Caloric restriction prevents carcinogen-initiated liver tumorigenesis in mice

Caloric restriction (CR) and endurance exercise elicit wide-ranging health benefits including reduced risk of select cancers. In addition, diet composition influences oncogenesis, although its interactions with exercise and CR are not well understood. Therefore, to investigate the potential interactions between diet and lifestyle interventions on liver tumorigenesis, the carcinogen diethylnitrosamine was administered to 72 male C57Bl/6 mice that were subsequently fed diets enriched with lard (CTL) or olive oil and were further stratified to voluntary wheel running (Ex) or 30% CR for 49 weeks. Although Ex and diet composition did not influence liver oncogenesis, CR prevented hepatic tumor formation. In addition, CR reduced steatosis, hepatocyte ballooning, inflammation, and immune cell infiltration, all of which are hallmarks in the progression of nonalcoholic fatty liver disease to liver tumorigenesis. RNA sequencing of nontransformed liver tissues from CR mice revealed changes in metabolic pathways and reduced inflammation, cytokine production, stellate cell activation and migration, and genes associated with liver injury and oncogenesis. These data demonstrate that CR protects against steatosis, liver inflammation, and liver injury and is a robust deterrent of carcinogen-induced hepatic oncogenesis.