growth factor expression in pigment epithelium cells in vitro
Wen-ChuanWu Ying-Hsien Kao
Departments of Ophthalmology， Kaohsiung Medical University Hospital， Kaohsiung，TaiwanHypoxia is the most common factor contributing to the pathogenesis of choroidalneovascularization， which is the major cause for blindness and occurs in proliferativediabetic retinopathy and age-related macular degeneration. The purpose of this study is toinvestigate the role of retinal pigment epithelial (RPE) cells in the regulation of subretinalneovascularization under hypoxia and the possible function of a heat shock protein 90(HSP90) inhibitor， geldanamycin (GA)， in the regulation of VEGF expression. An in vitrohypoxic experimental model was used to mimic the ischemicmicroenvironment of RPE cells。
The cell growth was measured by proliferation assay and the morphological observation wasdocumented by microscope. The gene expression of VEGF， HSP70， HSP90?and HSP90?were measured using semi-quantitative RT-PCR. The VEGF release from RPE cells weredetected by ELISA. No alteration in growth rate and cell morphology under 1% O2 conditionfor 24h was noticed. The proangiogenic growth factor VEGF， but not bFGF， released from
hypoxia-treated cells were higher than that of normoxic control. A similar tendency of VEGFgene expression， detected by RT-PCR， was noticed in hypoxia-treated cells. Heat shockpretreatment elevated HSP70 and VEGF gene expression and augmented thehypoxia-induced VEGF gene expression and protein release. Pretreatment with GA can
significantly suppress the hypoxia-induced VEGF gene expression in and peptide releasefrom RPE cells. This in vitro finding suggests that HSP90 inhibitors could be considered as anovel anti-angiogenesis agent for diseases with intraocular neovascularization.
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