Prostaglandin F2a (PGF) receptor (FP) expression is up-regulated in neoplastic epithelial and perivascular cells in endometrial adenocarcinomas, indicating potential regulation of vascular function by PGF via the FP receptor. This study investigated the potential role of PGF-FP receptor signalling in modulating vascular function in endometrial adenocarcinomas.
Endometrial biopsies were obtained in accordance with Ethics Committee guidance with informed patient consent. FP receptor and vascular endothelial growth factor (VEGF) expression and localization were determined by real-time RT-PCR analysis and dual immunofluorescence. FP receptor and VEGF expression were elevated in endometrial adenocarcinoma (32.5 plus/minus 16.9 and 21.9 plus/minus 10.2 respectively) compared to normal endometrium (0.4 plus/minus 0.12 vs 1.12 plus/minus 0.25; p less than 0.05), and co-localized together in the neoplastic epithelial and perivascular compartments. VEGF expression in carcinoma tissues was determined by RT-PCR analysis in response to 100nM PGF or PGF and AL8810 (FP receptor antagonist) or inhibitors for EGFR kinase (AG1478) and MEK (PD98059). Treatment of adenocarcinoma tissues with PGF up-regulated the expression of VEGF mRNA (P less than 0.05). Co-treatment of tissue explants with AL8810, AG1478 or PD98059 abolished VEGF expression.
The role of EGFR and ERK1/2 in FP receptor signalling to VEGF was investigated using an Ishikawa FP receptor overexpressing cell line (FPS cells) and VEGF promoter luciferase reporter. FPS cells were co-transfected with cDNA for cMyc-tagged ERK1/2 or VEGF promoter luciferase construct, together with dominant negative (DN) Ras, DN-EGFR or DN-MEK, and stimulated with 100nM PGF or PGF and AL8810. Treatment of FPS cells with PGF phosphorylated ERK1/2 and activated VEGF expression. ERK1/2 phosphorylation and activation of VEGF was abolished by co-treatment with AL8810 and co-transfection of cells with DN-Ras, DN-EGFR and DN-MEK (P less than 0.05). These data outline an intracellular pathway for regulation of expression of angiogenic genes, such as VEGF, via PGF-FP receptor interaction.