Development of blood-based methylation biomarkers for CRC risk prediction

开发基于血液的甲基化生物标志物用于CRC风险预测 非裔美国人（AA）的结直肠癌（CRC）发病率和死亡率不成比例地高 美国白人（Caucasian Americans，CA）目前的非侵入性筛查工具，如粪便潜血试验 （FOBT）或脑炎疫苗在癌症发生后检测癌症，以及预防和治疗癌症的更有效工具。 高风险个体，如结肠镜检查或内窥镜检查，是侵入性的，不太受欢迎和主观的。 因此，鉴定区分癌症患者的正常结肠粘膜与 非癌症患者的正常结肠粘膜可能减少CRC的种族差异。我们已经确定了一 使用正常组织甲基化组将患者亚组定义为具有“异常甲基化表型”（OMP）。OMPs 是高度表观遗传破坏，并显示异常的DNA甲基化模式，在他们的整个 表观基因组我们已经能够显著地将这种表型与CRC患者相关联，而不是与健康人相关联。 对照此外，AA CRC患者出现OMP的可能性是CA的两倍多。我国现行 在申请拨款的同时，我们建议通过以下方式开发OMP作为一种微创CRC筛查和预后工具： 评价低侵袭性（全血）组织与侵袭性组织中OMP状态的一致性 （正常结肠直肠粘膜）。在具体目标1A中，我们将测试在结直肠组织中鉴定的OMP是否可以 还在200例CRC患者（100例AA，100例CA）的全血样本中鉴定出， 和位置（结直肠组织）匹配400名健康对照者（200名有腺瘤病史，200名有结肠癌病史）。 无腺瘤病史），使用来自>850K CpG的表观基因组范围数据。在具体目标1B中，我们 分析CRC患者中OMP与已知CRC分子亚型或CpG等突变的相关性 岛甲基化表型（CIMP）、KRAS、BRAF、MLH1，以估计OMP是否为替代物 任何已知CRC分子亚型的标记物。在具体目标1C中，我们将跟踪控制（特别是 OMPs），并比较临床结局，以评估其相关性 这种表型在筛查或CRC预防中的作用。我们还将研究遗传（特定目的） 2)和环境（具体目标3）因素与OMP。在特定目标2中，我们将对血液DNA进行基因分型， 确认我们样本中自我认定的种族血统，并研究遗传变异与 OMPs的异常甲基化。在具体目标3中，我们将评估饮食和社会决定因素的影响， 健康在OMP总体而言，拟议的研究旨在确定和表征分子标记物（OMP）， 侵入性较小的组织（全血），可用作诊断和预后工具，特别是在 CRC筛查率最低、CRC发病率最高的贫困AA人群， CRC死亡率最高。

Development of blood-based methylation biomarkers for CRC risk prediction Colorectal cancer (CRC) incidence and mortality rates are disproportionately higher in African Americans (AA) compared to Caucasian Americans (CA). Current non-invasive screening tools like fecal occult blood test (FOBT) or Cologuard detect cancer after it occurs, and more effective tools for prevention and treatment of higher risk individuals, such as colonoscopy or endoscopy, are invasive, less popular and subjective. Therefore, identification of early biomarkers that distinguish normal colon mucosa of cancer patients from normal colon mucosa of patients without cancer might decrease racial disparities in CRC. We have identified a subgroup of patients as having “Outlier Methylation Phenotype” (OMP) using normal tissue methylome. OMPs are highly epigenetically disrupted and display abnormal DNA methylation patterns throughout their epigenome. We have been able to significantly associate this phenotype with CRC patients over healthy controls. Furthermore, AA CRC patients appear more than twice as likely to have OMP than CA. In our current grant application, we propose to develop OMP as a less- invasive CRC screening and prognostic tool by evaluating the consistency of OMP status in a less-invasive (whole blood) tissue with an invasive tissue (normal colorectal mucosa). In Specific Aim 1A, we will test whether OMPs identified in colorectal tissues can also be identified in whole blood samples in 200 CRC patients (100 AA, 100CA) and age, sex, racial ancestry and location (for colorectal tissues) matched 400 healthy controls (200 with history of adenomas and 200 without history of adenomas) using epigenome-wide data from >850K CpGs. In Specific Aim 1B, we will analyze the association of OMP in CRC patients with known CRC molecular subtypes or mutations like CpG island methylation phenotype (CIMP), KRAS, BRAF, MLH1 to estimate whether or not OMP is a surrogate marker of any known CRC molecular subtype. In Specific Aim 1C, we will follow-up the controls (especially OMPs) after 3-4years of screening colonoscopy and compare the clinical outcomes to evaluate the relevance of this phenotype in screening or CRC prevention. We will also study the association of genetic (Specific Aim 2) and environmental (Specific Aim 3) factors with OMPs. In Specific Aim 2, we will genotype the blood DNA to confirm the self-identified racial ancestry of our samples and to study the association of genetic variants with abnormal methylation in OMPs. In Specific Aim 3, we will evaluate the effect of diet and social determinants of health on OMP. Overall, the proposed study aims to identify and characterize molecular markers (OMP) in a less- invasive tissue (whole blood) that can be used both as a diagnostic and a prognostic tool, especially in the underprivileged AA population who have the lowest CRC screening rates, highest CRC incidence and highest CRC mortality rates.