Characterization of Prostaglandin and Thromboxane Receptors Expressed on a Megakaryoblastic Leukemia Cell Line, MEG-01s

• Published in: Blood 1991-11, Vol.78 (9), p.2328-2336
• Main Authors: Watanabe, Tsuyoshi, Yatomi, Yutaka, Sunaga, Shinji, Miki, Ichiro, Ishii, Akio, Nakao, Akihide, Higashihara, Masaaki, Seyama, Yousuke, Ogura, Michinori, Saito, Hidehiko, Kurokawa, Kiyoshi, Shimizu, Takao
• Format: Article
• Language: English
• Subjects: Adenylate Cyclase Toxin; Alprostadil - metabolism; Alprostadil - pharmacology; Biological and medical sciences; Blood Platelets - metabolism; Bridged Bicyclo Compounds, Heterocyclic; Calcium - metabolism; Cell structures and functions; Cyclic AMP - metabolism; Cyclic GMP - metabolism; Dinoprostone - metabolism; Dinoprostone - pharmacology; Epoprostenol - pharmacology; Fatty Acids, Unsaturated; Fundamental and applied biological sciences. Psychology; Humans; Hydrazines - metabolism; Iloprost - metabolism; Iloprost - pharmacology; Leukemia, Megakaryoblastic, Acute - metabolism; Molecular and cellular biology; Pertussis Toxin; Prostaglandin D2 - metabolism; Prostaglandins F - metabolism; Receptors, Prostaglandin - metabolism; Receptors, Thromboxane; Thrombin - pharmacology; Tumor Cells, Cultured; Virulence Factors, Bordetella - pharmacology
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V78.9.2328.2328

MEG-01s, an established human megakaryoblastic leukemia cell line, exhibited specific high-affinity binding sites for [3H]iloprost, a stable prostaglandin (PG) l2 analogue, for [3H]SQ-29548, a stable thromboxane (TX) A2 antagonist and, for [3H]PGE2/pge1, but not for [3H]PGD2. In the MEG-01s cells, iloprost/PGI2, or PGE, stimulated cAMP production with ED50 values practically identical to the IC50 values for the [3H] iloprost binding. STA2 and U46619, TXA2/PGH2 agonists, PGE2/ PGE1, iloprost/ PGI2, and thrombin elevated the intracellular concentrations of Ca2+ ([Ca2+]1), as determined by Fura-2 fluorescence signals. Elevation of [Ca2+]1 by PGE2/PGE1 and iloprost, but not that by TX-agonists or thrombin, was totally dependent on the presence of extracellular Ca2+. This effect by PGE2/PGE1 was partially inhibited by prior treatment of the cells with islet-activating protein (IAP), while that by TX-agonists or by PGI2/iloprost was not affected. We tentatively conclude from these results that: (1) MEG-01s cells express (a) PGI2/PGE1 receptor(s) coupled to adenylate cyclase and Ca2+ influx, a TXA2/PGH2 receptor coupled to the phosphatidylinositol-turnover-Ca2+ system, and the PGE2/ PGE1 receptor coupled to Ca2+ influx; (2) the receptors for TXA2/ PGH2 and iloprost and those for PGE2/PGE1 and thrombin are coupled to IAP-insensitive and lAP-sensitive GTP-binding proteins, respectively, and function in a different manner to elevate [Ca2+]1. Thus, the MEG-01s cell line is a pertinent model for studying eicosanoid receptor-mediated signal transduction in platelet/megakaryocyte systems