Uehara R, Suzuki Y, Ichikawa Y
Department of Rheumatic and Allergic Diseases, St Marianna University School of Medicine, Kawasaki, Japan.
J Rheumatol. 2001 Feb;28(2):251-6.
To clarify the mechanism of impaired bone formation during low dose methotrexate (MTX) therapy.
The in vitro effects of MTX on the function and differentiation of osteoblastic cells were investigated using (1) a mouse osteogenic cell line (MC3T3-E1) with the capacity to differentiate into osteoblastic or osteocytes, (2) a human osteoblastic osteosarcoma cell line (SaOS-2) with a mature osteoblastic phenotype, and (3) mouse bone marrow stromal cells containing osteoblast precursors. Osteoblast function was assessed by measuring the cellular activity of alkaline phosphatase (ALP) and the mineralization capacity of cultures.
MTX suppressed ALP activity dose-dependently in growing MC3T3-E1 cells, but proliferation of these cells was only inhibited by a high concentration of MTX. In contrast, inhibition of ALP activity in MC3T3-E1 cells of mature osteoblastic phenotype was only observed with 10(-8) M and 10(-7) M MTX, and proliferation was not influenced. ALP activity and the proliferation of SaOS-2 cells were not inhibited by MTX, even when growing cells were treated. However, both ALP activity and formation of calcified nodules in bone marrow stromal cell cultures were significantly suppressed by MTX at concentrations between l0(-10) and 10(-7) M.
These results suggest that MTX suppresses bone formation by inhibiting the differentiation of early osteoblastic cells.
阐明低剂量甲氨蝶呤（MTX）治疗期间骨形成受损的机制。
使用以下三种细胞研究MTX对成骨细胞功能和分化的体外影响：（1）具有分化为成骨细胞或骨细胞能力的小鼠成骨细胞系（MC3T3-E1）；（2）具有成熟成骨细胞表型的人成骨骨肉瘤细胞系（SaOS-2）；（3）含有成骨细胞前体的小鼠骨髓基质细胞。通过测量碱性磷酸酶（ALP）的细胞活性和培养物的矿化能力来评估成骨细胞功能。
MTX在生长的MC3T3-E1细胞中剂量依赖性地抑制ALP活性，但只有高浓度的MTX才能抑制这些细胞的增殖。相比之下，仅在10^(-8) M和10^(-7) M MTX处理时，才观察到成熟成骨细胞表型的MC3T3-E1细胞中ALP活性受到抑制，而增殖未受影响。即使处理生长中的细胞，MTX也不会抑制SaOS-2细胞的ALP活性和增殖。然而，在10^(-10)至10^(-7) M浓度范围内，MTX可显著抑制骨髓基质细胞培养物中的ALP活性和钙化结节的形成。
这些结果表明，MTX通过抑制早期成骨细胞的分化来抑制骨形成。
