A step forward in understanding sulforaphane induced cardioprotection by proteomic analysis in cultured cardiomyocytes

Isothiocyanates are metabolites derived from hydrolysis of glucosinolates, a class of compounds present in plants of the Brassicaceae family. The sulforaphane (SF), in particular, is an isothiocyanate produced after hydrolysis of the glucoraphanin by the enzyme myrosinase, a tioglucosidase present in these plants. SF is known for its chemopreventive, anti-inflammatory a nd neuroprotective action (1, 2). A previous study conducted in our laboratory has shown that SF protects cardiomyocytes by oxidative stress inducing a pattern of antioxidant/phase II detoxifying enzymes (3). In order to clarify the mechanisms underlying the cardioprotection induced by SF, the purpose of this study was the identification of new molecular targets of the compound SF, by proteomic analysis. As model system we used primary cultures of rat neonatal cardiomyocytes. Cells were treated with 5 μM SF for different times (1-48 h). The protein extracts were analyzed by 2D-PAGE electrophoresis combined with enzymatic digestion of the spots of interest, MALDI/MS of digested and identification of proteins by bioinformatics analysis. About 60 differently expressed proteins were identified, 4 of which are potentially involved in the cardioprotective mechanisms previously observed. In particular, there was a significant up-regulation of macrophage migration inhibitory factor (MIF), gliossalase I, elfin and a down-regulation of heat shock protein 60 (HSP60). The data for these proteins were confirmed by immunoblotting analysis using specific antibodies. These results suggest that the cardioprotection elicited by SF is a complex mechanism that involves the modulation of proteins with different cardioprotective role.