Hypermetabolic state is associated with circadian rhythm disruption in mouse and human cancer cells.

Crosstalk between metabolism and circadian rhythms is a fundamental building block of multicellular life, and disruption of this reciprocal communication could be relevant to disease. Here, we investigated whether maintenance of circadian rhythms depends on specific metabolic pathways, particularly in the context of cancer. We found that in adult mouse fibroblasts, ATP levels were a major contributor to signal from a clock gene luciferase reporter, although not necessarily to the strength of circadian cycling. In contrast, we identified significant metabolic control of circadian function across a series of pancreatic adenocarcinoma cell lines. Metabolic profiling of congenic tumor cell clones revealed substantial diversity among these lines that we used to identify clones to generate circadian reporter lines. We observed diverse circadian profiles among these lines that varied with their metabolic phenotype: The most hypometabolic line [exhibiting low levels of oxidative phosphorylation (OxPhos) and glycolysis] had the strongest rhythms, while the most hypermetabolic line had the weakest rhythms. Pharmacological enhancement of OxPhos decreased the amplitude of circadian oscillation in a subset of tumor cell lines. Strikingly, inhibition of OxPhos enhanced circadian rhythms only in the tumor cell line in which glycolysis was also low, thereby establishing a hypometabolic state. We further analyzed metabolic and circadian phenotypes across a panel of human patient-derived melanoma cell lines and observed a significant negative association between metabolic activity and circadian cycling strength. Together, these findings suggest that metabolic heterogeneity in cancer directly contributes to circadian function and that high levels of glycolysis or OxPhos independently disrupt circadian rhythms in these cells.
Competing Interests: Competing interests statement:The authors declare no competing interest.