DNA Polymerase Beta and Gastric Cancer

DNA 聚合酶 Beta 与胃癌

• 批准号: 8304905
• 负责人: Dawit Kidane Mulat
• 金额: $ 8.35万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8304905
• 关键词: Address; Affinity; Alkylating Agents; Alleles; Base Excision Repairs; Biological; Biological Assay; Cancer Etiology; Cells; Cessation of life; Chromosomal Instability; Chromosomal Stability; Chromosome abnormality; Chromosomes; Critiques; DNA; DNA Binding; DNA Damage; DNA Polymerase beta; DNA Repair; DNA Repair Pathway; DNA Sequence Rearrangement; DNA biosynthesis; DNA lesion; DNA-Directed DNA Polymerase; Data; Deoxyribose; Development; Disease; Environmental Risk Factor; Enzymes; Epithelium; Excision; Exonuclease; Gastric Tissue; Generations; Genes; Genetic; Genetic Predisposition to Disease; Genome; Genomic Instability; Goals; Helicobacter Infections; Human; In Vitro; Incidence; Individual; Inflammation; Knock-in Mouse; Lead; Left; Link; Lyase; Maintenance; Malignant Neoplasms; Mammalian Cell; Mus; Mutagenesis; Mutation; Nonhomologous DNA End Joining; Nucleotides; Oxidative Stress; Pathway interactions; Polymerase; Process; Proteins; Reporting; Role; Smoking; Stimulus; Stomach; Testing; Transgenic Mice; Variant; Writing; cancer cell; carcinogenesis; cytotoxicity; global health; homologous recombination; inorganic phosphate; malignant stomach neoplasm; meetings; metaplastic cell transformation; mortality; prevent; repaired; research study; tumor; tumorigenesis

DESCRIPTION (provided by applicant): Gastric cancer is a global health problem with a high rate of tumor incidence and mortality. Environmental and genetic factors are both important to promote genomic instability and possibly gastric carcinogenesis. The maintenance of genome integrity is dependent on numerous mechanisms, which notably allow fidelity of DNA replication and repair of damaged DNA. Those processes require a large number of proteins including DNA polymerase beta (Pol ?). Pol ? is a key enzyme for the protection of oxidative DNA lesions via its role in base excision repair (BER). Approximately 30% of tumors studied to date express Pol ? variant proteins, and several tumors over express Pol ?. If Pol ? becomes defective, DNA damage will be left resulting in genomic instability. Genomic instability occurs in two different pathways, one resulting in an increased mutation rate at the nucleotide level and the other corresponding to chromosomal instability leading to abnormal chromosome numbers or rearrangement. Direct sequencing of the PolB gene from different cancer cells identified a number of mutations including L22P gastric cancer associated variant of Pol ? (dRP lyase deficient). It is well documented that dRP lyase activity of Pol ? protect cells from cytotoxicity of alkylating agents. Data showing that L22P lacks dRP lyase and has less DNA-binding affinity are consistent with the possibility that this variant is linked to human cancer. In order to further our understanding of the biological consequences of L22P in BER and, in particular, the effect of L22P expression on DNA repair fidelity as well as chromosomal stability, we will assess genomic instability after expressing L22P variant of Pol ?. The goal of this study is to determine whether the L22P gastric cancer-associated Pol ? variant induces genomic instability and promotes tumorigenesis. Specifically, we will focus to answer how L22P induces genomic instability using mutagenesis and chromosomal aberration studies. To achieve our objective, we will construct L22P conditional knock-in transgenic mice and characterize spontaneous tumorigenesis as well as host genetic predisposition after Helicobacter infection. This project will help to get mechanistic data that could promote our basic understanding of the host genetic factors and environmental stimuli to accelerate initiation or progression of gastric cancer.

描述（申请人提供）：胃癌是一个全球性的健康问题，肿瘤发病率和死亡率很高。环境和遗传因素对于促进基因组不稳定和可能的胃癌发生都很重要。基因组完整性的维持依赖于多种机制，尤其是 DNA 复制的保真度和受损 DNA 的修复。这些过程需要大量蛋白质，包括 DNA 聚合酶 beta (Pol ?)。波尔？是通过其在碱基切除修复 (BER) 中的作用来保护 DNA 氧化损伤的关键酶。迄今为止研究的肿瘤中大约有 30% 表达 Pol ?变异蛋白，以及一些肿瘤过度表达 Pol ?。如果波尔？一旦出现缺陷，DNA 损伤就会留下，导致基因组不稳定。基因组不稳定发生在两种不同的途径中，一种导致核苷酸水平突变率增加，另一种对应于染色体不稳定，导致染色体数量异常或重排。对不同癌细胞的 PolB 基因进行直接测序，鉴定出许多突变，包括 Pol 的 L22P 胃癌相关变体。 （dRP 裂解酶缺陷）。 Pol 的 dRP 裂解酶活性已得到充分记录。保护细胞免受烷化剂的细胞毒性。显示 L22P 缺乏 dRP 裂解酶且 DNA 结合亲和力较低的数据与该变体与人类癌症相关的可能性一致。为了进一步了解 L22P 在 BER 中的生物学后果，特别是 L22P 表达对 DNA 修复保真度以及染色体稳定性的影响，我们将在表达 Pol α 的 L22P 变体后评估基因组不稳定性。本研究的目的是确定L22P是否与胃癌相关Pol？变异会诱导基因组不稳定并促进肿瘤发生。具体来说，我们将重点通过诱变和染色体畸变研究来回答 L22P 如何诱导基因组不稳定。为了实现我们的目标，我们将构建L22P条件敲入转基因小鼠，并表征螺杆菌感染后的自发肿瘤发生以及宿主遗传易感性。该项目将有助于获得机制数据，从而促进我们对宿主遗传因素和环境刺激的基本了解，从而加速胃癌的发生或进展。