GCN5 contributes to intracellular lipid accumulation in human primary cardiac stromal cells from patients affected by Arrhythmogenic cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is a genetic disease associated with sudden cardiac death and cardiac fibro‐fatty replacement. Over the last years, several works have demonstrated that different epigenetic enzymes can affect not only gene expression changes in cardiac diseases but also cellular metabolism. Specifically, the histone acetyltransferase GCN5 is known to facilitate adipogenesis and modulate cardiac metabolism in heart failure. Our group previously demonstrated that human primary cardiac stromal cells (CStCs) contribute to adipogenesis in the ACM pathology. Thus, this study aims to evaluate the role of GCN5 in ACM intracellular lipid accumulation. To do so, CStCs were obtained from right ventricle biopsies of ACM patients and from samples of healthy cadaveric donors (CTR). GCN5 expression was increased both in ex vivo and in vitro ACM samples compared to CTR. When GCN5 expression was silenced or pharmacologically inhibited by the administration of MB‐3, we observed a reduction in lipid accumulation and a mitigation of reactive oxygen species (ROS) production in ACM CStCs. In agreement, transcriptome analysis revealed that the presence of MB‐3 modified the expression of pathways related to cellular redox balance. Altogether, our findings suggest that GCN5 inhibition reduces fat accumulation in ACM CStCs, partially by modulating intracellular redox balance pathways.

Function of GCN5 in the TGF-β1-induced epithelial-to-mesenchymal transition in breast cancer

Histone acetyltransferase GCN5 is a critical component of the TGF-β/Smad signaling pathway in breast cancer cells; however, it remains unknown whether it is involved in the development and progression of breast cancer. The present study investigated the role of GCN5 in the induction of the EMT by TGF-β1 in breast cancer cells and its underlying molecular mechanism of action. GCN5 activity was elevated and GCN5 mRNA expression and protein expression were increased in MDA-MB231 cells following stimulation with TGF-β1. Furthermore, TGF-β1 stimulation decreased expression of the epithelial cell marker E-cadherin and increased expression of the mesenchymal cell markers, N-cadherin and vimentin, as well as the expression of other EMT markers, including snail and slug. However, these changes were reversed following GCN5 knockdown leading to the downregulation of GCN5 expression. GCN5 knockdown also inhibited the viability, migration and invasion of MDA-MB231 cells, decreased the expression of p-STAT3, p-AKT, MMP9 and E2F1, and increased the expression of p21 in MDA-MB231 cells compared with cells stimulated with TGF-β1 alone. Therefore, GCN5 may work downstream of TGF-β/Smad signaling pathway to regulate the EMT in breast cancer.