Moses A C, Freinkel A J, Knowles B B, Aden D P
J Clin Endocrinol Metab. 1983 May;56(5):1003-8. doi: 10.1210/jcem-56-5-1003.
Insulin-like growth factors (IGF's) circulate in blood complexed to specific carrier proteins. The BRL 3A and BRL 3A2 rat liver cell lines secrete a 30,000-50,000 mol wt IGF carrier protein. Since the liver parenchymal cell is a likely source of IGF carrier protein synthesis, we have evaluated medium conditioned by three human hepatocellular carcinoma- or hepatoblastoma-derived cell lines for the presence of IGF carrier protein. The HEP G2 and the HEP 3B, but not the PLC/PRF/5, cell lines secrete a specific IGF carrier protein(s) into serum-free medium. This carrier protein is specific for IGF molecules. Multiplication-stimulating activity, IGF I, and IGF II were equipotent in competing for the binding of [125I]multiplication-stimulating activity to HEP G2 medium. The HEP G2 IGF carrier protein is trypsin sensitive, acid stabile, and does not contain a glycoprotein moiety. It has a molecular size of 30,000-50,000, as assessed by Sephadex G-200 gel filtration. These studies suggest that the HEP G2 cell line is a useful model to study the synthesis and secretion of human IGF carrier protein.
胰岛素样生长因子（IGF's）以与特定载体蛋白结合的形式在血液中循环。BRL 3A和BRL 3A2大鼠肝细胞系分泌一种分子量为30,000 - 50,000的IGF载体蛋白。由于肝实质细胞可能是IGF载体蛋白合成的来源，我们评估了三种源自人肝细胞癌或肝母细胞瘤的细胞系所培养的培养基中是否存在IGF载体蛋白。HEP G2和HEP 3B细胞系（但PLC/PRF/5细胞系不分泌）能向无血清培养基中分泌一种特定的IGF载体蛋白。这种载体蛋白对IGF分子具有特异性。增殖刺激活性、IGF I和IGF II在竞争[125I]增殖刺激活性与HEP G2培养基的结合方面具有同等效力。HEP G2的IGF载体蛋白对胰蛋白酶敏感、对酸稳定，且不含糖蛋白部分。通过Sephadex G - 200凝胶过滤评估，其分子大小为30,000 - 50,000。这些研究表明，HEP G2细胞系是研究人IGF载体蛋白合成与分泌的有用模型。
