Study On Structural Changes Of Intestinal Flora And Gene Function Prediction Of Different Flora In Patients With Colorectal Cancer

Objective:16S rRNA sequencing technology was applied to explore the structural changes of intestinal flora in colorectal cancer patients and to predict the function of different flora,providing inspiration for CRC diagnosis and potential treatment.Methods:According to the inclusion and exclusion criteria,patients diagnosed with colorectal cancer in the Affiliated Hospital of Yangzhou University from September 2022 choose until December 2022 as the experimental group,and healthy people as the control group.Fecal samples were collected for DNA extraction and PCR amplification.Intestinal flora abundance and structure differences were compared using 16 S rRNA gene sequencing and SILVA(release 132)database.R language and Linear discriminant analysis Effect Size(LEfSe)were used to analyze the abundance and diversity of bacteria,and analyze and screen the disease marker bacteria.The functions of different bacterial species were predicted using The Phylogenetic Investigation of Unobserved States2(PICRUST2)software.SPSS 23.0 and R language 4.0.5 were used for data analysis.Ttest was used for continuous variables.All tests were bilateral,and P<0.05 was considered statistically significant.Results: 1.According to the clustering method,OTU results were obtained,which showed that there were 720 unique characteristic data in the control group,440 unique characteristic data in the colorectal cancer group,and 1566 common characteristic data in the two groups.The dilution curve constructed tends to be flat,indicating that the depth of sequencing is basically sufficient with few detected species.2.Diversity analysis,α diversity: compared with healthy people,the diversity and abundance of intestinal flora in colorectal cancer patients showed a downward trend,but the difference was not statistically significant(P > 0.05).Beta diversity: patients with colorectal cancer There was no significant difference in intestinal flora distribution between the two groups(P > 0.05).3.Species difference analysis: at the phylum level,Bacteroides,Firmicutes and Actinomyces were the three most abundant phyla in both groups.Compared with the healthy group,the abundance of Firmicutes and Bacteroides in the colon cancer group was lower,the abundance of chlorophyll,Aspergillus flavus,Aspergillus flavus and other plants is relatively high.No significant difference between the two groups(P > 0.05),while Verrucomicrobia was higher in the colorectal cancer group than in the control group(P>0.05).At the genus level,Bacteroides was the most abundant in the CRC group,while Prevotella was the most abundant in the healthy group,and the difference was not statistically significant(P > 0.05).The Actinobacteria,Lachnospira,Bilophila and Butyricimonas were significantly different at phylum and genus level(P < 0.05).LEfSe analysis showed that there were 7 taxa that were different between the colorectal cancer group and the healthy group(LDA value > 4).Among them,compared with the healthy group,the colorectal cancer group: The abundance of Fusobacteriales,Fusobacteria,Enterobacteriaceae and Escherichia＿coli were relatively high.The abundance of Ruminococcaceae,Faecalibacterium and Phascolarctobacterium were lower(P < 0.05).PICRUS2 software was used to analyze the characteristic data,and a total of 29 metabolic pathways were significantly different.Compared with the healthy group,12 metabolic pathways were significantly increased in the colorectal cancer group,including MAPK signaling pathway,linoleic acid metabolism,ether lipid metabolism,etc.There were 17 the metabolic pathways of normal people are significantly higher than those of colorectal cancer patients,including cysteine and methionine metabolism,fatty acid biosynthesis,pantothenate and coenzyme a biosynthesis,etc.Conclusions: 1.The diversity of gut microbiota in patients with colorectal cancer shows a decreasing trend,while the microbial community structure does not change.Among them,the abundance of Firmicutes and Bacteroidetes was low,and the abundance of Proteobacteria,Actinobacteria and Fusobacteria was high.At the phylum level,the relative abundance of Verrucomicrobia was relatively high,while at the genus level,the abundance of Bacteroides was the highest.Actinobacteria,Lachnospira,Bilophila and Butyricimonas were significantly different at phylum and genus levels.2.The functional metabolism of intestinal flora in patients with colorectal cancer changes,as shown by enhanced MAPK signaling pathway,linoleic acid metabolism and ether lipid metabolism,while decreased cysteine and methionine metabolism,fatty acid biosynthesis,pantothenate and co A biosynthesis.3.The imbalance of intestinal flora is closely related to the occurrence of colorectal cancer,and the monitoring of intestinal flora may be conducive to the early detection and timely intervention of colorectal cancer.