C-src Is the Primary Signaling Mediator of Pcb-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 (HMEC) with specific PCB congener, 2,2’,4,6,6’-pentachlorobiphenyl (PCB 104), dosedependently 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 104treated HMEC. Site-directed mutagenesis of the IL-8 promoter and DNA binding assays revealed that AP-1 and 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 HMEC 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.