Role of Ki-ras in the Pathogenesis of Lung Cancer

描述(申请人提供)：对人体和动物模型的研究 研究表明，Ki-ras基因突变在肺癌发生中是一个关键的早期事件。 我们和其他人已经表明，Ki-ras中存在的突变类型可能 影响肿瘤进展，并似乎与患者的生存相关。我们 从而假设环境诱导Ki-ras基因的不同突变 致癌物质表现出不同的致癌潜力，并且类型 该基因最初诱导的突变将决定肿瘤发生的速度 腺癌的进展。很难明确地确定这一角色 突变的ras基因在肿瘤发生和发展中的作用 化学致癌物可能会导致其他基因位点的改变。因此，我们 建议开发3个品系的转基因小鼠，这些小鼠要么含有野生的 人Ki-ras基因的类型、VAL12或CyS12突变等位基因与 Tet可诱导启动子，指定肺组织特异性表达 转基因。这3个等位基因的生化特征和活性将 与每个等位基因的致瘤性进行比较和关联。 致癌性生物测定将被用来确定 不同ras基因突变在肿瘤发生发展中的作用。的影响 3个等位基因中的每一个都与肿瘤抑制基因的后续损伤有关 在人类和小鼠肺肿瘤的发病机制中，尤其是pl6Ink4a， Rb和细胞周期蛋白D1基因将通过甲基化特异性的PCR-SSCP进行评估 聚合酶链式反应，检测基因产物的表达水平 逆转录-聚合酶链式反应。这些“人性化”基拉的发展 转基因小鼠将代表着这一领域的关键进步，并提供 重要的新研究工具，将使我们能够确定Ki-ras的作用 肺癌发病机制中的突变。我们预计，拟议的 研究将阐明不同突变的ras等位基因对肺癌的影响。 发病机制，并将对未来的研究具有重要的长期意义 关于糖尿病的病因、遗传学、预防和新疗法的开发 肺癌。

DESCRIPTION (provided by applicant): Studies in humans and animal models have shown that mutation of Ki-ras is a critical, early event in lung tumorigenesis. We and others have shown that the type of mutation present in Ki-ras may influence tumor progression and appears to correlate with patient survival. We thus hypothesize that different mutations induced in Ki-ras by environmental carcinogens exhibit different oncogenic potential, and that the type of mutation initially induced in this gene will determine how rapidly tumors progress to adenocarcinomas. It is difficult to definitively determine the role of mutated ras genes in tumor initiation and progression because treatment with chemical carcinogens may cause alterations at other genetic loci. We thus propose to develop 3 strains of transgenic mice that contain either the wild type, VAL12, or CYS12 mutant alleles of the human Ki-ras gene linked to a tet-inducible promoter that specifies lung specific expression of the transgene. The biochemical characteristics and activity of the 3 alleles will be compared and correlated with the oncogenicity of each allele. Carcinogenicity bioassays will be employed to determine the effects of different ras mutations on tumor development and progression. The effect of each of the 3 alleles on subsequent damage to tumor suppressor loci implicated in both human and murine lung tumor pathogenesis, in particular the pl6Ink4a, Rb, and cyclin D1 genes, will be assessed by PCR-SSCP, methylation specific PCR, and determination of the levels of expression of the gene products by reverse transcription PCR. The development of these "humanized" Ki-ras transgenic mice will represent a critical advance in this field and provide an important new research tool that will allow us to determine the role of Ki-ras mutations in the pathogenesis of lung cancer. We anticipate that the proposed studies will elucidate the effect of different mutant ras alleles on lung tumor pathogenesis and will have important long term implications for future research on the etiology, genetics, prevention, and development of novel therapies for lung cancer.