Cervical Cancer Cofactors and HPV DNA Integration

描述（由申请人提供）：宫颈的人乳头瘤病毒（HPV）感染可导致鳞状上皮内病变（SIL），可通过越来越多的低分化阶段发展为宫颈癌（CaCx）。绝大多数CaCx与高危型HPV有关。HPV-16通过HPV E6干扰肿瘤抑制蛋白p53的功能，通过HPV E7蛋白干扰pRB的功能。HPV-16癌蛋白破坏这些活性可导致突变积累，最终导致CaCx。SIL发展为CaCx的早期事件尚不清楚。然而，很明显，病毒基因组物理状态的变化（从个体到整合）可能促成了CaCx的发展。整合病毒DNA的转录本比附带体病毒DNA的转录本更稳定，并且在整合序列的细胞中，病毒癌蛋白的水平更高。HPV-16的转录本是多顺反子的，所有早期mrna都含有E7和E5序列。整合后，E5序列通过病毒基因组与宿主序列的融合而丢失。我们已经开发了一种简单的PCR测试，以区分从ThlnPrep子宫颈抹片残留的PreservCyt液中提取的RNA的完整序列或片段序列获得的转录本。只有一小部分患有SIL的女性会发展为CaCx。人们已经认识到辅助因子与CaCx的风险增加有关。这些因素包括吸烟、亚甲基四氢叶酸还原酶（MTHFR）多态性、HPV-16变异、脆弱组氨酸三联体（FHIT）基因表达缺失和沙眼衣原体感染。由于病毒基因组与宿主基因组的整合是癌症进展的核心，因此具有一种或多种这些风险因素的妇女应该在SIL中整合了病毒DNA。我们已经表明，大约22%的女性ASCUS（意义不明的异常鳞状细胞）含有HPV-16 E7 RNA，与E7转录物相比，E5转录物的缺失或低水平整合了序列。我们假设，整合HPV-16序列的女性有一个或多个与宫颈癌风险增加相关的危险因素。整合如何通过这些辅因子发生的机制尚不清楚。我们建议检测具有整合DNA和附带DNA的女性的危险因素，以确定一个或多个危险因素的存在是否与整合序列有关。这种关联将导致研究宿主和病毒基因组之间相互作用的实验室研究，使我们更好地了解导致恶性转化的事件。

DESCRIPTION (provided by applicant): Human papillomavirus (HPV) infection of the cervix can result in a squamous intraepithelial lesion (SIL) that can progress through increasing less differentiated stages giving rise to cervical cancer (CaCx). The vast majority of CaCx are associated with high risk HPV types. HPV-16 perturbs the function of the tumor suppressor proteins p53 by HPV E6 and pRB by HPV E7 proteins. Abrogation of these activities by HPV-16 oncoproteins can result in the accumulation of mutations and eventually CaCx. Early events in the progression of SIL to CaCx are not well understood. However, it is clear that a change in the physical state of the viral genome (episomal to integrated) likely precipitate CaCx development. Transcripts from integrated virus DNA are more stable than those from episomal virus DNA and the level of viral oncoproteins is higher in cells with integrated sequences. Transcripts of HPV-16 are polycistronic and all early mRNAs contain E7 and E5 sequences. After integration the E5 sequences are lost through fusion of the viral genome with host sequences. We have developed a simple PCR test to distinguish transcripts obtained from integrated or episomal sequences on RNA extracted from residual PreservCyt fluid of the ThlnPrep Pap smear. Only a small percentage of women with SIL will develop CaCx. It has been recognized that cofactors are associated with increased risk for CaCx. These include smoking, methylenetetrahydrofolate reductase (MTHFR) polymorphism, HPV-16 variants, loss of fragile histidine triad (FHIT) gene expression and ChIamydia trachomatis infection. Since integration of the viral genome into the host genome is central to progression to cancer, then women with one or more of these risk factors should have integrated virus DNA in SIL. We have shown that about 22% of women with ASCUS (abnormal squamous cells of undetermined significance) that contain HPV-16 E7 RNA have integrated sequences based on the absence or low levels of E5 transcripts compared to E7 transcripts. We hypothesize that women with integrated HPV-16 sequences have one of more risk factors that are associated with increased risk for cervix cancer. The mechanism of how integration occurs through these cofactors is unknown. We propose to assay for risk factors in women with integrated versus episomal DNA to determine whether the presence of one of more risk factors is associated with integrated sequences. An association will lead to laboratory studies investigating interactions between host and viral genomes giving us a better understanding of events leading to malignant transformation.