title: Cardiomyocyte resistance to doxorubicin mediated by A(3) adenosine receptor.
abstract: Recently, we reported that the activation of A(3) adenosine receptor (A(3)R) in newborn cultured cardiomyocytes by highly selective agonist Cl-IB-MECA (2-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide) induces protection against the anthracycline antibiotic doxorubicin (DOX) cardiotoxicity. The present study was undertaken to further characterize the cardioprotective action of A(3)R activation by revealing the structural changes in cardiomyocytes elicited upon exposure to DOX. Morphological observations (ultrastructural and immunocytochemical) indicate that after DOX treatment, the cardiomyocytes undergo destructive alterations, and protective action of A(3)R is not connected with its anti-apoptotic activity. A(3)R activation appeared to prevent destructive alterations of cardiomyocyte mitochondria and dissipation of mitochondrial membrane potential. In DOX-treated cardiomyocytes, appearance of disorganized desmin and contractile filaments was related to detrimental alterations in the mitochondrial structure, in particular their position and transmembrane potential. In intact cardiomyocytes, diazoxide, a selective mitochondrial K(ATP) channel opener, induced an increase in ATP synthesis within 15 min of application. Similar effect was obtained by activation of adenosine A(1)R. However, A(3)R agonist Cl-IB-MECA did not affect ATP synthesis. Neither A(1)R agonist CCPA (2-chloro-N(6)-cyclopentyladenosine) nor diazoxide protected cardiomyocytes from the detrimental effects of DOX. Thus, the opening of mitochondrial K(ATP) channels does not seem to be effective during the slow development of anthracycline cytotoxicity. Our results indicate that DOX increases the activity of lysosomes, which may contribute to cell injury in an "oncotic" manner and also demonstrate the proinflammatory potency of the drug. Furthermore, the decreased acidification of cytoplasm upon activation of A(3)R may attenuate the ongoing inflammatory response. The present study identifies a novel role for A(3)R selective agonist Cl-IB-MECA and suggests its importance in regulating cardiac cellular function.
authors.affiliation: Gonda (Goldschmied) Medical Diagnostic Research Center, Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Shneyvays
authors.forename: Liaman K
authors.initials: LK
authors.lastname: Mamedova
authors.forename: Avishag
authors.initials: A
authors.lastname: Korkus
authors.forename: Asher
authors.initials: A
authors.lastname: Shainberg
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology* / Q000633:toxicity; D016923:Cell Death; D002478:Cells, Cultured; D053938:DNA Fragmentation; D004317:Doxorubicin / Q000494:pharmacology* / Q000633:toxicity; D004351:Drug Resistance / Q000502:physiology; D020287:In Situ Nick-End Labeling; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D058906:Purinergic P1 Receptor Agonists; D051381:Rats; D018047:Receptors, Purinergic P1 / Q000378:metabolism*
chemical_list: D000903:Antibiotics, Antineoplastic; D058906:Purinergic P1 Receptor Agonists; D018047:Receptors, Purinergic P1; D004317:Doxorubicin