Anthracycline anticancer agents, such as daunorubicin and doxorubicin, rank among the most effective and widely used anticancer drugs. However, their benefit is markedly reduced by the risk of severe cardiotoxicity. Anthracyclines undergo metabolic reduction of the side chain carbonyl group, producing hydroxy metabolites implicated in the cardiotoxicity. This study investigated toxicity, metabolism and cellular disposition of daunorubicin and its hydroxy metabolite, daunorubicinol, in isolated rat neonatal cardiomyocytes. Daunorubicin induced concentration-dependent cytotoxicity, whereas the toxicity of exogenously administered daunorubicinol was significantly lower despite induction of similar DNA damage. UHPLC-MS analyses revealed that daunorubicin rapidly penetrates cardiomyocytes and is metabolized to daunorubicinol, which is then released from the cells. The intracellular concentration of daunorubicinol was consistently lower than that of daunorubicin, indicating a reduced tendency for daunorubicinol to accumulate in cardiomyocytes. P-glycoprotein 1 has been shown to actively facilitate the efflux of both daunorubicin and daunorubicinol from cardiomyocytes. Dexrazoxane, the only approved agent for anthracycline cardiotoxicity prevention, did not affect the cellular metabolism or disposition of daunorubicin or its hydroxy metabolite, but it effectively reduced not only daunorubicin-induced cardiotoxicity, but also provided protection against the lower toxicity of daunorubicinol. Moreover, dexrazoxane reduced DNA damage induced by both daunorubicin and its hydroxy metabolite. These findings suggest that daunorubicin is the primary driver of cardiomyocyte cytotoxicity, while its hydroxy metabolite, daunorubicinol, plays a more limited role, challenging the notion that it serves as a significant toxic reservoir.

• Klíčová slova
• Anthracycline cardiotoxicity, DNA damage, Daunorubicin, Daunorubicinol, Dexrazoxane protection,
• MeSH
• daunomycin * toxicita   analogy a deriváty   farmakokinetika   metabolismus   MeSH
• dexrazoxan * farmakologie   MeSH
• kardiomyocyty * účinky léků   metabolismus   patologie   MeSH
• kardiotonika * farmakologie   MeSH
• kardiotoxicita prevence a kontrola   MeSH
• krysa rodu Rattus MeSH
• kultivované buňky MeSH
• novorozená zvířata MeSH
• poškození DNA * účinky léků   MeSH
• potkani Sprague-Dawley MeSH
• protinádorová antibiotika * toxicita   farmakokinetika   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• daunomycin * MeSH
• daunorubicinol MeSH Prohlížeč
• dexrazoxan * MeSH
• kardiotonika * MeSH
• protinádorová antibiotika * MeSH

Topoisomerase II alpha and beta (TOP2A and TOP2B) isoenzymes perform essential and non-redundant cellular functions. Anthracyclines induce their potent anti-cancer effects primarily via TOP2A, but at the same time they induce a dose limiting cardiotoxicity through TOP2B. Here we describe the development of the obex class of TOP2 inhibitors that bind to a previously unidentified druggable pocket in the TOP2 ATPase domain to act as allosteric catalytic inhibitors by locking the ATPase domain conformation with the capability of isoform-selective inhibition. Through rational drug design we have developed topobexin, which interacts with residues that differ between TOP2A and TOP2B to provide inhibition that is both selective for TOP2B and superior to dexrazoxane. Topobexin is a potent protectant against chronic anthracycline cardiotoxicity in an animal model. This demonstration of TOP2 isoform-specific inhibition underscores the broader potential to improve drug specificity and minimize adverse effects in various medical treatments.

• MeSH
• antracykliny * škodlivé účinky   farmakologie   MeSH
• DNA-topoisomerasy typu II * metabolismus   chemie   MeSH
• inhibitory topoisomerasy II * farmakologie   chemie   MeSH
• kardiotonika * farmakologie   chemie   MeSH
• kardiotoxicita * prevence a kontrola   MeSH
• lidé MeSH
• myši MeSH
• proteiny vázající poly-ADP-ribosu antagonisté a inhibitory   metabolismus   chemie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antracykliny * MeSH
• DNA-topoisomerasy typu II * MeSH
• inhibitory topoisomerasy II * MeSH
• kardiotonika * MeSH
• proteiny vázající poly-ADP-ribosu MeSH
• TOP2A protein, human MeSH Prohlížeč
• TOP2B protein, human MeSH Prohlížeč

Anthracyclines, such as doxorubicin (adriamycin), daunorubicin, or epirubicin, rank among the most effective agents in classical anticancer chemotherapy. However, cardiotoxicity remains the main limitation of their clinical use. Topoisomerase IIβ has recently been identified as a plausible target of anthracyclines in cardiomyocytes. We examined the putative topoisomerase IIβ selective agent XK469 as a potential cardioprotective and designed several new analogs. In our experiments, XK469 inhibited both topoisomerase isoforms (α and β) and did not induce topoisomerase II covalent complexes in isolated cardiomyocytes and HL-60, but induced proteasomal degradation of topoisomerase II in these cell types. The cardioprotective potential of XK469 was studied on rat neonatal cardiomyocytes, where dexrazoxane (ICRF-187), the only clinically approved cardioprotective, was effective. Initially, XK469 prevented daunorubicin-induced toxicity and p53 phosphorylation in cardiomyocytes. However, it only partially prevented the phosphorylation of H2AX and did not affect DNA damage measured by Comet Assay. It also did not compromise the daunorubicin antiproliferative effect in HL-60 leukemic cells. When administered to rabbits to evaluate its cardioprotective potential in vivo, XK469 failed to prevent the daunorubicin-induced cardiac toxicity in either acute or chronic settings. In the following in vitro analysis, we found that prolonged and continuous exposure of rat neonatal cardiomyocytes to XK469 led to significant toxicity. In conclusion, this study provides important evidence on the effects of XK469 and its combination with daunorubicin in clinically relevant doses in cardiomyocytes. Despite its promising characteristics, long-term treatments and in vivo experiments have not confirmed its cardioprotective potential.

• Klíčová slova
• XK469, anthracyclines, cardiotoxicity, dexrazoxane, topoisomerase II,
• MeSH
• antracykliny * toxicita   terapeutické užití   MeSH
• chinoxaliny * MeSH
• daunomycin toxicita   terapeutické užití   MeSH
• DNA-topoisomerasy typu II metabolismus   terapeutické užití   MeSH
• doxorubicin toxicita   MeSH
• inhibitory topoisomerasy II * toxicita   terapeutické užití   MeSH
• kardiotoxicita MeSH
• králíci MeSH
• krysa rodu Rattus MeSH
• poškození DNA MeSH
• protinádorová antibiotika toxicita   MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antracykliny * MeSH
• chinoxaliny * MeSH
• daunomycin MeSH
• DNA-topoisomerasy typu II MeSH
• doxorubicin MeSH
• inhibitory topoisomerasy II * MeSH
• protinádorová antibiotika MeSH
• XK 469 MeSH Prohlížeč

Background: Anthracycline cardiotoxicity is a well-known complication of cancer treatment, and miRNAs have emerged as a key driver in the pathogenesis of cardiovascular diseases. This study aimed to investigate the expression of miRNAs in the myocardium in early and late stages of chronic anthracycline induced cardiotoxicity to determine whether this expression is associated with the severity of cardiac damage. Method: Cardiotoxicity was induced in rabbits via daunorubicin administration (daunorubicin, 3 mg/kg/week; for five and 10 weeks), while the control group received saline solution. Myocardial miRNA expression was first screened using TaqMan Advanced miRNA microfluidic card assays, after which 32 miRNAs were selected for targeted analysis using qRT-PCR. Results: The first subclinical signs of cardiotoxicity (significant increase in plasma cardiac troponin T) were observed after 5 weeks of daunorubicin treatment. At this time point, 10 miRNAs (including members of the miRNA-34 and 21 families) showed significant upregulation relative to the control group, with the most intense change observed for miRNA-1298-5p (29-fold change, p < 0.01). After 10 weeks of daunorubicin treatment, when a further rise in cTnT was accompanied by significant left ventricle systolic dysfunction, only miR-504-5p was significantly (p < 0.01) downregulated, whereas 10 miRNAs were significantly upregulated relative to the control group; at this time-point, the most intense change was observed for miR-34a-5p (76-fold change). Strong correlations were found between the expression of multiple miRNAs (including miR-34 and mir-21 family and miR-1298-5p) and quantitative indices of toxic damage in both the early and late phases of cardiotoxicity development. Furthermore, plasma levels of miR-34a-5p were strongly correlated with the myocardial expression of this miRNA. Conclusion: To the best of our knowledge, this is the first study that describes alterations in miRNA expression in the myocardium during the transition from subclinical, ANT-induced cardiotoxicity to an overt cardiotoxic phenotype; we also revealed how these changes in miRNA expression are strongly correlated with quantitative markers of cardiotoxicity.

• Klíčová slova
• DNA damage response, anthracyclines, cardiotoxicity, chronic cardiomyopathy, miRNA, myocardium,
• Publikační typ
• časopisecké články MeSH

Doxorubicin (DOX) is a chemotherapeutic drug widely used for cancer treatment, but its use is limited by cardiotoxicity. Although free radicals from redox cycling and free cellular iron have been predominant as the suggested primary pathogenic mechanism, novel evidence has pointed to topoisomerase II inhibition and resultant genotoxic stress as the more fundamental mechanism. Recently, a growing list of microRNAs (miRNAs) has been implicated in DOX-induced cardiotoxicity (DIC). This review summarizes miRNAs reported in the recent literature in the context of DIC. A particular focus is given to miRNAs that regulate cellular responses downstream to DOX-induced DNA damage, especially p53 activation, pro-survival signaling pathway inhibition (e.g., AMPK, AKT, GATA-4, and sirtuin pathways), mitochondrial dysfunction, and ferroptosis. Since these pathways are potential targets for cardioprotection against DOX, an understanding of how miRNAs participate is necessary for developing future therapies.

• Klíčová slova
• cardiotoxicity, doxorubicin, genotoxic stress, microRNA, p53,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH