METHYLATION PROFILING AND RISK OF COLORECTAL CANCER

甲基化谱和结直肠癌风险

• 批准号: 7284738
• 负责人: Hassan Ashktorab
• 金额: $ 8.29万
• 依托单位: HOWARD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7284738
• 关键词: African American; adenomatous polyps; biomarker; biopsy; cancer risk; carcinoma; chromosome deletion; clinical research; colorectal neoplasms; endoscopy; gastrointestinal imaging /visualization; gel electrophoresis; gene induction /repression; gene mutation; genetic screening; human subject; immunocytochemistry; loss of heterozygosity; methylation; neoplasm /cancer classification /staging; neoplasm /cancer genetics; neoplastic transformation; p53 gene /protein; polymerase chain reaction; prognosis; tumor suppressor genes

DESCRIPTION (provided by applicant): Colorectal carcinoma (CRC) is the most common gastrointestinal malignancy in the U.S and the rate of CRC is 1.5 times higher in African Americans (AA) than Caucasians. Recent advances in the field of molecular medicine has led to the use of microsatellite instability (MSI), loss of heterozygosity (LOH), and methylation specific PCR techniques which permit detection of chromosomal and gene alterations of colonic mucosal cells. The use of markers has helped to predict disease progression and prognosis. Epigenetic changes are early in the sequence of genetic alterations leading to CRC. Subsequent changes often include the loss of portions or whole chromosomes. MSI in neoplasms accumulates mutations in microsatellites within the coding region of certain genes. These data suggest that MSI, LOH and methylation profiling may add an important layer of information in the molecular phenotyping of malignances for prognostic purposes. We postulate that MSI-H, gene silencing for DNA repair gene hMHL1, p16 and LOH of APC, p53 and deleted in colorectal cancer (DCC), which are known to modulate cellular proliferation in colonic mucosa, may alter chromosome behavior in the pathway of neoplastic transformation. MSI will be measured using five microsatellite loci, and the level of p53, APC and DCC protein will be determined by immunohistochemistry in mucosal biopsies. By determining the methylation and mutation/deletion profiles of 250 cases, we determine specifically (1) to elucidate the effect of p16 and hMLH1 gene methylation in the pathway of neoplastic transformation in normal and cancer tissue of AA patients with CRC, (2) to determine the induction of MSI in colonic mucosa that may be reflected in the expression of biomarkers of neoplastic transformation and cellular proliferation from AA patients history of colonic adenomas, those with no history of adenomas, and those with a history of resected CRC. These experiments may assist in identifying persons at risk of developing adenomas and/or CRC, (3) to determine whether LOH or allelic loss occurs in APC, p53, and DCC genes in normal and cancer tissue of CRC patients and identify persons at risk of developing additional adenomas and/or CRC, (4) to analyze tumor tissue in AA patients with stage III and high-risk stage II CRC who had been treated with fluorouracil, and the ability of MSI and LOH markers to predict survival and/or response to treatment. These studies will help in the detection and profiling of genetic changes in the pathway of CRC in AA.

描述（由申请人提供）：结直肠癌（CRC）是美国最常见的胃肠道恶性肿瘤，非裔美国人（AA）的 CRC 发病率是白种人的 1.5 倍。分子医学领域的最新进展导致了微卫星不稳定性 (MSI)、杂合性丢失 (LOH) 和甲基化特异性 PCR 技术的使用，这些技术可以检测结肠粘膜细胞的染色体和基因改变。标记物的使用有助于预测疾病进展和预后。表观遗传变化处于导致结直肠癌的基因改变序列的早期。随后的变化通常包括部分或整个染色体的丢失。肿瘤中的 MSI 会累积某些基因编码区内微卫星的突变。这些数据表明，MSI、LOH 和甲基化分析可能会在恶性肿瘤的分子表型分析中添加一层重要的信息，以用于预后目的。我们假设 MSI-H，即 DNA 修复基因 hMHL1、p16 和 APC、p53 的 LOH 的基因沉默，以及结直肠癌 (DCC) 中已知可调节结肠粘膜细胞增殖的缺失，可能会改变细胞增殖途径中的染色体行为。肿瘤转化。将使用五个微卫星位点测量 MSI，并通过粘膜活检中的免疫组织化学测定 p53、APC 和 DCC 蛋白的水平。通过测定250例病例的甲基化和突变/缺失谱，我们具体确定（1）阐明p16和hMLH1基因甲基化在结直肠癌AA患者正常组织和癌组织肿瘤转化途径中的作用，（2）确定结肠粘膜中 MSI 的诱导，这可能反映在有结肠腺瘤病史、无腺瘤病史的 AA 患者的肿瘤转化和细胞增殖的生物标志物的表达中，以及有结直肠癌切除史的患者。这些实验可能有助于识别有患腺瘤和/或 CRC 风险的人，(3) 确定 CRC 患者正常组织和癌组织中的 APC、p53 和 DCC 基因是否发生 LOH 或等位基因丢失，并识别有患腺瘤和/或 CRC 风险的人。发展额外的腺瘤和/或 CRC，(4) 分析接受过氟尿嘧啶治疗的 AA III 期和高危 II 期 CRC 患者的肿瘤组织，以及 MSI 和 LOH 标记物预测生存的能力和/或对治疗的反应。这些研究将有助于检测和分析 AA 中 CRC 通路的遗传变化。