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

Abstract

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-␤-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 Ͼ4N 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 THE CLINICAL USE OF ANTHRACYCLINES in anti-cancer treatment is limited by their adverse cardiotoxic effects, which include cardiomyopathy and heart failure (22). At high doses, cardiotoxicity often occurs within a few months, whereas low doses rarely cause deterioration of ventricular function in the first year after therapy (58). However, there is now increasing evidence that, several years after therapy, one of three patients treated with low-dose anthracyclines develops hypokinetic cardiomyopathy (21). A number of mechanisms have been proposed to explain anthracycline cardiotoxicity. Although the most accredited hypothesis states that anthracyclines induce myocyte loss through oxidative stress and apoptotic cell death (3, 48), there is controversy whether apoptosis contributes to late onset cardiotoxicity induced by low doses of doxorubicin (4). Maejima et al. (34) recently showed that when cultured neonatal rat cardiomyocytes are exposed to low concentrations of doxorubicin, the cells do not enter apoptotic program but exhibit a senescence-like phenotype. The hallmark of cellular senescence is the cell cycle arrest that is accompanied by important changes in many aspects of cell morphology (20,38). Senescence is the result of changes in the expression of many proteins that regulates cell cycle, cytoskeletal function, and cellular architecture and causes impairment o...

Doxorubicin anti-tumor mechanisms include Hsp60 post-translational modifications leading to the Hsp60/p53 complex dissociation and instauration of replicative senescence

“…The data obtained here demonstrated that doxorubicin induced the expression of the tumor suppressor protein p53. This is in agreement with previous studies reporting that the drug can intercalate DNA, generating reactive oxygen species, leading to a DNA damageresponse mediated by p53 [26,44]. Coincident with these findings, our data provided evidence that doxorubicin was able to promote in lung mucoepidermoid NCI-H292 cells the activation of DNA damage response as suggested by the increase in gH2AX.…”

“…For example, doxorubicin, an anthracycline antitumor drug widely used in clinical chemotherapy, induces senescence at low doses and apoptosis at high doses in breast cancer cells and in neonatal rat cardiomyocytes [24,25,26]. Hsp60 over-expression suppressed doxorubicin-induced apoptosis in cardiomyocytes [27], and doxorubicin-induced apoptosis in HeLa cells triggering Hsp60 up-regulation [23].…”

Cytosolic p53 inhibits Parkin-mediated mitophagy and promotes mitochondrial dysfunction in the mouse heart

“…In addition, DOX-treated hearts exhibited aging-related alterations including the upregulation of SA-b-gal activity and expression of cell cycle inhibitors and proinflammatory cytokines ( Supplementary Fig. S2b-d) [20][21][22] . CCCP-induced Parkin and p62 translocation was also reduced in DOX-treated hearts (Fig.…”

Clinical evidence of the relationship between aspirin and breast cancer risk (Review)

“…Notwithstanding, the cardiotoxicity of anthracyclines is well documented; the secondary effects are mainly cardiomyopathy and cardiac syncope (5). Epidemiologic studies indicate that 50% of patients exposed to anthracyclines develop cardiac abnormalities after 10 to 20 years of chemotherapy; 40% of patients present with arrhythmia and 5% with heart failure (6).…”