叶酸及一碳单位代谢相关B族维生素与食管癌发病关系及其作用机制研究

A large number of studies have shown that lack of folic acid and one-carbon unit metabolism of B vitamins was related with esophageal cancer, but it still lacks a comprehensive system of population-based case-control studies and laboratory direct evidence. This case-control study based on the evaluation of the nutritional status of populations who were different stage of esophageal cancer, and selected 220 cases of new surgical cases in Jiangsu Huai'an which was the high esophageal cancer area from 2014 to 2015. According to the same region, the same sex, age difference less than two years, we match 220 precancerous cases with controls, collect the cancer tissue, precancerous cancer tissue and blood samples, and detect the genes DNA methylation and protein expression which related with folic acid metabolism and cell cycle. The nutrients in serum will also be detected, and the risk factors about dietary habits will be investigated. For the laboratory studies, we treat human normal esophageal epithelial cells with aflatoxin and nitrosamine, then intervene with folic acid and one-carbon unit metabolism of B vitamins, and observe the cytotoxicity, cell cycle, cell apoptosis and genes related DNA methylation and protein expression so that it could verify the results of population studies, investigate the effect and mechanism of B vitamins which related the metabolism of folate and one-carbon units in the incidence of esophageal cancer. All the results will provide a scientific basis for making the precautionary measures of esophageal cancer.

研究表明，叶酸及一碳单位代谢相关B族维生素的缺乏与食管癌发生有关，但仍缺乏全面系统的人群病例对照研究和实验室直接证据。本项目在江苏淮安食管癌高发地区选择2014-2015年的新发手术病例220例，以同地区、同性别、年龄相差2岁以内匹配癌前病变患者和健康居民各220例，测定食管癌不同阶段人群血清中叶酸及一碳单位代谢相关B族维生素水平，检测叶酸代谢相关基因、DNA修复相关基因、细胞周期相关基因DNA甲基化和蛋白表达，分析膳食营养等相关因素，开展三种人群的病例对照研究；实验室研究用黄曲霉毒素、亚硝胺染毒处理人类食管正常上皮细胞，同时用叶酸及一碳单位代谢相关B族维生素干预，观察细胞毒性、细胞周期、细胞凋亡的改变及相关基因DNA甲基化和蛋白表达的影响，验证人群研究结果，进一步探讨叶酸及一碳单位代谢相关B族维生素在食管癌的发生中的作用及机理，为食管癌一级预防措施的制定提供科学依据。

研究表明，叶酸及一碳单位代谢相关B族维生素的缺乏与食管癌发生有关，但仍缺乏全面系统的人群病例对照研究和实验室直接证据。本项目在江苏淮安食管癌高发地区选择2014-2015年的新发手术病例220例，以同地区、同性别、年龄相差2岁以内匹配癌前病变患者和健康居民各220例。（1）探讨食管癌高发区江苏省淮安区食管癌及癌前病变发生的影响因素，分析环境危险因素、一碳单位代谢相关B族维生素（叶酸、VB2、VB6、VB12）血清水平、MTHFR C677T基因多态性、DNA甲基化在食管癌和癌前病变发生中的作用及交互作用。结果表明食管癌组血清叶酸、VB2、VB6、VB12的中值浓度均低于正常组和癌前病变组，为三组中最低（P<0.05），p16、p53基因DNA甲基化频率在对照组、食管癌前病变组与食管癌组三组间差异有显著性（P＜0.05）。（2）并运用蛋白芯片技术检测包括p16/CDKN2A、TP53在内的共55种食管癌肿瘤相关抗原对应的血清自身抗体表达情况，验证DNA甲基化对蛋白表达的影响，并为食管癌早期诊断筛选血清差异性蛋白标志物，经多因素方差分析，在55种TAAs对应的血清自身抗体中，共有25种血清抗体表达水平在食管癌、食管癌前病变及健康人中差异有统计学意义。（3）实验室研究用黄曲霉毒素、微囊藻毒素染毒处理人类食管正常上皮细胞，同时用木犀草素、叶酸及一碳单位代谢相关B族维生素干预，观察细胞毒性、细胞周期、细胞凋亡的改变及相关基因DNA甲基化、mRNA和蛋白表达的影响，验证人群研究结果，进一步探讨叶酸及一碳单位代谢相关B族维生素在食管癌发生中的作用及机理，为食管癌一级预防措施的制定提供科学依据。