Human trabecular meshwork cell responses induced by bimatoprost, travoprost, unoprostone, and other FP prostaglandin receptor agonist analogues.
OBJECTIVE
To determine the functional agonist potencies of the intraocular pressure (IOP)-lowering prostaglandin F (FP)-class prostaglandin (PG) analogues (e.g., travoprost, latanoprost, bimatoprost, and unoprostone isopropyl ester) in human trabecular meshwork (h-TM) cells, by using phosphoinositide (PI) turnover and intracellular Ca(2+) ([Ca(2+)](i)) mobilization, and to confirm the FP nature of these receptors by using an FP receptor antagonist, 11beta-fluoro-15-epi-15-indanyl-PGF(2alpha) (AL-8810).


METHODS
FP-receptor-mediated PI turnover and [Ca(2+)](i) mobilization were measured in h-TM cells by determining the accumulation of [(3)H]-inositol phosphates ([(3)H]-IPs) by anion-exchange chromatography and real-time fluorescence imaging, respectively.


RESULTS
Various PG analogues concentration-dependently stimulated production of [(3)H]-IPs in h-TM cells with the following agonist potencies (median effective concentration; EC(50)): travoprost acid (EC(50) = 2.4 nM) > cloprostenol (EC(50) = 4.5 nM) > (+/-)-fluprostenol (EC(50) = 10.8 nM) > latanoprost acid (EC(50) = 34.7 nM) > bimatoprost acid (EC(50) = 112 nM) > PGF(2alpha) (EC(50) = 120 nM) >> unoprostone (UF-021; EC(50) = 3280 nM) > S-1033 (EC(50) = 4570 nM; all n = 3-9). Prodrug derivatives of these compounds exhibited the following potencies: travoprost (isopropyl ester; EC(50) = 89.1 nM) > latanoprost (isopropyl ester; EC(50) = 778 nM) > bimatoprost (amide; EC(50) = 1410-6940 nM). Travoprost acid, PGF(2alpha,) unoprostone, and S-1033 were tested in addition for [Ca(2+)](i) mobilization and found to have rapid and dose-dependent effects. The FP receptor-selective antagonist AL-8810 antagonized the (+/-)-fluprostenol-induced PI turnover in these cells (K(i) = 2.56 +/- 0.62 micro M) as well as that induced by bimatoprost and acids of latanoprost and travoprost. The agonist and antagonist potencies of the PG analogues from the PI turnover assays in h-TM cells correlated well with PI turnover data obtained from the cloned human ciliary body FP receptor (r = 0.92; P < 0.0001).


CONCLUSIONS
The pharmacology of the h-TM cell FP-receptor-mediated PI turnover and [Ca(2+)](i) mobilization was defined using numerous synthetic (FP-selective) PG agonist analogues and an FP receptor antagonist, AL-8810. Bimatoprost, travoprost, latanoprost, unoprostone isopropyl ester, and their respective free acids were shown to be FP agonists in the h-TM cells.
Sharif
Najam A
NA
Molecular Pharmacology Unit, Glaucoma Research, Alcon Research, Ltd., Fort Worth, Texas, USA.
Kelly
Curtis R
CR
Crider
Julie Y
JY
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000577:Amides; D000069580:Bimatoprost; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003008:Cloprostenol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015237:Dinoprost / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007223:Infant; D007429:Intraocular Pressure / Q000187:drug effects; D000077338:Latanoprost; D008055:Lipids / Q000494:pharmacology*; D008875:Middle Aged; D010716:Phosphatidylinositols / Q000378:metabolism; D011461:Prostaglandins F, Synthetic / Q000494:pharmacology*; D011982:Receptors, Prostaglandin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014129:Trabecular Meshwork / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000069557:Travoprost
D000577:Amides; D008055:Lipids; D010716:Phosphatidylinositols; D011461:Prostaglandins F, Synthetic; D011982:Receptors, Prostaglandin; C034671:prostaglandin F2alpha receptor; C121227:AL 8810; D003008:Cloprostenol; C072630:isopropyl unoprostone; D000077338:Latanoprost; D015237:Dinoprost; D000069580:Bimatoprost; D002118:Calcium; D000069557:Travoprost