Interaction between VEGF and Calcium-Independent Phospholipase A2 in Proliferation and Migration of Retinal Pigment Epithelium

Abstract

Purpose: Inhibition of VEGF in the eye is an important treatment modality for reducing proliferation and migration of retinal pigment epithelium (RPE) in age-related macular degeneration (AMD). Additionally, previous studies suggest calcium-independent phospholipase A2 group VIA (iPLA2-VIA) to be a potential regulator of cell proliferation and migration, and evidence show abundant expression of iPLA2-VIA in RPE cells. The aim of the present study was to evaluate the potential role of iPLA2-VIA in VEGF-induced proliferation and migration of RPE cells.Materials and methods: The human RPE cell line, ARPE-19, was used in all assays. To explore the role of iPLA2-VIA in VEGF-induced RPE proliferation and migration, iPLA2-VIA inhibition by the iPLA2-VIA specific inhibitor, bromoenol lactone, was done. RPE cell proliferation and migration were evaluated by measurements of incorporated radioactive thymidine in DNA and by a Boyden chamber technique, respectively. A luciferase assay monitored the VEGF-induced iPLA2-VIA transcriptional activity. Western blot analysis and an activity assay were used to detect the protein levels and activity of iPLA2-VIA respectively after treatment with VEGF.Results: RPE cells treated with VEGF showed significant increased proliferation and migration. Furthermore, inhibition of iPLA2-VIA significantly reduced the spontaneous proliferation and migration as well as the VEGF-induced proliferation and migration. Finally, inhibition of iPLA2-VIA reduced the VEGF-induced iPLA2-VIA-activity, -protein level, and -promoter activity.Conclusions: A significant interaction between VEGF and iPLA2-VIA in the regulation of RPE cells appears to be relevant in elucidating the exact mechanisms of action in the proliferative and migratory phenotype of RPE cells in AMD.