Quaking Inhibits Doxorubicin-Mediated Cardiotoxicity Through Regulation of Cardiac Circular RNA Expression

Rationale: RNA-binding proteins (RBPs) have been described to be expressed and regulated in various organs including the heart. Little is known about the role of RBPs in heart failure induced by the chemotherapy drug doxorubicin and their interaction with circular RNAs. Objective: We aimed to identify key RBPs involved in doxorubicin-mediated heart failure and to elucidate their function. Methods and Results: Global transcriptome profiling from murine myocardium exposed to doxorubicin identified five differentially expressed RBPs. Expression of the RNA-binding protein Quaking (QKI) in response to doxorubicin was strongly downregulated in rodent cardiomyocytes and human induced pluripotent stem cell-derived cardiomyocytes in vitro and in vivo in mice. Knockdown of Qki in primary cardiomyocytes increased apoptosis and atrophy after treatment with doxorubicin, while lentiviral-mediated overexpression of Qki5 inhibited the doxorubicin-induced apoptosis in cardiomyocytes. In vivo, AAV9-mediated cardiac overexpression of Qki5 prevented cardiac apoptosis and cardiac atrophy induced by doxorubicin and improved cardiac function. Mechanistically, by lentiviral-based overexpression and CRISPR/Cas9-mediated silencing of Qki5 we identified regulated expression of specific circular RNAs derived from Ttn, Fhod3, and Strn3 Moreover, inhibition of Tt derived circular RNA increased the susceptibility of cardiomyocytes to doxorubicin. Conclusions: We here show that overexpression of Qki5 strongly attenuates the toxic effect of doxorubicin via regulating a set of circular RNAs. Qki5 is thus an interesting target molecule to combat doxorubicin-induced cardiotoxicity.