Benzo[a]pyrene induces oxidative stress and endothelial progenitor cell dysfunction via the activation of the NF-κB pathway.

Smoking is a major risk factor for atherosclerosis. In this study, we evaluated the effects of benzo[a]pyrene (BaP, a prominent component of tobacco smoke) on the function and pro-inflammatory response of human endothelial progenitor cells (EPCs). EPCs were isolated from umbilical cord blood and treated with different concentrations (10, 20 and 50 µmol/l) of BaP. The proliferation, migration, adhesion and angiogenesis of BaP-treated EPCs were evaluated using the cell counting kit-8 (CCK-8), Transwell assay, adhesion assay and in vitro tube formation assay, respectively. The activation of nuclear factor-κB (NF-κB) was evaluated by measuring the mRNA expression of NF-κB p65 and p50 by real-time RT-PCR and NF-κB translocation assay. Reactive oxygen species (ROS) production was determined by the reduction of fluorescent 2',7'-dichlorofluorescein diacetate (DCFH-DA). The results demonstrated that BaP treatment significantly inhibited the proliferation, migration, adhesion and angiogenesis of EPCs in vitro. In addition, BaP induced the release of interleukin (IL)-1β and tumor necrosis factor-α from these cells. Moreover, the exposure of EPCs to BaP induced ROS generation and the activation of NF-κB. Experiments with EPCs pre-treated with pyrrolidine dithiocarbamate, an inhibitor of NF-κB, revealed that the BaP-mediated inhibition of proliferation, migration, adhesion and angiogenesis of EPCs is mainly regulated by NF-κB. Thus, tobacco smoke may induce oxidant-mediated stress responses in EPCs and impair their function via the activation of the NF-κB pathway.