Doxorubicin induces senescence or apoptosis in rat neonatal cardiomyocytes by regulating the expression levels of the telomere binding factors 1 and 2.
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-beta-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.
Research Center of Cardiovascular Biology, Division of Cardiology, University of Genoa, Viale Benedetto XV, 6, 16132 Genoa, Italy.
Paolo
P
Spallarossa
Paola
P
Altieri
Concetta
C
Aloi
Silvano
S
Garibaldi
Chiara
C
Barisione
Giorgio
G
Ghigliotti
Giuseppina
G
Fugazza
Antonio
A
Barsotti
Claudio
C
Brunelli
D000818:Animals; D000831:Animals, Newborn; D000873:Anthracenes / Q000494:pharmacology; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D052160:Benzothiazoles / Q000494:pharmacology; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects*; D064447:Checkpoint Kinase 2; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000633:toxicity*; D007093:Imidazoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008938:Mitosis / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D035321:Telomeric Repeat Binding Protein 1 / Q000235:genetics / Q000378:metabolism*; D035341:Telomeric Repeat Binding Protein 2 / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014050:Toluene / Q000031:analogs & derivatives / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D000873:Anthracenes; D000903:Antibiotics, Antineoplastic; C494828:Bax protein, rat; D052160:Benzothiazoles; D007093:Imidazoles; D047428:Protein Kinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D011725:Pyridines; C534796:TRF2 protein, mouse; D035321:Telomeric Repeat Binding Protein 1; D035341:Telomeric Repeat Binding Protein 2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; C432165:pyrazolanthrone; D014050:Toluene; D004317:Doxorubicin; C121565:pifithrin; D064447:Checkpoint Kinase 2; C578633:Chek2 protein, mouse; C578632:Chek2 protein, rat; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580