Analysis of composition differences of intestinal microbiota in patients with colon cancer and rectal cancer / 肿瘤研究与临床

ABSTRACT

Objective:To analyze the composition differences of intestinal microbiota in patients with colon cancer and rectal cancer.Methods:The fecal samples of 72 patients in the Second Affiliated Hospital of Harbin Medical University from July 2018 to January 2019 were collected, and they were divided into colon cancer group and rectal cancer group, 36 cases in each group. DNA from fecal samples was extracted, and then high-throughput sequencing was performed on DNA. Bioinformatics was used to analyze the diversity and composition differences of intestinal microbiota between the two groups, and the potential cancer-promoting mechanisms of the differential flora were also discussed.Results:From high-throughput sequencing, 2 356 560 original sequences and 32 730 high-quality sequences were obtained from 72 samples. The average length of the sample sequence was mainly in the interval of 401-460 bp. And 1 409 operational taxonomic units (OTU) were acquired after OTU species taxonomy annotation of all the sequences. Alpha diversity analysis showed that Shannon index of the rectal cancer group and the colon cancer group was 2.61±0.56 and 2.43±0.67, respectively, and the difference was statistically significant ( t = 1.229, P = 0.223); Simpson index of the rectal cancer group and the colon cancer group was 0.17±0.09 and 0.21±0.16, respectively, and the difference was statistically significant ( t = 1.449, P = 0.151). Differences analysis of both groups and linear discriminant analysis (LDA) showed at the phylum level, Firmicutes were more abundant in the intestine of patients with rectal cancer (LDA = 4.67, P = 0.014), while Proteobacteria were more abundant in the gut of colon cancer patients (LDA = 4.49, P = 0.042). From the perspective of class level, the abundance of Gammaproteobacteria was higher in the intestine of patients with colon cancer (LDA = 4.50, P = 0.033), while the abundance of Erysipelotrichia was higher in the intestine of patients with rectal cancer (LDA = 3.50, P = 0.035). At the order level, the abundance of Erysipelotrichales was higher in the intestine of patients with rectal cancer (LDA = 3.50, P = 0.035); at the family level, the abundance of Porphyromonadaceae was higher in the intestine of patients with rectal cancer (LDA = 3.97, P = 0.033). Conclusion:The compositions of intestinal microbiota in patients with colon cancer and rectal cancer are significantly different, indicating that the different floras may contribute to the progression of colon cancer and rectal cancer.