Integrative study of skeletal muscle mitochondrial dysfunction in a murine pancreatic cancer-induced cachexia model

Pancreatic Ductal AdenoCarcinoma (PDAC), the most common pancreatic cancer, is a deadly cancer, often diagnosed late and resistant to current therapies. PDAC patients are frequently affected by cachexia characterized by muscle mass and strength loss (sarcopenia) contributing to patient frailty and poor therapeutic response. The objective of this work was to investigate the mechanisms underlying mitochondrial remodeling in the cachectic skeletal muscle, through an integrative study combining functional, morphological and omics-based evaluation of gastrocnemius muscle from genetically-engineered mice developing autochthonous pancreatic tumor and cachexia (KIC GEMM).KIC cachectic PDAC mice exhibit severe sarcopenia with loss of muscle mass and strength associated with reduced muscle fiber’s size and induction of protein degradation processes. Mitochondria in PDAC atrophied muscles show reduced respiratory capacities and structural alterations, associated with deregulation of oxidative phosphorylation and mitochondrial dynamics pathways. Beyond the metabolic pathways known to be altered in sarcopenic muscle (carbohydrates, proteins, and redox), lipid and nucleic acid metabolisms are also affected. While the number of mitochondria per cell is not altered, mitochondrial mass is decreased by a factor of 2 and the mitochondrial DNA by a factor of 3, suggesting a defect in mitochondrial genome homeostasis.Muscle atrophy is associated with strong mitochondrial metabolic defects that are not limited to carbohydrate, protein and redox metabolism, but concern also lipid and nucleic acid metabolism.This work provides a framework to guide towards the most relevant targets in the clinic to limit PDAC-induced cachexia, in particular mitochondrial fatty acid metabolism.