Doxorubicin (DOX) is a widely used anti-tumour drug. Cardiotoxicity is a major toxic side effect of DOX therapy. Although recent studies implicated an apoptotic pathway in DOX-induced cardiotoxicity, the mechanism of DOX-induced apoptosis remains unclear. In the present study, we investigated the role of reactive oxygen species and the nuclear transcription factor nuclear factor κB (NF-κB) during apoptosis induced by DOX in bovine aortic endothelial cells (BAECs) and adult rat cardiomyocytes. DOX-induced NF-κB activation is both dose- and time-dependent, as demonstrated using electrophoretic mobility-shift assay and luciferase and p65 (Rel A) nuclear-translocation assays. Addition of a cell-permeant iron metalloporphyrin significantly suppressed NF-κB activation and apoptosis induced by DOX. Overexpression of glutathione peroxidase, which detoxifies cellular H2O2, significantly decreased DOX-induced NF-κB activation and apoptosis. Inhibition of DOX-induced NF-κB activation by a cell-permeant peptide SN50 that blocks translocation of the NF-κB complex into the nucleus greatly diminished DOX-induced apoptosis. Apoptosis was inhibited when IκB mutant vector, another NF-κB inhibitor, was added to DOX-treated BAECs. These results suggest that NF-κB activation in DOX-treated endothelial cells and myocytes is pro-apoptotic, in contrast with DOX-treated cancer cells, where NF-κB activation is anti-apoptotic. Removal of intracellular H2O2 protects endothelial cells and myocytes from DOX-induced apoptosis, possibly by inhibiting NF-κB activation. These findings suggest a novel mechanism for enhancing the therapeutic efficacy of DOX.
- Fe(III)tetrakis(4-benzoic acid)porphyrin (FeTBAP)
- glutathione peroxidase-1 (GPx-1)
- superoxide dismutase-mimetic
Abbreviations used: BAEC, bovine aortic endothelial cell; DMEM, Dulbecco's modified Eagle's medium; DOX, doxorubicin; DTT, dithiothreitol; FBS, fetal bovine serum; FeTBAP, Fe(III)tetrakis(4-benzoic acid)porphyrin; GPx-1, glutathione peroxidase-1; IκB, inhibitor of NF-κB; IKK, IκB kinase; l-NAME, NG-nitro-l-arginine methyl ester; NF-κB, nuclear factor κB; PDTC, pyrrolidine dithiocarbamate; ROS, reactive oxygen species; TNF-α, tumour necrosis factor-α; TUNEL, terminal deoxynucleotidyltransferase-mediated nick-end labelling.
- The Biochemical Society, London ©2002