title: Chronic cardiotoxicity of doxorubicin involves activation of myocardial and circulating matrix metalloproteinases in rats.
abstract: OBJECTIVE
  To investigate the role of matrix metalloproteinases (MMPs) in the responses of rats to a prolonged doxorubicin (DOX) treatment.
  
  
  METHODS
  Male Wistar rats were used. DOX was administered by intraperitoneal injections of seven doses (cumulative dose was 15 mg/kg). Control animals were treated with saline. Tissue or plasma samples were collected at four and eight weeks after the application of the last dose. Protein levels were determined by immunoblot assay, and MMP activities were measured by gelatin zymography. Superoxide content was analyzed using a lucigenin chemiluminescence assay and superoxide dismutase (SOD) activities with a SOD assay kit. Qualitative structural alterations of the heart were characterized by transmission electron microscopy.
  
  
  RESULTS
  Systolic blood pressure was higher in DOX-treated rats as compared with the control rats at 8 weeks after treatment. In contrast, there were no differences in the heart rate between the control and DOX-treated rats. DOX treatment caused marked heterogeneous subcellular alterations of cardiomyocytes and structural disorganizations of the cardiac extracellular space. The effects of DOX were linked to a stimulation of plasma MMP-2 and MMP-9 activities that had already increased by 4 weeks after the end of the treatment. In the left ventricle, however, DOX only led to increased MMP-2 activation at 8 weeks after the end of treatment. These changes in tissue MMP-2 were connected with stimulation of Akt kinase activation, inhibition of SOD, an increase in superoxide levels, induction of iNOS protein expression and caspase-3 activation.
  
  
  CONCLUSIONS
  Our results show that MMPs are involved in the chronic cardiotoxicity of DOX in rats. The data also suggest that reactive oxygen species (superoxide), NO production (iNOS) and the Akt kinase pathway can modulate MMP-2 activities in rat hearts influenced by DOX.
authors.affiliation: Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovakia.
authors.forename: Monika
authors.initials: M
authors.lastname: Ivanová
authors.forename: Ima
authors.initials: I
authors.lastname: Dovinová
authors.forename: Ludmila
authors.initials: L
authors.lastname: Okruhlicová
authors.forename: Narcisa
authors.initials: N
authors.lastname: Tribulová
authors.forename: Petra
authors.initials: P
authors.lastname: Simončíková
authors.forename: Monika
authors.initials: M
authors.lastname: Barteková
authors.forename: Jana
authors.initials: J
authors.lastname: Vlkovičová
authors.forename: Miroslav
authors.initials: M
authors.lastname: Barančík
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D053148:Caspase 3 / Q000378:metabolism; D004317:Doxorubicin / Q000633:toxicity*; D004789:Enzyme Activation / Q000187:drug effects; D006321:Heart / Q000187:drug effects*; D008297:Male; D020782:Matrix Metalloproteinases / Q000097:blood / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D013481:Superoxides; D004317:Doxorubicin; D013482:Superoxide Dismutase; D053148:Caspase 3; D020782:Matrix Metalloproteinases