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Effects of dexamethasone on human lens epithelial cells in culture.

Petersen A, Carlsson T, Karlsson JO, Jonhede S, Zetterberg M - Mol. Vis. (2008)

Bottom Line: No effect on superoxide production by dexamethasone was seen.Dexamethasone-induced apoptosis in HLECs does not seem to involve oxidative mechanisms.The proapoptotic effect of dexamethasone does not appear to act through the glucocorticoid receptor.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biomedicine, Department of Medical Chemistry and Cell Biology, the Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden. anne.petersen@gu.se

ABSTRACT

Purpose: Treatment with glucocorticoids is a well known risk factor for cataract development, although the pathogenic mechanism has not been elucidated. The aim of the study was to investigate the effects of glucocorticoids in cultured human lens epithelial cells.

Methods: Human lens epithelial cells (HLECs) were exposed to dexamethasone for 24 h. The number of viable cells was determined using the 3-[4, 5-dimethylthiazolyl-2]-2, 5-diphenyltetrazolium bromide (MTT) assay, and proliferation was quantified using Ki-67. Apoptosis was investigated by measuring caspase-3 activity and by evaluating nuclear morphology of cells stained with Hoechst 33342. Mitochondria depolarization was measured using the potential-sensitive color, JC-1. Cells were assayed for changes in superoxide production using dihydroethidium (HET), for alterations in peroxide production using dichlorofluorescein diacetate (DCFH-DA), and for glutathione (GSH) variations using monochlorobimane (MCB). Caspase-3 activity was also measured in HLECs simultaneously exposed to dexamethasone and the glucocorticoid antagonist, RU486.

Results: Low doses of dexamethasone (0.1 microM) resulted in increased proliferation of HLECs. Apoptosis was increased in HLECs exposed to 1 microM, 10 microM, and 100 microM of dexamethasone as revealed by nuclear morphology studies. Apoptosis was also confirmed by measuring caspase-3 activation. No effect on superoxide production by dexamethasone was seen. There were no effects on GSH levels or mitochondrial depolarization either. Only the highest concentration of dexamethasone (100 microM) caused an increase in peroxide production. In HLECs incubated with the glucocorticoid antagonist, RU486, apoptosis was induced at a lower concentration of dexamethasone (0.1 microM) than with dexamethasone alone.

Conclusions: Low doses of dexamethasone cause a moderate increase in proliferation of cultured HLECs. Slightly higher but still physiologically relevant concentrations of dexamethasone result in a dose-dependent increase in apoptosis. Dexamethasone-induced apoptosis in HLECs does not seem to involve oxidative mechanisms. The proapoptotic effect of dexamethasone does not appear to act through the glucocorticoid receptor. Effects on proliferation and/or dysregulation of apoptosis in lens epithelial cells may be an important factor in human steroid-induced posterior subcapsular cataract.

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Effect of dexamethasone plus or minus the glucocorticoid receptor antagonist RU486. HLECs were incubated with dexamethasone at concentrations ranging from 0 to 100 µM for 24 h with/without 10 µM of the glucocorticoid receptor antagonist RU-486, after which apoptosis was determined by the caspase-3 assay. No protection of human lens epithelial cells against dexamethasone-induced apoptosis was seen by 10 µM RU-486. Instead, simultaneous incubation with RU-486 significantly increased the proapoptotic effect seen by dexamethasone. Cells exposed to 10 µM RU-486 alone showed no increase in caspase-3 activity. Mean ±SEM from 3 separate culture wells are shown from one of four experiments with similar results; the asterisk indicates a p<0.05, the double asterisk indicates a p<0.01, and the triple asterisk indicates a p<0.001.
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f6: Effect of dexamethasone plus or minus the glucocorticoid receptor antagonist RU486. HLECs were incubated with dexamethasone at concentrations ranging from 0 to 100 µM for 24 h with/without 10 µM of the glucocorticoid receptor antagonist RU-486, after which apoptosis was determined by the caspase-3 assay. No protection of human lens epithelial cells against dexamethasone-induced apoptosis was seen by 10 µM RU-486. Instead, simultaneous incubation with RU-486 significantly increased the proapoptotic effect seen by dexamethasone. Cells exposed to 10 µM RU-486 alone showed no increase in caspase-3 activity. Mean ±SEM from 3 separate culture wells are shown from one of four experiments with similar results; the asterisk indicates a p<0.05, the double asterisk indicates a p<0.01, and the triple asterisk indicates a p<0.001.

Mentions: HLECs were incubated with increasing concentrations of dexamethasone for 24 h with and without 10 µM of the glucocorticoid receptor inhibitor RU-486, and apoptosis was determined by measuring caspase-3 activity (Figure 6). This concentration of RU-486 (10 µM) was chosen since it didn’t increase apoptosis when incubated with HLECs alone. At higher concentrations, RU-486 caused apoptosis in HLECs by itself, i.e. without the addition of dexamethasone (not shown). No protection of HLECs against dexamethasone-induced apoptosis was seen by simultaneous incubation with RU-486. On the contrary, the GR inhibitor, RU-486, increased the proapoptotic effect of dexamethasone, leading to even more apoptosis.


Effects of dexamethasone on human lens epithelial cells in culture.

Petersen A, Carlsson T, Karlsson JO, Jonhede S, Zetterberg M - Mol. Vis. (2008)

Effect of dexamethasone plus or minus the glucocorticoid receptor antagonist RU486. HLECs were incubated with dexamethasone at concentrations ranging from 0 to 100 µM for 24 h with/without 10 µM of the glucocorticoid receptor antagonist RU-486, after which apoptosis was determined by the caspase-3 assay. No protection of human lens epithelial cells against dexamethasone-induced apoptosis was seen by 10 µM RU-486. Instead, simultaneous incubation with RU-486 significantly increased the proapoptotic effect seen by dexamethasone. Cells exposed to 10 µM RU-486 alone showed no increase in caspase-3 activity. Mean ±SEM from 3 separate culture wells are shown from one of four experiments with similar results; the asterisk indicates a p<0.05, the double asterisk indicates a p<0.01, and the triple asterisk indicates a p<0.001.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2480483&req=5

f6: Effect of dexamethasone plus or minus the glucocorticoid receptor antagonist RU486. HLECs were incubated with dexamethasone at concentrations ranging from 0 to 100 µM for 24 h with/without 10 µM of the glucocorticoid receptor antagonist RU-486, after which apoptosis was determined by the caspase-3 assay. No protection of human lens epithelial cells against dexamethasone-induced apoptosis was seen by 10 µM RU-486. Instead, simultaneous incubation with RU-486 significantly increased the proapoptotic effect seen by dexamethasone. Cells exposed to 10 µM RU-486 alone showed no increase in caspase-3 activity. Mean ±SEM from 3 separate culture wells are shown from one of four experiments with similar results; the asterisk indicates a p<0.05, the double asterisk indicates a p<0.01, and the triple asterisk indicates a p<0.001.
Mentions: HLECs were incubated with increasing concentrations of dexamethasone for 24 h with and without 10 µM of the glucocorticoid receptor inhibitor RU-486, and apoptosis was determined by measuring caspase-3 activity (Figure 6). This concentration of RU-486 (10 µM) was chosen since it didn’t increase apoptosis when incubated with HLECs alone. At higher concentrations, RU-486 caused apoptosis in HLECs by itself, i.e. without the addition of dexamethasone (not shown). No protection of HLECs against dexamethasone-induced apoptosis was seen by simultaneous incubation with RU-486. On the contrary, the GR inhibitor, RU-486, increased the proapoptotic effect of dexamethasone, leading to even more apoptosis.

Bottom Line: No effect on superoxide production by dexamethasone was seen.Dexamethasone-induced apoptosis in HLECs does not seem to involve oxidative mechanisms.The proapoptotic effect of dexamethasone does not appear to act through the glucocorticoid receptor.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biomedicine, Department of Medical Chemistry and Cell Biology, the Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden. anne.petersen@gu.se

ABSTRACT

Purpose: Treatment with glucocorticoids is a well known risk factor for cataract development, although the pathogenic mechanism has not been elucidated. The aim of the study was to investigate the effects of glucocorticoids in cultured human lens epithelial cells.

Methods: Human lens epithelial cells (HLECs) were exposed to dexamethasone for 24 h. The number of viable cells was determined using the 3-[4, 5-dimethylthiazolyl-2]-2, 5-diphenyltetrazolium bromide (MTT) assay, and proliferation was quantified using Ki-67. Apoptosis was investigated by measuring caspase-3 activity and by evaluating nuclear morphology of cells stained with Hoechst 33342. Mitochondria depolarization was measured using the potential-sensitive color, JC-1. Cells were assayed for changes in superoxide production using dihydroethidium (HET), for alterations in peroxide production using dichlorofluorescein diacetate (DCFH-DA), and for glutathione (GSH) variations using monochlorobimane (MCB). Caspase-3 activity was also measured in HLECs simultaneously exposed to dexamethasone and the glucocorticoid antagonist, RU486.

Results: Low doses of dexamethasone (0.1 microM) resulted in increased proliferation of HLECs. Apoptosis was increased in HLECs exposed to 1 microM, 10 microM, and 100 microM of dexamethasone as revealed by nuclear morphology studies. Apoptosis was also confirmed by measuring caspase-3 activation. No effect on superoxide production by dexamethasone was seen. There were no effects on GSH levels or mitochondrial depolarization either. Only the highest concentration of dexamethasone (100 microM) caused an increase in peroxide production. In HLECs incubated with the glucocorticoid antagonist, RU486, apoptosis was induced at a lower concentration of dexamethasone (0.1 microM) than with dexamethasone alone.

Conclusions: Low doses of dexamethasone cause a moderate increase in proliferation of cultured HLECs. Slightly higher but still physiologically relevant concentrations of dexamethasone result in a dose-dependent increase in apoptosis. Dexamethasone-induced apoptosis in HLECs does not seem to involve oxidative mechanisms. The proapoptotic effect of dexamethasone does not appear to act through the glucocorticoid receptor. Effects on proliferation and/or dysregulation of apoptosis in lens epithelial cells may be an important factor in human steroid-induced posterior subcapsular cataract.

Show MeSH
Related in: MedlinePlus