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R. Landers, R. Yang, G.W. McCollum, D.P. Bingaman, J.S. Penn; Anecortave Acetate Inhibits the Hypoxic Induction of VEGF Splice Variants . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1755.
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© ARVO (1962-2015); The Authors (2016-present)
Preliminary studies have demonstrated that anecortave acetate (AA) inhibits angiogenesis, in part, by blocking signal transduction both upstream and downstream of VEGF ligand/receptor interaction. VEGF–A is known to have 5 isoforms in man due to variable expression of splice variants. In the present study, we determined the effect of AA on VEGF mRNA & splice variant expression induced by hypoxia in vitro and in vivo.
In vitro – Rat retinal Müller cells were exposed to 0.1µM–10µM AA or vehicle under hypoxic conditions (< 2% oxygen) for 24 hr then VEGF concentrations from culture medium were measured by ELISA and the VEGF mRNA isoforms from cell lysates were measured by real–time RT–PCR and quantified on agarose gels relative to ß–actin. Similar experiments with ARPE–19, astrocytes, and retinal endothelial cells are on–going. In vivo – In the rat model of OIR, retinas from vehicle–injected or AA–injected (10% suspension) eyes were harvested 0, 1, 3 or 6 days post–oxygen exposure, total mRNA collected and quantified as well as VEGF mRNA splice variants identified as above.
Hypoxia–induced roughly a 2.5–fold increase in VEGF within the media of rat Muller cells and AA treatment provided dose–dependent inhibition, where 10µM AA reduced VEGF levels to normoxic baseline (P<0.0005). Moreover, preliminary results suggest a reduction in VEGF mRNA isoforms. In vivo, total retinal VEGF expression was significantly inhibited (p < 0.0005) by anecortave acetate at 1 day post–exposure (14/1) in the rat OIR model, but at no other time points post–injection. VEGF–120, VEGF–164 and VEGF–188 mRNAs were detected in control and treated retinas, and all isotypes were reduced in AA–treated eyes by 72 hours post–injection, as compared to vehicle–injected controls.
Anecortave acetate (AA) blocks the upregulation of VEGF in hypoxic retinal cells both in vitro and in vivo. AA inhibited the induction of all VEGF isoforms identified in the animal tissues studied, leading to a significant reduction in VEGF protein levels, which may represent a key component of its antiangiogenic activity in man.
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