To study the influence of dexamethasone on membrane-associated mucins produced by human corneal epithelial cells.
Human corneal epithelial cells were cultured in medium supplemented with various concentrations of dexamethasone (ranging from 10−8 to 10−6 M). Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis using monoclonal antibodies specific for human MUC1 (HMFG-1), MUC4 (1G8), and MUC16 (OC125) were performed to evaluate the effect of dexamethasone on membrane-associated mucin expression. The effect of glucocorticoid receptor antagonist (RU38486) on dexamethasone-induced mucin expression was estimated.
RT-PCR revealed that MUC1 and MUC16 gene expression were upregulated 48 hours after addition of dexamethasone and that MUC4 gene expression was downregulated in the same condition. Western blot analysis showed that MUC1 and MUC16 proteins were increased after addition of dexamethasone. However, MUC4 was not detected by anti-MUC4 monoclonal antibody (1G8) for ASGP-2 under our conditions. Treatment with RU38486 inhibited the changes of MUC1, MUC4, and MUC16 by dexamethasone; thus, the effect of dexamethasone on mucin expression is mediated by glucocorticoid receptors.
This study shows that MUC1, MUC4, and MUC16 are regulated differently by dexamethasone in human corneal epithelial cells. External application of dexamethasone might affect the precorneal mucin.
From the *Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea; †Department of Ophthalmology, Inje University College of Medicine, Seoul Paik Hospital, Seoul, Korea; ‡Myunggok Eye Research Institute at Kim's Eye Hospital, Konyang University College of Medicine, Nonsan, Korea; §Cornea Dystrophy Research Institute, Yonsei University College of Medicine, Seoul, Korea; and ¶BK21 Project Team of Nanobiomaterials for Cell-based Implants, Yonsei University, Seoul, Korea.
Received for publication August 10, 2006; revision received January 16, 2007; accepted January 29, 2007.
Supported by Yonsei University Research Fund of 2003.
Reprints: Eung Kweon Kim, Department of Ophthalmology, Institute of Vision Research, Cornea Dystrophy Research Institute, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, CPO Box 8044, Seoul 120-752, Korea (e-mail: firstname.lastname@example.org).