POLYAMINES AND EPITHELIAL TUMORIGENESIS

多胺与上皮肿瘤发生

• 批准号: 6194035
• 负责人: Susan K. Gilmour
• 金额: $ 28.85万
• 依托单位: LANKENAU INSTITUTE FOR MEDICAL RESEARCH
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-05 至 2004-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6194035
• 关键词: angiogenesis; athymic mouse; carcinogenesis; cell differentiation; connective tissue cells; enzyme activity; epithelioma; gene induction /repression; genetically modified animals; guanine nucleotide binding protein; guanine nucleotide exchange factors; keratinization; keratinocyte; microarray technology; mitogen activated protein kinase; neoplasm /cancer genetics; neoplasm /cancer invasiveness; oncoprotein p21; ornithine decarboxylase; phosphatidylinositol 3 kinase; polyamines; representational difference analysis; skin neoplasms; wound healing

Ornithine decarboxylase (ODC) is a key regulatory enzyme in the biosynthesis of polyamines which are essential for normal cell growth and differentiation. The applicants have demonstrated that elevated levels of ODC and polyamines cooperate with a mutated Ha-ras gene to promote epithelial tumor formation and invasion. The applicant's hypothesis is that elevated levels of ODC and polyamines "activate" keratinocytes and dermal stromal cells to produce a phenotype similar to that in wounded skin, which is characterized by increased proliferation and migration, neoangiogenesis, altered differentiation, and increased expression of proteases. A corollary is that conditions (or oncogenes) that sustain this polyamine-induced activation of cells will result in the development of a tumor. The overall goal of this project is to identify downstream effectors that play a key role in mediating ODC-promoted tumorigenesis in skin. The objective is complicated when tumors arise as a consequence of a mutated ras (as is generally found in initiated skin) since multiple effector pathways contribute to Ras-mediated transformation of cells. Therefore, in order to achieve these goals, the applicant plans to dissect out the downstream effectors of polyamines as well as the downstream effectors of an activated ras that cooperate with ODC and polyamines to drive epithelial tumorigenesis. To this end, Dr, Gilmour proposes the following specific aims: 1. To determine if elevated levels of ODC and polyamines activate keratinocytes and dermal stromal cells in a manner similar to that in wounded skin, ODC will be expressed in both normal quiescent adult epidermis (using an inducible ODC transgenic mouse model), and in proliferative activated epidermis (abrading K6/ODC transgenic mouse skin). By controlling expression of ODC in either sedentary or activated keratinocytes, the applicants will evaluate this noninitiated (i.e. no mutated ras gene) skin for the induction of: A. a wound healing phenotype, and B. the formation of benign skin tumors dependent upon sustained ODC-induced activation of cells. 2. Using the inducible ODC transgenic mouse model, mRNA from ODC overexpressing skin will be compared with that from normal skin using representational difference analysis (RDA) and microarray approaches. Genes that are upregulated or downregulated by ODC will be evaluated for their role in mediating the tumorigenic and invasive effects of ODC when expressed with a mutated H-ras. 3. Dr. Gilmour will determine which downstream effectors of an activated Ha-Ras can cooperate with elevated levels of ODC and polyamines to convert epidermal cells to a malignant invasive phenotype. In particular, she plans to investigate possible cooperation between ODC and various partial function effector mutants of an activate Ha-Ras that specifically induce either the raf-1/ERK, RalGDS, or phosphoinostitie 3-OH kinase pathway.

鸟氨酸脱羧酶 (ODC) 是一种关键的调节酶 正常细胞生长所必需的多胺的生物合成 差异化。申请人已证明 ODC 水平升高 多胺与突变的 Ha-ras 基因配合促进上皮肿瘤 形成和侵袭。申请人的假设是，升高的水平 ODC和多胺“激活”角质形成细胞和真皮基质细胞以产生 与受伤皮肤相似的表型，其特征是 增殖和迁移增加，新血管生成，改变 分化，并增加蛋白酶的表达。一个推论是 维持这种多胺诱导的激活的条件（或癌基因） 细胞将导致肿瘤的发展。本次活动的总体目标 该项目的目的是确定在调解中发挥关键作用的下游效应器 ODC 促进皮肤肿瘤发生。当肿瘤发生时，目标就变得复杂了 由于 ras 突变而出现（通常在初始 皮肤），因为多种效应途径有助于 Ras 介导 细胞的转化。因此，为了实现这些目标， 申请人还计划剖析多胺的下游效应子 作为与 ODC 合作的激活 ras 的下游效应器 多胺驱动上皮肿瘤发生。为此，吉尔莫博士建议 具体目标如下： 1. 确定 ODC 和 多胺以类似的方式激活角质形成细胞和真皮基质细胞 与受伤皮肤中的情况相比，ODC 在正常静止成人中都会表达 表皮（使用诱导型 ODC 转基因小鼠模型）和增殖细胞 激活表皮（磨损 K6/ODC 转基因小鼠皮肤）。通过控制 ODC 在静止或激活的角质形成细胞中表达， 申请者将评估这种未启动（即没有突变的 ras 基因）皮肤 诱导：A. 伤口愈合表型，以及 B. 良性伤口的形成 皮肤肿瘤依赖于 ODC 诱导的细胞持续激活。 2. 使用 诱导型 ODC 转基因小鼠模型，来自 ODC 过表达皮肤的 mRNA 将使用代表性差异与正常皮肤进行比较 分析（RDA）和微阵列方法。上调的基因或 ODC 的下调将对其在调解中的作用进行评估 当 ODC 与突变的 H-ras 一起表达时，其致瘤和侵袭作用。 3. Gilmour 博士将确定激活的 Ha-Ras 的下游效应器 可以与升高水平的 ODC 和多胺配合，将表皮转化为 细胞恶性侵袭表型。她特别计划 研究ODC与各部分功能之间可能的合作 激活 Ha-Ras 的效应突变体，特异性诱导 raf-1/ERK、RalGDS 或磷酸肌醇 3-OH 激酶途径。