c-Src Is the Primary Signaling Mediator of Polychlorinated Biphenyl–Induced Interleukin-8 Expression in a Human Microvascular Endothelial Cell Line

Interleukin-8/CXCL8 (IL-8) is a prominent factor that modulates endothelial cell proliferation, migration, and angiogenesis. Therefore, the present study focused on the regulatory mechanisms of IL-8 expression induced by environmental pollutants such as polychlorinated biphenyls (PCBs). Treatment of human microvascular endothelial cells (HMECs) with specific PCB congener, 2,2′,4,6,6′-pentachlorobiphenyl (PCB 104), dose dependently increased levels of IL-8 mRNA and secreted protein. IL-8–neutralizing antibody inhibited migration of endothelial cells stimulated by conditioned media derived from PCB 104–treated HMECs. Site-directed mutagenesis of the IL-8 promoter– and DNA-binding assays revealed that activator protein 1 (AP-1) and nuclear factor κB (NF-κB) sites are required for PCB 104–induced IL-8 transcription. Most importantly, pharmacological inhibition of Src kinase activity or overexpression of dominant-negative c-src in HMECs resulted in a significant decrease in IL-8 expression and promoter activity. In contrast, ectopic expression of activated c-Src markedly increased promoter activity of IL-8. These stimulatory effects of dominant-positive c-src were abrogated by mutagenesis of AP-1– and NF-κB–binding sites in the IL-8 promoter.