Reduced myocilin expression in cultured monkey trabecular meshwork cells induced by a selective glucocorticoid receptor agonist: comparison with steroids.

Purpose: To assess in vitro myocilin (MYOC) expression in trabecular meshwork (TM) cells exposed to BOL-303242-X, a selective glucocorticoid receptor (GR) agonist (SEGRA), in comparison with dexamethasone (DEX), and prednisolone acetate (PA).

Methods: After drug treatment of monkey TM cultures, MYOC protein in conditioned media (CM) was measured by Western blot and densitometry. MYOC mRNA levels were analyzed by qRT-PCR. RU-486 was tested for antagonism of MYOC protein expression induced by DEX and BOL-303242-X.

Results: Baseline MYOC protein released into CM and MYOC mRNA were detected. DEX or PA elicited dose-dependent increases in MYOC in CM and also in MYOC mRNA. BOL-303242-X effects typified partial agonism, with significantly reduced MYOC protein and mRNA, compared with DEX. Maximum efficacy for BOL-303242-X was 53% of that for DEX. Mean EC(50) across all strains tested was lower, but not significantly different, for BOL-303242-X versus DEX. Compared with DEX, MYOC mRNA levels were significantly lower in BOL-303242-X-treated TM cells at the highest doses tested. EC(50)s for PA were higher than DEX, for both myocilin protein and mRNA. RU-486 displayed a dose-dependent antagonism to drug-induced increases in myocilin levels.

Conclusions: In vitro quantitative assays of myocilin expression in TM cells can be used for characterizing anti-inflammatory drugs that are GR ligands. The results suggest that, compared with traditional ocular steroids, therapeutic doses of BOL-303242-X elicit a reduced myocilin expression profile in TM cells by virtue of the partial agonist properties of this compound.