title: Characterization of a subtype of primary osteoclastoma: extracellular calcium but not calcitonin inhibits aggressive HLA-DR-positive osteoclastoma possessing 'functional' calcitonin receptors.
abstract: We report here a case of primary osteoclastoma that despite possessing HLA-DR-positive status and 'functional' calcitonin receptors, exhibited aggressive in vitro and in vivo bone resorptive activity. In the osteoclast bone slice assay employing scanning electron microscopy, the giant cell-mediated bone resorption was uninhibited by salmon calcitonin (10 nM) and significantly inhibited by raised extracellular calcium (20 mM). In Fura-2AM based microspectrofluorimetric assays, the presence of the 'functional' calcitonin receptors was ascertained by a rise in intracellular calcium induced by calcitonin and high extracellular calcium. These findings provide evidence for a hitherto unrecognized subtype of giant cells that have HLA-DR-positive status, exhibit avid bone resorptive activity, but remain insensitive to calcitonin despite possessing calcitonin receptors.
authors.affiliation: Department of Clinical Biochemistry, Medical School, University of Newcastle-upon Tyne, U.K.
authors.forename: H
authors.initials: H
authors.lastname: Rathod
authors.forename: A J
authors.initials: AJ
authors.lastname: Malcolm
authors.forename: J I
authors.initials: JI
authors.lastname: Gillespie
authors.forename: V
authors.initials: V
authors.lastname: Berry
authors.forename: J
authors.initials: J
authors.lastname: Pooley
authors.forename: N H
authors.initials: NH
authors.lastname: Piggott
authors.forename: H K
authors.initials: HK
authors.lastname: Datta
mesh_terms: D000328:Adult; D000700:Analgesics / Q000494:pharmacology*; D001859:Bone Neoplasms / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D001862:Bone Resorption; D002116:Calcitonin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D018212:Giant Cell Tumor of Bone / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D006684:HLA-DR Antigens / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D008855:Microscopy, Electron, Scanning; D018003:Receptors, Calcitonin / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D014407:Tumor Cells, Cultured
chemical_list: D000700:Analgesics; D006684:HLA-DR Antigens; D018003:Receptors, Calcitonin; C028815:salmon calcitonin; D002116:Calcitonin; D002118:Calcium