Preclinical Multi-Omic Assessment of Pioglitazone in Skeletal Muscles of Mice Implanted with Human HER2/neu Overexpressing Breast Cancer Xenografts
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Breast cancer (BC) is the most prevalent cancer worldwide and is accompanied by fatigue during both active disease and remission in the majority of cases. Our lab has measured fatigue in isolated muscles from treatment-naive BC patient-derived orthotopic xenograft (BC-PDOX) mice. Here, we conducted a preclinical trial of pioglitazone in BC-PDOX mice to determine its efficacy in ameliorating BC-induced muscle fatigue, as well as its effects on transcriptomic, metabolomic, and lipidomic profiles in skeletal muscle.
Methods
The pioglitazone and vehicle groups were treated orally for 4 weeks upon reaching a tumor volume of 600 mm 3 . Whole-animal indirect calorimetry was used to evaluate systemic metabolic states. The transcriptome was profiled using short-read bulk RNA sequencing (RNA-seq). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to profile the metabolome and lipidome. Fast and slow skeletal muscle function were evaluated using isolated ex vivo testing.
Results
Pioglitazone was associated with a significant overall decrease in metabolic rate, with no changes in substrate utilization. RNA-seq supported the downstream effects of pioglitazone on target genes and displayed considerable upregulation of mitochondrial bioenergetic pathways. Skeletal muscle metabolomic and lipidomic profiles exhibited dysregulation in response to BC, which was partially restored in pioglitazone-treated mice compared to vehicle-treated BC-PDOX mice. Despite molecular support for pioglitazone’s efficacy, isolated muscle function was not affected by pioglitazone treatment.
Conclusions
BC induces multi-omic dysregulation in skeletal muscle, which pioglitazone partially ameliorates. Future research should focus on profiling systemic metabolic dysfunction, identifying molecular biomarkers of fatigue, and testing alternative pioglitazone treatment regimens.
Statement of Translational Relevance
Breast cancer-induced fatigue is a prevalent and debilitating symptom that affects a majority of patients, leading to early treatment discontinuation and poorer outcomes. Despite its significant impact on patient quality of life, there are currently no approved therapies for this condition. Our previous work in the clinically relevant breast cancer patient-derived orthotopic xenograft (BC-PDOX) mouse model suggests that disruptions in the PPARγ signaling pathway may contribute to the development of cancer-related fatigue. Using this model that recapitulates the fatigue phenotype observed in patients, we conducted a preclinical trial evaluating the FDA-approved PPARγ agonist, pioglitazone, as a treatment for fatigue. Our multi-omic analysis of skeletal muscle from BC-PDOX mice revealed that pioglitazone treatment partially restored dysregulated lipid profiles and mitochondrial bioenergetic transcriptomic alterations. These findings suggest that pioglitazone may have potential as a therapeutic option for managing cancer-related fatigue in breast cancer patients.
