Brown P C, Tlsty T D, Schimke R T
Mol Cell Biol. 1983 Jun;3(6):1097-107. doi: 10.1128/mcb.3.6.1097-1107.1983.
We investigated various parameters associated with the initial selection of mouse 3T6 cells for resistance to single concentrations of methotrexate and characterized resistant colonies for the presence of additional (amplified) copies of the dihydrofolate reductase gene. Our results indicate that the frequency of occurrence of dihydrofolate reductase gene amplification varies with the selecting concentration of methotrexate and is highly variable between clonally derived sublines of mouse 3T6 cells. Second, we increased the frequency of occurrence of cells with amplified dihydrofolate reductase genes by transiently inhibiting DNA synthesis with hydroxyurea before the selection of cells in single concentrations of methotrexate. This effect was dependent on the concentration of hydroxyurea, the time of exposure to the drug, and the time interval between the removal of hydroxyurea and the selection of cells in methotrexate.
我们研究了与小鼠3T6细胞对单一浓度甲氨蝶呤耐药性初始选择相关的各种参数，并对耐药菌落进行了二氢叶酸还原酶基因额外（扩增）拷贝存在情况的鉴定。我们的结果表明，二氢叶酸还原酶基因扩增的发生频率随甲氨蝶呤的选择浓度而变化，并且在小鼠3T6细胞的克隆衍生亚系之间高度可变。其次，我们通过在单一浓度甲氨蝶呤中选择细胞之前用羟基脲短暂抑制DNA合成，提高了二氢叶酸还原酶基因扩增细胞的发生频率。这种效应取决于羟基脲的浓度、药物暴露时间以及去除羟基脲与在甲氨蝶呤中选择细胞之间的时间间隔。
