Mucosal microbiome dysbiosis in gastric carcinogenesis.

Olabisi Oluwabukola Coker, Zhenwei Dai, Yongzhan Nie, Guijun Zhao, Lei Cao, Geicho Nakatsu, William Kk Wu, Sunny Hei Wong, Zigui Chen, Joseph J Y Sung, Jun Yu

Journal: Gut 2018;67(6):1024-1032

PMID: 28765474

Plain Language Summary

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Gastric cancer (GC) is the 4th most common cancer and a leading cause of cancer-related deaths worldwide. Infection with Helicobacter pylori is an important risk factor for GC and other changes in gastric microbial composition are thought to play role in gastric carcinogenesis. This observational study aimed to elucidate the microbial changes that are characteristic for the different stages of gastric tumor development. The authors found significant changes in microbial composition in stomach cancer patients compared to patients with pre-cancerous mucosal changes, with an increase of some and a depletion of other bacteria, in particular an increase in oral bacteria, which is also found in other gastrointestinal cancers. They also found that interactions between the depleted and enriched bacterial species progressively increased with progressing carcinogenesis. Whilst there was no difference in the diversity of bacteria between H. pylori-positive and negative samples, more bacterial interactions were observed in H. pylori-negative samples. The authors conclude that significant gastric dysbiosis can be seen in samples of stomach cancer patients, however, they point out that from their study it is impossible to tell whether the bacteria increased in GC are “drivers” or “passengers” of gastric carcinogenesis. Their call for more research focusses on using this knowledge to develop better diagnostic biomarkers, rather than using this information for prevention or treatment of stomach cancer.

Abstract

OBJECTIVES

We aimed to characterise the microbial changes associated with histological stages of gastric tumourigenesis.

DESIGN

We performed 16S rRNA gene analysis of gastric mucosal samples from 81 cases including superficial gastritis (SG), atrophic gastritis (AG), intestinal metaplasia (IM) and gastric cancer (GC) from Xi'an, China, to determine mucosal microbiome dysbiosis across stages of GC. We validated the results in mucosal samples of 126 cases from Inner Mongolia, China.

RESULTS

We observed significant mucosa microbial dysbiosis in IM and GC subjects, with significant enrichment of 21 and depletion of 10 bacterial taxa in GC compared with SG (q<0.05). Microbial network analysis showed increasing correlation strengths among them with disease progression (p<0.001). Five GC-enriched bacterial taxa whose species identifications correspond to , , , and had significant centralities in the GC ecological network (p<0.05) and classified GC from SG with an area under the receiver-operating curve (AUC) of 0.82. Moreover, stronger interactions among gastric microbes were observed in -negative samples compared with -positive samples in SG and IM. The fold changes of selected bacteria, and strengths of their interactions were successfully validated in the Inner Mongolian cohort, in which the five bacterial markers distinguished GC from SG with an AUC of 0.81.

CONCLUSIONS

In addition to microbial compositional changes, we identified differences in bacterial interactions across stages of gastric carcinogenesis. The significant enrichments and network centralities suggest potentially important roles of , , , and in GC progression.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Address: Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China.; State Key Laboratory of Cancer Biology, Xijing Hospital, Fourth Military Medical University, Xian, China.; Department of Gastroenterology and Hepatology, Inner Mongolia People's Hospital, Hohhot, China.; Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.

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