Dose-dependent microbiome, metabolome and lipidome shifts in a mouse model of colitis-associated colorectal cancer using azoxymethane and dextran sodium sulphate

Abstract

Colorectal cancer (CRC) remains a major health burden, underscoring the need for continued research to improve screening methods and treatment outcomes. The colitis-associated azoxymethane (AOM) and dextran sodium sulphate (DSS) mouse model has proven valuable for CRC research, as it closely mimics human CRC development and captures the complex interactions between the gut microbiome and immune system. However, variations in AOM/DSS dosing reported in literature can influence baseline conditions, thereby affecting the outcome and interpretation of experimental and therapeutic interventions. This study evaluated the impact of varying AOM and DSS doses on CRC development and the gut microbiome, metabolome and lipidome in mouse faeces ( n = 29). Inflammation-driven CRC progression was more pronounced in mice treated with high-dose AOM (12.5 mg/kg) combined with high-dose DSS (2%) than in those receiving lower doses. Faecal 16S rRNA-based microbiome analysis revealed significant shifts in the high-dose AOM groups, which coincided with the highest tumour burden. Operational taxonomic units (OTUs) belonging to Prevotella , Turicibacter , Intestinimonas and Akkermansia muciniphila displayed patterns linked to inflammation and tumour progression, with distinct temporal abundance increases across AOM/DSS dosing groups. State-of-the-art, validated UHPLC-HRMS methodologies for faecal metabolomics and lipidomics fingerprinting (7951 features) and profiling (202 targets) identified imidazolepropionic acid, a microbe-derived metabolite, as a candidate biomarker associated with inflammation-driven CRC. In addition, mice with a high tumour burden presented elevated levels of lactic acid and γ-glutamylphenylalanine as well as decreased levels of fumaric acid, 6-deoxygalactose, glucosamine/mannosamine and L-threonine, all of which are associated with gut barrier dysfunction and inflammation. Furthermore, there was a decreased abundance of a short-chain acylcarnitine and both odd-chain and even-chain fatty acids, suggesting that altered energy metabolism may be associated with CRC progression. Multi-omics integration revealed a factor shaped by differential contributions from metabolites and lipids linked to Lachnospiraceae spp., with compounds like lactic acid, methylmalonic acid, linoleic acid and palmitoleic acid positively associated with inflammation and CRC, while hypoxanthine, nicotinic acid/2-picolinic acid, L-carnitine and deoxycarnitine, showed potential protective associations. These findings highlight the complex interplay between gut inflammation, microbiome dynamics and metabolic reprogramming in CRC and suggest that AOM/DSS dosing substantially influences these interactions.