来促进肿瘤生长，佛波酯诱导那些携带致癌物诱导的 H-Ras 基因激活突变的角质形成细胞的克隆扩增。佛波酯和 Ras 信号传导在肿瘤促进中相互作用的性质尚未明确。尽管蛋白激酶 C (PKC) 历来被认为是所有佛波酯作用的原因，但非 PKC 受体的发现使人们对 PKC 介导的唯一作用的假设产生了怀疑。我们最近将新型 Ras 激活剂 RasGRP1 定性为佛波酯的高亲和力受体，我们的初步数据表明 RasGRP1 在表皮角质形成细胞（化学致癌作用中的靶细胞）中表达。这些数据表明 RasGRP1 可能代表了表皮中 Ras 和佛波酯信号传导之间的新颖且直接的联系。本提案将解决这种可能性。我们假设佛波酯可以调节角质形成细胞中的 RasGRP1 活性，并且这种调节有助于癌症形成过程中肿瘤促进所激活的机制。检验该假设的具体目的是：（1）明确RasGRP1对佛波酯在角质形成细胞中诱导的反应（包括生长停滞、分化和凋亡）的功能作用； (2) 确定 RasGRP1 信号传导在起始（H-Ras 突变）角质形成细胞中是否通过 RasGRP1 表达水平的变化、底物亲和力的变化或两者同时发生改变； （3）建立体内模型，研究Ra​​sGRP1在皮肤癌发生和肿瘤促进中的作用（RasGRP1基因敲除和转基因动物）。总而言之，这项研究的结果有可能揭示一个新的分子靶标，用于传递与致癌作用有关的佛波酯信号。这些信息可能会导致未来开发针对肿瘤促进事件的新型化学预防化合物的方法。