J Cancer Prev.  2017 Jun;22(2):108-114. 10.15430/JCP.2017.22.2.108.

Comparisons of Gut Microbiota Among Healthy Control, Patients With Conventional Adenoma, Sessile Serrated Adenoma, and Colorectal Cancer

Affiliations
  • 1Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea. nayoungkim49@empas.com
  • 2Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, Seoul, Korea.
  • 3Gastroenterology and Digestive Disease Research Institute, Wonkwang University Sanbon Hospital, Gunpo, Korea.

Abstract

BACKGROUND
Studies on gut microbiota regarding colorectal carcinogenesis, including sessile serrated adenoma (SSA), have been scarce. The aim of this study is to investigate the role of mucosa-associated gut microbiota in the colorectal carcinogenesis.
METHODS
We collected biopsy samples of normal rectal mucosa during colonoscopy from healthy control and patients with conventional adenoma, SSA, and colorectal cancer (CRC), respectively (n = 6). Pyrosequencing for 16S rRNA gene of bacteria was performed to compare gut microbiota.
RESULTS
The most abundant phylum in total samples was Proteobacteria (55.6%), followed by Firmicutes (27.4%) and Bacteroidetes (11.6%). There was no significant difference in relative abundance of the phylum level among the four groups. Fusobacterium nucleatum, known to be frequently detected during colorectal carcinogenesis, was found in only one sample of patient with SSA. The rarefaction curves showed that the diversity of mucosal communities of patients with CRC is the lowest among the four groups and the diversity of mucosal communities of patients with SSA is higher than that of healthy control. Among the four groups, Shannon's and Simpson's index for diversity was the lowest and the highest in the patients with CRC, respectively; it did not reach statistical significance. The proportion of genus Pseudomonas was very high in the samples of patients with stage II-IV CRC compared with those with stage I CRC (59.3% vs. 0.3%, P = 0.064).
CONCLUSIONS
Our study suggests no significant role of mucosa-associated gut microbiota in the colorectal carcinogenesis. Further study for many samples or using fecal material could be helpful.

Keyword

Microbiota; Colonic neoplasms; Colon cancer; Colon adenoma; Sessile serrated adenoma

MeSH Terms

Adenoma*
Bacteria
Bacteroidetes
Biopsy
Carcinogenesis
Colonic Neoplasms
Colonoscopy
Colorectal Neoplasms*
Firmicutes
Fusobacterium nucleatum
Gastrointestinal Microbiome*
Genes, rRNA
Humans
Microbiota
Mucous Membrane
Proteobacteria
Pseudomonas
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