Isozyme specific effects of PKCs in thyroid cells

甲状腺细胞中 PKC 的同工酶特异性作用

• 批准号: 7585238
• 负责人: JUDY L MEINKOTH
• 金额: $ 23.19万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7585238
• 关键词: Acute; Adenoviruses; Anaplastic Carcinomas; Apoptosis; Area; Autopsy; Benign; Cell Cycle Progression; Cell Cycle Regulation; Cell Death; Cell Proliferation; Cells; Cellular biology; Chronic; Complex; Country; DNA Sequence Rearrangement; Data; Development; Differentiated Gene; Disease; Down-Regulation; Endocrine; Event; Exhibits; Frequencies; Gene Expression; Genes; Goals; Growth; Human; Individual; Isoenzymes; Maintenance; Malignant Neoplasms; Mediating; Modeling; Molecular; Mutation; N-terminal; Oncogenic; Papillary; Papillary Carcinoma; Papillary Neoplasm; Patients; Peptides; Phorbol Esters; Play; Positioning Attribute; RAS genes; RET Oncogene; RNA Interference; Rattus; Reagent; Reporting; Research Personnel; Role; Signal Pathway; Specialized Epithelial Cell; Staging; Thyroid Gland; Thyroid Hormones; adenoma; base; carcinogenesis; cell transformation; clinically relevant; experience; inhibitor/antagonist; insight; neoplastic cell; novel; novel strategies; outcome forecast; programs; thyroid neoplasm; tumor

DESCRIPTION (provided by applicant): Thyroid tumors are the most common endocrine malignancy. It has been estimated that up to 90% of the autopsies performed in this country reveal the presence of slow-growing thyroid tumors. While the prognosis for patients with well-differentiated follicular and papillary thyroid tumors is good, anaplastic thyroid tumors are rapidly fatal. Activating Ras mutations are particularly prevalent in human thyroid tumors. Ras mutations are found in benign adenomas and at a higher frequency in follicular and anaplastic carcinomas. Mutations in B-Raf, a downstream Ras effector, are the most frequent mutational event in papillary thyroid tumors. These observations support roles for Ras in the initiation and progression of thyroid tumors. A large proportion of papillary thyroid tumors exhibit amplification and rearrangement of the PKCepsilon gene, leading to the expression of an N-terminal fragment of PKCepsilon structurally similar to the V1 domain, a peptide that selectively inhibits PKCepsilon translocation. Interestingly, most papillary thyroid tumors exhibit decreased expression of PKCepsilon. Moreover, expression of the RET/PTC oncogene induced the selective translocation, followed by downregulation of PKCepsilon. PKCalpha expression is increased in follicular thyroid tumors, tumors that also harbor Ras mutations. It is our hypothesis that individual PKC isozymes play essential roles in the initiation and maintenance of thyroid cell transformation by Ras. Our preliminary data demonstrate that PKCdelta selectively reproduces the acute effects of oncogenic Ras on aberrant cell cycle progression and apoptosis; that PKCepsilon is required for Ras-induced morphological changes; that PKCs mimic the inhibitory effects of Ras on thyroid differentiation; and that Ras-transformed thyroid cells exhibit alterations in PKC expression and activity. The proposed studies investigate the roles of individual PKC isozymes in the initiation and maintenance of Ras transformation in rat thyroid cells. This will be accomplished using highly specific molecular reagents including adenoviruses for PKC isozymes, selective PKC peptide activators and inhibitors and RNA interference. This analysis will provide novel insight into the molecular mechanisms through which Ras dysregulates thyroid cell proliferation, differentiation and survival, and may give rise to the development of new strategies to selectively impair tumor cell proliferation and/or reactivate differentiated gene expression.

描述（由申请人提供）：甲状腺肿瘤是最常见的内分泌恶性肿瘤。据估计，该国高达 90% 的尸检显示存在生长缓慢的甲状腺肿瘤。虽然分化良好的滤泡状和乳头状甲状腺肿瘤患者的预后良好，但未分化的甲状腺肿瘤会迅速致命。激活 Ras 突变在人类甲状腺肿瘤中尤其普遍。 Ras 突变见于良性腺瘤，且在滤泡性癌和间变性癌中出现频率较高。 B-Raf（Ras 下游效应子）的突变是甲状腺乳头状肿瘤中最常见的突变事件。这些观察结果支持 Ras 在甲状腺肿瘤的发生和进展中的作用。大部分甲状腺乳头状肿瘤表现出 PKCepsilon 基因的扩增和重排，导致 PKCepsilon N 末端片段的表达，其结构与 V1 结构域相似，V1 结构域是一种选择性抑制 PKCepsilon 易位的肽。有趣的是，大多数甲状腺乳头状肿瘤表现出 PKCepsilon 表达降低。此外，RET/PTC癌基因的表达诱导选择性易位，随后下调PKCepsilon。滤泡性甲状腺肿瘤（也含有 Ras 突变的肿瘤）中 PKCα 表达增加。我们假设单个 PKC 同工酶在 Ras 引发和维持甲状腺细胞转化中发挥重要作用。我们的初步数据表明，PKCdelta 选择性地再现致癌 Ras 对异常细胞周期进程和细胞凋亡的急性影响； Ras 诱导的形态变化需要 PKCepsilon； PKC 模仿 Ras 对甲状腺分化的抑制作用； Ras 转化的甲状腺细胞表现出 PKC 表达和活性的改变。拟议的研究调查了单个 PKC 同工酶在大鼠甲状腺细胞 Ras 转化的启动和维持中的作用。这将通过使用高度特异性的分子试剂来完成，包括 PKC 同工酶的腺病毒、选择性 PKC 肽激活剂和抑制剂以及 RNA 干扰。该分析将为 Ras 调节甲状腺细胞增殖、分化和存活的分子机制提供新的见解，并可能促进开发选择性损害肿瘤细胞增殖和/或重新激活分化基因表达的新策略。