Objectives: To evaluate if timolol affects expression of 3 open-angle glaucoma genes and to study its ability to modulate dexamethasone-induced up-regulation of MYOC.
Methods: We used quantitative polymerase chain reaction assay of glaucoma gene transcript levels from human trabecular meshwork (HTM) cultures exposed to 3 different doses of timolol. Three HTM cell cultures were grown with or without 1 of 3 timolol doses in the presence or absence of dexamethasone.
Results: All 3 concentrations of timolol reduced MYOC RNA levels in 1 HTM culture compared with an untreated control and showed negligible effects in the other 2 cultures. Timolol had no effect on dexamethasone-induced MYOC transcript levels in any of the 3 cultures. Timolol, dexamethasone, and dexamethasone plus timolol had a negligible effect on OPTN and WDR36 RNA levels.
Conclusions: Timolol can reduce MYOC RNA levels in HTM cultures from some individuals. Timolol does not alter OPTN or WDR36 levels or ameliorate MYOC induction by dexamethasone in vitro.
Clinical relevance: It remains to be determined whether timolol could reduce production of misfolded myocilin protein by HTM cells in individuals with MYOC missense mutations. A broader survey of interindividual variation in response to timolol as well as mechanistic studies are still needed before potential therapeutic implications can be explored.