Oxidative DNA Damage And Repair In Prostate Cancer

前列腺癌中的氧化 DNA 损伤和修复

• 批准号: 6815197
• 负责人: michele k evans
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6815197
• 关键词: DNA damage; DNA repair; carcinogenesis; human tissue; mitochondrial DNA; neoplasm /cancer genetics; nucleic acid sequence; oxidative stress; phosphoester ligase; prostate neoplasms

Prostate cancer is the most prevalent cancer among American men and is classified as the second leading cause of their cancer mortality. In the United States, there will be 220,900 new cancer cases in 2003 making prostate cancer one of the cancers with the fastest rising incidence in this country as well as in Western Europe. While certain dietary, genetic, lifestyle and environmental factors are implicated in prostate cancer risk, the molecular mechanisms underlying the etiology of the disease are largely unknown. Mutagenic oxidative DNA base damage increases with age in prostatic tissue. Many factors may influence this increase including: increased production of reactive oxygen species, increased susceptibility to oxidative stress, alterations in detoxifying enzyme levels or defects in DNA repair. Several research groups have begun to identify genes associated with heritable forms of prostate cancer and genes, in which somatic mutations or other somatic alterations may set the stage for the development and/or progression of the disease. To this end, it has been shown by several groups that hypermethylation of the B-class glutathione S-transferase gene (GSTP1) promoter region inhibits transcription of the gene and is associated with prostate cancer development. The function of GSTP1 has been proposed as a gene that defends genomic DNA in prostate cells from environmental or endogenous DNA-damaging agents. Environmental carcinogens such as heterocyclic amines and polycyclic aromatic hydrocarbons that result from cooking meat at high temperatures may play a role as it has been shown that 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine can induce prostate cancer in rats. Reactive oxygen species (ROS), most notably the hydroxyl radical, generated endogenously by cellular metabolism are known to cause oxidative DNA damage that has been implicated in prostate carcinogenesis. Research on the development of prostate cancer suggests that symptomatic and asymptomatic chronic and acute inflammation occurs in the prostate over the life span and acts in synergy with environmental, genetic, and dietary factors to cause injury to prostatic epithelium. In response to this injury, cellular proliferation has been shown to occur. This proliferation is accompanied by oxidative stress that is related to the ongoing inflammatory process that in turn may result in high rates of oxidative damage to DNA. Other findings that implicate a role for oxidative DNA damage in prostate carcinogenesis include work by Bostwick et al. showing that SOD1, SOD2 and catalase levels are lower in prostate intraepithelial neoplasia and prostate cancer relative to benign prostate epithelium. There is also a significant increase in the proportion of mutagenic oxidatively induced DNA base lesions, 8-hydroxyadenine (8-oxoA) and 8-hydroxyguanine (8-oxoG) present in malignant prostatic tissue as well as an increase in the levels of these lesions in benign prostatic tissue with aging. Further evidence supporting the hypothesis that defective repair of oxidative DNA damage may be pivotal in prostate carcinogenesis has been provided by work on genetic polymorphisms in the base excision repair (BER) gene OGG1. Taken together these data suggest that reactive oxygen species and oxidative DNA damage may be critical in the development of prostate cancer. Using LC/MS and GC/MS, we show increased levels of oxidative DNA base damage over the baseline in PC-3 and DU-145 prostate cancer cells following exposure to ionizing radiation and a repair period. Nuclear extracts of PC-3 and DU-145 prostate cancer cell lines have defective incision of the DNA base lesions, 8-hydroxyguanine (8-oxoG), 5-hydroxycytosine (5OHC) and thymine glycol (TG) when compared to the non-malignant prostate cell line. Concomitantly, the levels of NEIL1 and NEIL2, enzymes that incise these lesions, are reduced in both cancer cell lines. Mitochondrial extracts from PC-3 and DU-145 also have defective incision of 8-oxoG compared to the control. PC-3 mitochondrial extracts are severely defective in the incision of TG and 5OHC. Consistent with the incision data, NTH1 and OGG1 2a protein levels are decreased in mitochondria of PC-3 cells. The antioxidant enzymes, glutathione peroxidase (GPx), catalase, and superoxide dismutases (SOD1, SOD2) have altered expression patterns in the cancer cell lines. Genetic analysis of the OGG1 gene reveals that both PC-3 and DU-145 cell lines harbor polymorphisms associated with a higher susceptibility to certain cancers. These data suggest that the malignant phenotype in PC-3 and DU-145 cell lines is associated with defects in base excision repair (BER), alterations in expression of BER and antioxidant enzymes, and OGG1 genetic polymorphisms.

前列腺癌是美国男性中最常见的癌症，被列为癌症死亡的第二大原因。在美国，2003年将有220,900个新癌症病例，使前列腺癌成为该国以​​及西欧发病率增长最快的癌症之一。虽然某些饮食、遗传、生活方式和环境因素与前列腺癌风险有关，但该疾病病因学的分子机制在很大程度上尚不清楚。 前列腺组织中的诱变性氧化 DNA 碱基损伤随着年龄的增长而增加。许多因素可能会影响这种增加，包括：活性氧产生增加、对氧化应激的敏感性增加、解毒酶水平的改变或 DNA 修复缺陷。几个研究小组已经开始鉴定与前列腺癌的遗传形式相关的基因和基因，其中体细胞突变或其他体细胞改变可能为疾病的发生和/或进展奠定基础。为此，多个研究小组已经证明，B 类谷胱甘肽 S 转移酶基因 (GSTP1) 启动子区域的高甲基化会抑制该基因的转录，并与前列腺癌的发展相关。 GSTP1 的功能被认为是一种保护前列腺细胞基因组 DNA 免受环境或内源性 DNA 损伤剂侵害的基因。高温烹调肉类产生的杂环胺和多环芳烃等环境致癌物可能发挥作用，因为有研究表明2-氨基-1-甲基-6-苯基咪唑并[4,5-b]吡啶可诱发前列腺癌老鼠的癌症。 众所周知，细胞代谢内源性产生的活性氧 (ROS)，尤其是羟基自由基，会导致氧化性 DNA 损伤，从而导致前列腺癌发生。对前列腺癌发展的研究表明，有症状和无症状的慢性和急性炎症在整个生命周期中都会发生在前列腺中，并与环境、遗传和饮食因素协同作用，导致前列腺上皮损伤。为了应对这种损伤，细胞增殖已被证明会发生。这种增殖伴随着氧化应激，而氧化应激与持续的炎症过程有关，进而可能导致 DNA 氧化损伤率很高。 Bostwick 等人的研究也表明氧化 DNA 损伤在前列腺癌发生中的作用。结果表明，相对于良性前列腺上皮，前列腺上皮内瘤变和前列腺癌中的 SOD1、SOD2 和过氧化氢酶水平较低。恶性前列腺组织中存在的诱变氧化诱导的 DNA 碱基病变、8-羟基腺嘌呤 (8-oxoA) 和 8-羟基鸟嘌呤 (8-oxoG) 的比例也显着增加，并且这些病变的水平也增加在良性前列腺组织中随着老化。对碱基切除修复 (BER) 基因 OGG1 的遗传多态性的研究提供了进一步的证据，支持氧化 DNA 损伤修复缺陷可能在前列腺癌发生中起关键作用这一假设。综上所述，这些数据表明活性氧和氧化性 DNA 损伤可能在前列腺癌的发展中至关重要。 使用 LC/MS 和 GC/MS，我们发现在暴露于电离辐射和修复期后，PC-3 和 DU-145 前列腺癌细胞的氧化 DNA 碱基损伤水平较基线有所增加。与非前列腺癌细胞系相比，PC-3 和 DU-145 前列腺癌细胞系的核提取物的 DNA 碱基损伤、8-羟基鸟嘌呤 (8-oxoG)、5-羟基胞嘧啶 (5OHC) 和胸腺嘧啶乙二醇 (TG) 的切口有缺陷。恶性前列腺细胞系。与此同时，两种癌细胞系中切开这些病变的酶 NEIL1 和 NEIL2 的水平都会降低。与对照相比，来自 PC-3 和 DU-145 的线粒体提取物也具有 8-oxoG 切口缺陷。 PC-3线粒体提取物在TG和5OHC的切口中存在严重缺陷。与切口数据一致，PC-3 细胞线粒体中的 NTH1 和 OGG1 2a 蛋白水平降低。抗氧化酶、谷胱甘肽过氧化物酶 (GPx)、过氧化氢酶和超氧化物歧化酶（SOD1、SOD2）改变了癌细胞系中的表达模式。 OGG1 基因的遗传分析表明，PC-3 和 DU-145 细胞系都具有与某些癌症较高易感性相关的多态性。这些数据表明，PC-3 和 DU-145 细胞系中的恶性表型与碱基切除修复 (BER) 缺陷、BER 和抗氧化酶表达的改变以及 OGG1 遗传多态性有关。