title: Aqueous outflow-enhancing effect of tert-butylhydroquinone: involvement of AP-1 activation and MMP-3 expression.
abstract: OBJECTIVE
  To test the effect of stimulators of activator protein (AP)-1, on expression of stromelysin (MMP-3) in human TM cells and on aqueous outflow in perfused human anterior segments.
  
  
  METHODS
  Change in MMP-3 expression was determined by immunoassay of proMMP-3 levels in the media of cultured human TM cells. Anterior segments of human donor eyes with or without glaucoma were perfused with vehicle or the AP-1 stimulator tert-butylhydroquinone (tBHQ). The outflow rates or intraocular pressure (IOP), and proMMP-3 levels in the perfusate were monitored.
  
  
  RESULTS
  AP-1 stimulators, such as beta-naphthoflavone, 3-methylcholanthrene, and tBHQ, significantly upregulated (2-4-fold) TM cell expression of MMP-3. The stimulatory effect of tBHQ was concentration dependent, with an EC(50) of approximately 3 micro M, and was blocked by concomitant treatment with 100 nM SR11302, which sequesters AP-1. When nonglaucomatous human eyes were perfused with tBHQ (10 micro M), both outflow rates and perfusate proMMP-3 level increased significantly within the first 24 hours. The outflow effect of tBHQ was suppressed when SR11302 (100 nM) was added in the perfusate. tBHQ also lowered the IOP by more than 40% in perfused glaucomatous eyes.
  
  
  CONCLUSIONS
  An AP-1 activator, tBHQ, upregulated expression of MMP-3 in cultured human TM cells and perfused human eyes and enhanced outflow ex vivo. These effects were blocked by sequestering AP-1, suggesting that activation of AP-1 can lead to increased MMP-3 production in the TM, which in turn improves outflow facility. This unique mechanism may provide a novel therapy for glaucoma.
authors.affiliation: Alcon Research, Ltd., Fort Worth, Texas 76134, USA. iok-huo.pang@alconlabs.com
authors.forename: Iok-Hou
authors.initials: IH
authors.lastname: Pang
authors.forename: Debra L
authors.initials: DL
authors.lastname: Fleenor
authors.forename: Peggy E
authors.initials: PE
authors.lastname: Hellberg
authors.forename: Karen
authors.initials: K
authors.lastname: Stropki
authors.forename: Mitchell D
authors.initials: MD
authors.lastname: McCartney
authors.forename: Abbot F
authors.initials: AF
authors.lastname: Clark
mesh_terms: D000869:Anterior Eye Segment / Q000187:drug effects / Q000378:metabolism; D000975:Antioxidants / Q000494:pharmacology*; D001082:Aqueous Humor / Q000378:metabolism*; D018929:Cell Culture Techniques; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005902:Glaucoma, Open-Angle / Q000188:drug therapy / Q000378:metabolism; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology*; D007429:Intraocular Pressure; D019278:Matrix Metalloproteinase 3 / Q000096:biosynthesis*; D008748:Methylcholanthrene / Q000494:pharmacology; D009924:Organ Culture Techniques; D014129:Trabecular Meshwork / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D015854:Up-Regulation; D019324:beta-Naphthoflavone / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D006873:Hydroquinones; D018808:Transcription Factor AP-1; D008748:Methylcholanthrene; D019324:beta-Naphthoflavone; C018855:2-tert-butylhydroquinone; D019278:Matrix Metalloproteinase 3