OBJECTIVE: To explore the effect of hypoxia and high glucose concentration on the production and secretion of vascular endothelial growth factor (VEGF) and pigment epithelium derived factor (PEDF), an antiangiogenesis factor, in the cultured human retinal pigment epithelium (RPE) cells. METHODS: Human RPE cells were cultured under normoxic or hypoxic (1% O(2)) condition with or without (25 mmol/L) glucose. RT-PCR and real-time quantificaton analysis were used to examine the expression of VEGF and of PEDF mRNAs. Western blot analysis was used to measure the levels of VEGF and PEDF proteins. RESULTS: The expression of VEGF mRNA in RPE cells under hypoxic condition for 12 hours was 2.6 times that under the normoxic condition (P = 0.001), and the expression of PEDF mRNA was only 0.77 time that of the controls (P = 0.251). Under hypoxic condition with high concentration of glucose the expression of VEGF mRNA in RPE cells was 3.8 times that under the normoxic condition (P < 0.001), and the expression of PEDF mRNA was further decreased (only 0.23 time that of the controls, P = 0.02). The expression levels of VEGF protein under hypoxic condition with and without glucose were 1.69 and 1.27 times respectively those under the normoxic condition (P < 0.0001 and P = 0.004). The expression level of PEDF protein under hypoxic condition with glucose was 0.49 time that under the normoxic condition (P < 0.0001) and the expression level of PEDF protein under hypoxic condition without glucose was 0.92 time that under the normoxic condition (P = 0.114). CONCLUSION: Hypoxia indirectly influence the downregulation of PEDF and high concentration of glucose directly downregulates the expression of PEDF and increases the expression of VEGF simultaneously, thus supporting the concept that hyperglycemia is one of the most dangerous consequences of diabetes-associated "glucose toxicity" in vivo.
OBJECTIVE: To explore the effect of hypoxia and high glucose concentration on the production and secretion of vascular endothelial growth factor (VEGF) and pigment epithelium derived factor (PEDF), an antiangiogenesis factor, in the cultured human retinal pigment epithelium (RPE) cells. METHODS:Human RPE cells were cultured under normoxic or hypoxic (1% O(2)) condition with or without (25 mmol/L) glucose. RT-PCR and real-time quantificaton analysis were used to examine the expression of VEGF and of PEDF mRNAs. Western blot analysis was used to measure the levels of VEGF and PEDF proteins. RESULTS: The expression of VEGF mRNA in RPE cells under hypoxic condition for 12 hours was 2.6 times that under the normoxic condition (P = 0.001), and the expression of PEDF mRNA was only 0.77 time that of the controls (P = 0.251). Under hypoxic condition with high concentration of glucose the expression of VEGF mRNA in RPE cells was 3.8 times that under the normoxic condition (P < 0.001), and the expression of PEDF mRNA was further decreased (only 0.23 time that of the controls, P = 0.02). The expression levels of VEGF protein under hypoxic condition with and without glucose were 1.69 and 1.27 times respectively those under the normoxic condition (P < 0.0001 and P = 0.004). The expression level of PEDF protein under hypoxic condition with glucose was 0.49 time that under the normoxic condition (P < 0.0001) and the expression level of PEDF protein under hypoxic condition without glucose was 0.92 time that under the normoxic condition (P = 0.114). CONCLUSION:Hypoxia indirectly influence the downregulation of PEDF and high concentration of glucose directly downregulates the expression of PEDF and increases the expression of VEGF simultaneously, thus supporting the concept that hyperglycemia is one of the most dangerous consequences of diabetes-associated "glucose toxicity" in vivo.