Abstract
BACKGROUND: Cachexia is a debilitating syndrome associated with involuntary weight loss, often occurring in cancer patients. In both humans and animal models, alterations in endocannabinoid (eCB) signaling occur in association with both metabolic disorders and several types of tumors. The wider signaling system, including the two eCBs, anandamide (AEA) and 2-arachidonoyl-glycerol (2-AG), their congeners and other long chain fatty acid amides, as well as their metabolic enzymes and receptors, is known as endocannabinoidome (eCBome). The eCBome is involved, among others, in the control of energy balance and cancer and interacts with the gut microbiome. METHODS: Using mass spectrometry-based targeted lipidomics, we measured the hepatic and intestinal concentrations of eCBome mediators in mice injected with colon carcinoma 26 (C26) cells, a model of cancer cachexia characterized, among others, by weight loss, hepatic dyslipidemia, and gut microbiome dysbiosis. RESULTS: We report that, 10 days after C26 cell injection, concomitant with >10% weight loss, eCBome lipids levels, namely 2-AG, AEA, and some of its N-acyl-ethanolamine congeners, as well as N-oleoyl-glycine, N-acyl-serotonins, and N-acyl-taurines (NATs), are altered in intestinal sections and the liver of C26 mice (e.g., hepatic 2-AG -30%, jejunal 2-AG + 30%, jejunal AEA -55%, hepatic N-oleoyl-ethanolamine (OEA) + 223%, hepatic NATs +144%, +141%, +216%). Gut dysbiosis was evident in these mice (PERMANOVA at the family level: R² = 69%, p < 0.001), with altered levels in 3 phyla (mainly the Proteobacteria, +1484%), 12 families, and 12 genera (all with adjusted p < 0.05). Additionally, 2-AG, AEA, OEA, N-arachidonoyl-serotonin, and NAT levels in the liver positively correlated with hepatic total lipids, triglycerides, and cholesterol, whereas N-docosahexaenoyl-ethanolamine and N-docosahexaenoyl-serotonin showed negative correlations. Jejunal AEA negatively, and hepatic OEA and NATs positively, correlated with weight loss. Intestinal eCBome mediators correlated with several cecal microbial taxa, including genera known to include strains beneficial in metabolic disorders, such as Bacteroides, Parabacteroides, Dysosmobacter, and Prevotella. CONCLUSIONS: These observations pinpoint eCBome mediators as new multi-functional players in the hepatic complications and gut dysbiosis accompanying cancer cachexia.