Loss of Mrp1 potentiates doxorubicin-induced cytotoxicity in neonatal mouse cardiomyocytes and cardiac fibroblasts

Abstract

Doxorubicin (DOX) induces dose-dependent cardiotoxicity in part due to its ability to induce oxidative stress. We showed that loss of multidrug resistance-associated protein 1 (Abcc1/Mrp1) potentiates DOX-induced cardiac dysfunction in mice in vivo. Here, we characterized DOX toxicity in cultured cardiomyocytes (CM) and cardiac fibroblasts (CF) derived from C57BL wild type (WT) and Mrp1 null (Mrp1-/-) neonatal mice. CM accumulated more intracellular DOX relative to CF but this accumulation did not differ between genotypes. Following DOX (0.3-4 lM), Mrp1-/- CM, and CF, especially CM, showed a greater decrease in viability and increased apoptosis and DNA damage, demonstrated by higher caspase 3 cleavage, poly (ADP-ribose) polymerase 1 (PARP) cleavage and phosphorylated histone H2AX (cH2AX) levels versus WT cells. Saline- and DOX-treated Mrp1-/- cells had significantly higher intracellular GSH and GSSG compared with WT cells (P