Mismatch Repair Functions Affected During Tumorigenesis

肿瘤发生过程中受影响的错配修复功能

• 批准号: 7372343
• 负责人: Christopher D. Heinen
• 金额: $ 24.17万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-09 至 2013-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7372343
• 关键词: Address; Adenosine; Affect; Antibodies; Apoptosis; BRCA1 gene; Binding; Biochemical; Biological Assay; CHEK2 gene; CHES1 gene; Cancer Etiology; Cancer Patient; Cell Cycle Checkpoint; Cell Line; Cells; Cellular biology; Cessation of life; Co-Immunoprecipitations; Colon Carcinoma; Colorectal; Colorectal Cancer; Cultured Cells; DNA; DNA Binding; DNA Damage; DNA Repair; DNA-Directed DNA Polymerase; Defect; Development; Diagnostic; Disease; Disruption; EXO1 gene; End Point; Endometrial; Familial disease; General Population; Genes; Genetic Recombination; Genomic Instability; Hereditary Nonpolyposis Colorectal Neoplasms; Human; In Vitro; Inherited; Lead; MLH1 gene; Malignant Neoplasms; Malignant neoplasm of lung; Mass Spectrum Analysis; Mismatch Repair; Missense Mutation; Modeling; Molecular; Mutagens; Mutation; Nuclear Extract; Nucleotides; Ovarian; PCNA gene; Pathway interactions; Patients; Phenotype; Phosphorylation; Play; Preventive; Process; Property; Proteins; Rate; Recombinants; Recruitment Activity; Role; Signal Transduction; Signaling Molecule; Site; Slide; Small Interfering RNA; System; Testing; Therapeutic; Tumor Suppressor Genes; Western Blotting; Woman; base; in vitro Assay; insight; men; mutant; novel; novel diagnostics; protein expression; repaired; response; stem; therapeutic target; tool; tumor; tumorigenesis

DESCRIPTION (provided by applicant): Colon cancer is the third most common cancer affecting men and women and the second leading cause of cancer death. The most common disease predisposing patients to colorectal cancer is hereditary non-polyposis colon cancer (HNPCC) which stems from mutations in DNA mismatch repair (MMR) genes. In addition, MMR defects are also detected in 10-30% of sporadic colorectal, endometrial and other cancers. This proposal will address the broad question of why defects in the MMR pathway cause tumorigenesis. The MMR system corrects mispaired or damaged DNA resulting from DNA polymerase errors, recombination between heterologous sequences or endogenous and exogenous mutagens. Thus, loss of MMR function results in an elevated mutation rate (mutator phenotype). However, the MMR system is also required for the activation of cell cycle checkpoints and apoptosis in response to DNA damage. We hypothesize that this MMR-dependent checkpoint/apoptosis response plays a significant role in tumor protection as its disruption would allow cells with increased genomic instability to grow unchecked. A prediction based on this hypothesis is that tumors harbor mutations in MMR genes that disrupt damage repair and checkpoint/apoptosis response functions. We will test this prediction by determining whether cancer-associated missense mutations of the MMR genes hMSH2 and hMSH6 affect both DNA repair and checkpoint/apoptosis response. We propose 3 aims to evaluate the functional consequences of cancer- associated missense mutations in hMSH2 and hMSH6. We have previously detailed the effects of seven hMSH2 missense mutations associated with HNPCC on the biochemical functions of the hMSH2-hMSH6 heterodimer. In Aim 1, we will examine the biochemical effects of cancer-associated missense mutations in hMSH6. In Aim 2, we will devise an in vitro assay to examine how the hMSH2-hMSH6 heterodimer interacts with other proteins involved in repair and checkpoint/apoptosis signaling and whether cancer-associated missense mutations affect these interactions. Finally, in Aim 3 we will examine the effects of missense mutations in hMSH2 and hMSH6 on DNA repair and checkpoint/apoptosis functions in human cell culture models. Through this thorough integration of biochemical and cell biology approaches we will utilize cancer-causing missense mutations as tools to further understand the molecular mechanism of MMR and how those mechanisms are disrupted during tumorigenesis.Colon cancer is the third most common malignancy in men and women and ranks behind only lung cancer in cancer deaths. Inherited mutations in genes of the mismatch repair pathway cause the disease hereditary non-polyposis colon cancer, while defects in this pathway are also detected in 10-30% of colorectal, endometrial and other cancers in the general population. Understanding at the molecular level why alterations in this pathway promote tumorigenesis will aide the development of more targeted therapeutic, preventive and diagnostic strategies.

描述（由申请人提供）：结肠癌是影响男性和女性的第三大常见癌症，也是癌症死亡的第二大原因。导致患者罹患结直肠癌的最常见疾病是遗传性非息肉病性结肠癌 (HNPCC)，它源于 DNA 错配修复 (MMR) 基因的突变。此外，10-30%的散发性结直肠癌、子宫内膜癌和其他癌症中也检测到MMR缺陷。该提案将解决为什么 MMR 通路缺陷会导致肿瘤发生这一广泛问题。 MMR 系统可纠正由于 DNA 聚合酶错误、异源序列或内源性和外源性诱变剂之间的重组而导致的错配或损坏的 DNA。因此，MMR 功能的丧失会导致突变率（突变表型）升高。然而，错配修复系统对于响应 DNA 损伤而激活细胞周期检查点和细胞凋亡也是必需的。我们假设这种依赖于 MMR 的检查点/凋亡反应在肿瘤保护中发挥着重要作用，因为它的破坏将使基因组不稳定性增加的细胞不受控制地生长。基于这一假设的预测是，肿瘤中存在 MMR 基因突变，这些突变会破坏损伤修复和检查点/凋亡反应功能。我们将通过确定与癌症相关的 MMR 基因 hMSH2 和 hMSH6 错义突变是否影响 DNA 修复和检查点/凋亡反应来测试这一预测。 我们提出3的目的是评估hMSH2和hMSH6中与癌症相关的错义突变的功能后果。我们之前详细介绍了与 HNPCC 相关的 7 个 hMSH2 错义突变对 hMSH2-hMSH6 异二聚体生化功能的影响。在目标 1 中，我们将检查 hMSH6 中与癌症相关的错义突变的生化影响。在目标 2 中，我们将设计一种体外测定法来检查 hMSH2-hMSH6 异二聚体如何与参与修复和检查点/凋亡信号传导的其他蛋白质相互作用，以及癌症相关的错义突变是否影响这些相互作用。最后，在目标 3 中，我们将研究 hMSH2 和 hMSH6 错义突变对人类细胞培养模型中 DNA 修复和检查点/凋亡功能的影响。通过生化和细胞生物学方法的彻底整合，我们将利用致癌的错义突变作为工具，进一步了解 MMR 的分子机制以及这些机制在肿瘤发生过程中如何被破坏。结肠癌是男性和女性中第三大常见的恶性肿瘤，在癌症死亡人数中仅次于肺癌。错配修复途径基因的遗传性突变导致遗传性非息肉病性结肠癌，而普通人群中 10-30% 的结直肠癌、子宫内膜癌和其他癌症中也检测到该途径的缺陷。在分子水平上了解为什么该途径的改变会促进肿瘤发生将有助于开发更有针对性的治疗、预防和诊断策略。