Mechanisms of inhibition of DNA synthesis by 2-chlorodeoxyadenosine in human lymphoblastic cells.
Mechanisms of inhibition of DNA synthesis by 2-chlorodeoxyadenosine in human lymphoblastic cells.
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发表时间：
1989-12
期刊：
影响因子：
11.2
通讯作者：
J. Griffig;R. Koob;Raymond L. Blakley
中科院分区：
文献类型：
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作者：
J. Griffig;R. Koob;Raymond L. Blakley
2-氯-2‘-脱氧腺苷5’-三磷酸(CldATP)对CCRF-CEM提取物中核糖核苷酸还原酶还原ADP、CDP、UDP和GDP有很强的抑制作用，在0.1~0.3微米范围内抑制50%。在0.3微米的2-氯-2‘-脱氧腺苷(CldAdo)作用下，细胞内CldATP浓度在15分钟内达到2微米，细胞DNA合成在30分钟内被抑制90%。在抑制DNA合成的胞外CldAdo浓度下，胞内胞苷向脱氧胞苷核苷酸的转化也受到显著抑制，表明胞内对核苷酸还原酶有显著的抑制作用。0.3微米CldAdo可使细胞在30分钟内dCTP减少63%，dATP和dTTP减少20%，dGTP减少较少。当其他核糖核苷酸还原酶抑制剂的存在浓度导致类似的DNA合成抑制时，这些池中也会出现类似的下降。被CldAdo抑制的细胞经脱氧胞苷处理后，dCTP和其他池得以恢复，但DNA合成的恢复是不完整的，这表明除了耗尽脱氧核糖核酸池外，还有另一种机制抑制DNA合成。这种替代机制可能与CldAdo并入DNA有关，尽管细胞内CldATP水平比dATP低25倍。
2-Chloro-2'-deoxyadenosine 5'-triphosphate (CldATP) is a strong inhibitor of the reduction of ADP, CDP, UDP and GDP by ribonucleotide reductase in extracts of CCRF-CEM with 50% inhibition at concentrations of 0.1 to 0.3 microM. In cells exposed to 0.3 microM 2-chloro-2'-deoxyadenosine (CldAdo), the intracellular concentration of CldATP reaches 2 microM within 15 min, and DNA synthesis by the cells is inhibited 90% within 30 min. At concentrations of extracellular CldAdo that inhibit DNA synthesis, there is also marked inhibition of intracellular conversion of cytidine to deoxycytidine nucleotides indicating significant intracellular inhibition of ribonucleotide reductase. Exposure of cells to 0.3 microM CldAdo decreases dCTP by 63% in 30 min, dATP and dTTP by 20% and dGTP by a smaller amount. Similar decreases in these pools occur when other inhibitors of ribonucleotide reductase are present at concentrations causing similar inhibition of DNA synthesis. Deoxycytidine treatment of cells inhibited by CldAdo restores dCTP and other pools, but restoration of DNA synthesis is incomplete, indicating that there is another mechanism for inhibition of DNA synthesis in addition to depletion of deoxyribonucleotide pools. This alternate mechanism is probably related to the incorporation of CldAdo into DNA that occurs despite a 25-times lower intracellular level of CldATP than dATP.