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: 7046885
• 负责人: JUDY L MEINKOTH
• 金额: $ 23.88万
• 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/7046885
• 关键词: RNA interference; apoptosis; biological signal transduction; cell differentiation; cell growth regulation; cell proliferation; enzyme activity; enzyme induction /repression; isozymes; kinase inhibitor; molecular oncology; neoplasm /cancer genetics; neoplastic transformation; oncogenes; protein kinase C; protein transport; thyroid neoplasm; tissue /cell culture

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，在这个国家进行的尸检中，高达90%的尸体发现存在缓慢生长的甲状腺肿瘤。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，但未分化甲状腺肿瘤是迅速致命的。激活Ras突变在人类甲状腺肿瘤中特别普遍。Ras突变在良性腺瘤中发现，在滤泡癌和未分化癌中频率更高。下游Ras效应子B-Raf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发展中的作用。大部分乳头状甲状腺肿瘤表现出PKC β基因的扩增和重排，导致PKC β N-末端片段的表达，该片段在结构上类似于V1结构域，是一种选择性抑制PKC β易位的肽。有趣的是，大多数乳头状甲状腺肿瘤显示PKC β的表达降低。此外，RET/PTC癌基因的表达诱导选择性易位，随后下调PKC β。PKCalpha表达在滤泡性甲状腺肿瘤中增加，这些肿瘤也含有Ras突变。我们假设单个PKC同工酶在Ras诱导甲状腺细胞转化的启动和维持中起重要作用。我们的初步数据表明，PKC δ选择性地再现致癌Ras对异常细胞周期进展和凋亡的急性效应; PKC δ是Ras诱导的形态学变化所需的; PKC模拟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。拟议的研究调查的作用，个别PKC同工酶在启动和维持Ras转化在大鼠甲状腺细胞。这将使用高度特异性的分子试剂来完成，包括用于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。这种分析将提供新的见解，通过Ras失调甲状腺细胞增殖，分化和生存的分子机制，并可能导致新的策略，选择性地损害肿瘤细胞增殖和/或重新激活分化的基因表达的发展。