title: Androgen regulation of thromboxane A2/prostaglandin H2 receptor expression in human erythroleukemia cells.
abstract: Thromboxane A2 (TxA2), a platelet aggregator and vasoconstrictor, has been implicated as a potential mediator of cardiovascular diseases. Abuse of androgenic steroids has been associated with thrombotic cardiovascular diseases. Human erythroleukemia (HEL) cells, a megakaryocyte-like cell line, express functional TxA2/prostaglandin H2 (PGH2) receptors with characteristics similar to those seen in platelets. This study characterized testosterone regulation of HEL cell TxA2/PGH2 receptors. TxA2/PGH2 receptor affinity (Kd) and density (Bmax) were determined via equilibrium binding experiments using the radiolabeled TxA2 mimetic (1S-[1 alpha,2 beta(5Z),3 alpha(1E,3R*),4 alpha])-7-(3-[3-hydroxy-4-(4'- iodophenoxy)-1-butenyl]-7-oxabicyclo[2.2.1]heptan-2-yl)-5-he ptenoic acid (125I-labeled BOP). Testosterone (200 nM) but not estradiol increased Bmax from 108 +/- 9 fmol/mg protein to 157 +/- 9 fmol/mg protein (n = 7 experiments; P < 0.01) without any significant change in Kd. Testosterone had no significant effect on alpha 2-adrenergic receptor density. The maximum increase in intracellular free calcium induced by the TxA2 agonists I-BOP or U-46619 was significantly (P < 0.005) greater in testosterone-treated cells compared with controls. Hydroxyflutamide (1 microM), an androgen-receptor antagonist, completely blocked the effect of testosterone (P < 0.01). Dihydrotestosterone, the active metabolite of testosterone, also increased Bmax in a concentration-dependent manner and was more potent than testosterone. The effect of testosterone to increase Bmax was significantly (P < 0.01) inhibited by coincubation with cycloheximide (0.1 microgram/ml) or actinomycin D (10 ng/ml). These results indicate that androgenic steroids regulate the expression of functional TxA2/PGH2 receptors in HEL cells. These findings may have relevance to cardiovascular disease.
authors.affiliation: Department of Pharmacology and Medicine, Medical University of South Carolina, Charleston 29425.
authors.forename: K
authors.initials: K
authors.lastname: Matsuda
authors.forename: R S
authors.initials: RS
authors.lastname: Mathur
authors.forename: E
authors.initials: E
authors.lastname: Duzic
authors.forename: P V
authors.initials: PV
authors.lastname: Halushka
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D058891:5-alpha Reductase Inhibitors; D001378:Azasteroids / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D013196:Dihydrotestosterone / Q000031:analogs & derivatives / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D007700:Kinetics; D004915:Leukemia, Erythroblastic, Acute; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D044262:Prostaglandin H2; D011463:Prostaglandins H / Q000378:metabolism; D011982:Receptors, Prostaglandin / Q000096:biosynthesis*; D017482:Receptors, Thromboxane / Q000096:biosynthesis*; D044244:Receptors, Thromboxane A2, Prostaglandin H2; D013739:Testosterone / Q000494:pharmacology*; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D058891:5-alpha Reductase Inhibitors; D001378:Azasteroids; D011450:Prostaglandin Endoperoxides, Synthetic; D011463:Prostaglandins H; D011982:Receptors, Prostaglandin; D017482:Receptors, Thromboxane; D044244:Receptors, Thromboxane A2, Prostaglandin H2; D014662:Vasoconstrictor Agents; D013196:Dihydrotestosterone; D003609:Dactinomycin; D013739:Testosterone; D044262:Prostaglandin H2; D004958:Estradiol; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C047523:17-N,N-diisopropylcarbamoyl-4-azaandrostan-3-one; D003513:Cycloheximide; D002118:Calcium