Opposite effects of prostaglandin-J 2 on VEGF in normoxia and hypoxia: role of HIF-1 Alicja J ozkowicz, a,b, * Anneliese Nigisch, c Joanna We ßgrzyn, d Guenter Weigel, c Ihor Huk, b and J ozef Dulak d a Department of Molecular Genetics, Faculty of Biotechnology, Jagiellonian University, Krakow, Poland b Department of Vascular Surgery, University of Vienna, Austria c Department of Cardiothoracic Surgery, University of Vienna, Austria d Department of Cell Biochemistry, Faculty of Biotechnology, Jagiellonian University, Krakow, Poland Received 10 December 2003 Abstract The vascular endothelial growth factor (VEGF) is produced in response to hypoxia or inflammatory cytokines. In normoxia VEGF synthesis is upregulated by 15-deoxy-D 12;14 -prostaglandin-J 2 (15d-PGJ 2 ) via induction of heme oxygenase-1 (HO-1). Here we compared the influence of 15d-PGJ 2 on VEGF expression in human microvascular endothelial cells in normoxia (20% O 2 ) and hypoxia (2% O 2 ). Regardless of the oxygen concentration, 15d-PGJ 2 inhibited activity of hypoxia inducible factor-1 (HIF-1), the major hypoxic regulator of VEGF. However, in normoxic conditions 15d-PGJ 2 (1–10 lM) activated the VEGF promoter and in- creased synthesis of the VEGF protein. Concomitantly, it strongly induced expression of HO-1. In contrast, in hypoxia, 15d-PGJ 2 decreased VEGF promoter activity and reduced VEGF release by 50%. Inhibition of HO-1 activity additionally attenuated VEGF synthesis in hypoxia. We conclude that induction of HO-1 by 15d-PGJ 2 results in augmentation of VEGF synthesis in normoxia. In hypoxia, however, the stimulatory effect of HO-1 is outweighed by 15d-PGJ 2 -mediated inhibition of the HIF-1 pathway. Ó 2003 Elsevier Inc. All rights reserved. Keywords: Peroxisome proliferator-activated receptor-c; Prostaglandin-J 2 ; Endothelial cells; Hypoxia; Normoxia; Vascular endothelial growth factor; Hypoxia inducible factor-1; Heme oxygenase-1 The vascular endothelial growth factor (VEGF) is a specific endothelial cell mitogen and survival agent, which induces angiogenesis in ischemic or inflamed tis- sues, e.g., during tumor growth, wound healing, rheu- matoid arthritis or diabetic retinopathy. It is generated by many cell types in response to some growth factors or proinflammatory cytokines, but the strongest inducer of its expression is hypoxia [1]. Prostaglandin-D 2 (PGD 2 ) and its derivative 15- deoxy-D 12;14 -prostaglandin-J 2 (15d-PGJ 2 ) are the most abundantly produced prostaglandins within the vessel wall [2]. They cause a variety of biologic effects, in- cluding induction of vasodilatation, inhibition of plate- let aggregation, a decrease in inflammatory response, and a cessation of cell growth [2]. 15d-PGJ 2 is best known as a natural ligand of the peroxisome prolifera- tor-activated receptor-c (PPARc) transcription factor [3,4]. It is also one of the most potent inducers of heme oxygenase-1 (HO-1) [5], a stress-inducible enzyme which catalyzes the oxidation of heme to biologically active molecules: carbon monoxide (CO), iron, and biliverdin [6]. Several reports have demonstrated that 15d-PGJ 2 and other PPARc activators can induce expression of the VEGF protein in macrophages [7,8], vascular smooth muscle cells (VSMC) [8–10], and endothelial cells [5,11]. The upregulation of VEGF is accompanied by activation of PPARc and results from increased transcription rate [8]. However, the VEGF promoter does not seem to include the consensus sequence of the PPAR responsive element, suggesting that PPARc ligands augment VEGF expression indirectly or through different pathway(s) [8,11]. * Corresponding author. Fax: +48-12-664-6902. E-mail address: alicia@mol.uj.edu.pl (A. J ozkowicz). 0006-291X/$ - see front matter Ó 2003 Elsevier Inc. All rights reserved. doi:10.1016/j.bbrc.2003.12.059 Biochemical and Biophysical Research Communications 314 (2004) 31–38 BBRC www.elsevier.com/locate/ybbrc