Acidic Fibroblast Growth Factor (FGF-1) and FGF Receptor 1 Signaling in Human Y79 Retinoblastoma

Abstract

Objectives: Fibroblast growth factors (FGFs) represent potent effectors and play essential roles in both normal development and many pathological processes. Little is known about their possible implication in retinoblastoma growth. We sought to examine FGF high-and lowaffinity receptor (FGFR) expression, activation of FGFR1 by acidic FGF (FGF-1), and proliferative effects on Y79 cells. Methods: Expression of FGFR1 to FGFR4 was screened in Y79 cells by means of immunochemical and reverse transcriptase polymerase chain reaction techniques. Tyrosine phosphorylation of FGFR1 induced by FGF was examined by immunoprecipitation after stimulation with FGF-1 in the presence or absence of heparin. Retinoblastoma proliferation was monitored by radiolabeled thymidine incorporation or a vital dye-based assay, after addition of FGF-1 with or without inclusion of a specific FGFR1 neutralizing antibody or FGFR1 antisense oligonucleotides. Low-affinity heparan sulfate proteoglycan coreceptors were blocked through sodium chlorate or heparinase treatment of Y79 cells. Results: Y79 retinoblastoma expressed all 4 FGFRs, at both the protein and messenger RNA levels. The FGFR1 was differentially phosphorylated in a time-and heparindependent manner by FGF-1. Proliferation of Y79 cells induced by FGF-1 was entirely mediated by FGFR1, since inclusion of specific neutralizing antibodies or antisense oligonucleotides completely prevented tumor cell multiplication. Finally, FGF-1-induced proliferation was dependent on the presence and sulfation of heparan sulfate proteoglycan. Conclusions: Y79 retinoblastoma expresses all 4 FGFRs, but FGFR1 activation entirely accounts for FGF-1-driven cell proliferation. Clinical Relevance: These studies demonstrate a role for the FGF-1/FGFR1 pathway in retinoblastoma proliferation, and may contribute to developing therapeutic strategies to limit retinoblastoma growth.

Basic Fibroblast Growth Factor Impact on Retinoblastoma Progression and Survival

“…bFGF and FGF receptor expression have been reported in RB 25–27 ; however, the role of bFGF in tumorigenesis, tumor growth, and chemoresistance has not been explored. The purpose of this study was threefold: (1) to evaluate bFGF expression and localization in human RB and transgenic murine RB, particularly during tumorigenesis; (2) to determine whether exogenous bFGF promotes tumor proliferation and inhibits apoptosis; and (3) to determine whether there are differences in bFGF isoform expression between aggressive and indolent RB cell lines.…”

The bone marrow metastasis niche in retinoblastoma

“…There are four different receptors for the FGF proteins: FGFR1-FGFR4. In vitro studies have indicated that the expression of all FGFRs, and activation of FGFR1, are responsible for FGF1-driven Rb cell proliferation [25]. Therefore, FGF is a likely factor to be implicated in Rb development.…”

FGF19 Exhibits Neuroprotective Effects on Adult Mammalian Photoreceptors In Vitro

“…Analyses were performed largely according to previously published methods. 23 After the different incubations, cells were immediately frozen in liquid nitrogen, thawed on ice, and centrifuged (900g) for 5 minutes. Pellets were resuspended in cold lysis buffer (100 mM Tris [pH 7.4], 150 mM sodium fluoride, 1 mM EDTA, 1% Nonidet P40, protease inhibitor cocktail and phosphatase inhibitor, 1 mM NaVO 4 ) and stored on crushed ice.…”

“…20,21 FGFR-1 and FGFR-2 are expressed at high levels throughout the retina, FGFR-3 is concentrated within the inner retina, especially within the retinal ganglion cells (RGCs), 21 and FGFR-4 is abundantly expressed by photoreceptors and photoreceptor-derived retinoblastoma. 22,23 These receptor profiles can be used as a guide to select candidate FGF family members. The preferred ligand for FGFR-3 is FGF-9, 24 and we showed this molecule exerts dose-dependent neurotrophic effects on RGCs in vitro.…”