Molecular Epidemiology of DNA Repair in Head and Neck Cancer

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发展为SCCHN，这表明遗传易感性的作用。我们发现SCCHN风险增加与次理想DNA修复能力（DRC）之间存在关联，这可能由不利的遗传变异（如核苷酸切除修复（NER）基因中的单核苷酸多态性（snp））决定。因此，我们建议深入研究NER通路，将先前研究的5个非同音snp （nssnp）扩展到定义明确的8个NER核心基因（即ERCC1、XPA、XPB、XPC、XPD、XPE、XPF和XPG）中的85个共同标记snp (tsnp)，将变异等位基因/基因型或单倍型/二倍型与NER 3种表型（即NER mRNA表达、NER蛋白表达和NER DRC）联系起来，并评估其与SCCHN风险的相关性。为了实现这些目标，我们将纳入1,600例SCCHN病例和1,600例年龄、性别和种族匹配的对照，这些对照包括先前招募的800例病例和800例对照，以及在本应用中使用相同的研究设计、选择标准和数据收集工具招募的额外800例病例和800例对照。为了对SCCHN中的NER进行全面分析，我们的具体目标是：目的1：确定在1600例SCCHN病例和1600例对照中，8个NER基因和DRC表型中tsps的变异等位基因/单倍型和基因型/二倍型的频率与SCCHN风险的关系。我们将检验这些选定基因的不良等位基因/单倍型或基因型/二倍型以及次优DRC表型与SCCHN风险增加相关的假设。目的2：通过实时RT-PCT检测和高通量反相蛋白裂解芯片检测，分别测定400例患者和400例对照组培养淋巴细胞中8种NER蛋白的mRNA和蛋白表达水平。我们将检验低水平的NER mRNA和蛋白表达与SCCHN风险增加相关的假设。目的3：通过将变异等位基因/单倍型和基因型/二倍型的频率与8个NER基因的mRNA和蛋白表达水平和DRC表型相关联，确定8个NER基因tSNPs的选定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整合所有生物标志物和流行病学协变量的风险评估模型。这次更新中相对较大的样本量允许通过肿瘤部位（即口腔，咽和喉），各种基因型/二倍型及其组合基因型和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肾内肾素在SCCHN病因学中的作用，并可能为初级预防提供可能的目标。公共卫生意义：本研究旨在研究DNA修复能力（DRC）的遗传因素及其与烟草和酒精使用的相互作用在口腔、咽和喉部鳞状细胞癌（SCCHN）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个单核苷酸多态性，在1600个病例和1600个对照的大型研究中，我们对8个DNA修复基因的mRNA和蛋白质表达进行了分析，并将我们新开发的mRNA和蛋白质表达分析应用于400个病例和400个对照。因此，本研究将有助于了解DRC基因型（snp）与表型（mRNA和蛋白质的表达以及DRC）之间的相关性及其在SCCHN病因学中的作用。本研究的长期目标是确定有效的生物标志物，可用于识别高危个体，这些个体将成为普通人群中SCCHN一级预防的目标。

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.