Expression of prostaglandin receptors EP4 and FP in human lens epithelial cells

To examine the expression of prostaglandin (PG) receptors EP2, EP4, and FP in a human lens epithelial cell line (HLE-B3) at molecular and pharmacologic levels.

Reverse transcription-polymerase chain reactions (RT-PCR) were performed with total RNA preparations from HLE-B3 cells using sense and antisense primers for each of the three prostaglandin receptors. The PCR products were hybridized with specific 32P-labeled probes and, for further confirmation, digested with appropriate restriction enzymes. At the pharmacologic level, the expression of EP4 receptors was determined by measuring intracellular cyclic adenosine monophosphate (cAMP) formation in response to PGE2 (EP1, EP2, EP3, and EP4 agonist) and the EP4 receptor-selective antagonist AH23848. The expression of FP receptors in HLE-B3 cells was explored by measuring intracellular [Ca2+]i mobilization.

RT-PCR generated DNA products of predicted sizes corresponding to the EP2, EP4, and FP receptors. Hybridization of the PCR products with specific 32P-labeled probes and restriction digestion of the PCR products further confirmed that they were generated from the respective EP2, EP4, and FP mRNAs. The EP receptor agonist PGE2 significantly increased the cAMP level in HLE-B3 cells. The formation of cAMP by PGE2 was concentration-dependently inhibited by the EP4 receptor-selective antagonist AH23848. Stimulation of HLE-B3 cells by the FP receptor agonist fluprostenol increased [Ca2+]i in a time-dependent manner.

The results of the molecular biologic and pharmacologic experiments showed conclusively the presence of EP4 and FP receptor messenger RNAs and proteins, respectively, in HLE-B3 cells.