STEPWISE TRANSFORMATION OF PRIMARY THYROID EPITHELIAL-CELLS BY A MUTANT HA-RAS ONCOGENE - AN INVITRO MODEL OF TUMOR PROGRESSION
STEPWISE TRANSFORMATION OF PRIMARY THYROID EPITHELIAL-CELLS BY A MUTANT HA-RAS ONCOGENE - AN INVITRO MODEL OF TUMOR PROGRESSION
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DOI：
10.1002/mc.2940060208
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发表时间：
1992-01-01
影响因子：
4.6
通讯作者：
WYNFORDTHOMAS, D
中科院分区：
文献类型：
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作者：
BURNS, JS;BLAYDES, JP;WYNFORDTHOMAS, D
ras 癌基因家族的激活突变在人类和实验的甲状腺肿瘤发生的所有阶段都以高频率发生。为了测试这种关联的因果性质，并研究 ras 突变的生物学作用，我们使用共向性逆转录病毒载体将突变的 c-Ha-ras 基因引入正常大鼠甲状腺滤泡细胞中。主要的直接效果是大大延长了培养中这些细胞的增殖寿命，从不到 3 倍增加到超过 15 倍，而没有任何可观察到的生长因子依赖性或分化功能的损失。这种体外表型有力地支持了 ras 突变在体内良性甲状腺肿瘤（腺瘤）发生中的起始作用。在突变型 ras 表达细胞的连续培养中观察到低频率的自发转化，产生完全永生化、不依赖生长因子的高致瘤性细胞系。转化与 (i) 对生长抑制剂 TGF-β1 的反应性丧失，以及 (ii) p53 蛋白的核水平大大增加有关，这出乎意料地不是由于 p53 编码序列保守区的点突变所致。我们假设这两种现象彼此之间以及与转化的表型之间存在因果关系。
Activating mutations of the ras oncogene family occur at high frequency in all stages of thyroid tumorigenesis, both human and experimental. To test the causal nature of this association, and to investigate the biological role of ras mutation, we introduced a mutant c-Ha-ras gene into normal rat thyroid follicular cells using an ecotropic retroviral vector. The major immediate effect was to greatly extend the proliferative lifespan of these cells in culture from less than 3 to more than 15 doublings, without any observable loss of growth-factor dependence or differentiated functions. This in vitro phenotype strongly supports an initiating role for ras mutation in the genesis of benign thyroid tumors (adenomas) in vivo. Spontaneous transformation was observed at low frequency on continuous culture of mutant ras-expressing cells, giving rise to fully immortalized, growth factor-independent, highly tumorigenic lines.Transformation was associated with (i) loss of responsiveness to the growth inhibitor TGF-beta1, and (ii) greatly increased nuclear levels of p53 protein, which unexpectedly was not due to point mutation in the conserved regions of the p53-coding sequence. We postulate that these two phenomena are causally related to each other and to the transformed phenotype.