结直肠癌相关肠道微生物组时空动态规律研究

Two gut bacteria Escherichia coli and Fusobacterium nucleatum can elicit carcinogenesis in the human large intestine recently reported in Science and Cell Host & Microbe,respectively. These findings will lead to increase in the research about how gut bacterial infections contribute to colorectal cancer (CRC). However, temporal and spatial dynamics of gut microbiome associated with developing CRC remain poorly elucidated.In surprise, few studies was performed for Chinsese in this facet.For this key issue, based on a preliminary study on Chinese in Yunnan, this project will further perform a large-scale molecular analysis of gut bacteria 16S rRNA gene associated with the development of CRC in Yunnan Chinese via both high-throughput 454 pyrosesquencing and various ecological measures. Firstly, we will dicover spatial heterogenety of CRC microbiome by analyzing the differences of CRC-tissue associated bacteria among the 210 CRCs occuring unique to any one of the seven sites (one site with 30 cases) along the intestine, including ileocecal valve,ascending colon,transverse colon,descending colon,sigmoid colon and rectum. Next, we wil also reveal temporal heterogeneity of CRC microbiome by clarifying the differences of mucosal bacteria associated with normal intestinal tissues (published), 60 hyperproliferative matched to carcinoma,60 adenoma tissues matched to carcinoma, and 60 carcinoma tissues from two different gut sites with significant divergent bacteria corresponding to four stages in the development of CRC. Conclusively, this project will be expected to provide novel insights into both understanding gut bacterial disorder and identifying specific gut bacteria associated with the development of CRC in Chinese.

《Science》和《Cell Host & Microbe》两大杂志近期报道了大肠杆菌和具核梭杆菌均能诱发结直肠癌的发生，这开启从肠道细菌感染出发探讨结直肠癌发生机制的先河。然而，结直肠癌发生发展相关肠道细菌的时空动态规律至今仍不清楚；针对中国人群的研究几乎是空白。为此，本项目基于前期对云南人群的初步探讨，进一步利用高通量454测序技术以及生态学方法，通过对云南人群结直肠癌发生发展相关肠道细菌16S rRNA基因大规模分子分析，开展两方面研究：①分析唯一发生在回肠末端、盲肠、升结肠、横结肠、降结肠、乙状结肠、直肠各30份癌变组织黏附细菌的差异；②分析肠道部位匹配的正常组织（已发表）、60份增生组织、60份腺瘤组织、60份癌组织（两个细菌差异显著的部位）黏附细菌的差异（对应结直肠癌发生四个阶段）。本项目将为我们全面理解中国人群结直肠癌发生发展相关肠道菌群失调提供重要的前期积累和理论参考。

大肠杆菌和具核梭杆菌等肠道微生物诱发结直肠癌的发生，但结直肠癌发生、发展相关肠道细菌的时空动态规律至今仍不清楚，针对中国人群的研究几乎是空白。本研究基于前期对云南人群肠道菌群的初步探讨，进一步利用高通量测序技术以及生态学方法，对云南人群结直肠癌发生发展相关肠道细菌16S rRNA 基因大规模分子分析，开展两方面研究：①分析分别发生在回肠末端、盲肠、升结肠、横结肠、降结肠、乙状结肠、直肠癌变组织黏附细菌的差异；②分析肠道部位匹配的正常组织、增生组织、 腺瘤组织、癌组织黏附细菌的差异。通过本研究发现：①不同部位（横结肠、乙状结肠、直肠）发病的结直肠癌组织内，均有大量Escherichia coli（大肠杆菌）、Propionibacterium（丙酸杆菌）、Fecalibacterium（粪杆菌）、Bacteroides（拟杆菌）、Streptococcus（链球菌）定植。②沿着结直肠生理结构横结肠→乙状结肠→直肠，微生物定植丰度显著减少，尤其是Escherichia coli（大肠杆菌）。③ 结直肠癌组织和癌旁组织定植微生物的种类和丰度相似，但癌旁定植丰度小于癌组织。④ Escherichia coli 与结直肠癌发病和化疗直接相关的Bacteroides（拟杆菌）、Fusobacterium nucleatum（具核梭杆菌）在直肠癌组织的定植远少于乙状结直肠癌和横结肠癌。本研究为全面理解云南地区人群结直肠癌发生发展相关肠道菌群失调提供了重要的前期积累和理论参考。

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