Abstract：
Exogenous polyamines, including putrescine (PUT), spermidine (SPD), and spermine (SPM), and the irreversible inhibitor of the rate-limiting enzyme ornithine decarboxylase (ODC) of polyamine biosynthesis, α-difluoromethylornithine (DFMO), are implicated as stimulants for bone formation. We demonstrate in this study the osteogenic potential of exogenous polyamines and DFMO in human osteoblasts (hOBs), murine monocyte cell line RAW 264.7, and an ovariectomized rat model. The effect of polyamines and DFMO on hOBs and RAW 264.7 cells was studied by analyzing gene expression, alkaline phosphatase (ALP) activity, tartrate-resistant acid phosphatase (TRAP) activity, and matrix mineralization. Ovariectomized rats were treated with polyamines and DFMO and analyzed by micro computed tomography (micro CT). The mRNA level of the early onset genes of osteogenic differentiation, Runt-related transcription factor 2 (Runx2) and ALP, was significantly elevated in hOBs under osteogenic conditions, while both ALP activity and matrix mineralization were enhanced by exogenous polyamines and DFMO. Under osteoclastogenic conditions, the gene expression of both receptor activator of nuclear factor-κB (RANK) and nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) was reduced, and TRAP activity was suppressed by exogenous polyamines and DFMO in RAW 264.7 cells. In an osteoporotic animal model of ovariectomized rats, SPM and DFMO were found to improve bone volume in rat femurs, while trabecular thickness was increased in all treatment groups. Results from this study provide in vitro and in vivo evidence indicating that polyamines and DFMO act as stimulants for bone formation, and their osteogenic effect may be associated with the suppression of osteoclastogenesis.
摘要：
外源性多胺,包括腐胺（PUT），亚精胺(SPD),精胺（SPM），和多胺生物合成的限速酶鸟氨酸脱羧酶（ODC）的不可逆抑制剂，α-二氟甲基鸟氨酸(DFMO),被认为是骨形成的刺激物。我们在这项研究中证明了外源多胺和DFMO在人成骨细胞（hOB）中的成骨潜力，鼠单核细胞系RAW264.7和去卵巢大鼠模型。通过分析基因表达，研究了多胺和DFMO对hOB和RAW264.7细胞的影响，碱性磷酸酶(ALP)活性,抗酒石酸酸性磷酸酶（TRAP）活性，和基质矿化。用多胺和DFMO治疗卵巢切除的大鼠，并通过显微计算机断层扫描（microCT）进行分析。成骨分化早期发病基因的mRNA水平,Runt相关转录因子2(Runx2)和ALP,在成骨条件下hOB显著升高，而外源多胺和DFMO增强了ALP活性和基质矿化作用。在破骨细胞条件下，核因子-κB受体活化因子（RANK）和活化T细胞核因子的基因表达，细胞质1（NFATc1）减少，RAW264.7细胞中的TRAP活性被外源多胺和DFMO抑制。在去卵巢大鼠的骨质疏松动物模型中，发现SPM和DFMO可以改善大鼠股骨的骨体积，所有治疗组的骨小梁厚度均增加。这项研究的结果提供了体外和体内证据，表明多胺和DFMO可作为骨形成的兴奋剂。它们的成骨作用可能与抑制破骨细胞生成有关。
