破骨细胞在多发性骨髓瘤发病中的作用

目的研究多发性骨髓瘤（MM）细胞对破骨细胞（OC）生成及OC对MM细胞生长与存活的相互作用。方法在不同培养体系中行MM细胞与破骨细胞前体共培养，耐酒石酸酸性磷酸酶（TRAP）染色鉴定OC的生成；以RT-PCR检测MM细胞对NF-KB受体激活剂配体（RANKL）／护骨素（OPG）的表达及MM细胞系8226细胞、IL-6依赖性MM细胞系XG1细胞对小鼠原代骨髓基质细胞（pBMSC）表达RANKL／OPG的影响；MM细胞与OC共培养后，采用碘化丙锭（PI）染色，以流式细胞术检测OC对MM细胞增殖周期的影响，Annexin V／PI标记检测OC对MM细胞存活的影响。结果8226及XG1细胞均可直接促进破骨细胞前体向TRAP阳性多个核OC分化。8226、XG1及XG7细胞均不表达RANKL及OPG，8226及XG1细胞促进pBMSC对RANKL的表达，抑制OPG的表达。MM细胞促进OC存活，OC明显促进MM细胞增殖，共培养3d后XG1细胞增殖至（3．8±0．1）×10^9／孔，XG7细胞增殖至（3．9±0．1）×10^5／孔，8226细胞增殖至（4．0±0．1）×10^5／孔，共培养7d后XG1细胞增殖至（8．7±0．1）×10^5／孔，XG7细胞增殖至（9．1±0．1）×10^5／孔，8226细胞增殖至（9．0±0．1）×10^5／孔（P〈0．01）。OC抑制去血清培养诱导的MM细胞凋亡，8226、XG1及XG7细胞与OC共培养后Annexin V^-及PI^-细胞分别为57．71％、82．18％、90．92％（P〈0．01），但对地塞米松诱导的MM细胞凋亡并无拮抗作用。结论MM细胞直接和（或）通过破坏RANKL与OPG之间的平衡间接促进破骨细胞前体向OC分化，OC促进MM细胞生长与存活，从而在MM细胞与OC之间形成恶性循环。

Effects of the osteoclast in pathogenesis of multiple myeloma

OBJECTIVE: To investigate the effects of myeloma cells on the differentiation of osteoclast precusors (pOCs) into OCs in different culture systems in vitro and the interaction between OCs and myeloma cells. METHODS: Myeloma cell lines 8226, XG1 and XG7 and pOCs were cocultured in different culture system. OCs was examined by TRAP staining. RT-PCR was used to evaluate the expression of receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG) of myeloma cells and the effects of myeloma cells on RANKL/OPG expression in coculture. The role of OCs in myeloma cells cycle was measured by FCM with PI staining. The supportive effects of OCs on myeloma cells survival were determined by FCM with double staining for annexin V and PI. RESULTS: 8226 and XG1 cells could directly stimulate the differentiation of pOCs into TRAP+ multinuclear mature OCs. Myeloma cells, which expressed neither RANKL nor OPG, upregulated RANKL expression and decreased OPG expression in mouse primary bone marrow stromal cells (pBMSC). When OCs were co-cultured with myeloma cells, all OCs apparently remained alive after 7 days while devoid of sRANKL and M-CSF. OCs stimulated the proliferation of myeloma cells in co-culture systems,the cell number increased to (3.8 +/- 0.1) x 10(5)/well, (3.9 +/- 0.1) x 10(5)/well, (4.0 +/- 0.1) x 10(5)/well, and to (8.7 +/- 0.1) x 10(5)/well, (9.1 +/- 0.1) x 10(5)/well, (9.0 +/- 0.1 ) x 10(5)/well after co-culture for 3 days and 7 days for XG1 cells, XG7 cells and 8226 cells, respectively (P <0.01). However, OCs could counteract cytotoxic effects of dexamethasone. The proportion of Annexin V-/PI- cells were 57.71%, 82.18% and 90.92% for 8226 cells, XG1 and XG7 cells after co-culture with OCs (P <0.01). CONCLUSION: Myeloma cells stimulated the differentiation of pOCs into TRAP+ multinuclear mature OCs by directly and/or indirectly disrupting the balance of RANKI/OPG, OCs promoted MM cells growth and survival, thus maintaining a vicious circle between myeloma cells and osteoclasts.