3-Bromofluoranthene-induced cardiotoxicity of zebrafish and apoptosis in the vascular endothelial cells via intrinsic and extrinsic caspase-dependent pathways

Fluoranthene, a high-molecular-weight polycyclic aromatic hydrocarbon (PAH), is widely present in air pollutants, including fine inhalable particulate matter. 3-Bromofluoranthene (3-BrFlu), which is a brominated fluoranthene and halogenated PAH, is generated from waste combustion, metallurgical processes, cement production, e-waste dismantling, and photoreaction. Vascular endothelial cells have key functions in the homeostasis and the development of the cardiovascular system. The zebrafish model has been widely employed to study cardiotoxicity and embryotoxicity. However, no evidence has indicated that 3-BrFlu induces cytotoxicity in vascular endothelial cells, or cardiotoxicity and embryotoxicity in zebrafish. In this study, 3-BrFlu induced concentration-dependent changes in embryo- and cardiotoxicity. Cytotoxicity was also induced by 3-BrFlu in a concentration-dependent manner through apoptosis and necrosis in vascular endothelial cells, SVEC4-10 cells. The activities of caspase-3, -8, and -9 were induced by 3-BrFlu via an intrinsic pathway constituting Bcl-2 downregulation, Bad upregulation, and mitochondrial dysfunction; the extrinsic pathway included the expression of death receptors, including tumour necrosis factor α and Fas receptors. These results indicated that 3-BrFlu caused cardio- and embryotoxicity in zebrafish through vascular endothelial cells cytotoxicity resulting from caspase-dependent apoptosis through intrinsic and extrinsic pathways.