Regulation of human corneal epithelial cell proliferation and apoptosis bydexamethasone

PURPOSE. To investigate whether human corneal epithelial cells express the glucocorticoid receptor (GR) and to assess the influence of dexamethasone ( DEX) on these cells. METHODS. Human corneal epithelial cells were cultured in medium supplemente d with various concentrations of DEX (ranging from 10(-10) to 10(-4) M). Ce ll, proliferation was analyzed by 3(4,5-dimethylthiazol-2-yl)-5-(3-carboxy- methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay at 2 , 4, and 6 days of culture. Apoptosis was studied by nucleus labeling using a fluorescent dye and immunostaining by APO 2.7 at 6 days of culture. GR m RNA was detected in corneal epithelium and cultured corneal epithelial cell s by means of reverse transcription-polymerase chain reaction (RT-PCR). Imm unocytochemical staining of the epithelial cells was performed with a monoc lonal anti-human GR. RESULTS. RT-PCR and immunocytochemistry showed the expression of GR (mRNA a nd protein) in corneal epithelial cells. DEX significantly increased cornea l epithelial cell proliferation with concentrations ranging from 10(-10) to 10(-6) M, with a maximum effect at 10(-7) M (P < 0.005). However, DEX also induced apoptosis of cultured corneal epithelial cells at anp concentratio n used. CONCLUSIONS. These results indicate that human corneal epithelial cells exp ress the GR and proliferate in response to DEX stimulation which also induc es corneal epithelial cell apoptosis.