Platelet-Derived Growth Factor–Stimulated Superoxide Anion Production Modulates Activation of Transcription Factor NF-κB and Expression of Monocyte Chemoattractant Protein 1 in Human Aortic Smooth Muscle Cells

Abstract

Background Platelet-derived growth factor (PDGF) and superoxide anion (O 2 ·− ) have been implicated in vascular diseases. We investigated whether PDGF stimulates the production of O 2 ·− in human aortic smooth muscle cells (HSMCs) and whether O 2 ·− leads in this way to the activation of nuclear factor–κB (NF-κB) and induction of monocyte chemoattractant protein 1 (MCP-1) in PDGF-stimulated HSMCs. Methods and Results PDGF-AB concentration- and time-dependently stimulated O 2 ·− generation from HSMCs. The stimulatory effect of PDGF-AB was mimicked by PDGF-BB but not by PDGF-AA. The generation of O 2 ·− by PDGF-AB was attenuated by the NAD(P)H oxidase inhibitor iodonium diphenyl, the specific protein kinase C (PKC) inhibitor Ro 31-8220, and the phosphatidylinositol 3-kinase inhibitor wortmannin. Allopurinol and nifedipine had no effect on PDGF-AB–induced O 2 ·− release, whereas indomethacin potentiated this response. Gel mobility shift assay revealed that PDGF-AB increased the binding activity of NF-κB, which contained predominantly the p50/p65 heterodimer in nuclear extracts from HSMCs. Superoxide dismutase as well as iodonium diphenyl, Ro 31-8220, and wortmannin attenuated PDGF-AB–induced activation of NF-κB and expression of MCP-1 mRNA. In contrast, superoxide dismutase did not inhibit the interleukin-1β–induced NF-κB activation. Conclusions The results demonstrate that PDGF stimulates O 2 ·− generation in HSMCs via PKC-dependent and wortmannin-sensitive pathways involving flavoenzyme(s). This PDGF-induced O 2 ·− production may be involved in vascular lesion formation by mediating, at least in part, NF-κB activation and MCP-1 induction.