MiR-526b-3p mediates doxorubicin-induced cardiotoxicity by targeting STAT3 to inactivate VEGFA.

Doxorubicin (DOX), a wide-spectrum chemotherapeutic agent, is recognized to have cardiotoxic side effects when it is applied in hematological diseases and solid tumor management. However, the mechanisms behind the DOX-induced anomaly of vascular homeostasis remain mostly elusive. qRT-PCR and immumohistochemical staining indicated cardiac increase of miR-526b-3p, and decrease of CD31 and CD34 in DOX-treated mice. The regulatory function of miR-526b-3p on cardiac function and cardiac microvessel density was detected via the transfection of miR-526b-3p mimics or inhibitor into Human Umbilical Vein Endothelial Cells (HUVECs) and the administration of rAAV in mice. HUVECs proliferation, apoptosis, tube formation, and migration were inspected by EdU, flow cytometry, tube formation and transwell assays. MiR-526b-3p was anti-proliferative but apoptosis-initiating in HUVECs, and aggravated cardiac abnormalities caused by DOX. Mechanically, the relationship between miR-526b-3p and VEGFA was disclosed by qRT-PCR. VEGFA and STAT3 interaction was confirmed by ChIP and luciferase reporter assay. MiR-526b-3p targeted STAT3 to reduce VEGFA transcription. We designed rescue assays and presented that the negative effects of miR-526b-3p on cardiac dysfunction and HUVECs were rescued by VEGFA reintroduction in DOX-affected mice. Overall, miR-526b-3p accelerated doxorubicin-induced cardiotoxicity through modulating STAT3/VEGFA, highlighting that targeting miR-526b-3p as a potential method to protect against DOX-induced cardiac dysfunction.