Yang K P, Samaan N A, Liang Y F, Castillo S G
Department of Medical Specialties, University of Texas M.D. Anderson Cancer Center, Houston 77030.
Henry Ford Hosp Med J. 1992;40(3-4):293-5.
Since the TT human medullary thyroid carcinoma cell line required fewer exogenous growth factors (serum), we investigated whether this line has an autocrine mechanism by examining the effects of antibodies directed toward insulin-like growth factor I (IGF-I) and its receptor on TT cell growth in serum-free conditions. Treating cells with anti-IGF-I antibody for four days reduced the cell number by more than 50% compared with a nonimmune IgG control. Furthermore, a monoclonal antibody to the IGF-I receptor suppressed DNA synthesis when determined by a [3H]thymidine incorporation assay. Exogenous IGF-I (20 ng/mL) stimulated [3H]thymidine incorporation in serum-free medium; approximately 70% of the IGF-I-induced stimulation was blocked by the presence of the receptor antibody. Treating TT cells with IGF-I for 48 hours increased the cell population in the S phase by 62% when analyzed by flow cytometry. These data suggest that TT cells might respond to endogenously produced IGF-I and therefore provide an in vitro model for autocrine regulation of human tumor cell growth by IGF-I.
由于TT人甲状腺髓样癌细胞系所需的外源性生长因子（血清）较少，我们通过检测针对胰岛素样生长因子I（IGF-I）及其受体的抗体在无血清条件下对TT细胞生长的影响，来研究该细胞系是否具有自分泌机制。与非免疫IgG对照相比，用抗IGF-I抗体处理细胞四天后，细胞数量减少了50%以上。此外，通过[3H]胸苷掺入试验测定，针对IGF-I受体的单克隆抗体可抑制DNA合成。外源性IGF-I（20 ng/mL）在无血清培养基中刺激[3H]胸苷掺入；受体抗体的存在可阻断约70%的IGF-I诱导的刺激。通过流式细胞术分析，用IGF-I处理TT细胞48小时后，S期细胞群体增加了62%。这些数据表明，TT细胞可能对内源性产生的IGF-I有反应，因此为IGF-I对人肿瘤细胞生长的自分泌调节提供了一个体外模型。
