Doxorubicin induces senescence or apoptosis in rat neonatal cardiomyocytes by regulating the expression levels of the telomere binding factors 1 and 2

• Published in: American journal of physiology. Heart and circulatory physiology 2009-12, Vol.297 (6), p.H2169-H2181
• Main Authors: Spallarossa, Paolo, Altieri, Paola, Aloi, Concetta, Garibaldi, Silvano, Barisione, Chiara, Ghigliotti, Giorgio, Fugazza, Giuseppina, Barsotti, Antonio, Brunelli, Claudio
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Anthracenes - pharmacology; Antibiotics, Antineoplastic - toxicity; Apoptosis; Apoptosis - drug effects; bcl-2-Associated X Protein - metabolism; Benzothiazoles - pharmacology; Cell cycle; Cells; Cells, Cultured; Cellular Senescence - drug effects; Checkpoint Kinase 2; Cytoskeleton - drug effects; Cytoskeleton - metabolism; Dose-Response Relationship, Drug; Doxorubicin - toxicity; Drug dosages; Imidazoles - pharmacology; JNK Mitogen-Activated Protein Kinases - antagonists & inhibitors; JNK Mitogen-Activated Protein Kinases - metabolism; Mitosis - drug effects; Myocytes, Cardiac - drug effects; Myocytes, Cardiac - metabolism; Myocytes, Cardiac - pathology; p38 Mitogen-Activated Protein Kinases - antagonists & inhibitors; p38 Mitogen-Activated Protein Kinases - metabolism; Phenotype; Protein Kinase Inhibitors - pharmacology; Protein-Serine-Threonine Kinases - metabolism; Proto-Oncogene Proteins c-bcl-2 - metabolism; Pyridines - pharmacology; Rats; Rats, Sprague-Dawley; Ribonucleic acid; RNA; RNA Interference; Rodents; Telomeric Repeat Binding Protein 1 - genetics; Telomeric Repeat Binding Protein 1 - metabolism; Telomeric Repeat Binding Protein 2 - genetics; Telomeric Repeat Binding Protein 2 - metabolism; Time Factors; Toluene - analogs & derivatives; Toluene - pharmacology; Tumor Suppressor Protein p53 - antagonists & inhibitors; Tumor Suppressor Protein p53 - metabolism
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00068.2009

1 Research Center of Cardiovascular Biology, Division of Cardiology, and 2 Laboratory of Cytogenetics, Department of Internal Medicine, University of Genoa, Italy Submitted January 21, 2009 ; accepted in final form September 28, 2009 Low or high doses of doxorubicin induce either senescence or apoptosis, respectively, in cardiomyocytes. The mechanism by which different doses of doxorubicin may induce different stress-response cellular programs is not well understood. A recent study showed that the level of telomere dysfunction may induce senescence or apoptosis. We investigated the pathways to both apoptosis and senescence in neonatal rat cardiomyocytes and in H9c2 cells exposed to a single pulsed incubation with low or high doses of doxorubicin. High-dose doxorubicin strongly reduces TRF2 expression while enhancing TRF1 expression, and it determines early apoptosis. Low-dose doxorubicin induces downregulation of both TRF2 and TRF1, and it also increases the senescence-associated-β-galactosidase activity, downregulates the checkpoint kinase Chk2, induces chromosomal abnormalities, and alters the cell cycle. The involvement of TRF1 and TRF2 with apoptosis and senescence was assessed by short interfering RNA interference. The cells maintain telomere dysfunction and a senescent phenotype over time and undergo late death. The increase in the phase >4N and the presence of micronuclei and anaphase bridges indicate that cells die by mitotic catastrophe. p38 modulates TRF2 expression, whereas JNK and cytoplasmic p53 regulate TRF1. Pretreatment with specific inhibitors of MAPKs and p53 may either attenuate the damage induced by doxorubicin or shift the cellular response to stress from senescence to apoptosis. In conclusion, various doses of doxorubicin induce differential regulation of TRF1 and TRF2 through p53 and MAPK, which is responsible for inducing either early apoptosis or senescence and late death due to mitotic catastrophe. p53; mitogen-activated protein kinases; anthracyclines Address for reprint requests and other correspondence: P. Altieri, Research Center of Cardiovascular Biology, Division of Cardiology, Univ. of Genoa, Viale Benedetto XV, 6, 16132 Genoa, Italy (e-mail: paola.altieri{at}unige.it ).