Bechtner G, Fröschl H, Sachse A, Schopohl D, Gärtner R
Medizinische Klinik, Klinikum Innenstadt, Ludwig-Maximilians-Universität München, Germany.
Biochimie. 1999 Apr;81(4):315-20. doi: 10.1016/s0300-9084(99)80076-5.
For thyroid cells in culture DNA fragmentation and morphological changes related to apoptosis were first described in dog thyroid cells after deprivation of serum, epidermal growth factor or thyrotropin. With intact porcine thyroid follicles in three-dimensional culture, the effect of deprivation of growth factors and of incubation with transforming growth factor beta1 (TGF-beta1), epidermal growth factor (EGF), thyrotropin (TSH) or insulin-like growth factor I (IGF-I) on the incidence of apoptosis was studied. Thyroid follicles were embedded in growth factor-depleted Matrigel and cultured in serum-free medium with or without growth factors for 7 days followed by incubation for 4, 24 and 72 h with TGF-beta1 (2 or 5 ng/mL). The percentage of apoptotic cells was determined by direct counting in electron-microscopy. Approximately 1% of apoptotic bodies could be detected in unstimulated follicles. This was unchanged in the presence of TSH (1 mU/mL) or IGF (10 ng/mL) but significantly increased up to 3.99 +/- 1.24% with 2 ng/mL of EGF. After incubation with TGF-beta apoptosis increased dose-dependently to 4.05 +/- 0.67% with 2 ng/mL TGF-beta1 and 5.16 +/- 1.75% with 5 ng/mL TGF-beta1. The incidence of necrotic cells remained constant at about 1 to 2%. Preincubation of follicles with 2 ng/mL of EGF followed by incubation with 5 ng/mL TGF-beta1 increased the rate of apoptic bodies up to 13.19 +/- 1.9%. We conclude that growth factor depletion in thyroid follicles in three-dimensional culture does not lead to apoptosis. TGF-beta1, however, induces apoptosis even in quiescent thyroid follicular cells and is significantly more pronounced in growing thyroid cells. EGF, which is a dedifferentiating growth factor for thyroid cells, also induces apoptosis. As EGF enhances TGF-beta1 mRNA and protein in thyroid follicular cells, the induction of apoptosis by EGF might also be due to TGF-beta1.
在培养的甲状腺细胞中，DNA片段化以及与细胞凋亡相关的形态学变化最早是在犬甲状腺细胞血清、表皮生长因子或促甲状腺素缺乏后被描述的。利用完整的猪甲状腺滤泡进行三维培养，研究了生长因子缺乏以及与转化生长因子β1（TGF-β1）、表皮生长因子（EGF）、促甲状腺素（TSH）或胰岛素样生长因子I（IGF-I）孵育对细胞凋亡发生率的影响。将甲状腺滤泡包埋于生长因子缺乏的基质胶中，在无血清培养基中添加或不添加生长因子培养7天，随后用TGF-β1（2或5 ng/mL）孵育4、24和72小时。通过电子显微镜直接计数来确定凋亡细胞的百分比。在未受刺激的滤泡中可检测到约1%的凋亡小体。在TSH（1 mU/mL）或IGF（10 ng/mL）存在的情况下，这一比例没有变化，但在2 ng/mL EGF作用下显著增加至3.99±1.24%。与TGF-β孵育后，凋亡率呈剂量依赖性增加，2 ng/mL TGF-β1时为4.05±0.67%，5 ng/mL TGF-β1时为五.16±1.75%。坏死细胞的发生率保持在约1%至2%不变。滤泡先用2 ng/mL EGF预孵育，然后用5 ng/mL TGF-β1孵育，凋亡小体的比例增加至13.19±1.9%。我们得出结论，三维培养的甲状腺滤泡中生长因子缺乏不会导致细胞凋亡。然而，TGF-β1即使在静止的甲状腺滤泡细胞中也能诱导细胞凋亡，并且在生长的甲状腺细胞中更为明显。EGF是甲状腺细胞的去分化生长因子，也能诱导细胞凋亡。由于EGF可增强甲状腺滤泡细胞中TGF-β1的mRNA和蛋白表达，EGF诱导的细胞凋亡可能也归因于TGF-β1。
