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[This corrects the article DOI: 10.18632/oncotarget.6868.].
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PURPOSE: Expression of the hypoxia-inducible factor (HIF)-1-regulated gene product, vascular endothelial growth factor (VEGF), correlates with tumor vascularity in patients with uveal melanoma (UM). While the relationship between HIF-1 and VEGF in cancer is well-studied, their relative contribution to the angiogenic phenotype in UM has not previously been interrogated. Here we evaluate the contribution of HIF-1, VEGF, and a second HIF-1-regulated gene product, angiopoietin-like 4 (ANGPTL4), to angiogenesis in UM. EXPERIMENTAL DESIGN: UM cells were examined for expression of HIF-1α, VEGF, and ANGPTL4. Their contribution to the angiogenic potential of UM cells was assessed using the endothelial cell tubule formation and directed in vivo angiogenesis assays. These results were corroborated in tissue from UM animal models and in tissue from patients with UM. RESULTS: Inhibition of VEGF partially reduced tubule formation promoted by conditioned medium from UM cells. Inhibition of ANGPTL4, which was highly expressed in hypoxic UM cells, a UM orthotopic transplant model, a UM tumor array, and vitreous samples from UM patients, inhibited the angiogenic potential of UM cells in vitro and in vivo; this effect was additive to VEGF inhibition. CONCLUSIONS: Targeting both ANGPTL4 and VEGF may be required for the effective inhibition of angiogenesis in UM.
Assuntos
Angiopoietinas/metabolismo , Movimento Celular , Regulação Neoplásica da Expressão Gênica , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Melanoma/irrigação sanguínea , Neovascularização Patológica/patologia , Neoplasias Uveais/irrigação sanguínea , Fator A de Crescimento do Endotélio Vascular/metabolismo , Proteína 4 Semelhante a Angiopoietina , Angiopoietinas/genética , Animais , Apoptose , Western Blotting , Estudos de Casos e Controles , Hipóxia Celular , Proliferação de Células , Células Cultivadas , Endotélio Vascular/metabolismo , Endotélio Vascular/patologia , Feminino , Imunofluorescência , Seguimentos , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Técnicas Imunoenzimáticas , Melanoma/metabolismo , Melanoma/patologia , Camundongos , Camundongos Nus , Estadiamento de Neoplasias , Neovascularização Patológica/metabolismo , Fenótipo , Prognóstico , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Neoplasias Uveais/metabolismo , Neoplasias Uveais/patologia , Fator A de Crescimento do Endotélio Vascular/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Diabetic eye disease is the most common cause of severe vision loss in the working-age population in the developed world, and proliferative diabetic retinopathy (PDR) is its most vision-threatening sequela. In PDR, retinal ischemia leads to the up-regulation of angiogenic factors that promote neovascularization. Therapies targeting vascular endothelial growth factor (VEGF) delay the development of neovascularization in some, but not all, diabetic patients, implicating additional factor(s) in PDR pathogenesis. Here we demonstrate that the angiogenic potential of aqueous fluid from PDR patients is independent of VEGF concentration, providing an opportunity to evaluate the contribution of other angiogenic factor(s) to PDR development. We identify angiopoietin-like 4 (ANGPTL4) as a potent angiogenic factor whose expression is up-regulated in hypoxic retinal Müller cells in vitro and the ischemic retina in vivo. Expression of ANGPTL4 was increased in the aqueous and vitreous of PDR patients, independent of VEGF levels, correlated with the presence of diabetic eye disease, and localized to areas of retinal neovascularization. Inhibition of ANGPTL4 expression reduced the angiogenic potential of hypoxic Müller cells; this effect was additive with inhibition of VEGF expression. An ANGPTL4 neutralizing antibody inhibited the angiogenic effect of aqueous fluid from PDR patients, including samples from patients with low VEGF levels or receiving anti-VEGF therapy. Collectively, our results suggest that targeting both ANGPTL4 and VEGF may be necessary for effective treatment or prevention of PDR and provide the foundation for studies evaluating aqueous ANGPTL4 as a biomarker to help guide individualized therapy for diabetic eye disease.