The Role of PARylation in Skeletal Muscle During the Development of Cancer Cachexia

Abstract

Cancer cachexia is a wasting syndrome causing involuntary weight loss and muscle atrophy. PARP1 is a nicotinamide dinucleotide-dependent enzyme that modifies target proteins by PARylation. The reversal process, dePARylation, is mediated by the PARG enzyme. PARP1 inhibitors are potent cancer agents, while PARG inhibitors are in clinical trials for similar cancers. Here we examine the role of PARylation on muscle homeostasis in cancer cachexia. We employed mouse models with inducible muscle specific knockouts of Parp1 (Parp1-IMKO) or Parg (Parg-IMKO) to investigate their implications on skeletal muscle in a cancer cachexia model. We assessed muscle loss, grip strength, and gene expression. Results show that Parp1- IMKO mice had increased muscle wasting, while Parg-IMKO had degradation rates similar to wild-type mice during cancer cachexia. This suggests reduced PARylation might worsen cancer cachexia, while an increase does not. This supports PARG inhibitor development as anticancer alternatives. Our study highlights challenges with PARP1 inhibitors and the need to study PARylation and dePARylation in muscle health during cancer cachexia, impacting clinical strategies using PARP1 or PARG inhibitors.