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多达90％表明存在缓慢的甲状腺肿瘤。虽然分化良好的卵泡和乳头状甲状腺肿瘤患者的预后良好，但甲状腺肿瘤的甲状腺肿瘤却迅速致命。在人甲状腺肿瘤中激活RAS突变尤其普遍。在良性腺瘤中发现了RAS突变，并且在卵泡和肿瘤癌中以较高的频率发现。 B-RAF（下游RAS效应子）中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RA在甲状腺肿瘤的启动和进展中的作用。很大一部分乳头状甲状腺肿瘤表现出PKCEPSILON基因的扩增和重排，从而导致PKCepsilon的N末端片段在结构上与V1结构域相似，这是一种选择性地抑制PKCepsilon易位的肽。有趣的是，大多数甲状腺乳头状肿瘤表现出pKcepsilon的表达降低。此外，RET/PTC癌基因的表达诱导了选择性易位，然后下调PKCEPSILON。在卵泡甲状腺肿瘤中，pKcalpha表达增加，肿瘤也含有RAS突变。我们的假设是，单个PKC同工酶在RAS通过甲状腺细胞转化的启动和维持中起着重要作用。我们的初步数据表明，PKCDELTA有选择地再现致癌性RAS对异常细胞周期进展和凋亡的急性影响。 RAS引起的形态变化需要PKCEPSILON。 PKC模仿Ras对甲状腺分化的抑制作用； RAS转化的甲状腺细胞在PKC表达和活性中表现出改变。拟议的研究研究了单个PKC同工酶在大鼠甲状腺细胞中RAS转化的启动和维持中的作用。这将使用高度特异性的分子试剂（包括PKC同工酶，选择性PKC肽激活剂，抑制剂和RNA干扰）来完成。该分析将提供对分子机制的新洞察力，通过这种机制，RAS会导致甲状腺细胞增殖，分化和存活率失调，并可能引起新策略的发展，以选择性地损害肿瘤细胞的增殖和/或反应分化的基因表达。