Tseng Y C, Burman K D, Lahiri S, D'Avis J, Wartofsky L
Department of Medicine, Walter Reed Army Medical Center, Washington, DC.
Thyroid. 1992 Fall;2(3):181-7. doi: 10.1089/thy.1992.2.181.
Previous studies had shown that epidermal growth factor (EGF) will stimulate growth of cultured thyroid cells in vitro, and TSH will stimulate total assayable EGF receptor in cultured porcine thyroid cells. In this study, we report the effect of TSH on EGF binding to human thyroid cells. Addition of bTSH (1 mU/mL) in binding buffer during receptor assay stimulated specific EGF binding to cells, with an increase of 44% observed over the control after 1 h incubation at 37 degrees C. Affinity crosslinking of the [125I]EGF-receptor complex showed a single labeled band with molecular size of 170 kD. No additional band was detected in the presence of TSH. Preincubation of cells with chloroquine, which inhibits lysosomal degradative enzyme activity, caused a continuous accumulation of bound EGF over a 4 h study period at 37 degrees C, and TSH stimulated an increase in internalized EGF. In the presence of chloroquine, total specific bound EGF was linearly correlated to incubation time up to 4 h and can be expressed as Bound = slope*time+intercept (time0) Addition of TSH during the binding assay significantly increased the value of the slope when compared to control (p < 0.002). The rate at which prebound [125I]EGF was released into medium was not affected by the presence of TSH, indicating that TSH-enhanced binding may not be attributed to a reduction in EGF degradation. Coincubation of thyroid cells with EGF at 0 and 1 ng/mL and increasing concentrations of TSH (0-10 mU/mL) indicated that EGF stimulated thymidine incorporation, although TSH failed to synergistically enhance EGF-stimulated cell growth.(ABSTRACT TRUNCATED AT 250 WORDS)
以往研究表明，表皮生长因子（EGF）可在体外刺激培养的甲状腺细胞生长，促甲状腺激素（TSH）可刺激培养的猪甲状腺细胞中可检测到的总EGF受体。在本研究中，我们报告了TSH对EGF与人甲状腺细胞结合的影响。在受体检测过程中，于结合缓冲液中添加bTSH（1 mU/mL）可刺激EGF与细胞的特异性结合，在37℃孵育1小时后，与对照组相比，观察到结合增加了44%。[125I]EGF受体复合物的亲和交联显示出一条分子大小为170 kD的单一标记带。在TSH存在的情况下未检测到额外的条带。用氯喹预处理细胞，氯喹可抑制溶酶体降解酶活性，在37℃的4小时研究期间导致结合的EGF持续积累，且TSH刺激内化的EGF增加。在氯喹存在的情况下，总特异性结合的EGF与长达4小时的孵育时间呈线性相关，可表示为结合量=斜率×时间+截距（时间0）。与对照组相比，在结合检测过程中添加TSH显著增加了斜率值（p<0.002）。预先结合的[125I]EGF释放到培养基中的速率不受TSH存在的影响，表明TSH增强的结合可能不归因于EGF降解的减少。甲状腺细胞与0和1 ng/mL的EGF以及浓度递增的TSH（0 - 10 mU/mL）共同孵育表明，EGF刺激了胸腺嘧啶核苷掺入，尽管TSH未能协同增强EGF刺激的细胞生长。（摘要截短于250字）
