Protective effect of ellagic acid against angiotensin II-induced cardiomyocyte hypertrophy in H9c2 myocardial cells: Role of calcineurin/NFAT pathway

Background: Ellagic acid, a major ellagitannin found in pomegranate extract, might be an attractive natural and safe bioactive compound for prevention of cardiac hypertrophy in many pathological conditions that are associated with elevated circulating angiotensin II (Ang II). Ang II stimulates multiple signal transduction pathways involved in hypertrophy including calcineurin/nuclear factor of activated T cell (NFAT). Objective: The present study aimed to explore the possible anti-hypertrophic activity of ellagic acid against Ang II-induced cardiomyocyte hypertrophy and the role of calcineurin/ NFAT signaling pathway in this action. Methods: H9c2 myocardial cells were treated with different concentrations of ellagic acid one hour before exposure to Ang II. Biological markers of cardiac hypertrophy including changes in cell size and protein content, and atrial natriuretic peptide (ANP) protein expression were assessed using light microscopy, Bradford method and western blotting, respectively. The effects of ellagic acid on the protein expression of calcineurin and nuclear localization of NFATc4 were also investigated using western blotting and immunofluorescence assay, respectively. Results: The results showed that pretreatment with ellagic acid could efficiently prevent Ang II-induced hypertrophic response which was associated with changes in hypertrophy-related biomarkers including increase in cell size and protein content, and ANP overexpression. Moreover, ellagic acid inhibited Ang II-induced calcineurin up-regulation and nuclear localization of NFATc4. Conclusion: In summary, our findings showed that ellagic acid effectively inhibited Ang II-induced cardiomyocyte hypertrophy. This is the first report demonstrating the role of calcineurin/NFAT pathway inhibition in this protective effects. Future in vivo studies are required to elucidate if ellagic acid could ameliorate cardiac hypertrophy and its transition to heart failure.