Human Papilloma Virus Infection in Patients with Colorectal Cancer

描述(申请人提供)：目前的结直肠癌发生模式的特点是逐渐积累导致息肉发展的基因改变，继而成为原发癌症。最近的研究表明，人乳头瘤病毒(HPV)感染也可能在结直肠癌(CRC)的发生发展中发挥作用。HPV感染是世界上最常见的性传播疾病，一些证据支持这种病毒的血源性传播也是可能的。HPV感染与宫颈癌和肛门癌的发展之间的联系已经明确。已有多项研究证实结直肠组织中存在HPV，提示感染可能与结直肠癌的发生发展有关。然而，HPV可能的作用和导致结直肠癌发生的机制仍有待确定。这项应用的总体目标是检测HPV的存在、整合状态和病毒载量，并确定关键的HPV癌基因(E6和E7)的表达水平，以阐明HPV是否为结直肠癌的危险因素。我们的中心假设是，HPV癌基因(E6和E7)整合到人类基因组中会导致细胞周期失调，导致结直肠组织肿瘤的发展。(1)目的1.评估HPV DNA在结直肠癌组织中的感染率，以确定HPV感染与结直肠癌之间是否存在相关性(采用套式聚合酶链式反应检测HPV-16和HPV-18DNA；对聚合酶链式反应产物进行测序以进行HPV基因分型)。(2)目的2.检测HPV L1阳性的大肠组织中HPV的基因分布，确定HPV基因在肿瘤基因组中的整合情况(用针对HPV-16 E6/E7和HPV-18 E6/E7病毒癌基因的特异性引物进行套式聚合酶链式反应；用实时定量聚合酶链式反应检测整合状态)。(3)目的3.定量检测HPV阳性病例中HPV-16、HPV-18癌基因E6、E7的mRNA表达水平(采用QRT-PCR Taqman反应策略)。我们建议使用合理的研究设计和经过验证的实验室方法，在一个具有良好特征的西班牙裔患者群体中描述HPV感染和CRC的关系。我们预计，我们的建议将填补关于HPV感染在结直肠癌中的作用的现有空白，并将研究导致结肠癌发生的生物学机制。将HPV确定为结直肠癌发生的病因因素可能会影响目前的分子模型、预防策略和治疗算法。

DESCRIPTION (provided by applicant): The current model of colorectal carcinogenesis is characterized by a gradual accumulation of genetic alterations leading to the development of polyps, which subsequently become primary carcinomas. Recent studies have suggested that Human Papillomavirus (HPV) infections may also play a role in the development of colorectal cancer (CRC). HPV infections are the most frequently sexually transmitted diseases in the world and some evidence supports that hematogenous spread of this virus may also be possible. The association between HPV infections and the development of cervical and anogenital cancer has been clearly established. Several studies have identified the presence of HPV in colorectal tissues suggesting that infection may be associated with the development and progression of CRC. However, the possible role of HPV and the mechanistic pathways leading to colorectal carcinogenesis remain to be defined. The overall objective of this application is to detect the presence, integration status and viral load of HPV, and to determine the expression level of key HPV oncogenes (E6 and E7) to elucidate if HPV is a risk factor for CRC. Our central hypothesis is that integration of the HPV oncogenes (E6 and E7) into the human genome cause cell cycle dysregulation, leading to the development of neoplasia in colorectal tissues. The following aims have been proposed: (1) Aim 1. To assess the prevalence of HPV DNA in malignant (cases) and non- malignant (controls) colorectal tissues in order to determine if there is an association between HPV infection and CRC (using nested PCR to detect HPV-16 and HPV-18 DNA; sequencing of PCR products for HPV genotyping). (2) Aim 2. To examine the genotype distribution of HPV in colorectal tissues HPV L1 positive cases, and determine integration of HPV genes into tumor genome (using nested PCR with primers specific for HPV-16 E6/E7, and HPV-18 E6/E7 viral oncogenes; integration status assessed with quantitative Real- Time PCR). (3) Aim 3. To quantify the mRNA expression levels of the HPV-16 and HPV-18 viral oncogenes E6 and E7 in HPV-positive cases (using QRT-PCR Taqman reaction strategy). We propose to describe the relationship of HPV infection and CRC, using a sound study design and validated laboratory methods, in a well-characterized population of Hispanic patients. We anticipate that our proposal will fill an existing gap regarding the role of HPV-infection in CRC and will examine the biological mechanisms responsible for colon carcinogenesis. Identification of HPV as an etiologic factor in CRC carcinogenesis may impact current molecular models, prevention strategies and treatment algorithms.