Expression of EGF, HGF, KGF, basic FGF, TGFβ1 and their receptor mRNAs in cultured Human Trabecular Meshwork (HTM) cells

Purpose: Elevated intraocular pressure is often associated with primary open angle glaucoma and is due to impaired aqueous humor outflow through the trabecular meshwork. Defects in the structure, function, or number of human trabecular meshwork cells (HTM) may underlie the pathophysiology of this disease. Growth factors are known to control a diverse number of biological functions. However, the role growth factors and their receptors play m the normal structure and function of HTM cells has not been extensively studied. The purpose of this study was to begin to establish which growth factors and growth factor receptors are expressed in normal, cultured HTM cells. Methods: Total cellular RNA isolation, cDNA synthesis, reverse transcriptase-polymerase chain reaction (RT-PCR) and agarose gel electrophoresis were performed using well characterized HTM cell lines obtained from a 48 day and a 54 year old donor. The PCR printers for specific growth factors or growth factor receptors were established using Entrez (NCBI, Bethesda, MD.) and Oligo 4.0 (National Biosciences, Inc., Plymouth, MN.). Nucleic acid sequencing was performed by cloning PCR products in the TA Cloning Vector (Invitrogen, San Diego, CA.) and sequencing with Sequenase 2.0 (United States Biochemical, Cleveland. OH.). Results: We detected mRNA's for hepatocyte growth factor (HGF), keratinocyte growth factor (KGF; FGF-7), epidermal growth factor (EGF), transforming growth factor β1 (TGFβ1), and basic fibroblast growth factor (FGP-2) in both cell lines. These cell lines express message for the following growth factor receptors: HGFR, KGFR, EGFR, TGFβR-1, TGFβR-2, and FGFR-1(flg). Message for an alternatively spliced form of HGFR and TGFβR-2 was detected. In addition, HGF (5 ng/ml), and EGF (10 ng/ml) were found to stimulate HTM cell proliferation in low serum media but there was no significant proliferate effect with KGF. Conclusions: These results indicate that HTM cells express message for several growth factors and growth factor receptors that may be important for the structure and function of the trabecular meshwork. We also show that HGF and EGF stimulate proliferation of HTM cells.