A bioassay to measure energy metabolism in mouse colonic crypts, organoids, and sorted stem cells.

Evidence suggests that targeting cancer cell energy metabolism might be an effective therapeutic approach for selective ablation of malignancies. Using a Seahorse Extracellular Flux Analyzer, we have demonstrated that select environmental agents can alter colonic mitochondrial function by increasing respiration-induced proton leak, thereby inducing apoptosis, a marker of colon cancer risk. To further probe bioenergetics in primary intestinal cells, we developed methodology that can be modified and adapted to measure the bioenergetic profiles of colonic crypts, the basic functional unit of the colon, and colonic organoids, an ex vivo 3D culture of colonic crypts. Furthermore, in combination with the MoFlo Astrios High-Speed Cell Sorter, we were able to measure the bioenergetic profiles of colonic adult stem and daughter cells from Lgr5-EGFP-IRES-creER(T2) transgenic mice. We examined the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a full arylhydrocarbon receptor agonist, known to affect gastrointestinal function and cancer risk, on the bioenergetic profiles of intestinal epithelial cells. Mouse colonic crypts, organoids, or sorted single cells were seeded onto Matrigel-precoated Seahorse XF24 microplates for extracellular flux analysis. Temporal analyses revealed distinct energy metabolic profiles in crypts and organoids challenged with TCDD. Furthermore, sorted Lgr5(+) stem cells exhibited a Warburg-like metabolic profile. This is noteworthy because perturbations in stem cell dynamics are generally believed to represent the earliest step toward colon tumorigenesis. We propose that our innovative methodology may facilitate future in vivo/ex vivo metabolic studies using environmental agents affecting colonocyte energy metabolism.