title: Role for autocrine TGF-beta 1 in regulating differentiation of a human leukemic cell line toward osteoclast-like cells.
abstract: Increasing evidence suggests that transforming growth factor-beta (TGF-beta) is involved in bone formation during remodeling. Using a recently cloned human leukemic cell line (FLG 29.1 cells) we demonstrate that these cells synthesize and secrete TGF-beta 1 and that exogenous or autocrine TGF-beta 1 can induce the same features of osteoclastic-like cells, exerting its effects through the binding to TGF-beta specific receptors. Scatchard analysis of 125I-labeled TGF-beta 1 to FLG 29.1 cells revealed the presence of a single high affinity binding site with a Kd value of approximately 25 pM and a binding capacity of approximately 900 sites/cell. Affinity labeling experiments showed that FLG 29.1 cells express type I and type II TGF-beta receptors. Stimulation of FLG 29.1 cells with low TGF-beta 1 doses reduced cell proliferation and increased cell adhesion and tartrate resistant acid phosphatase (TRAcP) activity. Pretreatment of FLG 29.1 cells with TGF-beta 1 caused a significant and dose-dependent response to calcitonin. Northern blot of total mRNA and analysis of the conditioned media (CM) showed that TGF-beta 1 was synthesized by FLG 29.1 cells. TPA treatment, which induces partial differentiation of these cells, markedly increased TGF-beta 1 mRNA expression and growth factor release. The majority of TGF-beta 1 secreted by TPA-treated cells was in its latent form. However, anti-TGF-beta antibodies inhibited TGF-beta 1 and TPA-induced growth inhibition, calcitonin responsiveness, and TRAcP activity, suggesting that the TPA effect is mediated in part by autocrine TGF-beta 1 and indicating that the cells can activate and respond to the TGF-beta that they secrete. These findings support a potential autocrine role for TGF-beta 1 in osteoclast differentiation.
authors.affiliation: Department of Clinical Physiopathology, University of Florence, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Fiorelli
authors.forename: R T
authors.initials: RT
authors.lastname: Ballock
authors.forename: L M
authors.initials: LM
authors.lastname: Wakefield
authors.forename: M B
authors.initials: MB
authors.lastname: Sporn
authors.forename: F
authors.initials: F
authors.lastname: Gori
authors.forename: L
authors.initials: L
authors.lastname: Masi
authors.forename: U
authors.initials: U
authors.lastname: Frediani
authors.forename: A
authors.initials: A
authors.lastname: Tanini
authors.forename: P A
authors.initials: PA
authors.lastname: Bernabei
authors.forename: M L
authors.initials: ML
authors.lastname: Brandi
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D001345:Autoradiography; D001667:Binding, Competitive; D002116:Calcitonin / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000378:metabolism; D004351:Drug Resistance; D000091344:Filaggrin Proteins; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007938:Leukemia / Q000378:metabolism / Q000473:pathology*; D010010:Osteoclasts / Q000473:pathology*; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D000071681:Tartrate-Resistant Acid Phosphatase; D013644:Tartrates / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007527:Isoenzymes; D018125:Receptors, Transforming Growth Factor beta; D013644:Tartrates; D016212:Transforming Growth Factor beta; D002116:Calcitonin; D000242:Cyclic AMP; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase