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Anticancer treatments (chemo- and radiation therapies), such as Doxorubicin (Dox), used to treat many types of cancer are associated with many side effects such as cardiotoxicity mainly leading to a dilated cardiomyopathy (DCM) in chronic. There is a need for new treatment options and strategies aiming at reducing Doxorubicin side effects in the heart. Among these mechanisms Epac (exchange protein directly activated by cAMP) signaling could be worth investigating. We have investigated the time/dose-dependent Dox effect on Epac signaling in both in vivo mice model (C57Bl63/Knock-out Epac1 mice, iv injections, 12 mg/kg cumulative dose) and in vitro using primary culture of neonatal rat cardiomyocytes (NRVM, 24 h, Dox 1 μM). Then we investigated the effect of Epac inhibition on human cancer cell lines (24 h, Dox 1-10 μM). Dox-treated mice developed a DCM associated with Ca2+ homeostasis dysfunction. In vitro, as measured by flow cytometry and western blot, Dox induced DNA damages and cell death. This cell death is associated with apoptotic features including mitochondrial membrane permeabilization, caspase activation, cell size reduction and relative plasma membrane integrity. The inhibition of Epac1 (ESI09, CE3F4), but not Epac2 (ESI05), prevented DNA/TopIIβ complexes, decreased Dox-induced DNA damage, loss of mitochondrial membrane potential, apoptosis and finally cardiomyocyte death. These results were confirmed in vivo since Dox-induced cardiotoxicity was prevented in Epac1 KO mice as evidenced by unaltered cardiac function (no DCM) 15 weeks post-treatment. Interestingly, the protection conferred by Epac1 inhibition was not transferred to human cancer cell lines treated by Dox. Inhibition of Epac1 may thus represents a novel strategy to prevent Anthracyclines-induced cardiotoxicity. Moreover, Epac1 inhibition seems to be a valuable therapeutic strategy to treat cancer by potentiating Dox toxicity. [ABSTRACT FROM AUTHOR]

Doxorubicin (Dox) is an Anthracycline commonly used to treat many types of cancer; unfortunately this chemotherapeutic agent often induces side effects such as cardiotoxicity leading to cardiomyocyte death and dilated cardiomyopathy (DCM). This cardiotoxicity has been related to reactive oxygen species generation, DNA intercalation, topoisomerase II inhibition and bioenergetics alterations resulting in DNA damages leading to cardiomyocyte death. There is a need for new therapeutic agents and strategies aiming at reducing Dox side effects in the heart. Among these mechanisms, the role of Epac (exchange protein directly activated by cAMP) could be worth investigating. Therefore we have investigated the time/dose-dependent Dox effect on Epac signaling in both in vivo mice model (C57BL/6 vs. Epac1 KO mice, iv injections, 12 mg/kg) and in vitro (primary culture of neonatal rat cardiomyocytes (NRVM), Dox 1 μM). In vivo, Dox-treated mice developed a DCM associated with Ca2+ homeostasis dysfunction. In vitro, as measured by flow cytometry and western blot, Dox induced DNA damage and cell death. This cell death is associated with apoptotic features including mitochondrial membrane permeabilization, caspase activation, cell size reduction and relative plasma membrane integrity. We also observed that Dox led to a modification of the protein level of Epac1 and Epac2 isoforms. The inhibition of Epac1 (ESI09, CE3F4), but not of Epac2 (ESI05), prevented DNA/TopIIβ complexes, decreased Dox-induced DNA damage, loss of mitochondrial membrane potential, apoptosis and finally cardiomyocyte death. These results were confirmed in vivo since Dox-induced cardiotoxicity was prevented in Epac1 KO mice as evidenced by unaltered cardiac function (no DCM) 15 weeks post-treatment. Inhibition of Epac1 could be a valuable therapeutic strategy to limit Dox-induced cardiomyopathy during cancer chemotherapy. [ABSTRACT FROM AUTHOR]