Doxorubicin-Induced Cardiotoxicity and Novel GATA4-Targeted Compounds

Doxorubicin (DOX) is a widely used anticancer drug which, unfortunately, induces dose-related cardiotoxicity. A deep understanding of DOX’s toxicity is still unclear, partly because most in vitro studies have evaluated the effects of short-term high-dose DOX treatments. Thus, a more precise model of DOX cardiotoxicity is needed to more accurately simulate clinical scenario. The first aim of this study was to establish an in vitro model of long-term low-dose administration of DOX utilizing human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). The second aim was to investigate if novel GATA4-targeted compounds can protect CMs from DOX toxicity. Acute toxicity was studied in both primary neonatal rat ventricular cardiomyocytes (NRVCs) and hiPSC-CMs. The cells were exposed to 0.1-3 μM DOX for 48 h, after which the lactate dehydrogenase and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays were carried out. To study long-term toxicity, hiPSC-CMs were exposed to 100 nM DOX for up to 14 days. MTT assay and high-content analysis were carried out after 4, 7 and 14-day exposures. The effect of the test compound was studied by exposing the cells simultaneously to DOX and the compound. A 48-hour exposure to DOX at 1 and 3 μM concentrations induced more than 62% reductions in both NRVC and hiPSC-CM viability, whereas a 14-day exposure to 100 nM DOX induced a 26% reduction in hiPSC-CM viability. A 4-day exposure to 100 nM DOX induced a 3.1-fold increase in the percentage of cells positive for pro-B-type natriuretic peptide (proBNP) compared to control. When the cells were exposed simultaneously to 100 nM DOX and the test compound (10 μM), the percentage of proBNP+ cells increased only 1.4-fold compared to control. However, over 14-day exposure the compound at 10 μM concentration reduced hiPSC-CM viability 50% compared to control. A long-term exposure of hiPSC-CMs can be utilized as an in vitro model to investigate the mechanisms of delayed DOX-induced cardiotoxicity. The GATA4-targeted test compound exhibited cardioprotective potential against subacute DOX toxicity. Over chronic exposure the compound was, however, toxic to CMs, indicating that further structural optimization is required to develop non-toxic derivatives.