Impaired cAMP-PKA-CREB1 signalling drives mitochondrial dysfunction in skeletal muscle during cancer cachexia.

Skeletal muscle wasting is a defining feature of cancer cachexia, a multifactorial syndrome that drastically compromises patient quality of life and treatment outcomes. Mitochondrial dysfunction is a major contributor to skeletal muscle wasting in cancer cachexia, yet the upstream molecular drivers remain elusive. Here we show that cancer impairs the activity of cAMP-dependent protein kinase A (PKA) and of its transcriptional effector CREB1 in skeletal muscle, ultimately contributing to the downregulation of a core transcriptional network that supports mitochondrial integrity and function. The restoration of cAMP-PKA-CREB1 signalling through pharmacological inhibition of the cAMP-hydrolysing phosphodiesterase 4 (PDE4) rescues the expression of mitochondrial-related genes, improves mitochondrial function and mitigates skeletal muscle wasting in male mice. Altogether, our data identify tumour-induced suppression of the cAMP-PKA-CREB1 axis as a central mechanism contributing to mitochondrial dysfunction in skeletal muscle during cancer cachexia. Furthermore, these findings highlight PDE4, particularly the PDE4D isoform, as a potential therapeutic target to preserve muscle mitochondrial function and counteract muscle wasting in cancer cachexia.