Role of Ki-ras in the Pathogenesis of Lung Cancer

描述（由申请人提供）：对人类和动物模型的研究已经 表明 Ki-ras 突变是肺肿瘤发生中关键的早期事件。 我们和其他人已经证明 Ki-ras 中存在的突变类型可能 影响肿瘤进展并似乎与患者生存相关。我们 因此假设环境因素在 Ki-ras 中诱导了不同的突变 致癌物表现出不同的致癌潜力，并且致癌物的类型 该基因最初诱导的突变将决定肿瘤发生的速度 进展为腺癌。角色很难确定 突变的 ras 基因在肿瘤发生和进展中的作用，因为用 化学致癌物可能会导致其他基因位点的改变。我们因此 提议开发 3 种转基因小鼠，其中含有野生小鼠 人类 Ki-ras 基因的 VAL12 或 CYS12 突变等位基因与 tet诱导型启动子，指定肺特异性表达 转基因。 3 个等位基因的生化特征和活性将 与每个等位基因的致癌性进行比较和关联。 将采用致癌性生物测定来确定以下物质的影响： 不同的ras突变对肿瘤发生和进展的影响。的效果 3个等位基因中的每一个都与抑癌基因座的后续损伤有关 在人类和小鼠肺肿瘤发病机制中，特别是 pl6Ink4a， Rb 和细胞周期蛋白 D1 基因将通过 PCR-SSCP、甲基化特异性进行评估 PCR，并通过以下方法测定基因产物的表达水平 逆转录PCR。这些“人性化”Ki-ras 的发展 转基因小鼠将代表该领域的重大进步，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型ras等位基因对肺肿瘤的影响 发病机制将对未来的研究产生重要的长期影响 病因学、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.