MOLECULAR PATHOGENESIS OF CANCER OF MUTATOR PHENOTYPE

突变表型癌症的分子发病机制

• 批准号: 2667978
• 负责人: MANUEL PERUCHO
• 金额: $ 61.85万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-05-01 至 1999-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2667978
• 关键词: cancer risk; carcinogenesis; cell fusion; colorectal neoplasms; gene expression; human genetic material tag; human tissue; hybrid cells; molecular cloning; molecular oncology; neoplasm /cancer diagnosis; neoplasm /cancer genetics; nucleic acid chemical synthesis; nucleic acid repetitive sequence; oncogenes; phenotype; polymerase chain reaction; prognosis; restriction fragment length polymorphism; tissue /cell culture; transfection; tumor suppressor genes

Using the Arbitrarily Primed Polymerase Chain Reaction (AP-PCR) we have found that about 12% of colorectal carcinomas contain somatic mutations in simple repeated sequences in numbers that may surpass a million. These mutations are significantly associated with an early cancer onset, with poorly differentiated carcinomas of the proximal colon, with tumors of blacks, and with carcinomas with low incidence of metastases at diagnosis and with ras and p53 gene mutations. Therefore, these ubiquitous mutations have revealed a new molecular genetic mechanism for oncogenesis (corresponding to the "cancer as a mutator phenotype" hypothesis). Because these ubiquitous clonal mutations were present in all neoplastic areas (from the most superficial to the most invasive) of each of multiple (5) tumors from the same individual, including adenomas, we conclude 1) that these mutations are the consequence of a mutation in a gene coding for a DNA replication or repair factor that results in decreased fidelity in any of these processes (a "mutator mutation"); 2) that is mutator mutation plays an ultimate causal role in tumorigenesis, and 3) that the occurrence of this mutator mutation may have an inherited predisposition. Our main goal is to gain further information on this distinct mechanism for cancer development. Our specific aims are 1) to determine the timing of occurrence of these somatic clonal mutations in simple repeats relative to the mutations in oncogenes and tumor suppressor genes, by the Selective Ultraviolet Radiation Fractionation (SURF) method. If these ubiquitous mutations in simple repeats precede the oncogene and antioncogene mutations, this will confirm that they are the molecular symptoms of a distinct genetic pathway for cancer development. 2) to determine the presence or absence of these mutations in cells from normal tissues from patients with hereditary or sporadic forms of cancers of the mutator phenotype, by AP-PCR and standard PCR. This will establish the possible application of these ubiquitous mutations as immediate diagnostic tools for cancer risk assessment. 3) to determine the differential gene expression pattern of tumors of the mutator phenotype relative to those of the classical oncogene/tumor suppressor gene pathway by RNA fingerprinting (RAP). This should identify novel gene(s) playing an active role in tumorigenesis of cancer of the mutator phenotype. 4) to determine the possible existence of similar mechanisms for the development of other subsets of tumors by a different mutator mutation, specifically ubiquitous single base substitutions, by a combination of AP-PCR and Single Stranded Conformation Polymorphisms (SSCP). This could unravel the molecular etiology for other defined subsets of tumors. And 5) to determine the recessive or dominant nature of the mutated mutator gene and to isolate it by a genetic approach involving the construction of somatic cell hybrids and transfection assays using tumor cells with the mutated mutator gene and those without ubiquitous mutations.

利用随机引物聚合酶链式反应(AP-PCR)，我们得到了 发现大约12%的结直肠癌含有体细胞突变 在简单的重复序列中，数字可能超过一百万。 这些突变与癌症的早期发病密切相关， 近端结肠低分化癌，肿瘤 对于黑人，以及转移发生率较低的癌症， 诊断并伴有ras和p53基因突变。因此，这些 普遍存在的突变揭示了一种新的分子遗传学机制 致癌(对应于“癌症作为突变者的表型” 假设)。因为这些无处不在的克隆突变存在于 所有肿瘤区(从最浅的到最具侵袭性的) 来自同一个体的多个肿瘤，包括腺瘤， 我们的结论是：1)这些突变是基因突变的结果 编码DNA复制或修复因子的基因，导致 这些过程中的任何一个过程的保真度降低(“突变因子突变”)；2) 也就是说，突变子突变在肿瘤的发生中起着最终的因果作用， 3)这种突变子突变的发生可能具有遗传性 性情。 我们的主要目标是获得关于这一独特机制的进一步信息 用于癌症的发展。我们的具体目标是：1)确定时间 这些体细胞克隆突变在简单重复序列中的发生情况 相对于癌基因和抑癌基因的突变， 选择性紫外光辐射分离(SURF)方法。如果这些 简单重复序列中普遍存在的突变先于癌基因和 抑癌基因突变，这将证实它们是分子 癌症发展的独特遗传途径的症状。2)至 确定正常细胞中是否存在这些突变 遗传性或散发性癌症患者的组织 突变株表型，采用AP-PCR和标准PCR。这将确立 这些无处不在的突变的可能应用 癌症风险评估的诊断工具。3)确定 突变子表型肿瘤的差异基因表达谱 相对于经典的癌基因/抑癌基因通路 通过RNA指纹分析(RAP)。这应该识别新基因(S)的发挥 突变体表型在肿瘤发生中的积极作用。4) 以确定是否可能存在类似的机制 通过不同的突变子突变发展成其他亚群的肿瘤， 特别是普遍存在的单碱基替换，通过组合 AP-PCR和单链构象多态(SSCP)。这可能会 揭示其他已确定的肿瘤亚群的分子病因学。和 5)确定突变突变体的隐性或显性 基因，并通过涉及构建的遗传方法分离它 体细胞杂交和使用肿瘤细胞进行的转基因检测 突变的突变基因和那些没有普遍存在的突变。