Ishibe M, Nojima T, Ishibashi T, Koda T, Rosier R N, Puzas J E, Kaneda K
Department of Orthopaedic Surgery, NTT (Nippon Telegraph and Telephone Corporation) Sapporo Hospital, Japan.
J Orthop Res. 1995 Sep;13(5):643-8. doi: 10.1002/jor.1100130502.
Insulin-like growth factor-II is known to stimulate the proliferation and differentiation of osteoblasts in part through activation of the type-2 insulin-like growth factor receptor. The present study examined the type-2 insulin-like growth factor receptors of three normal osteoblast-like cells and three osteosarcoma-derived osteoblast-like cells (OGA, SU, and IMAI) from humans. [125I]insulin-like growth factor-II was used for the binding studies. All of the cell types had high affinity binding sites for insulin-like growth factor-II (dissociation constants [Kd] < or = 1 nM). The concentration of these sites was 10 to 24-fold higher in normal osteoblasts than in the osteosarcoma cells studied. Unlabeled insulin-like growth factor-II inhibited the binding of [125I]insulin-like growth factor-II to the cells in a dose-dependent manner; however, unlabeled insulin-like growth factor-I and insulin were less effective. Covalent crosslinking of insulin-like growth factor-II binding sites gave molecular mass estimates of M(r) 250,000 in human osteoblast cells, 250,000 and 130,000 in OGA cells, 240,000 in SU cells, and 250,000 and 130,000 in IMAI cells. Unlabeled insulin-like growth factor-II inhibited all affinity labeling. In Northern blot analysis, the type-2 insulin-like growth factor receptor mRNA of normal osteoblasts was seen in greater abundance than it was in osteosarcoma cells. These results indicate that the numbers of type-2 insulin-like growth factor receptors differ between normal and transformed osteoblasts and that the differential expression of the receptor may be due to the differentiation of osteoblasts.
已知胰岛素样生长因子-II部分通过激活2型胰岛素样生长因子受体来刺激成骨细胞的增殖和分化。本研究检测了来自人类的三种正常成骨样细胞和三种骨肉瘤来源的成骨样细胞（OGA、SU和IMAI）的2型胰岛素样生长因子受体。使用[125I]胰岛素样生长因子-II进行结合研究。所有细胞类型对胰岛素样生长因子-II都有高亲和力结合位点（解离常数[Kd]≤1 nM）。这些位点的浓度在正常成骨细胞中比所研究的骨肉瘤细胞高10至24倍。未标记的胰岛素样生长因子-II以剂量依赖方式抑制[125I]胰岛素样生长因子-II与细胞的结合；然而，未标记的胰岛素样生长因子-I和胰岛素的作用较小。胰岛素样生长因子-II结合位点的共价交联在人成骨细胞中给出的分子量估计值为M(r) 250,000，在OGA细胞中为250,000和130,000，在SU细胞中为240,000，在IMAI细胞中为250,000和130,000。未标记的胰岛素样生长因子-II抑制所有亲和标记。在Northern印迹分析中，正常成骨细胞的2型胰岛素样生长因子受体mRNA的丰度高于骨肉瘤细胞。这些结果表明，正常和成骨细胞转化后的2型胰岛素样生长因子受体数量不同，受体的差异表达可能归因于成骨细胞的分化。
