Acrolein-induced Vascular Smooth Muscle Cells (VSMC) Cytotoxicity: Differential Effects of N-Acetylcysteine and Ebselen
Shirlette G. Milton
Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston Texas, USA.
Omana P. Mathew
Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston Texas, USA.
Kasturi Ranganna *
Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston Texas, USA.
Zivar Yousefipour
Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston Texas, USA.
Mohammad Newaz
Pharmaceutical Sciences, Chicago State University, Chicago Illinois, USA.
*Author to whom correspondence should be addressed.
Abstract
Aim: Acrolein, a vascular toxin implicated in atherogenesis, causes vascular smooth muscle cells (VSMC) cytotoxicity. To understand the mechanism of acrolein-induced VSMC cytotoxicity and to assess contribution of acrolein-induced activation of cellular signaling to VSMC cytotoxicity, effects of n-acetylcysteine, ebselen, and inhibitors of ROS generating enzymes on acrolein-induced cytotoxicity and activation of protein tyrosine phosphorylation and MAPKs are investigated.
Place of the Study: Department of Pharmaceutical Sciences, Texas Southern University, Houston Texas, USA.
Methodology: VSMC were preincubated or co-incubated in the presence or absence of test compounds and then exposed to acrolein to determine their effect on acrolein-induced: Cytotoxicity by tetrazolium-based colorimetric assay; activation of protein tyrosine phosphorylation and MAPKs by western blotting; cellular glutathione and reactive oxygen species (ROS) by fluorometric methods.
Results: (i) N-acetylcysteine, a glutathione precursor abolishes acrolein-induced VSMC cytotoxicity and activation of protein tyrosine phosphorylation and MAPKs; (ii) Acrolein causes oxidative stress by depleting cellular glutathione and increasing ROS level that is insensitive to allopurinol, L-NAME, rotenone and apocynin; (iii) buthionine sulfoximine (BSO), a glutathione biosynthesis inhibitor, accentuates acrolein-induced ROS generation and offers no protection against acrolein effects on VSMC in the absence of n-acetylcysteine but provides protection in the presence of n-acetylcysteine; and (iv) ebselen, a glutathione peroxidase (GPX) mimic, significantly protects VSMC from acrolein-induced cytotoxicity and activation of protein tyrosine phosphorylation, however, activation of MAPKs is insensitive to ebselen.
Conclusion: Oxidative stress resulting from glutathione depletion mediates acrolein-induced cytotoxicity via modulation of redox-sensitive signal transduction pathways as illustrated by the differential effects of n-acetylcysteine and ebselen, specifically MAPKs activation. Considering the recent studies that indicate acrolein-induced activation of MAPKs is linked to direct modification of thioredoxin reductase1/thioredoxin1 (TrxR1/Trx1) by acrolein, being a GPX mimic, ebselen may be inefficient to prevent TrxR1/Trx1 inactivation, but by allowing glutathione synthesis, n-acetylcysteine may protect TrxR1/Trx1 and inhibit MAPKs activation.
Keywords: Acrolein, vascular smooth muscle cells, atherogenesis, n-acetylcysteine.