The Correlative Research Between Structural Changes Of Gut Microbiota And Development Of Colorectal Adenocarcinoma

Objective: To investigate the structural changes of gut microbiota in patients with colorectal adenocarcinoma and adenomatous polyps,and the relationship between gut microbiota and the development of colorectal adenocarcinoma.Methods: The patients of colorectal adenocarcinoma and adenomatous polyps from Wuhan Tianyou hospital and Shiyan Taihe hospital and the healthy control cases were choosen in the study.The fecal samples were sequencing the V4 region of the 16 S r RNA gene on Illumina Miseq high-throughput sequencing platform.Bioinformatics methods were used to analyze the changes of abundance,diversity and structure of gut microbiota,and the and significant microbial species between the Healthy Control,CRA(Colorectal Adenomatous polyps),CRC(Colorectal Adenocarcinoma)groups were found by Significant difference analysis.Result: 1、The study included 51 CRC patients and 54 CRA patiens and 42 healthy control cases.There was no difference in age or gender between groups;2、After sequencing and analyzing by OTUs,we get 1416 OTUs in all 3 groups..Alpha diversity analysis based on the observed species metric,chao metric,shannon metric,simpson metric and rank abundance curves suggested a good sequenced coverage,and a good balance between the depth of sequencing and the species richness among 3 groups.The diversity of cases in HC,CRC,CRA groups is decreasing;3、On phylum level,the dominant phyla of 3 groups were Bacteroidetes,Firmicutes and Proteobacteria.The samples in each group showed obvious individual differences.On genus level,these 3 groups contained 168 genus bacteria.The highest diversity genus were from Firmicutes phylum,and the highest abundant genus was from Bacteroidetes phylum;4、The PCA and PCo A analysis found that the gut microbiota between CRA and HC groups and the gut microbiota between CRC and HC groups is significantly different,and the gut microbiota between CRA and CRC groups has no significant difference;5、On phylum level,the abundance of Proteobacteria and Fusobacteria is increasing with the development of health-adenomas-adenocarcinoma disease,and the abundance of Firmicutes is decreasing in CRA and CRC groups.The Firmicutes/ Bacteroidetes ratio is decreasing in CRC group.On genus level,the abundance of Lactobacillus,Peptostreptococcus,Parvimonas,Fusobacterium,Campylobacter,Neisseria,Pseudomonas,Paracoccus,Morganella,Aggregatibacter,Marinobacter,Bacteroides,Porphyromonas,Capnocytophaga,Clostridium,Leptotrichia,Bulleidia,Atopobium,Scardovia and Treponema is increasing in CRA and CRC groups,and the abundance of Roseburia,Coprococcus,Faecalibacterium,Blautia,Anaerostipes and Prevotella is decreasing significantly with the development of health-adenomas-adenocarcinoma disease(P<0.01).Conclusion: Gut microbiota is closely related to the occurrence and development of colorectal cancer and adenomatous polyps.The butyrate-producing strains of Roseburia and Faecalibacterium are lowly expressed in CRC and CRA groups,and the changes of relative abundance of Campylobacter,Pseudomonas and Fusobacterium are positively correlated with the carcinogenesis process.