Interaction between VEGF and calcium-independent phospholipase A2 in proliferation and migration of retinal pigment epithelium.

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 A(2) group VIA (iPLA(2)-VIA) to be a potential regulator of cell proliferation and migration, and evidence show abundant expression of iPLA(2)-VIA in RPE cells. The aim of the present study was to evaluate the potential role of iPLA(2)-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 iPLA(2)-VIA in VEGF-induced RPE proliferation and migration, iPLA(2)-VIA inhibition by the iPLA(2)-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 iPLA(2)-VIA transcriptional activity. Western blot analysis and an activity assay were used to detect the protein levels and activity of iPLA(2)-VIA respectively after treatment with VEGF.

Results: RPE cells treated with VEGF showed significant increased proliferation and migration. Furthermore, inhibition of iPLA(2)-VIA significantly reduced the spontaneous proliferation and migration as well as the VEGF-induced proliferation and migration. Finally, inhibition of iPLA(2)-VIA reduced the VEGF-induced iPLA(2)-VIA-activity, -protein level, and -promoter activity.

Conclusions: A significant interaction between VEGF and iPLA(2)-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.