Isozaki O, Kohn L D
Section on Cell Regulation, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Mol Endocrinol. 1987 Nov;1(11):839-48. doi: 10.1210/mend-1-11-839.
Removal of TSH, insulin, and cortisol from the medium, and decreasing the serum content to 0.2%, abolishes both the proliferate and differentiated state of FRTL-5 rat thyroid cells in culture. In these basal conditions, the individual addition of TSH, insulin, insulin-like growth factor-I (IGF-I), phorbol 12-myristate 13-acetate (TPA), alpha 1-adrenergic agents, or A23187, increase c-myc and/or c-fos proto-oncogene expression. Under the same conditions, only the addition of TSH increased cAMP levels; 8-bromo-cAMP can increase c-myc or c-fos mRNA levels. Pretreatment of cells with phorbol 12,13-dibutyrate, an agent which down regulates the C-kinase, completely inhibits the effect of TPA on proto-oncogene expression but has no affect on the A23187 induced-increase. The sum of these results indicate that at least four separate signal systems independently increase c-myc or c-fos gene expression in FRTL-5 cells cAMP (TSH), C-kinase (TPA), Ca++/phosphoinositide (A23187), and that influenced by insulin/IGF-I. None of the ligands, when individually returned to cells in basal medium (no TSH, insulin, or cortisol and only 0.2% serum), increases cell number; norepinephrine, and A23187 do not increase [3H]thymidine incorporation into DNA under these conditions; and combinations of the ligands can be more than additive in effecting [3H]thymidine incorporation into DNA but are only additive in effecting proto-oncogene expression. Insulin/IGF-I plus TSH or insulin/IGF-I plus norepinephrine can increase both proto-oncogene expression and [3H]thymidine incorporation into DNA to the same extent; however, the former combination can increase cell number whereas the latter cannot. There is therefore no simple correlation between the ability of the above ligands to increase proto-oncogene expression and their ability to increase cell number or induce DNA synthesis. Under conditions where insulin and IGF-I increase proto-oncogene expression but not cell number, they can increase thyroglobulin gene expression. In the presence of TSH, insulin and IGF-I are not additive with each other in their ability to increase thyroglobulin or proto-oncogene gene expression but are additive in their ability to increase cell number. Proto-oncogene expression in FRTL-5 rat thyroid cells, as in other cell systems, may thus be related to functional as well as proliferative responses.
从培养基中去除促甲状腺激素（TSH）、胰岛素和皮质醇，并将血清含量降至0.2%，可消除培养的FRTL-5大鼠甲状腺细胞的增殖和分化状态。在这些基础条件下，单独添加TSH、胰岛素、胰岛素样生长因子-I（IGF-I）、佛波酯12-肉豆蔻酸酯13-乙酸酯（TPA）、α1-肾上腺素能药物或A23187，可增加c-myc和/或c-fos原癌基因的表达。在相同条件下，只有添加TSH可增加环磷酸腺苷（cAMP）水平；8-溴-cAMP可增加c-myc或c-fos信使核糖核酸（mRNA）水平。用佛波酯12,13-二丁酸（一种下调C激酶的药物）预处理细胞，可完全抑制TPA对原癌基因表达的作用，但对A23187诱导的增加无影响。这些结果表明，至少有四个独立的信号系统可独立增加FRTL-5细胞中c-myc或c-fos基因的表达，即cAMP（TSH）、C激酶（TPA）、Ca++/磷酸肌醇（A23187）以及受胰岛素/IGF-I影响的信号系统。在基础培养基（无TSH、胰岛素或皮质醇，只有0.2%血清）中单独将任何一种配体重新加入细胞时，均不会增加细胞数量；在这些条件下，去甲肾上腺素和A23187不会增加[3H]胸腺嘧啶核苷掺入DNA的量；配体组合在影响[3H]胸腺嘧啶核苷掺入DNA方面的作用可能大于相加，但在影响原癌基因表达方面仅为相加。胰岛素/IGF-I加TSH或胰岛素/IGF-I加去甲肾上腺素可在相同程度上增加原癌基因表达和[3H]胸腺嘧啶核苷掺入DNA；然而，前一种组合可增加细胞数量，而后一种则不能。因此，上述配体增加原癌基因表达的能力与其增加细胞数量或诱导DNA合成的能力之间没有简单的相关性。在胰岛素和IGF-I增加原癌基因表达但不增加细胞数量的条件下，它们可增加甲状腺球蛋白基因的表达。在有TSH存在的情况下，胰岛素和IGF-I在增加甲状腺球蛋白或原癌基因表达的能力上彼此无相加作用，但在增加细胞数量的能力上具有相加作用。因此，FRTL-5大鼠甲状腺细胞中的原癌基因表达，与其他细胞系统一样，可能与功能以及增殖反应有关。
