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 mu M. 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-gamma-S much greater than ADP. Several other agonists, including beta,gamma-methylene-ATP, 2-MeS-ATP, and BzATP were ineffective. This ligand-selective profile indicates the expression of the P2Y(2)R subtype in endometrial cells. Accordingly, reverse transcription-PCR using P2Y(2) 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-trisphosphate and diacylglycerol productions. These receptors are also coupled to the phospholipase D-l pathway, leading to accumulation of phosphatidic;acid, Activation of P2Y(2) receptors by a slowly degradable ATP analog, ATP-gamma-S, was associated with a significant suppression of cell proliferation without affecting the cellular apoptosis. These results indicate that P2Y(2) receptors may participate in control of the cell cycle of endometrial carcinoma cells.