高危型HPV致癌因子E5在宫颈癌中的作用及其机制

Cervical cancer progression is strongly associated with infection of high-risk human papillomavirus (HPV) (e.g.HPV-16 and HPV-18), which are detected in nearly all cervical cancers.However, the molecular mechanisms of cervical carcinogenesis remain elusive, particularly the early steps of HPV infection that may transform normal cervical epithelium into a pre-neoplastic state. HPV is a small, nonenveloped DNA virus expressing some key oncoproteins.HPV E5 was found to be expressed in high-risk HPV and early stage cervical cancer.Recently,We have found a group of microRNAs were aberrantly decreased in HPV16-positive normal cervical tissues, and these groups of microRNAs are further reduced in cervical carcinoma.Among them, miR196a expression is low in HPV16-positive cervical cancer cell lines but high in HPV16-negative cervical cancer cell lines. Furthermore,only HPV16 early gene E5 specifically down-regulated miRNA196a in the cervical cancer cell lines. HPV16 E5 induce decreasion the experssion of miR-196a which may be a potential tumor suppressor through inhibited cell proliferation,induced G0/G1 arrest and blocked the cell cycle progression from the G1 to S phase.Moreover,we also found another group of microRNAs mapped to 14q32 locus were aberrantly decreased in HPV16-positive cervical cancer tissues.Based upon the above fundamental work, we would like to further systematically study the biological functions of high-risk HPV E5 and explore its molecular mechanisms, including interactions of proteins, related signal pathways and regulation of pathway activities,especially the relationship between E5 and HPV-related miRNAs. Through this study,it is possible to find new strategies for preventing or treating cervical cancer in early stage of HPV infection.It should be of important theoretical value and practical significance to comprehensively understand the exact mechanism in cervical cancer carcinogenesis,and to explore new approaches to prevent and cure cervical cancer.

宫颈癌是妇女第二大恶性肿瘤，呈现新发病例增多及年轻化的趋势，对发病机制、诊治研究提出了挑战。高危HPV感染是其主要病因，其编码的致癌因子E5的表达特点提示其可能在HPV感染早期发挥致癌作用，但具体功能和机制不清楚。本课题前期研究发现系列microRNA在宫颈癌不同阶段发挥作用，其中HPV16 E5通过miR-196a使其在HPV16感染的早期表达下调而不能发挥肿瘤抑制因子的作用引发宿主细胞恶性转化，并可能引发后期miRNA家族变化使肿瘤进展。因此本课题拟在前期研究的基础上，通过深入研究E5的生物学功能并系统性探讨E5作用的相关机制，特别是E5调控相关miRNA及其与其他关键因子的相互作用机制，下游通过何种通路引起肿瘤的恶性转化及继续进展，以全面认识宫颈癌的发生发展。通过本课题的实施，对于早期阻断高危型HPV的致癌作用，寻找宫颈癌防治的新方法新靶点具有重要理论和实际意义。

本项目旨在通过研究HPV16致癌蛋白E5的生物学功能并系统性探讨E5作用的相关机制，特别是E5调控相关miRNA及其与其他关键因子的相互作用机制，下游通过何种通路引起肿瘤的恶性转化及继续进展，以帮助寻找宫颈癌防治的新方法新靶点。. 为此，在项目的实施过程中，我们对前期研究所得到的miRNA进行生物信息学分析，寻找与之相关的转录因子，选择并搜集HPV16阳性的宫颈癌及宫颈癌前病变组织标本，经免疫组化染色分析E5相关的转录因子与HPV16感染的关系，并结合现有肿瘤标志物SCC-Ag和CYFRA21-1评价转录因子与宫颈癌病变程度、进展的相关性及与肿瘤侵袭转移、生存预后的关系，构建系列预测模型指导治疗以及对生存和复发进行预测。. 其次本项目在细胞水平体外研究HPV16 E5 对于宫颈癌细胞恶性表型的影响。通过调节细胞中HPV16 E5 的表达，并比较调节前后两组miRNA 的表达、宫颈癌细胞增殖、侵袭、转移和凋亡等变化明确HPV16 E5在细胞恶性转化、增殖、凋亡、侵袭转移中的作用。明确了两组miRNA与HPV16 E5及其相关转录因子的关系，并发现两组miRNA之间亦存在调控关系。. 特别是在HPV16 E5影响宫颈癌细胞恶性表型的过程中，我们首次发现并证明了以miR-133a介导并连接转录因子REL与下游一组miRNA之间的反馈通路在其中发挥了重要的作用，即HPV16感染后，致癌蛋白E5引起炎症通路REL为主的系列转录因子表达升高，REL升高抑制了miR-133a及miR-133b表达，通过他们进一步抑制了第二组miRNA的表达，在这过程中，miR-133a的抑制可反馈性的提高REl的表达，导致形成反馈闭环，其结果是在HPV感染后促癌性转录因子REL本身不断上调，而具有肿瘤抑制功能的miR-133a表达不断被抑制，病变发展后导致第二组肿瘤抑制功能的miRNA群体性抑制，引起后续细胞增殖、凋亡、自噬等一系列改变，为HPV16 E5致癌作用的重要机制。. 因此上述高危型HPV致癌蛋白、转录因子以及系列miRNA，形成了复杂调控网络参与宫颈癌的发生发展，具备重要的临床意义。.

内容获取失败，请点击重试