inositol-1-4-5-trisphosphate and Endometrial-Neoplasms

In endometrial adenocarcinomas COX-2 and F-series prostanoid (FP) receptor expression and prostanoid biosynthesis (PGE(2) and PGF(2alpha)) are elevated. In the present study, we investigated the effect of PGE(2) and PGF(2alpha) on the expression of COX-2 via the FP receptor in endometrial adenocarcinoma cells stably expressing the FP receptor (FPS cells). Using chemical inhibitors of intracellular signaling pathways, reporter gene assays and quantitative RT-PCR analysis, we show that PGE(2) and PGF(2alpha) can mobilize inositol 1,4,5-trisphosphate, induce ERK1/2 phosphorylation via the phospholipase Cbeta-protein kinase A-epidermal growth factor receptor pathway and induce cyclooxygenase-2 (COX-2) expression via the FP receptor. In addition we show that the PGE(2) or PGF(2alpha)-regulation of COX-2 via the FP receptor is mediated via the cAMP response element (CRE) binding site on the COX-2 promoter. These data indicate that PGE(2) and PGF(2alpha) biosynthesized locally within endometrial adenocarcinomas can regulate tumor cell function in an autocrine/paracrine manner via the FP receptor.

Topics: Adenocarcinoma; Cell Line, Tumor; Cyclooxygenase 2; Dinoprost; Dinoprostone; Endometrial Neoplasms; Enzyme Activation; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Female; Gene Expression Regulation, Enzymologic; Genes, Reporter; Humans; Inositol 1,4,5-Trisphosphate; Promoter Regions, Genetic; Prostaglandin Antagonists; Receptors, Prostaglandin; Receptors, Prostaglandin E; Response Elements; Signal Transduction; Xanthones

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 microM. 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 >> 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 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-trisphosphate and diacylglycerol productions. These receptors are also coupled to the phospholipase D-1 pathway, leading to accumulation of phosphatidic acid. Activation of P2Y2 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 P2Y2 receptors may participate in control of the cell cycle of endometrial carcinoma cells.

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Apoptosis; Calcium; Calcium Channels; Cell Division; Diglycerides; Endometrial Neoplasms; Female; Gene Expression; Humans; Inositol 1,4,5-Trisphosphate; Ion Channel Gating; Phosphatidic Acids; Receptors, Purinergic P2; Receptors, Purinergic P2Y2; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Tumor Cells, Cultured; Type C Phospholipases; Uridine Triphosphate