ROLE OF S-ADENOSYLHOMOCYSTEINE IN ADENOSINE-MEDIATED TOXICITY IN CULTURED MOUSE T-LYMPHOMA CELLS
ROLE OF S-ADENOSYLHOMOCYSTEINE IN ADENOSINE-MEDIATED TOXICITY IN CULTURED MOUSE T-LYMPHOMA CELLS
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DOI：
10.1016/0092-8674(77)90157-x
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发表时间：
1977-01-01
期刊：
影响因子：
64.5
通讯作者：
MARTIN, DW
中科院分区：
文献类型：
--
作者：
KREDICH, NM;MARTIN, DW
使用由培养的S49小鼠淋巴瘤细胞与ADA抑制剂-通过加入外源尿苷或通过腺苷激酶的突变丧失而使细胞对腺苷诱导的嘧啶饥饿具有抗性的细胞仍然对浓度> 15 μ M的腺苷敏感。通过向培养基中添加L-同型半胱氨酸硫内酯[LHT]，可明显增强这种作用。腺苷的细胞毒性浓度还引起SAH的细胞内水平的显著升高，其通过100 μ M外源性LHT额外增加数倍。一个公平的相关性之间存在一个单一的时间点测定细胞内SAH和72小时后的生长抑制的程度，但复杂的时间依赖性变化SAH很难比较的情况下获得的结果和存在外源性LHT。将细胞暴露于已知引起尿苷抗性细胞毒性的浓度的腺苷，可显著抑制S49细胞中的体内DNA甲基化。这种甲基化的抑制用放射性标记的短期脉冲测量，并且在腺苷和LHT的所有测试组合下与SAH的细胞内浓度良好相关。腺苷对ADA抑制的S49细胞的尿苷抗性细胞毒性作用可能继发于腺苷代谢物SAH对SAM[S-腺苷甲硫氨酸]介导的甲基化反应的抑制。
A model system consisting of cultured S49 mouse lymphoma cells together with the ADA inhibitor, erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA), was used to determine whether SAH (S-adenosylhomocysteine) is a mediator of adenosine cytotoxicity. Cells rendered resistant to adenosine-induced pyrimidine starvation by the addition of exogenous uridine or by the mutational loss of adenosine kinase are still sensitive to adenosine at concentrations > 15 .mu.M. This effect is appreciably enhanced by the addition of L-homocysteine thiolactone [LHT] to the culture medium. Cytotoxic concentrations of adenosine also cause significant elevations in intracellular levels of SAH, which are increased an additional several fold by 100 .mu.M exogenous LHT. A fair correlation exists between a single time point determination of intracellular SAH and the degree of growth inhibition after 72 h, but complicated time-dependent variations in SAH make it difficult to compare results obtained in the absence and presence of exogenous LHT. In vivo DNA methylation in S49 cells is markedly inhibited by exposure of cells to concentrations of adenosine known to cause uridine-resistant cytotoxicity. This inhibition of methylation was measured with short-term pulses of radiolabel, and correlates well with intracellular concentrations of SAH at all tested combinations of adenosine and LHT. The uridine-resistant cytotoxic effects of adenosine on ADA-inhibited S49 cells may be secondary to the inhibition of SAM[S-adenosylmethionine]-mediated methylation reactions by the adenosine metabolite SAH.