title: Novel effect of Y-24180, a presumed specific platelet-activating factor receptor antagonist, on Ca2+ levels and growth of human osteosarcoma cells.
abstract: In human osteosarcoma MG63 cells, the effect of Y-24180, a presumed specific platelet-activating factor (PAF) receptor antagonist, on intracellular Ca(2+) concentration ([Ca(2+)](i)) and proliferation was measured by using fura-2 and tetrazolium as fluorescent dyes, respectively. Y-24180 (1-5 microM) caused a rapid and sustained [Ca(2+)](i) rise in a concentration-dependent manner. The [Ca(2+)](i) rise was inhibited by 35% by dihydropyridines or removal of extracellular Ca(2+), but was not altered by verapamil and diltiazem. In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic [Ca(2+)](i) rise, after which 5 microM Y-24180 failed to increase [Ca(2+)](i); conversely, depletion of Ca(2+) stores with 5 microM Y-24180 abolished thapsigargin-induced [Ca(2+)](i) rise. U73122, an inhibitor of phoispholipase C, inhibited histamine-induced, but not 5 microM Y-24180-induced [Ca(2+)](i) rise. Overnight treatment with 0.1-5 microM Y-24180 inhibited cell proliferation in a concentration-dependent manner. Together, these findings suggest that Y-24180 acts as a potent and cytotoxic Ca(2+) mobilizer in human osteosarcoma cells, by inducing both extracellular Ca(2+) influx and intracellular Ca(2+) release. Alterations in cytosolic Ca(2+) regulation may lead to interferences of various cellular functions; thus, attention should be exercised in using Y-24180 as a selective PAF receptor antagonist.
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan.
authors.forename: Chung-Ren
authors.initials: CR
authors.lastname: Jan
authors.forename: Yu-Ying
authors.initials: YY
authors.lastname: Chao
mesh_terms: D001381:Azepines / Q000494:pharmacology* / Q000627:therapeutic use; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006131:Growth Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D012516:Osteosarcoma / Q000188:drug therapy* / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D001381:Azepines; D006131:Growth Inhibitors; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; D014230:Triazoles; C039351:platelet activating factor receptor; C068035:4-(2-chlorophenyl)-2-(2-(4-isobutylphenyl)ethyl)-6,9-dimethyl-6H-thieno(3,2-f)(1,2,4)triazolo(4,3-a)(1,4)diazepine; D002118:Calcium