Resveratrol Ameliorates Cardiac Hypertrophy by Down‐regulation of miR‐155 Through Activation of Breast Cancer Type 1 Susceptibility Protein

BACKGROUND The polyphenol resveratrol (Rev) has been reported to exhibit cardioprotective effects, such as inhibition of TAC (transverse aortic constriction) or isoprenaline (ISO)-induced hypertrophy. MicroRNA-155 (miR-155) was found to be decreased in hypertrophic myocardium, which could be further reduced by pretreatment of Rev. The study was designed to investigate the molecular effects of miR-155 on cardiac hypertrophy, focusing on the role of breast cancer type 1 susceptibility protein (BRCA1). METHODS AND RESULTS We demonstrated that Rev alleviated severity of hypertrophic myocardium in a mice model of cardiac hypertrophy by TAC treatment. Down-regulation of miR-155 was observed in pressure overload- or ISO-induced hypertrophic cardiomyoctyes. Interestingly, administration of Rev substantially attenuated miR-155 level in cardiomyocytes. In agreement with its miR-155 reducing effect, Rev relieved cardiac hypertrophy and restored cardiac function by activation of BRCA1 in cardiomyoctyes. Our results further revealed that forkhead box O3a (FoxO3a) was a miR-155 target in the heart. And miR-155 directly repressed FoxO3a, whose expression was mitigated in miR-155 agomir and mimic treatment in vivo and in vitro. CONCLUSIONS We conclude that BRCA1 inactivation can increase expression of miR-155, contributing to cardiac hypertrophy. And Rev produces their beneficial effects partially by down-regulating miR-155 expression, which might be a novel strategy for treatment of cardiac hypertrophy.