Abstract MP131: The CDK2-FOXO1 Axis Mediates Doxorubicin-induced Cardiomyocyte Apoptosis and Atrophy

Abstract

Recent clinical investigations indicate that anthracycline-based chemotherapy induces early declines in heart mass in cancer patients. A decline in heart mass can be caused by a decrease in cardiac cell number due to exaggerated cell death, and/or a reduction in cell size via atrophy. Our previous study reveals that the anthracycline doxorubicin (DOX) induces apoptotic death of cardiomyocytes through activation of cyclin-dependent kinase 2 (CDK2). However, the signaling pathway downstream of CDK2 remains to be characterized. In addition, it is unclear whether the same pathway also mediates cardiac atrophy. Here we demonstrated that DOX exposure induced CDK2-dependent phosphorylation of forkhead box O1 (FOXO1) at S249, leading to transcription of its pro-apoptotic target gene Bim. In cultured cardiomyocytes, treatment with the small molecule FOXO1 inhibitor AS1842856, or transfection with FOXO1-specific siRNAs protected against DOX-induced apoptosis and mitochondrial damage. Oral administration of AS1842856 in mice hindered apoptosis and prevented DOX-induced decline in left ventricular systolic function. Intriguingly, pharmacologic inhibition of FOXO1 also attenuated DOX-induced cardiac atrophy, likely due to repression of MuRF1, a pro-atrophic FOXO1 target gene. In conclusion, DOX exposure induces CDK2-dependent FOXO1 activation, resulting in cardiomyocyte apoptosis and atrophy. Our results identify FOXO1 as a promising drug target for DOX-induced cardiotoxicity. FOXO1 inhibitors may represent a novel class of therapeutics for cardioprotection during chemotherapy.