DC-SIGN/L-SIGN多态性与鼻咽癌易感性关联分析及其功能探索

Dendritic cell-specific intercellular adhesion molecule 3 grabbing non-integrin (DC-SIGN) is an important pathogen recognition receptor on the surface of some subsets of dendritic cell, which plays an important role in innate immune system in human body. DC-SIGN could directly recognize and capture many pathogens in including viruses (HIV-1,Ebola, Cytomegalovirus, et,al) and present them to susceptible cells, facilitating infection of these cells with the pathogens. As a relevant protein, liver/lymph node-specific ICAM-3-grabbing nonintegrin (L-SIGN) which have 77% homology with DC-SIGN may also play an important role in mediating the infection of various viruses. Nasopharyngeal carcinoma（NPC）is the most common malignant tumor in South China. It has been well documented that Epstein-Barr Virus (EBV) infection plays a center role the initiation and development of this tumor, and nearly 100% of the tumor cells are EBV positive. However, the exact mechanism of how EBV infect the nasopharyngeal epithelial cells remain unknown. The participation of DC-SIGN / L-SIGN in mediating virus infection raises the speculation that EBV may infect nasopharyngeal epithelial cells through DC-SIGN/L-SIGN pathway. Recent studies supported this speculation indicating that DC-SIGN may be key receptor for EBV infection in NPC and variations in promoters of DC-SIGN may affect the susceptibility of NPC in the population of Guangdong. However, the relations between DC-SIGN/L-SIGN and EBV infection and NPC occurrence are far from definitive due to limited number of relevant studies. To further investigate the role of DC-SIGN/L-SIGN in NPC, we perform a case-control study, and collect and analyze the materials including EBV status of NPC patients and healthy subjects from the population of Guangxi province. Using bioinformatics and molecular biology methods, the possible genetic variants of DC-SIGN/L-SIGN are selected and the influences of these variations on the function of DC-SIGN/L-SIGN, the NPC susceptibility, EBV status and other clinical characteristics are analyzed and validated. Our results would give a deeper insight into the role of EBV infection in the mechanism of NPC occurrence and improve the effectiveness of its early diagnosis.

树突状细胞特异性细胞间粘附分子-3结合非整合素因子（DC-SIGN）是人体免疫系统固有的病原识别受体，其相关蛋白L-SIGN特异性表达于肝脏及淋巴细胞表面，与DC-SIGN序列有77%的同源性。二者多态性与多种传染性疾病的易感性相关。鼻咽癌（NPC）是中国南方常见的恶性肿瘤，EB病毒感染上皮细胞是其发病的重要因素之一，有研究显示DC-SIGN有可能是EBV侵入上皮细胞的关键受体，其启动子区多态性与广东地区的鼻咽癌易感性密切相关。我们的前期研究亦提示二者可能存在关联，为进一步深入研究，本课题拟通过病例对照实验，结合EBV感染情况及临床病历资料，在广西地区鼻咽癌人群中开展DC-SIGN及L-SIGN的多态性位点研究，分析其与鼻咽癌易感性的关系，并经生物信息学预测后验证不同区域风险点对该分子功能的影响，为探索EBV感染上皮细胞和鼻咽癌的发病机制及早期预警奠定基础。

树突状细胞特异性细胞间粘附分子-3结合非整合素因子（DC-SIGN）是人体免疫系统固有的病原识别受体，主要表达于淋巴组织及外周组织未成熟的树突状细胞(DC)表面，其相关蛋白L-SIGN(DC-SIGNR)特异性表达于肝脏及淋巴结细胞表面，与DC-SIGN序列有77%的同源性，部分研究表明二者多态性与多种传染性疾病的易感性相关。鼻咽癌（nasopharyngeal carcinoma，NPC）是中国南方常见的恶性肿瘤，EB病毒感染上皮细胞是其发病的重要因素之一。本研究收集1000余例广西地区鼻咽癌初诊患者及正常对照人群外周血DNA，通过MALDI-TOF质谱分型及生物信息学分析，筛选鼻咽癌差异表达位点，结果发现rs7252229, rs4804803, 和rs735240位点与鼻咽癌的发生存在相关性。通过DC-SIGN/ DC-SIGNR颈区重复片段特异性PCR-电泳分型，分析结果显示本组健康人群样品中DC-SIGN颈区重复片段基因型和等位基因频率在广西健康人群与美国白人间的差异无统计学意义，和鼻咽癌患者间的差异也无统计学意义（P＞0.05）。而DC-SIGNR颈区基因型和等位基因频率在广西人群和美国白人群的差异有统计学意义，其等位基因的分布频率在广西鼻咽癌患者和健康人群间存在统计学差异（P<0.05），其中9次重复在鼻咽癌患者中占有的比例明显高于健康人群。通过EBV直接感染及细胞-细胞接触共培养模式建立EBV感染鼻咽癌上皮细胞模型，通过转录组测序筛选EBV感染鼻咽癌细胞不同时段的差异表达基因，其中DC-SIGNR表达随EBV的感染有少量的增加。通过外周血PBMC感染EBV实验亦证实EBV感染起始阶段可以使DC-SIGNR上调，但鼻咽部组织样品检测在鼻咽癌及鼻咽粘膜慢性炎中未发现明显差异。通过DC-SIGNR颈区7/9重复片段差异进行过表达载体构建，慢病毒包装后感染上皮细胞，研究不同重复片段长度的DC-SIGNR对EBV感染的影响,结果显示：DC-SIGNR的上调可以促进EBV感染细胞，其中颈区9重复者作用更明显，目前正在重复验证和进一步深入研究中。本研究的顺利开展为探索EBV感染上皮细胞和鼻咽癌的发病机制及早期预警奠定基础。

内容获取失败，请点击重试