CYCLIN GENES AND PROLIFERATION OF GUT EPITHELIAL CELLS

细胞周期蛋白基因与肠道上皮细胞的增殖

• 批准号: 2107340
• 负责人: E. AUBREY THOMPSON
• 金额: $ 17.62万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-24 至 1999-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2107340
• 关键词: animal genetic material tag; biological signal transduction; carcinogenesis; cell cycle; cell differentiation; cyclins; gastrointestinal epithelium; gene induction /repression; genetic promoter element; genetic transcription; neoplastic transformation; nuclear runoff assay; tissue /cell culture; transforming growth factors

The morbidity of colon cancer reflects the lack of an effective chemotherapeutic strategy for treatment of the disseminated form of the disease. Our long term objective is to devise strategies that permit intervention at the level of the primary regulatory defect that leads to malignant transformation. Our strategy is based upon four observations concerning growth factor regulation of epithelial cell proliferation. l) TGF-beta is a major effector of gut epithelial cell differentiation. 2) Undifferentiated colon adenocarcinoma is unresponsive to TGF-beta, as are intestinal epithelial cells that have been transformed with activated Ras genes. 3) Growth factors, including TGF-beta, regulate the expression of D cyclins, which are important in maintaining the proliferative state. 4) D cylcin genes are oncogenic in many different types of adenocarcinoma. Our immediate objective is to elucidate the role of TGF-beta in regulating gut epithelial cell proliferation and the role of D cyclins in that process. Our initial studies will focus upon IEC-6 intestinal epithelial cells, which, like normal gut epithelial cells, cease to proliferate in the presence of TGF-beta. Our data indicate that the gene encoding cyclin D1 (CcnD1) is the primary focus of TGF-beta inhibition of IEC-6 cells. TGF-beta inhibits transcription of CcnD1 resulting in G0 arrest. Antisense oligonucleotides directed against cyclin D1 mRNA can recapitulate the effects of TGF-beta. Inducible overexpession of cyclin D1 renders the cells resistant to TGF-beta. Two related hypotheses are derived from our initial observations. Hypothesis l: We propose that TGF-beta inhibition of cyclin D1 expression accounts for the normal cessation of proliferation that accompanies differentiation of the gut epithelium. This hypothesis will be tested by experiments described in the companion IRPG proposal, submitted by R.D. Beauchamp, M.D. Hypothesis 2: We propose that TGF-beta inhibition of epithelial cell proliferation is due to inhibition of CcnD1 transcription. The proposal in hand addresses the second hypothesis. Five specific aims are proposed to test predictions that emanate from the working hypothesis. Specific Aims l deals with analysis of nuclear run-on transcription and mRNA turnover in IEC-6 cells in the presence and absences of TGF-beta. Specific Aims 2A address the cloning and analysis of CcnD7 promoter structure. Specific Aim 5 addresses the hypothesis that cyclin D1 is both the target of TGF-beta and a component of the TGF-b signal transduction pathway. Our objective is to understand CcnD7 regulation in detail sufficient to the framing of hypotheses concerning means to block cyclin D1 expression in tumor cells.

结肠癌的发病率反映了缺乏有效的治疗方法。 化疗策略，用于治疗播散形式的 疾病我们的长期目标是制定战略， 在主要监管缺陷层面进行干预， 恶性转化我们的战略基于四点观察 关于上皮细胞增殖的生长因子调节。（一） TGF-β是肠道上皮细胞分化的主要效应子。（二） 未分化结肠腺癌对TGF-β无反应， 已经用活化的Ras转化的肠上皮细胞 基因. 3)生长因子，包括TGF-β，调节 D细胞周期蛋白，对于维持增殖状态很重要。四、 D细胞周期蛋白基因在许多不同类型的腺癌中是致癌的。 我们的近期目标是阐明TGF-β在调节细胞凋亡中的作用。 肠上皮细胞增殖及D细胞周期蛋白在其中的作用 过程 我们的初步研究将集中在IEC-6肠上皮细胞 细胞，像正常的肠上皮细胞一样，停止增殖， TGF-β的存在。我们的数据表明，编码细胞周期蛋白的基因 D1（CcnD 1）是IEC-6细胞TGF-β抑制的主要焦点。 TGF-β抑制CcnD 1的转录，导致G 0阻滞。反义 针对细胞周期蛋白D1 mRNA的寡核苷酸可以概括 TGF-β的作用 细胞周期蛋白D1的诱导性过度表达使得细胞周期蛋白D1的表达水平降低。 对TGF-β有抵抗力的细胞。两个相关的假设来自我们的 初步意见。假设1：我们认为TGF-β抑制 细胞周期蛋白D1的表达解释了细胞增殖的正常停止 伴随着肠上皮细胞的分化这一假设 将通过IRPG配套提案中描述的实验进行测试， 由R.D.提交Beauchamp，医学博士 假设2：我们认为TGF-β 上皮细胞增殖的抑制是由于CcnD 1的抑制 转录。目前的提案针对的是第二种假设。五 提出了具体的目标，以测试来自 工作假设具体目标1：分析核反应堆 转录和mRNA周转在IEC-6细胞的存在和 缺乏TGF-β。具体目标2A涉及克隆和分析 CcnD 7启动子结构。具体目标5涉及以下假设： 细胞周期蛋白D1既是TGF-β的靶点，也是TGF-β的一种成分， 信号转导途径 我们的目标是了解CcnD 7 监管的详细程度足以构建有关假设， 是指阻断肿瘤细胞中的细胞周期蛋白D1表达。