POLYAMINES AND EPITHELIAL TUMORIGENESIS

鸟氨酸脱羧酶（ODC）是一种关键的调节酶， 多胺的生物合成，多胺是正常细胞生长所必需的， 分化申请人已经证明，ODC水平升高 多胺与突变的Ha-ras基因协同促进上皮肿瘤 形成和入侵。申请人的假设是， ODC和多胺“激活”角质形成细胞和真皮基质细胞， 与受伤皮肤中的表型相似，其特征在于： 增殖和迁移增加，新血管生成，改变 分化和蛋白酶表达增加。一个推论是， 条件（或癌基因），维持这种多胺诱导的激活， 细胞会导致肿瘤的发展。这个项目的总体目标是 一个项目是确定下游效应，发挥关键作用，在调解 ODC促进皮肤中的肿瘤发生。当肿瘤发生时， 作为突变的ras的结果出现（如通常在启动的 皮肤），因为多个效应途径有助于Ras介导的 细胞的转化。为了实现这些目标， 申请人还计划剖析多胺的下游效应物 作为与ODC合作的激活ras的下游效应物， 多胺来驱动上皮肿瘤发生。为此，吉尔摩博士建议， 具体目标如下：1.为了确定ODC水平升高， 多胺以类似的方式激活角质形成细胞和真皮基质细胞 与创伤皮肤相比，ODC在正常静止期成人和创伤后皮肤中均有表达， 表皮（使用诱导型ODC转基因小鼠模型），以及增殖性表皮（使用诱导型ODC转基因小鼠模型）。 活化的表皮（摩擦K6/ODC转基因小鼠皮肤）。通过控制 ODC在静止或活化的角质形成细胞中的表达， 申请人将评估这种非起始（即没有突变的ras基因）皮肤 诱导：A.伤口愈合表型，和B.良性肿瘤的形成 皮肤肿瘤依赖于持续的ODC诱导的细胞活化。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来自正常皮肤的比较 分析（RDA）和微阵列方法。上调的基因或 将评估ODC下调的细胞在介导细胞凋亡中的作用。 当ODC与突变的H-ras一起表达时，ODC的致瘤性和侵袭性作用。3. 吉尔摩博士将确定激活的Ha-Ras的下游效应子 可以与ODC和多胺水平升高合作， 细胞转化为恶性侵袭性表型。特别是，她计划 研究ODC和各种分部功能之间可能合作 激活Ha-Ras的效应子突变体，其特异性诱导 raf-1/ERK、RalGDS或磷酸肌醇3-OH激酶途径。

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.