The Study of Mechamism of Calcification and Differentiation of an Osteoblastic Clonal Cell Line from Human Mandibular Osteosarcoma

建立了具有成骨细胞表型和致瘤性的人下颌骨骨肉瘤细胞系。该细胞系在接种后立即显示出高碱性磷酸酶（ALP）活性，其峰值在培养的第7至第10天左右。甲状旁腺激素（PTH）以浓度依赖性方式增强ALP活性以及细胞内cAMP的产生。PTH对ALP活性和cAMP产生的影响在对数生长期结束时比静止期更强烈。1，25（OH）_2D_3对ALP活性也有一定的促进作用，但作用强度较低，且在培养的不同阶段无明显差异。将这些细胞移植到BALB/C裸鼠体内，观察到与原始肿瘤相似的肿瘤，具有丰富的类骨质。然而，在培养基中未检测到I型胶原的合成。结果表明，该细胞系表达未成熟的前成骨细胞表型。由于这些特性，该细胞系应是有用的，不仅在人成骨细胞的分化表型的研究，而且在人类颌骨骨肉瘤的诊断，治疗和病因学的研究。

A human mandibular osteosarcoma cell line with osteoblastic phenotypes and tumorgenicity was established. The cell line showed high alkaline phosphatase (ALP) activity immediately after seeding, with its peak around the 7th to 10th day of culture. Parathyroid hormone (PTH) enhanced the ALP activity as well as intracellular cAMP production in a concentration-dependent manner. The effects of PTH on both ALP activity and cAMP production were expressed more strongly at the end of logarithmic cell growth than at the resting stage. 1, 25 (OH) 2D3 also stimulated the ALP activity, but its effect was low and was not differentin any of the different culture stages. When these cells were transplanted to BALB/C nude mice, similar tumors to the original one, with abundant osteoid were observed. However, the synthesis of type I collagen was not detected in the culture medium. The results indicate that the this cell line expresses an immature preosteoblastic phenotype. Because of these characteristics, this cell line should be useful, not only in studies on the differentiated phenotypes of human osteoblasts, but also in studies on the diagnosis, treatment and etiology of human osteosarcoma of the jaw.