Yonsei Med J.  2007 Dec;48(6):949-954. 10.3349/ymj.2007.48.6.949.

IGF-1 Counteracts TGF-beta-Mediated Enhancement of Fibronectin for in Vitro Human Lens Epithelial Cells

• Chung SH
• Jung SA
• Cho YJ
• Lee JH
• Kim EK

• KMID: 1786208
• DOI: http://doi.org/10.3349/ymj.2007.48.6.949

Abstract

PURPOSE: To determine whether insulin-like growth factor (IGF-1) affects transforming growth factor (TGF-beta)- mediated fibronectin accumulation in human lens epithelial cell line (HLE B-3) cells. MATERIALS AND METHODS: HLE B-3 cells were incubated for 24 hours with TGF-beta (10ng/ mL), IGF-1 (10ng/mL), or both. Expression of the fibronectin gene was determined using a real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Fibronectin levels were examined using western blot analysis and immunofluorescence staining. RESULTS: Expression of the fibronectin gene was not different between the TGF-beta/IGF-1 treated group and the TGF-beta treated group (p= 0.116). However, western blot analysis demonstrated decreased fibronectin levels in human lens epithelial cells treated with TGF-beta and IGF-1 compared to those treated with TGF-beta only (p < 0.01). Immunofluorescence staining disclosed inhibition of TGF-beta-induced fibronectin in the presence of IGF-1. CONCLUSION: This study suggests that IGF-1 counteracts TGF-beta-mediated fibronectin accumulation in human lens epithelial cells.

Keyword

Fibronectin; IGF-1; lens epithelial cells; TGF-beta

MeSH Terms

Cell Line
Epithelial Cells/cytology/*drug effects/metabolism
Fibronectins/*genetics/metabolism
Fluorescent Antibody Technique
Gene Expression Regulation/drug effects
Humans
Insulin-Like Growth Factor I/*pharmacology
Lens, Crystalline/cytology
Reverse Transcriptase Polymerase Chain Reaction
Transforming Growth Factor beta/*pharmacology

Figure

• 

  Fig. 1 The real-time polymerase chain reaction (PCR) demonstrated that no change was detected in the expression of the fibronectin gene following 24 hour treatment with insulin-like growth factor (IGF)-1 in human lens epithelial cells (HLE B-3). The amount of fibronectin transcripts significantly increased following treatment with TGF-β1. There was no significant difference in the amount of fibronectin (FN) gene transcripts between control and IGF-1 treatment groups, and between TGF-β1 only and TGF-β1 and IGF-1 treatment groups. The graphs show the mean values of the three independent experiments with the error bars representing the standard deviation.

• 

  Fig. 2 IGF-1 counteracts TGF-β-mediated fibronectin accumulation in the human lens epithelial cell line (HLE B-3 cells). HLEB-3 cells in serum-free media were incubated for 24 hours with TGF-β1 (10 ng/mL), IGF-1 (10 ng/mL), or both. Fibronectin levels increased following treatment with TGF-β1 (10 ng/mL) in the western blot analysis. However, fibronectin (FN) levels decreased after treatment with TGF-β1 (10 ng/mL) and IGF-1 (10 ng/mL) when compared to treatment with TGF-β1 (10 ng/mL) only. Values in these graphs represent the mean of the three experiments and error bars represent the standard deviation. Values were normalized to the density of the respective β-actin band.

• 

  Fig. 3 Comparative fluorescent micrographs showing IGF-1 inhibition of TGF-β-mediated fibronectin accumulation in HLE B-3 cells. Cells were maintained (A) in serum free media alone; (B) treated with 10 ng/mL TGF-β1 for 24 hr; (C) treated with 10 ng/mL IGF-1 for 24 hr; (D) treated with 10 ng/mL IGF-1 in the presence of 10 ng/mL TGF-β1 for 24 hr. The bar represents 50 µm in A-D.

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