title: Granulocyte colony-stimulating factor induces osteoblast apoptosis and inhibits osteoblast differentiation.
abstract: Long-term treatment of mice or humans with granulocyte colony-stimulating factor (G-CSF) is associated with a clinically significant osteopenia characterized by increased osteoclast activity and number. In addition, recent reports have observed a decrease in number of mature osteoblasts during G-CSF administration. However, neither the extent of G-CSF's suppressive effect on the osteoblast compartment nor its mechanisms are well understood. Herein, we show that short-term G-CSF treatment in mice leads to decreased numbers of endosteal and trabecular osteoblasts. The effect is specific to mature osteoblasts, because bone-lining cells, osteocytes, and periosteal osteoblasts are unaffected. G-CSF treatment accelerates osteoblast turnover in the bone marrow by inducing osteoblast apoptosis. In addition, whereas G-CSF treatment sharply increases osteoprogenitor number, differentiation of mature osteoblasts is impaired. Bone marrow transplantation studies show that G-CSF acts through a hematopoietic intermediary to suppress osteoblasts. Finally, G-CSF treatment, through suppression of mature osteoblasts, also leads to a marked decrease in osteoprotegerin expression in the bone marrow, whereas expression of RANKL remains relatively constant, suggesting a novel mechanism contributing to the increased osteoclastogenesis seen with long-term G-CSF treatment. In sum, these findings suggest that the hematopoietic system may play a novel role in regulating osteoblast differentiation and apoptosis during G-CSF treatment.
authors.affiliation: Division of Oncology, Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA..
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Christopher
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Link
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects*; D019070:Cell Lineage / Q000187:drug effects; D002678:Chimera; D016179:Granulocyte Colony-Stimulating Factor / Q000008:administration & dosage / Q000494:pharmacology*; D006413:Hematopoietic System / Q000166:cytology; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D053244:Osteoprotegerin / Q000378:metabolism; D010521:Periosteum / Q000166:cytology; D053245:RANK Ligand / Q000378:metabolism; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000172:deficiency
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D016179:Granulocyte Colony-Stimulating Factor