Inhibited anabolic effect of insulin-like growth factor-I on stromal bone marrow cells in endothelial nitric oxide synthase-knockout mice.
OBJECTIVE
Insulin-like growth factor-I (IGF-I), parathyroid hormone (PTH) and PTH-related protein (PTHrP) are hormones that have anabolic effects on bone formation. The aim of this study was to investigate whether production of nitric oxide (NO) is involved in the effect of IGF-I and PTH/PTHrP on osteoblast-like cells.


METHODS
Bone marrow stromal cells from adult endothelial nitric oxide synthase (eNOS)-knockout (eNOSKO) mice and wild type (WT) counterparts were cultivated with osteogenic substances. The cells showed an osteoblastic phenotype measured as osteocalcin production and alkaline phosphatase activity. DNA synthesis was measured as [3H] thymidine incorporation in the bone marrow cells and in a human osteosarcoma cell-line (SaOS-2).


RESULTS
The stimulatory effect of IGF-I on thymidine incorporation seen in WT animals was absent in eNOSKO mice. Addition of a NO donor to eNOSKO cells recovered the effect of IGF-I on thymidine incorporation. PTH/PTHrP stimulated cell proliferation in both WT and eNOSKO mice. In SaOS-2 cells, incubation with IGF-I together with a NOS inhibitor resulted in an inhibition of the anabolic effect of IGF-I on cell proliferation.


CONCLUSIONS
The stimulatory effect of IGF-I on WT cell proliferation was abolished in eNOSKO cells, recovered by an NO donor and inhibited in osteosarcoma cells by a NOS inhibitor. The results indicate that the effect of IGF-I is dependent on NO production. The impaired IGF-I response may contribute to the bone defect formation seen in eNOSKO animals.
Department of Molecular Medicine, Endocrine and Diabetes Unit, Karolinska Institutet and Karolinska Hospital, Stockholm, Sweden.
A
A
Lagumdzija
G
G
Ou
M
M
Petersson
E
E
Bucht
A
A
Gonon
Y
Y
Pernow
D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism; D015675:Osteocalcin / Q000096:biosynthesis; D010281:Parathyroid Hormone / Q000502:physiology; D044162:Parathyroid Hormone-Related Protein / Q000502:physiology; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology
D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; C110881:S-nitro-N-acetylpenicillamine; D015675:Osteocalcin; D007334:Insulin-Like Growth Factor I; D004247:DNA; D019001:Nitric Oxide Synthase; D010396:Penicillamine; D019331:NG-Nitroarginine Methyl Ester