Altered gut microbiota of obesity subjects promotes colorectal carcinogenesis in mice

Xing Kang; Siu-Kin Ng; Changan Liu; Yufeng Lin; Yunfei Zhou; Thomas N Y Kwong; Yunbi Ni; Thomas Y T Lam; William K K Wu; Hong Wei; Joseph J Y Sung; Jun Yu; Sunny H Wong

doi:10.1016/j.ebiom.2023.104670

Altered gut microbiota of obesity subjects promotes colorectal carcinogenesis in mice

EBioMedicine. 2023 Jul:93:104670. doi: 10.1016/j.ebiom.2023.104670. Epub 2023 Jun 19.

Authors

Xing Kang¹, Siu-Kin Ng², Changan Liu¹, Yufeng Lin¹, Yunfei Zhou¹, Thomas N Y Kwong¹, Yunbi Ni³, Thomas Y T Lam¹, William K K Wu⁴, Hong Wei⁵, Joseph J Y Sung⁶, Jun Yu⁷, Sunny H Wong⁸

Affiliations

¹ Department of Medicine and Therapeutics, Faculty of Medicine, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China.
² Department of Medicine and Therapeutics, Faculty of Medicine, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.
³ Department of Anatomical and Cellular Pathology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China.
⁴ Department of Medicine and Therapeutics, Faculty of Medicine, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China; Department of Anaesthesia and Intensive Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China; Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China.
⁵ Department of Laboratory Animal Science, College of Basic Medical Sciences, Third Military Medical University, Chongqing, China; Department of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
⁶ Department of Medicine and Therapeutics, Faculty of Medicine, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore. Electronic address: josephsung@ntu.edu.sg.
⁷ Department of Medicine and Therapeutics, Faculty of Medicine, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China; Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China. Electronic address: junyu@cuhk.edu.hk.
⁸ Department of Medicine and Therapeutics, Faculty of Medicine, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore. Electronic address: sunny.wong@ntu.edu.sg.

Abstract

Background: Obesity is a risk factor for colorectal cancer (CRC). The role of gut microbiota in mediating the cancer-promoting effect of obesity is unknown.

Methods: Azoxymethane (AOM)-treated, Apc^Min/+ and germ-free mice were gavaged with feces from obese individuals and control subjects respectively. The colonic tumor load and number were recorded at the endpoint in two carcinogenic models. The gut microbiota composition and colonic transcriptome were assessed by metagenomic sequencing and RNA sequencing, respectively. The anticancer effects of bacteria depleted in fecal samples of obese individuals were validated.

Findings: Conventional AOM-treated and Apc^Min/+ mice receiving feces from obese individuals showed significantly increased colon tumor formation compared with those receiving feces from control subjects. AOM-treated mice receiving feces from obese individuals showed impaired intestinal barrier function and significant upregulation of pro-inflammatory cytokines and activation of oncogenic Wnt signaling pathway. Consistently, transferring feces from obese individuals to germ-free mice led to increased colonic cell proliferation, intestinal barrier function impairment, and induction of oncogenic and proinflammatory gene expression. Moreover, germ-free mice transplanted with feces from obese human donors had increased abundance of potential pathobiont Alistipes finegoldii, and reduced abundance of commensals Bacteroides vulgatus and Akkermansia muciniphila compared with those receiving feces from human donors with normal body mass index (BMI). Validation experiments showed that B. vulgatus and A. muciniphila demonstrated anti-proliferative effects in CRC, while A. finegoldii promoted CRC tumor growth.

Interpretation: Our results supported the role of obesity-associated microbiota in colorectal carcinogenesis and identified putative bacterial candidates that may mediate its mechanisms. Microbiota modulation in obese individuals may provide new approaches to prevent or treat obesity-related cancers including CRC.

Funding: This work was funded by National Key Research and Development Program of China (2020YFA0509200/2020YFA0509203), National Natural Science Foundation of China (81922082), RGC Theme-based Research Scheme Hong Kong (T21-705/20-N), RGC Research Impact Fund Hong Kong (R4632-21F), RGC-CRF Hong Kong (C4039-19GF and C7065-18GF), RGC-GRF Hong Kong (14110819, 14111621), and NTU Start-Up Grant (021337-00001).

Keywords: Colorectal cancer; Gut barrier; Microbiota; Obesity; Pro-inflammation.

MeSH terms

Animals
Azoxymethane / toxicity
Carcinogenesis
Colonic Neoplasms*
Colorectal Neoplasms* / genetics
Disease Models, Animal
Gastrointestinal Microbiome*
Humans
Mice
Mice, Inbred C57BL
Obesity / complications

Substances

Azoxymethane