MUCOSA-ASSOCIATED MICROBIOTA DIVERSITY SIGNIFICANTLY DIFFERS IN BARRETT'S ESOPHAGUS AND PROGRESSION TO ESOPHAGEAL ADENOCARCINOMA

Aim: Microbiota can affect cancer susceptibility and progression by diverse mechanisms, such as modulating inflammation, inducing DNA damage, and producing metabolites involved in oncogenesis or tumor suppression.But there has been few reports of gut microbiome change regarding to gastric cancer stage.Therefore, we conducted the metagenomic study to investigate the gut microbial omposition of human gut with the healthy and cancer.Moreover, we compared the intestinal microbiota change in cancer stage using 16S rRNA transcript amplicon sequencing and bacteria culture method.Methods: Stool samples were collected from 27 gastric cancer patients.16S rRNA genes from stool sample were sequenced on the Illumina Miseq platform and further analyzed to evaluate the gut bacterial community.And bacteria strains were isolated from fecal sample.The microbes were sub-cultivated for 3-7 days on the LB, BHI, GAM and PYG agar plate medium in aerobic and anaerobic condition.Then, further identified by using the 16s rRNA gene sequencing.Result: The metagenomics analysis revealed the intestinal microbiota composition in healthy group and cancer group was different.The relative abundance of the family Ruminococcus and the genus Streptococcus in cancer group was higher than in those of the healthy group.While genus Prevotella was diminished in the cancer group.In the cancer group, the phylum Firmicutes and Bacteroidetes which are involved in the carcinogenic process were basically dominant in all of the stages.However, the relative abundance of the phylum Firmicutes and Bacteroidetes was decreased in stage IV than the other stages.Among them, the relative abundance of class Ruminococcaceae and genus Bacteroides were reduced remarkably.On the contrary the phylum Proteobacteria and Actinobacteria were increased at stage IV.Especially, the family Enterobacteriaceae was observed highly in stage IV.In the bacterial culture-based approach, 40 genera including Enterococcus, Clostridium, Bacillus, Lactobacillus, Bifidobacteria, Eubacteria, Anaerostipes were isolated in stage I.However, only 14 genera such as Streptococcus, Shigella, Clostridium, Escherichia, Enterococcus, Bifidobacterium, and Bacteroides were isolated at the other stages.Conclusion: The microbial community in gastric cancer stage IV is characterized by the increase in the relative abundance of family Enterobacteriaceae of the phylum Proteobacteria, as well as the decrease in the relative abundance of Bacteroides and Firmicute than those of stage I, II, III.In the cultivated method, the diversity of isolated bacteria was substantially reduced in gastric cancer stage II, III, IV than the stage I. Su1988