Drach J C, Sandberg J N, Shipman C
J Dent Res. 1977 Mar;56(3):275-88. doi: 10.1177/00220345770560031301.
The effect of ara-A on cellular growth, DNA synthesis, and RNA synthesis, and RNA synthesis was measured in an established cell line (B-mix K-44/6) devoid of adenosine deaminase activity. Cells adapted to growth in a medium supplemented with horse serum provided an environment totally lacking adenosine deaminase activity whereas cultivation of cells in a medium supplemented with calf serum provided a system capable of deaminating ara-A to ara-H (half-life = 14 hours). Under deaminase-free conditions early log phase cells underwent 1.5 population doublings during 28 hours compared with 0.25 doublings in the presence of 37 micronM ara-A. When cells were grown in medium supplemented with calf serum the additionof 37 to 225 micronM ara-A resulted in a cessation of mitosis for periods of 5 to 30 hours respectively. Following this quiescent period growth resumed at the original rate. With 600 micronM ara-A mitosis was reversibly inhibited up to 35 hours after drug addition. The effects of ara-A on RNA and DNA synthesis were monitored by continuously or pulse labeling B-mix K-44/6 cells with [3H]-uridine or [3H]thymidine. Ara-A did not influence RNA synthesis as judged by labeled uridine incorporation. Under deaminase-free conditions, 5.4 micronM ara-A inhibited labeled thymidine incorporation by 50%. In the presence of the enzyme, approximately twice the ara-A concentration was required for the same inhibition; furthermore the initial inhibition was followed by a partial recovery in the rate of thymidine incorporation. Examination of thymidine incorporation. Examination of thymidine nucleotide pools during ara-A treatment revealed to changes in the labeling of dTMP, dTDP, and dTTP. Thus inhibition of [3H]thymidine incorporation by ara-A accurately reflected inhibition of DNA synthesis. We conclude that, in spite of an initial inhibition of DNA synthesis and mitosis by ara-A, B-mix K-44/6 cells recover from the inhibitory effects if the drug is removed either by a change in the culture medium or by metabolism to ara-H.
在一种缺乏腺苷脱氨酶活性的既定细胞系（B-mix K-44/6）中，检测了阿糖腺苷（ara-A）对细胞生长、DNA合成以及RNA合成的影响。适应于在添加马血清的培养基中生长的细胞提供了一个完全缺乏腺苷脱氨酶活性的环境，而在添加小牛血清的培养基中培养细胞则提供了一个能够将阿糖腺苷脱氨为阿糖次黄嘌呤（ara-H，半衰期 = 14小时）的系统。在无脱氨酶条件下，对数生长期早期的细胞在28小时内经历了1.5次群体倍增，而在存在37微摩尔阿糖腺苷的情况下仅为0.25次倍增。当细胞在添加小牛血清的培养基中生长时，添加37至225微摩尔阿糖腺苷分别导致有丝分裂停止5至30小时。在此静止期后，生长以原始速率恢复。使用600微摩尔阿糖腺苷时，有丝分裂在药物添加后长达35小时被可逆性抑制。通过用[³H] - 尿苷或[³H] - 胸苷连续或脉冲标记B-mix K-44/6细胞来监测阿糖腺苷对RNA和DNA合成的影响。根据标记尿苷掺入判断，阿糖腺苷不影响RNA合成。在无脱氨酶条件下，5.4微摩尔阿糖腺苷使标记胸苷掺入减少50%。在有该酶存在的情况下，相同抑制作用所需的阿糖腺苷浓度约为两倍；此外，最初的抑制之后胸苷掺入速率会部分恢复。在阿糖腺苷处理期间检查胸苷掺入情况以及胸苷核苷酸池，发现dTMP、dTDP和dTTP的标记没有变化。因此，阿糖腺苷对[³H] - 胸苷掺入的抑制准确反映了对DNA合成的抑制。我们得出结论，尽管阿糖腺苷最初会抑制DNA合成和有丝分裂，但如果通过更换培养基或代谢为阿糖次黄嘌呤来去除该药物，B-mix K-44/6细胞会从抑制作用中恢复。
