DNA Methylation as a Risk Factor for Cervical Neoplasia

描述(由申请人提供)：虽然人乳头瘤病毒(HPV)在宫颈癌及其前体、宫颈上皮内瘤变11级或原位癌(大于或等于CIN2-3)风险中的核心作用已得到充分证实，但大多数HPV感染会自发消失，只有少数进展为宫颈癌。因此，基于HPV的筛查通常对识别患有SCIN2-3的女性的特异性较低。显然，HPV感染以外的其他因素在宫颈肿瘤的发病机制中也起着重要作用。在包括宫颈癌在内的多种癌症中，已发现某些关键基因因启动子区CpG岛甲基化而丧失功能。几乎每一种肿瘤类型似乎都有多个基因的CpG高甲基化，不同的肿瘤存在独特的高甲基化特征。我们假设DNA甲基化异常与宫颈肿瘤的风险有关，在常规筛查中获得的脱落细胞样本中DNA甲基化的检测可以作为识别CIN2-3或以上高危女性的生物标志物。我们建议通过对NCI资助的正在进行的名为“宫颈癌筛查方法评估(EVA)”的项目中收集的样本子集进行额外的分析来有效地解决我们的假设，该研究旨在评估检测大于或等于CIN3的各种筛查策略。访谈数据、细胞学和组织学以及HPV结果将用于计划中的研究。我们计划通过在CIN2-3以上的女性(病例)和CIN1或组织学正常的女性(对照组)之间映射12个或更多候选基因的CpG岛的甲基化模式，来定义一组与大于或等于CIN2-3的风险密切相关的基因(目标一)。根据病例和对照之间的甲基化模式，我们将设计一种高通量检测方法(MethyLight)来检测宫颈拭子样本中的高甲基化基因。在第二个目标中，我们将检验用于识别CIN2-3以上或等于CIN2-3的女性的高甲基化基因组的性能。最后(目标三)，在感染HPV16的女性中，我们将确定HPV16基因组长控制区CpG低甲基化是否与大于或等于CIN2-3的风险增加、E7mRNA水平高以及重复HPV16阳性访问有关。这项拟议研究的数据不仅有助于我们了解CpG甲基化在宫颈癌发生发展中的作用，还有助于更好地设计未来的宫颈癌控制方案。

DESCRIPTION (provided by applicant): Although a central role of human papillomavirus (HPV) in risk for cervical cancer and its precursor, cervical intraepithelial neoplasia grades ll-lll or carcinoma in situ (greater than or equal to CIN2-3) has been well established, most of the HPV infections resolve spontaneously and only few progress to cervical cancer. Thus, an HPV-based screening usually suffers from a low specificity for identification of women with SCIN2-3. Clearly, factors other than HPV infection also play an important role in pathogenesis of cervical neoplasia. A loss of function of certain critical genes by methylation of CpG islands in promoter region has been found in a variety of cancers, including cancer of the cervix. Almost every tumor type appears to have CpG hypermethylation in multiple genes and a unique hypermethylation profile exists for different tumors. We hypothesize that aberrant DNA methylation is associated with risk of cervical neoplasia and its detection in the exfoliated cell sample obtained at the routine screening can serve as a biomarker for identification of women who are at high risk of greater than or equal to CIN2-3. We propose to efficiently address our hypotheses by performing additional analyses on a subset of samples collected in the ongoing NCI-funded project entitled "Evaluation of Cervical Cancer Screening Methods (EVA)," a study designed to evaluate a variety of screening strategies for detection of greater than or equal to CIN3. Interview data, cytology and histology, and HPV results will be available to the planned study. We plan to define a panel of genes that are closely related to risk of greater than or equal to CIN2-3 (Aim one) by mapping methylation patterns of CpG islands of the 12 or more candidate genes between women with greater than or equal to CIN2-3 (cases) and those with CIN1 or normal histology (controls). Based on the methylation patterns between the cases and controls, we will design a high throughput assay (MethyLight) for detecting the hypermethylated genes in cervical swab samples. In Aim two, we will examine performance of testing the panel of hypermethylated genes for identification of women with greater than or equal to CIN2-3. Lastly (Aim three), among women with HPV16 infection, we will determine whether CpG hypomethylation in the long control region of HPV16 genome is associated with an increased risk of greater than or equal to CIN2-3, high level of E7 mRNA, and repeated HPV16-positive visits. Data from the proposed study will not only shed light on our understanding of the role of CpG methylation in development of cervical neoplasia but also help to better design future cervical cancer control programs.