Abstract
Abstract: :
Purpose: To demonstrate that signal transducer and activator of transcription 3 (STAT3), an intra-cellular protein in hRPE cells, is stimulated by basic fibroblast growth factor (bFGF) and AG490, the Jak/STAT pathway inhibitor, inhibits it. Methods: Human eyes were obtained from Michigan Eye Bank. Human retinal pigment epithelial cells were cultured in Ham’s F-12 medium supplemented with 16% fetal bovine serum and then plated onto 16 mm wells for work. hRPE cells were exposed to increasing concentrations of bFGF and bFGF supplemented with AG490. Cell growth was assessed by trypan blue exclusion method and 3H-thymidine incorporation (3H-thy). STAT3 protein synthesis was assessed by immunoprecipitating 14C-methionine-STAT3 using STAT3 specific antibody. Data were analyzed by student ‘t’ test. p<0.05 was considered to be statistically significantly different. Results: bFGF (1-10 ng/ml) increased hRPE cell number and 3H-thy in a dose dependent manner. AG490 (0.05 mM) inhibited bFGF (10 ng/ml) stimulated 3H-thy (5565.5± 769.8 vs 9481.4±628.3, pvalue, mean CPM±SEM, p value, n=3). bFGF (10 ng/ml) stimulated 14C-methionine-STAT3 protein synthesis (3137.9±408.6 vs 1935.9±806.6, CPM±SEM, p value, n=3). AG490 (0.05 mM) inhibited bFGF (10ng/ml) stimulated 14C-methionine-STAT3 protein synthesis (1662.7±304.6 vs 3137.9±408.6, p value, mean CPM±SEM, p value, n=3). Conclusions: STAT3 may mediate the bFGF stimulated hRPE cell proliferation. This pathway may be a future target for pharmacologic treatments aimed at preventing proliferative eye disease. AG490 may prove to be an useful pharmacological agent in the treatment of proliferative eye diseases.
Keywords: growth factors/growth factor receptors • retinal pigment epithelium • second messengers