Sex differences in cachexia outcomes, anabolic signalling and BCAA metabolism following chemotherapy
Authors: Mora Stephen , Adegoke Olasunkanmi A.J. 
Published: May 2023

Sex is a risk factor for cancer. Affecting nearly 80% of cancer patients is cachexia, a body and skeletal muscle-wasting syndrome. Poor nutritional status, tumour related factors and chemotherapy contribute to cachexia. Although negative effects of chemotherapy on skeletal muscle are documented, the majority of studies are completed in male animals. Although the branched-chain amino acids (BCAA: leucine, isoleucine and valine) activate anabolic signalling in skeletal muscle and have been shown to reduce some of the effects of cachexia, BCAA nutritional support does not reverse cachexia and few studies have investigated the effects of chemotherapy on BCAA metabolism in skeletal muscle. Therefore, the objective of this study is to compare the effects of chemotherapy on cachexia outcomes and BCAA metabolism between male and female mice. Three-month-old CD2F1 male and female mice were treated with either the chemotherapy drug cocktail folfiri (50mg/kg 5-fluorouracil (5FU), 90mg/kg Leucovorin and 24mg/kg CPT11) (drug) or vehicle (10% DMSO in saline) for 6-weeks. Within sex, drug treatment led to reductions in body and skeletal muscle weights. Between sex, drug-treated female mice lost more body and gastrocnemius muscle weight compared to drug-treated males. Within sex, drug treated animals exhibited reductions in anabolic signalling, specifically AKT, S6K1, S6 and 4E-BP1. Between sex, drug-treated females mice showed greater loss of anabolic signalling compared to drug-treated males. Within sex, the drug cocktail reduced amino acid transporters SNAT1 and LAT1, while reducing BCAA concentrations in the skeletal muscle. Drug-treated female mice exhibited greater loss of LAT1 compared to male-drug treated mice. However, male-drug treated mice had greater decreases in BCAA concentrations compared to female drug-treated mice. In addition, minimal differences were found within sex for key enzymes involved in BCAA metabolism. However, the inhibitory phosphorylation of branched-chain alpha-ketoacid dehydrogenase complex (BCKD) was elevated only in drug-treated male animals. Lastly, within sex, drug treatment showed elevated levels of BCAA concentrations in the liver, but only male drug-treated mice showed elevated plasma BCAAs compared to male vehicle-treated mice. Our data suggests a link between muscle atrophy and decreased BCAA metabolism during chemotherapy. We found that drug-treated female mice had worsened outcomes for cachexia measures such as body, skeletal muscle weight and anabolic signalling compared to drug-treated male mice. However, drug-treated males exhibited greater decreases in BCAA concentrations and their metabolism compared to drug-treated females. Findings from this study suggest that altered availability and metabolism of the BCAAs may contribute to muscle wasting differently in males and females during chemotherapy and interventions that correct such alterations may need to consider sex in order to better manage cachexia. Nserc, York University This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.