The Intestinal Bacteria Group Relationship Between Change And The Development Of Colon Cancer

Objective To explore the structures of microbiota adherent to colonic mucosa or some kinds of bacteria as result of the occurrence and development of colon cancer and the mucosal bacterial communities from different position of colon within a normal individual.Methods Human colonic biopsies were taken at routine colonoscopy from32patients with colon cancer and31individuals with normal looking mucosa. For patients with colon cancer, samples were taken at cancerous region and paracancer mucosas (more than5cm apart). For normal individuals, colonic biopsies were taken at three sites of large intestine(descending colon, transverse colon, and ascending colon). Considering many factors which may influence the gut microbiomes such as obesity, receiving antibiotic therapy, inflammatory bowel diseases (crohn diseases and ulcerative colitis), chronic diarrhea, chronic constipation and metabolic diseases, follow-up visiting the operation situation, pathology and staging of cancer in time, we select the samples in line with criterions finally. The total DNA were extracted from biopsies using a common method Quantitation kit was used to quantify the amount of DNA extracted from the biopsy samples. Bacterial16S rRNA gene regions were amplified from the total nucleic acids using universal bacterial primers, the bacterial V316S rDNA region as well. PCR products of microbiota from cancerous region and paracancer mucosa were compared within the same patient by PCR DGGE, as well as the bacteria community adherent to mucosa from different sites of colon within the same normal individual. After, compare PCR products from normal individual and cancerous region of patients, then find the difference. At last, bacterial species were identified by sequencing special bands from DGGE gels and comparing data to sequence databases.Results Through screening, patients with cancer were divided into three groups according to their pathological position including descending colon, transverse colon, and ascending colon, the sample size is10,6and5respectively. The microbiota structure from cancerous region and paracancer mucosa within the same patient are almost the same on the respects of biodiversity and richness by analyzing the DGGE gel images. The number of normal individuals is20, with the same method, we find there are no difference among the biopsies from three sites within the same individual. However, when we compare normal individual with the patients, we discover that the diversity and richness of bacteria community from normal individuals’colonic mucosa are obviously higher than that from patients’sample At last, a special DGGE band was found, after being excised, purified,cloned,sequenced, we confirm that it has a high level of sequence similarity with Bacteroides.Conclusion There are no distinct difference between microbiota constructure from cancerous region and paracancer mucosa within the same patient. Bacteria composition from three colonic sites within the same normal individual are almost the same. The biodiversity and richness of bacteria community from normal individuals’ colonic mucosa are obviously higher than that from patients’ sample. Bacteroides is likely related to the occurrence or development of colon cancer...