Mitochondria govern histone acetylation in colorectal cancer

Cancer cells have an altered metabolic state that supports their growth, for example, aerobic glycolysis, known as the Warburg effect. Colorectal cancer cells have been reported to exhibit the Warburg effect and mainly rely on glycolysis for progression and have dysfunctional mitochondria. So far, how mitochondrial function influences the properties of colorectal cancer cells is unclear. Here, we demonstrated that mitochondria maintain histone acetylation, in particular acetylated histone H3 lysine 27 (H3K27ac), a surrogate epigenomic marker of active super-enhancers, in colorectal cancer cells. Immunohistochemistry was used on human colorectal adenocarcinoma specimens and showed that mitochondrial mass and H3K27ac marks were increased in adenocarcinoma lesions compared with adjacent non-neoplastic mucosa. Immunoblotting after using inhibitors of the mitochondrial respiratory complex or mitochondrial DNA-depleted human colorectal cancer cells revealed that mitochondria maintained pan-histone acetylation and H3K27ac marks. Notably, anchorage-independent growth, a feature of cancer, increased mitochondrial mass and H3K27ac marks in human colorectal cancer cells. These findings indicate that mitochondria in human colorectal cancer cells are not dysfunctional, as formerly believed, but function as inducers of histone acetylation. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.