Effects of methotrexate on human osteoblasts in vitro: modulation by 1,25-dihydroxyvitamin D3.
This study was designed to investigate whether methotrexate (MTX), used in the treatment of rheumatoid arthritis (RA), affects proliferation and differentiation of human osteoblasts in culture. The effects of MTX were assessed by analyzing markers of proliferation and differentiation of human trabecular bone-derived osteoblast-like cells cultured in the presence or absence of 1,25-dihydroxyvitamin D3 (1,25[OH]2D3). Treatment of the osteoblastic cells with MTX resulted in a strong dose-dependent inhibition of cell proliferation with half maximal response at a dose of 30 nM. MTX did not interfere with cellular alkaline phosphatase (AP) activity, the number of cells expressing cytochemical AP, or basal osteocalcin production. Addition of 1,25(OH)2D3 to the cultures caused an enhanced AP expression and osteocalcin production coinciding with a decreased osteoblast proliferation. Coincubation of 1,25(OH)2D3 with MTX in doses > or = 100 nM further inhibited osteoblast growth and induced a significant stimulation of AP expression and activity, and production of osteocalcin above the values reached in the 1,25(OH)2D3 cultures. In conclusion, MTX proved to be a potent inhibitor of osteoblast proliferation but did not affect basal osteoblastic phenotypic expression. In the presence of the osteoblast differentiation-promoter, 1,25(OH)2D3, MTX further inhibited cell growth which was associated with enhanced AP activity and osteocalcin production. Thus, MTX may have profound effects on bone metabolism and remodeling by interfering with bone cell turnover.
Scheven
B A
BA
Department of Geriatrics, University Hospital, Utrecht, The Netherlands.
van der Veen
M J
MJ
Damen
C A
CA
Lafeber
F P
FP
Van Rijn
H J
HJ
Bijlsma
J W
JW
Duursma
S A
SA
D000469:Alkaline Phosphatase / Q000378:metabolism; D000704:Analysis of Variance; D018501:Antirheumatic Agents / Q000627:therapeutic use / Q000633:toxicity*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy; D016723:Bone Remodeling / Q000187:drug effects / Q000502:physiology; D001842:Bone and Bones / Q000378:metabolism; D001973:Bromodeoxyuridine / Q000378:metabolism; D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005270:Femur Head / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D008727:Methotrexate / Q000627:therapeutic use / Q000633:toxicity*; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D015675:Osteocalcin / Q000096:biosynthesis; D011863:Radioimmunoassay
D018501:Antirheumatic Agents; D015675:Osteocalcin; D000469:Alkaline Phosphatase; D002117:Calcitriol; D001973:Bromodeoxyuridine; D008727:Methotrexate