The Relationship Between Mmicroecology Of Intestinal Flora And Colorectal Cancer

Objective: Colorectal cancer is a common malignant tumors in digestive system.But so far,the etiology and pathogenesis of colorectal cancer is still not entirely clear.The researchers believe that the development of colorectal cancer has a variety of reasons.Recent studies have found that some changes in intestinal micro-organisms and their metabolites may play an important role in the progression of colorectal cancer.The development of colorectal cancer induced by intestinal flora has attracted great attention.But the intestinal flora is how to participate in the occurrence and development of colorectal cancer is not clear.In this study,we used the high-throughput sequencing technique to explore the diversity,relative abundance and distribution of intestinal microflora in the cancer tissue and normal mucosa of patients with colorectal cancer,and to compared the difference of fecal flora between the cancer tissue and the normal mucosa.Aimed at exploring in the bacterial changes which may play an important role in the process of development of colorectal cancer.Methods: Selected 4 cases which meet the study requirements from the patients with colorectal cancer which had been resected in the department of gastrointestinal surgery,Second Hospital,Hebei Medical University from December 2014 to December 2016.A total of 16 biopsy specimens were collected which were cancer mucosa(CM group,n=4),stool in the cancer(CS group,n=4),normal tissue mucosa(NM group,n=4),stool in the normal organization(NS group,n=4).Bacterial DNA was extracted from each specimen.Three highly variable regions,including V3,V4 and V5,were amplified from the prokaryotes 16 S r RNA gene by a series of PCR primers designed by Jin Weizhi.Conducted MetaVx ? library construction and Illumina MiSeq sequencing,sequence aligning,species identification analysising,and then analyzed the relative abundance,diversity anddistribution of intestinal flora.Results: In this study,the total number of high-quality 16 S rRNA gene sequences were 1398172.The average number of samples was 87386(n=16).Based on 97% sequence similarity(bacterial species level),1384 OTUs were identified and the average number of OTUs was 86.5(n=16).The Good’S Coverage index is 99.9%.The difference of intestinal flora between colorectal cancer patients was significantly greater than that of individuals.Chaol index reaction flora richness,it showed that there was no significant difference between the two groups(P>0.05).Simpson index reflects the diversity of bacteria,the Simpson index in NM group was more significant than in CM group(P<0.05).Bacteria were classified at the level of the door,and there was no significant difference in the dominant flora of the intestinal flora(P > 0.05),and the flora composition showed obvious individual differences.The relative abundance of Negativicutes in CM group was significantly lower than that in NM group(P<0.05),and the relative abundance of Betaproteobacteria in CM group was higher than that in CS group(P<0.05).At the present level,the abundance of Lactobacillales and Erysipelotrichales in NM group was significantly higher than that in NS group,and there was statistical significance(P<0.05).The relative abundance of Selenomonadales in NM group was significantly higher than that in CM group(P <0.05).The relative abundance of Fusobacteriales in CM group was significantly higher than that in NM group,There was statistical significance(P<0.05).The relative abundance of Fusobacteriales in CS group was significantly higher than that in CM group,There was statistical significance(P<0.05).The relative abundance of Porphyromonadaceae in CM group was significantly higher than that in NM group(P<0.05).The relative abundance of Ruminococcaceae in CM group was significantly lower than that in NM group(P<0.05).At the level of the genus,the relative abundance of Bacteroides and Fusobacterium in CM group was significantly higher than that in NM group(P<0.05).The relative abundance of intestinal flora in the group of Coprococcus,Roseburia,Phascolarctobacterium and Odoribacter was significantly higher than that inCM group(P<0.05).The intestinal abundance of NS group in Blautia group was significantly higher than that in NM group(P<0.05).Conclusion:1 Compared with the microflora at the normal tissue,the intestinal microflora at the cancer tissue changed significantly.2 The microenvironment at the cancer tissue can not be replaced by the community structure of the stool sample bacteria.3 The relative abundance of bacteria at the cancerous tissue,which are beneficial to the intestinal tract(such as the butyrate-producing bacteria),is significantly reduced,while that at tumor tissue,which may cause intestinal inflammation and may further promote the development of various conditional pathogens occurring,was significantly increased.4 In the development of colorectal cancer,some changes of intestinal microflora may play an important role.