Analysis of the predictability of lung cancer using DNA Repair functional assays and cryopreserved blood samples of the PLCO prospective cohort

项目总结/摘要 阐明肺癌的病因与确定疾病的危险因素交织在一起， 并且对于推进预防和协助早期发现这种致命肿瘤至关重要。吸烟状态 和衰老是有据可查的肺癌的主要危险因素，沿着的还有其他几个危险因素 包括某些环境和职业致癌物暴露，我们的知识存在空白， 疾病的其他重要原因，包括可能改变疾病影响的生物过程， 风险因素或独立风险因素。因为DNA修复能力是避免突变的关键， 预防癌症，并可能反映了多种遗传和其他影响，我们以前已经开发了 一组三个功能性DNA修复血液测试，直接测量个人的有效性， 通过酶OGG 1、MPG和APE 1修复氧化DNA损伤。把这些测试用在一个案子上- 在对照研究中，我们发现，从三个测试中计算出的低DNA修复分数， 与肺癌的关系除了吸烟之外，也与吸烟无关。最近， 第二项病例对照研究表明，将DNA修复评分添加到目前的肺癌风险模型中， 很可能会大大改善风险预测。到目前为止的数据与肺中的致病作用一致 癌症，但因为研究结果是基于病例对照研究，其中疾病偏见不能排除 有说服力的证据支持低DNA修复评分在肺癌病因学中的作用， 在前瞻性队列研究中证明了其预测肺癌的能力。 我们的目标是在巢式病例中检查DNA修复评分对肺癌的预测能力- 前瞻性队列中的对照研究，即PLCO筛选试验。DNA修复活性将是 在来自PLCO诊断前冷冻保存的活全血样品的扩增T细胞中测量， 目前吸烟者和从不吸烟者随后患上肺癌，并将与 来自未患任何类型癌症的匹配对照组的样本， 肺癌的可能性很大。此外，DNA修复测试将扩大三个新的功能测试， DNA修复酶TDG、SMUG 1和NEIL 1。使用从PLCO收到的一组测试样品 试验中，我们已经证明T细胞可以有效地和高效地从全血中扩增， 冻存12年或20年的样品，适合于所有六种DNA修复酶的测定 活性，产生与新鲜淋巴细胞相当的可重复值。成功的结果 这项研究将支持氧化性DNA损伤的次优DNA修复在肺疾病病因学中的作用。 癌症，并将促进DNA修复评分适应临床验证的生物标志物的风险 肺癌的诊断预计这将改善风险估计，并提供更好的选择标准 用于通过低剂量CT等方法早期检测肺癌。 1

Project Summary/Abstract Elucidating the etiology of lung cancer is interwoven with the identification of risk factors for the disease, and is critical to advance prevention, and assist early detection of this lethal tumor. While smoking status and aging are well documented key lung cancer risk factors, along with several additional risk factors including certain environmental and occupational carcinogenic exposures, there is a gap in our knowledge of other important causes of the disease including biological processes that may modify the impact of exposures or be independent risk factors. Because DNA repair ability is key in avoiding mutations and preventing cancer, and likely reflects multiple inherited and other influences, we have previously developed a panel of three functional DNA repair blood tests, which directly measure an individual’s effectiveness at repairing oxidative DNA damage by the enzymes OGG1, MPG and APE1. Using these tests in a case- control study, we found that a low DNA repair score, calculated from the three tests, was strongly associated with lung cancer in addition to and independent of smoking. This was recently replicated in a second case-control study, suggesting that adding the DNA repair score to current lung cancer risk models is likely to substantially improve risk prediction. The data so far is consistent with a causative role in lung cancer, but because the findings are based on case-control studies, where disease bias cannot be ruled out, persuasive evidence to support a role of a low DNA repair score in lung cancer etiology requires demonstrating its ability to predict lung cancer in prospective cohort studies. Our goal is to examine the predictive ability of the DNA repair score for lung cancer in a nested case- control study within a prospective cohort, namely the PLCO Screening Trial. DNA repair activity will be measured in expanded T cells from PLCO pre-diagnostic cryopreserved viable whole blood samples of current smokers and never-smokers who subsequently developed lung cancer, and will be compared to samples from matched controls who did not develop any type of cancer, from which the ability to predict lung cancer can be inferred. Further, DNA repair tests will be expanded with three new functional tests for the DNA repair enzymes TDG, SMUG1 and NEIL1. Using a set of test samples received from the PLCO Trial, we have demonstrated that T cells could be effectively and efficiently expanded from whole blood samples cryopreserved for 12 or 20 years, and were suitable for measuring all six DNA repair enzyme activities, yielding reproducible values comparable to fresh lymphocytes. A successful outcome of this study will support the role of sub-optimal DNA repair of oxidative DNA damage in the etiology of lung cancer, and will facilitate the adaptation of the DNA repair score into clinically-validated biomarkers for risk assessment of lung cancer. This is expected to improve risk estimates, and provide better selection criteria for early detection of lung cancer by methods such as low-dose CT. 1