Microbial metabolite ammonia disrupts TGF-β signaling to promote colon cancer

Authors

Krishanu Bhowmick, Institute for Bioelectronic Medicine, Feinstein Institutes for Medical Research; Divisions of Gastroenterology and Hepatology, Department of Medicine, Northwell Health, Manhasset, NY, USA; Cold Spring Harbor Laboratory; Cold Spring Harbor, NY, USA. Electronic address: bhowmick.krishanu@gmail.com.
Xiaochun Yang, Institute for Bioelectronic Medicine, Feinstein Institutes for Medical Research; Divisions of Gastroenterology and Hepatology, Department of Medicine, Northwell Health, Manhasset, NY, USA; Cold Spring Harbor Laboratory; Cold Spring Harbor, NY, USA.
Taj Mohammad, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, India.
Xiyan Xiang, Institute for Bioelectronic Medicine, Feinstein Institutes for Medical Research; Divisions of Gastroenterology and Hepatology, Department of Medicine, Northwell Health, Manhasset, NY, USA; Cold Spring Harbor Laboratory; Cold Spring Harbor, NY, USA.
Christine L. Molmenti, Department of Occupational Medicine, Epidemiology and Prevention, Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, USA; Feinstein Institutes for Medical Research, Institute of Cancer Research, Manhasset, NY, USA; Department of Surgery, Northwell Health, Manhasset, NY, USA.
Bibhuti Mishra, Institute for Bioelectronic Medicine, Feinstein Institutes for Medical Research; Divisions of Gastroenterology and Hepatology, Department of Medicine, Northwell Health, Manhasset, NY, USA; Donald and Barbara Zucker School of Medicine at Hofstra/Northwell Health, Department of Neurology, Hempstead, NY, USA.
Srinivasan Dasarathy, Division of Gastroenterology and Hepatology, Cleveland Clinic, Cleveland, OH, USA.
Adrian R. Krainer, Cold Spring Harbor Laboratory; Cold Spring Harbor, NY, USA.
Md Imtaiyaz Hassan, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, India.
Keith A. Crandall, Computational Biology Institute and Department of Biostatistics and Bioinformatics, Milken Institute School of Public Health, George Washington University, Washington DC, USA.
Lopa Mishra, Institute for Bioelectronic Medicine, Feinstein Institutes for Medical Research; Divisions of Gastroenterology and Hepatology, Department of Medicine, Northwell Health, Manhasset, NY, USA; Cold Spring Harbor Laboratory; Cold Spring Harbor, NY, USA; Department of Surgery, George Washington University, Washington DC, USA. Electronic address: lopamishra2@gmail.com.

Document Type

Journal Article

Publication Date

4-29-2025

Journal

The Journal of biological chemistry

DOI

10.1016/j.jbc.2025.108559

Abstract

Colorectal cancer (CRC) is rising alarmingly in younger populations, potentially arising from factors such as obesity, pro-inflammatory gut microbiome and the accumulation of toxic metabolites. However, how metabolites such as ammonia impact key signaling pathways to promote CRC remains unclear. Our study investigates a critical link between gut microbiome alterations, ammonia, and their toxic effects on the TGF-β signaling pathway, driving CRC progression. We observe altered microbial populations in an obesity-induced mouse model of cancer, where ammonia promotes caspase-3-mediated cleavage of the SMAD3 adaptor βII-spectrin (SPTBN1). Cleaved SPTBN1 fragments form adducts with ammonia that induce pro-inflammatory cytokine expression and disrupt TGF-β signaling. Extending from AlphaFold docking simulations, we identified that ammonia interacts with N-terminal SPTBN1 potentially through residues D81, Y556, S663, Y666, N986, and D1177 to form hydrogen bonds that disrupt downstream SMAD3 signaling, altering TGF-β signaling to a protumorigenic phenotype. Blocking SPTBN1, through an SPTBN1-specific siRNA blocks ammonia toxicity and restores normal SMAD3/TGF-β signaling by reducing the abundance of SPTBN1 cleaved fragments in SW480 and Caco-2 (CRC) cell lines. In addition, our research establishes crosstalk between TGF-β signaling and a microbial sensor, carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), which is significantly overexpressed in CRC patients. We identified CEACAM1-SPTBN1 interactions at specific residues (E517 and Y520) within the immunoreceptor tyrosine-based inhibitory motif (ITIM) of CEACAM1 cytoplasmic domain, identifying distinguishing a potential axis that is harnessed by the altered microbiome. Our study identifies mechanistic insights into how microbial metabolites target TGF-β as a major signaling pathway to promote CRC.

APA Citation

Bhowmick, Krishanu; Yang, Xiaochun; Mohammad, Taj; Xiang, Xiyan; Molmenti, Christine L.; Mishra, Bibhuti; Dasarathy, Srinivasan; Krainer, Adrian R.; Hassan, Md Imtaiyaz; Crandall, Keith A.; and Mishra, Lopa, "Microbial metabolite ammonia disrupts TGF-β signaling to promote colon cancer" (2025). GW Authored Works. Paper 6966.
https://hsrc.himmelfarb.gwu.edu/gwhpubs/6966

Department

Biostatistics and Bioinformatics