Molecular Epidemiology of DNA Repair in Head and Neck Cancer

描述：虽然吸烟和饮酒是头颈部鳞状细胞癌(SCCHN)的主要危险因素，但只有一小部分吸烟者会患上SCCHN，这表明这与遗传易感性有关。我们发现SCCHN的风险增加与次优DNA修复能力(DRC)之间存在关联，这可能是由不利的遗传变异决定的，例如核苷酸切除修复(NER)基因中的单核苷酸多态(SNPs)。因此，我们建议深入研究NER途径，从先前研究的5个非同义SNPs(NsSNPs)扩展到明确定义的8个核心NER基因(即ERCC1、XPA、XPB、XPC、XPD、XPE、XPF和XPG)中的85个常见标签SNPs(TSNPs)，以将变异的等位基因/基因型或单倍型/二倍型与三种NER表型(即NER mRNA表达、NER蛋白表达和NER DRC)相关联，并评估它们与SCCHN风险的关系。为了实现这些目标，我们将纳入1600个SCCHN病例和1600个年龄、性别和种族匹配的对照，包括先前招募的800个病例和800个对照，以及将在本申请中使用相同的研究设计、选择标准和数据收集工具招募的另外800个病例和800个对照。为了全面分析SCCHN，我们的具体目标是：目的1：确定1600例SCCHN患者和1600例对照中8个NER基因和DRC表型变异等位基因/单倍型和tSNPs的基因型/二倍型与SCCHN风险的关系。我们将检验这些选定基因的不利等位基因/单倍型或基因类型/二倍型以及次优DRC表型与SCCHN风险增加相关的假设。目的：分别用实时定量RT-PCT法和高通量反相蛋白裂解产物芯片法检测400例慢性粒细胞白血病患者和400例正常对照淋巴细胞中8种NER蛋白的表达水平。我们将检验这一假设，即较低水平的NER mRNA和蛋白表达与SCCHN风险增加相关。目的：通过比较8个NER基因和DRC表型中tSNPs的变异等位基因/单倍型和基因型/二倍型的频率与其基因和蛋白表达水平的关系，确定8个NER基因tSNPs的变异等位基因和单倍型的功能相关性。这项研究将使我们能够开发风险评估模型，将所有检测的生物标记物和流行病学协变量整合在一起。这次更新的样本量相对较大，可以按肿瘤部位(即口腔、咽部和喉部)、各种基因类型/双倍型及其组合基因、流行病学协变量进行分层分析，以及评估可能的基因-基因和基因-环境相互作用。这项研究将有助于我们理解NER在SCCHN病因中的作用，并可能导致初级预防的可能靶点。公共卫生意义：这项拟议的研究旨在探讨DNA修复能力(DRC)的遗传因素以及它们与吸烟和酒精使用的相互作用在口腔、咽和喉鳞状细胞癌(SCCHN)的病因学中的作用，将我们的初步发现扩展到DRC及其遗传决定因素(85个单核苷酸多态，SNPs)在8个DNA修复基因中的作用，这项研究涉及1600例病例和1600名对照，并应用我们新开发的mRNA和蛋白质表达分析方法来检测400例病例和400名对照。因此，本研究将有助于了解DRC基因(SNPs)与表型(mRNA、蛋白质和DRC的表达)之间的相关性及其在SCCHN发病机制中的作用。这项研究的长期目标是确定有效的生物标志物，可用于识别将成为普通人群SCCHN一级预防目标的高危个体。

DESCRIPTION: Although smoking and alcohol use are major risk factors for squamous cell carcinoma of the head and neck (SCCHN), only a fraction of smokers develops SCCHN, suggesting a role for genetic susceptibility. We have found an association between increasing risk of SCCHN and suboptimal DNA repair capacity (DRC) that may be determined by adverse genetic variants such as single nucleotide polymorphisms (SNPs) in the nucleotide-excision repair (NER) genes. Therefore, we propose to focus in depth on the NER pathway by expanding from previously studied 5 non-synonymous SNPs (nsSNPs) to 85 common tagging SNPs (tSNPs) in the well-defined 8 core NER genes (i.e., ERCC1, XPA, XPB, XPC, XPD, XPE, XPF, and XPG), to correlate the variant alleles/genotypes or haplotypes/diplotypes with three NER phenotypes (i.e., NER mRNA expression, NER protein expression and NER DRC), and to evaluate their associations with risk of SCCHN. To accomplish these goals, we will include 1,600 SCCHN cases and 1,600 age-, sex-, and ethnicity-matched controls that consist of previously recruited 800 cases and 800 controls and an additional 800 cases and 800 controls to be recruited in this application using the same study design, selection criteria, and data collection instruments. To perform a comprehensive analysis of NER in SCCHN, our specific aims are: AIM 1: To determine the associations of the frequencies of variant alleles/haplotypes and genotypes/diplotypes of tSNPs in the 8 NER genes and the DRC phenotype with risk of SCCHN in 1,600 SCCHN cases and 1,600 controls. We will test the hypotheses that adverse alleles/haplotypes or genotypes/diplotypes of these selected genes and suboptimal DRC phenotype are associated with increased risk of SCCHN. AIM 2: To determine mRNA and protein expression levels of the 8 NER proteins by real-time RT-PCT assay and high-throughput reverse-phase protein lysate microarray assay, respectively, in cultured lymphocytes from 400 cases and 400 controls to be accrued. We will test the hypothesis that lower levels of NER mRNA and protein expression are associated with increased risk of SCCHN. AIM 3: To determine functional relevance of selected variant alleles and haplotypes of tSNPs of the 8 NER genes by correlating the frequencies of variant alleles/ haplotypes and genotypes/diplotypes with expression levels of mRNA and proteins of the 8 NER genes and DRC phenotype. This study will allow us to develop risk assessment models that integrate all biomarkers tested and epidemiological covariates. The relatively large sample size in this renewal allows for stratification analysis by tumor sites (i.e., oral cavity, pharynx and larynx), various genotypes/diplotypes and their combined genotypes, and epidemiologic covariates as well as for assessment of possible gene-gene and gene-environment interactions. This study will contribute to our understanding of the role of NER in the etiology of SCCHN and may lead to possible targets for primary prevention. PUBLIC HEALTH SIGNIFICANCE: This proposed study is to investigate the roles of genetic factors of DNA repair capacity (DRC), as well as their interactions with tobacco and alcohol use, in the etiology of squamous cell carcinomas of the oral cavity, pharynx, and larynx (SCCHN), expanding our preliminary findings to a role of DRC and its genetic determinants (85 single nucleotide polymorphisms, SNPs) in 8 DNA repair genes in a large study of 1600 cases and 1600 controls and applying our newly developed assays for mRNA and protein expression to 400 cases and 400 controls. Therefore, this study will help understand correlations between DRC genotypes (SNPs) and phenotypes (expression of mRNA and proteins and DRC) and their roles in the etiology of SCCHN. The long-term goal of this study is to identify effective biomarkers that can be used to identify at-risk individuals who will be targeted for primary prevention of SCCHN in the general population.