TGFBI gene transcript is transforming growth factor-ß1-responsive and cell density-dependent in a human corneal epithelial cell line

Abstract

Purpose: To determine the roles of transforming growth factor-ß 1 (TGF-ß 1 ), epidermal growth factor (EGF), and cell density on the regulation of the TGFBI gene transcript in a human corneal epithelial cell line (HCE-T). Methods: HCE-T cells (40–50% confluent), which possess the biochemical and morphological phenotype of human corneal epithelial cells, were treated with either TGF-ß 1 (20 ng/ml) or EGF (20 ng/ml) for 0, 24, 48, and 72 h. Total RNA was isolated at each time point from the treated cells and the placebo-treated controls. The TGFBI mRNA transcript level was quantitated using Northern blot analysis. Results: TGF-ß 1 upregulates TGFBI gene transcript in this human corneal epithelial cell line, reaching a peak of 2.5-fold of upregulation at 48 h after TGF-ß 1 treatment and a 1.5-fold at 72 h. In contrast, EGF treatment showed no effect on the TGFBI mRNA level. In addition, the TGFBI gene transcript appears to be cell density-dependent because the transcript level shows a trend of reduction as the cell density increases from 40–50% to full confluency. Conclusion: The TGFBI gene transcript in this human corneal epithelial cell line is upregulated by growth factor TGF-ß 1 , but is not affected by growth factor EGF. Furthermore, cell density appears to be an important regulatory mechanism in controlling the level of TGFBI gene expression in corneal epithelial cells.