A novel pharmacological action of ET-1 to prevent the cytotoxicity of doxorubicin in cardiomyocytes.
We previously reported that cardiomyocytes produce endothelin (ET)-1 and that the tissue level of ET-1 markedly increased in failing hearts in rats with chronic heart failure. Because the level of plasma ET-1 also increased progressively in patients with breast cancer who received doxorubicin (Dox; Adriamycin), which possesses cardiotoxicity, we hypothesized that ET-1 plays a role in the pathophysiology of cardiomyocytes injured by Dox. In this study, we investigated the effect of ET-1 on the cytotoxicity of Dox in primary cultured neonatal rat cardiomyocytes. The results showed that ET-1 effectively attenuated Dox-induced acute cardiomyocyte cytotoxicity (24-h incubation with Dox) evaluated by in vitro cell toxicity assay [3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay and lactate dehydrogenase release]. The cytoprotective effect of ET-1 was mediated via ET(A) receptors, because pretreatment with the ET(A)-receptor antagonist BQ123 completely suppressed the cytoprotective effect of ET-1, whereas the ET(B)-receptor antagonist BQ788 did not. The cytoprotective effect of ET-1 was abolished by pretreatment with cycloheximide or staurosporine. These results suggest that a protein molecule(s), which is synthesized de novo by the stimulation of protein kinase pathway, is involved in the cytoprotective effect of ET-1. ET-1 increased the expression of an endogenous antioxidant, manganese superoxide dismutase (Mn-SOD), in the cardiomyocytes, as demonstrated by a Western blotting analysis. Pretreatment with an antisense oligodeoxyribonucleotide of Mn-SOD markedly attenuated the cytoprotective effect of ET-1 on the Dox-induced cytotoxicity. However, under conditions of prolonged incubation with Dox (48 h), ET-1 did not affect Dox-induced cardiomyocyte cytotoxicity in culture. These results suggest that ET-1 prevents the early phase of Dox-induced cytotoxicity via the upregulation of the antioxidant Mn-SOD through ET(A) receptors in cultured cardiomyocytes.
Suzuki
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T
Cardiovascular Division, Department of Internal Medicine, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan. tsuzuki@m.u.tokyo.ac.jp
Miyauchi
T
T
D000818:Animals; D000831:Animals, Newborn; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D004317:Doxorubicin / Q000037:antagonists & inhibitors / Q000633:toxicity*; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000494:pharmacology*; D004790:Enzyme Induction; D006321:Heart / Q000187:drug effects; D006352:Heart Ventricles; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D009206:Myocardium / Q000166:cytology* / Q000473:pathology; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics
D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D007527:Isoenzymes; D020319:Oligodeoxyribonucleotides, Antisense; D009842:Oligopeptides; D010456:Peptides, Cyclic; D010880:Piperidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; C086539:BQ 788; D004317:Doxorubicin; D007770:L-Lactate Dehydrogenase; D013482:Superoxide Dismutase; C072247:cyclo(Trp-Asp-Pro-Val-Leu)