Karadag A, Scutt A M, Croucher P I
Division of Biochemical and Musculoskeletal Medicine, University of Sheffield Medical School, United Kingdom.
J Bone Miner Res. 2000 Oct;15(10):1935-43. doi: 10.1359/jbmr.2000.15.10.1935.
Multiple myeloma is associated with the development of osteolytic bone disease characterized by a disruption to normal bone resorption and bone formation. Although studies have shown that myeloma cells produce factors that promote bone resorption little data are available examining the mechanism of decreased bone formation or the factors that mediate this effect. In the present study we describe a novel in vitro coculture system in which to investigate the effect of myeloma cells on osteoblast recruitment and differentiation. Under appropriate conditions mesenchymal stem cells were shown to differentiate into colonies of cells, a proportion of which show characteristics of osteoblasts, in that they express alkaline phosphatase activity and stain positively for collagen and calcium. The addition of the human myeloma cells JJN-3, RPMI-8226, or NCI-H929 to these cultures stimulated a significant increase in the total number of colonies (p < 0.005) and the proportion of osteoblastic colonies (p < 0.005). Media conditioned by these cells also were able to promote the formation of both total and osteoblastic colonies (p < 0.005). The addition of an antibody against the interleukin-6 receptor (IL-6R) blocked myeloma cell and myeloma cell-conditioned media induced osteoblast recruitment (p < 0.01). Furthermore, media conditioned by myeloma cells incubated with phorbol ester, which promotes IL-6R shedding, or a metalloproteinase inhibitor, which inhibits IL-6R shedding, were able to stimulate (p < 0.005) and inhibit osteoblast recruitment (p < 0.005), respectively. In addition, soluble IL-6R (sIL-6R) and IL-6 together, but not alone, were able to promote osteoblastic colony formation (p < 0.01). Taken together these data show that myeloma cells promote osteoblast recruitment by release of sIL-6R from myeloma cells.
多发性骨髓瘤与溶骨性骨病的发生有关，其特征是正常骨吸收和骨形成受到破坏。尽管研究表明骨髓瘤细胞产生促进骨吸收的因子，但关于骨形成减少的机制或介导这种效应的因子的研究数据很少。在本研究中，我们描述了一种新型的体外共培养系统，用于研究骨髓瘤细胞对成骨细胞募集和分化的影响。在适当条件下，间充质干细胞可分化为细胞集落，其中一部分表现出成骨细胞的特征，即它们表达碱性磷酸酶活性，并对胶原蛋白和钙呈阳性染色。将人骨髓瘤细胞JJN-3、RPMI-8226或NCI-H929添加到这些培养物中，可刺激集落总数显著增加（p<0.005）和成骨细胞集落比例显著增加（p<0.005）。这些细胞条件培养基也能够促进总集落和成骨细胞集落的形成（p<0.005）。添加抗白细胞介素-6受体（IL-6R）抗体可阻断骨髓瘤细胞和骨髓瘤细胞条件培养基诱导的成骨细胞募集（p<0.01）。此外，用佛波酯（促进IL-6R脱落）或金属蛋白酶抑制剂（抑制IL-6R脱落）孵育的骨髓瘤细胞条件培养基分别能够刺激（p<0.005）和抑制成骨细胞募集（p<0.005）。此外，可溶性IL-6R（sIL-6R）和IL-6共同作用（而非单独作用）能够促进成骨细胞集落形成（p<0.01）。综上所述，这些数据表明骨髓瘤细胞通过从骨髓瘤细胞释放sIL-6R来促进成骨细胞募集。
