Expression and Responsiveness of P2Y2 Receptors in Human Endometrial Cancer Cell Lines

In single endometrial carcinoma HEC-1A and Ishikawa cells, ATP induced a rapid and extracellular Ca2+-independent rise in cytosolic Ca2+ concentration ([Ca2+]i) in a dose-dependent manner, with an ED50 of about 10 μm. The spike phase was followed by a sustained plateau phase that was dependent on Ca2+ influx through voltage-insensitive Ca2+ channels, whose gating was controlled by a capacitative Ca2+ entry mechanism. ADP was less potent in raising the cystolic Ca2+ concentration, and AMP and adenosine were ineffective. The order of agonist potency for this receptor was ATP = UTP > ATP-γ-S≫ADP. Several other agonists, including β,γ-methylene-ATP, 2-MeS-ATP, and BzATP were ineffective. This ligand-selective profile indicates the expression of the P2Y2R subtype in endometrial cells. Accordingly, reverse transcription-PCR using P2Y2 primers amplified the expected transcript from both cell lines. The coupling of these receptors to phospholipase C was confirmed by the ability of ATP to increase inositol 1,4,5-t...