HIV Associated DNA Hypermethylation in Cervical Cancer

我们的目标是了解HIV相关浸润性宫颈癌(ICC)及其前体宫颈上皮内瘤变3级(CIN-3)的分子发病机制，并利用这些信息开发在资源匮乏、艾滋病毒流行的情况下控制宫颈癌的分子检测方法。甚至在艾滋病毒流行之前，ICC就是发展中世界的一个主要公共卫生问题，艾滋病毒增加了CIN-3/ICC的风险，使ICC更加令人担忧。现有的宫颈癌控制策略(细胞学或基于HPV的CIN-3和原位癌(CIS)筛查、目视筛查和立即消融)不适合资源匮乏的艾滋病毒流行环境。细胞学检查不敏感且费用昂贵；大多数艾滋病毒阳性妇女感染HPV；在未确认疾病的情况下进行目视筛查和冷冻消融会导致过度治疗，这在艾滋病毒+妇女中令人担忧，因为冷冻治疗会导致与艾滋病毒传播风险增加相关的溃疡。此外，虽然我们已经报告了预防高危类型HPV感染(已知对ICC的发展至关重要)的疫苗似乎有效，但目前的疫苗在非洲可能兴趣有限，并且不能阻止那些已经感染HPV的人发生ICC。 众所周知，持续感染HPV的妇女亚群患ICC的风险增加，而与HIV感染相关的CIN-3/ICC风险增加被认为是HIV相关免疫抑制和无法解决HPV感染的结果。然而，持续的HPV感染本身并不足以进展到ICC，暴露于相关的辅助因素是必要的，我们的发现强调了这一事实，在HIV阳性的持续HPV感染的妇女中只有25%进展到CIN-3。我们假设，与HIV感染相关的进展风险的增加既是HIV诱导的HPV感染持续存在的结果，也是HIV诱导的许多基因的DNA高甲基化(沉默)的结果，包括许多对宫颈癌发生至关重要的基因。此外，我们假设这些分子变化是患有和面临CIN-3/ICC风险的女性的潜在生物标记物。这些假说建立在“体外”研究的基础上，这些研究表明HIV可诱导广泛的高甲基化；研究表明CpG岛DNA高甲基化在癌症的发病机制中起主要作用，并发生在癌症发生的早期；我们对宫颈活检的初步研究表明，HFV感染与许多基因的高甲基化风险增加有关，这些基因似乎在宫颈肿瘤的发生中起重要作用。为了解决这些假设，我们将首先确定一组在HIV和HIV+女性中预测CIN-3/ICC的高甲基化基因(目标1)，然后进行嵌套病例对照研究(目标2)，评估发生CIN-3的风险与HPV持久性、HIV以及候选高甲基化基因的存在或获得之间的关系。最后，我们将探索HIV相关因素(CD4计数、病毒载量、HAART)，它们可能与目的基因的高甲基化存在或获得有关。

Our goal is to understand the molecular pathogenesis of HIV-associated invasive cervical cancer (ICC) and its precursor, cervical intraepithelial neoplasia grade 3 (CIN-3), and to use this information to develop molecular assays for cervical cancer control in resource-poor settings with endemic HIV. Even prior to the HIV epidemic, ICC was a major public health problem in the developing world, and HIV increases the risk of CIN-3/ICC, making ICC of even greater concern. Available strategies for cervical cancer control (cytology or HPV based screening for CIN-3 and carcinoma in situ (CIS), visual screening with immediate ablation) are inappropriate for resource-poor settings with endemic HIV. Cytology is insensitive and costly; most HIV-positive women are infected with HPV; and visual screening and cryoablation without disease confirmation results in over-treatment, which is of concern in HIV+ women, since cryotherapy causes ulcers associated with increased risk of HIV transmission. Further, while we have reported that vaccines to prevent high risk types of HPV infection (which are known to be central to development of ICC) appear effective, current vaccines may be of limited interest in Africa, and do not prevent development of ICC in those already infected with HPV. It is known that the subset of women who develop persistent HPV infection are at increased risk of ICC, and the increased risk of CIN-3/ICC associated with HIV infection is thought the result of HIV-associated immune suppression and inability to resolve HPV infection. However, persistent HPV infection is alone not sufficient for progression to ICC and exposure to relevant co-factors is necessary, a fact underscored by our findings that only 25% of HIV-positive women with persistent HPV progressed to CIN-3. We hypothesize that the increased risk of progression associated with HIV infection is the result of both HIV-induced persistence of HPV infection and HIV induced DNA hypermethylation (silencing) of numerous genes, including many central to cervical cancer oncogenesis. Further, we hypothesize that these molecular changes are potential biomarkers for women with, and at risk of >CIN-3/ICC. These hypotheses are based on "in vitro" studies demonstrating HIV induction of widespread hypermethylation; studies showing that CpG island DNA hypermethylation plays a major role in the pathogenesis of cancers and occurs early in carcinogenesis; and our pilot studies of cervical biopsies demonstrating that HFV infection is associated with an increased risk of hypermethylation of many genes that appear to be important in oncogenesis of cervical neoplasia. To address these hypotheses, we will first identify a panel of hypermethylated genes that are predictive of CIN-3/ICC among both HIV and HIV+ women (Aim 1), and then perform a nested case control study (Aim 2) assessing the risk of developing CIN-3 in relationship to HPV persistence, HIV, and the presence or acquisition of the candidate hypermethylated genes. Lastly we will explore the HIV related factors (CD4 counts, viral load, HAART), which might be associated with the presence or acquisition of the hypermethylated genes of interest.