具核梭杆菌在食管癌发生发展中的作用及其机制的研究

The reports have suggested that the involvment of gut bacterial dysbiosis caused by symbiotic microbes abornomally growing in the carcinogenesis and progression of colorectal cancer. However, the microbiota composition in the tumor tissue of esophageal squo cell caricinoma (ESCC) and its roles are still unkonwn. Our previous transcriptome study on ESCC tissues has found that the distribution of microbiota between tumor tissues and normal tissues is significantly different, in which the mRNA copies of F. nucleatum (Fn) was the first highest observed in tumor tissues. Morover, the copies of F. nucleatum was found significantly increased in 140 tumor tissues compared to the matched normal tissues from three different areas and significantly associated with the tumor invasion depth and lymph node matastasis, suggesting that Fn may play a role in the tumorgenesis and development of ESCC, especially in tumor matastasis. This study will systemactically investigate the the roles of clinical anaerobic cultured F. nucleatum strains in the tumorgenesis and development of ESCC. The project will (1) separate the F. nucleatum strains from tumor tissues, whole-genome sequence of the Fn strains and find out the differences between the strains from other tissues and our separated strains; (2) investigate the biological effects of F. nucleatum acting on esophageal epithelium cells; (3) study the F. nucleatum roles in tumorgenesis and development of ESCC synergistically with carcinogens; (4) identify the mechanisms of F. nucleatum inducing of chronic inflammation microenviroment which boost the tuomrigenesis and development of ESCC. This study will be of help to open a new window in the pathology, diagnosis, prevention and treatment of esophageal cancer.

研究表明：共生细菌比例异常致微生态失调在结肠癌的发生发展起了重要作用。然而，食管癌中微生物组成及其作用却鲜为人知。本项目前期对食管鳞癌(ESCC)转录组学的研究中发现：与癌旁正常组织相比，癌组织中菌群组成发生显著改变，其中具核梭杆菌(F. nucleatum, Fn)丰度最高；通过进一步对比3个地区来源的140对ESCC癌/癌旁正常组织，我们发现Fn在癌组织中数量显著增高，且与浸润深度及淋巴结转移正相关，提示Fn参与了食管癌发生和发展，尤其是侵袭、转移过程。本研究已从新鲜ESCC组织中厌氧分离培养出Fn菌株，拟对Fn在食管癌发生发展中的作用进行系统研究，旨在阐明: ①食管癌相关的分离株与其他来源菌株的基因组学差异；②Fn对食管上皮细胞的生物学作用；③Fn的协同致瘤和促瘤作用；④Fn诱导慢性炎症微环境促食管癌发生和发展的机制。本项目的研究将为食管癌的病因、诊断、预防和治疗开启新的方向。

具核梭杆菌(F. nucleatum, Fn)是结直肠癌（CRC）相关性微生物，在结直肠癌的发生发展及治疗中均发挥重要作用。目前，Fn菌在食管癌（ESCC）中的作用及机制仍旧未知。本项目通过定量PCR，FISH等技术检测食管癌组织中Fn菌的丰度和定位，证实了Fn菌与食管癌相关；通过分离食管癌临床分离株并全基因组测序，证实食管癌组织驻留的Fn菌与口腔来源的标准株ATCC25586同源；通过细菌与食管癌细胞Eca109等共培养，炎症因子测定等，证实了Fn菌通过IL-6对食管癌细胞株的促增殖作用；通过Transwell等实验证实了Fn菌通过CCR7/CCL21轴， MM2/9促肿瘤细胞迁移的作用；进一步本项目通过Eca109移植瘤模型，证实了Fn菌促进了肿瘤的远处转移。此外，本项目还通过共培养等方式证实Fn菌在巨噬细胞内存活，并且IDO抑制剂可以解除细菌在细胞内的增殖限制，证实了Fn菌在体内逃避免疫的机制；通过血清抗体滴度的检测和蛋白质谱，确定了Fn菌候选抗原，并且证实了Fn-AhpC疫苗可减少Fn菌的体内负荷。以上研究明确了Fn菌是ESCC发展中的重要致病因子，为食管癌的病因、诊断、预防和治疗开启新的方向。