INITIAL STUDIES ON THE MECHANISM OF ACTION OF A NEW ONCOLYTIC THIAZOLE NUCLEOSIDE, 2-BETA-D-RIBOFURANOSYLTHIAZOLE-4-CARBOXAMIDE (NSC 286193)
INITIAL STUDIES ON THE MECHANISM OF ACTION OF A NEW ONCOLYTIC THIAZOLE NUCLEOSIDE, 2-BETA-D-RIBOFURANOSYLTHIAZOLE-4-CARBOXAMIDE (NSC 286193)
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DOI：
10.1016/0006-2952(82)90532-9
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发表时间：
1982-01-01
影响因子：
5.8
通讯作者：
COONEY, DA
中科院分区：
文献类型：
--
作者：
JAYARAM, HN;DION, RL;COONEY, DA
使用在培养物中生长的P388鼠白血病细胞对新的溶瘤核苷2-β-D-呋喃核糖基噻唑-4-甲酰胺的作用机制进行了研究。标题化合物在微摩尔水平下具有细胞毒性，但环和糖部分的许多简单取代使细胞毒性无效。细胞荧光分析表明，该药物将细胞阻滞在细胞周期的 S 期。在抗增殖浓度下，该药物抑制 RNA 和 DNA 的合成。预先形成的嘧啶（包括胸苷）的大分子掺入被药物抑制；在嘌呤中，这种效应仅延伸到腺嘌呤家族的成员，并且事实上，鸟嘌呤及其同系物的利用被可重复地刺激。当对一系列预先形成的嘌呤和嘧啶克服由于暴露于噻唑核苷酸引起的胸苷掺入抑制的能力进行检查时，鸟嘌呤特别有效；黄苷也被证明是一种活性解毒剂。通过高效液相色谱 (HPLC) 分析酸溶性提取物，证实该药物正在产生鸟嘌呤剥夺状态。接触药物后，GMP 和 GTP 浓度随时间下降； IMP 浓度增加约 .apprx。 15倍。根据这些发现，对暴露于细胞毒性浓度的药物的细胞中鸟嘌呤核苷酸生物合成所特有的酶学步骤进行了检查。在体外或培养中没有显示出对 GMP 合成酶的显着抑制作用，但在这两种情况下，IMP 脱氢酶的比活性均大幅降低。对暴露于超致死浓度的标题化合物的培养物提取物进行 HPLC 分析，提供了其他产物中 5''-单磷酸的适度合成代谢的证据；在体外，化学合成的2-β-D-呋喃核糖基噻唑-4-甲酰胺-5''-单磷酸样品在抑制IMP脱氢酶方面的效力比母体核苷强二十倍。根据动力学分析，这种抑制与作为可变底物的 IMP 不具有竞争性。
Studies on the mechanism of action of a new oncolytic nucleoside, 2-.beta.-D-ribofuranosylthiazole-4-carboxamide, were undertaken using P388 murine leukemia cells growing in culture. The title compound was cytotoxic at micromolar levels, but a number of simple substitutions of both the ring and sugar moieties nullified cytotoxicity. Cytofluorimetric analysis revealed that the drug arrests cells in the S phase of the cell cycle. At antiproliferative concentrations, the agent inhibited the synthesis of both RNA and DNA. The macromolecular incorporation of preformed pyrimidines, including thymidine, was inhibited by the drug; among the purines this effect extended only to members of the adenine family and, in fact, the utilization of guanine and its congeners was reproducibly stimulated. When an examination was made of the ability of a comprehensive series of preformed purines and pyrimidines to overcome the inhibition of thymidine incorporation provoked by exposure to the thiazole nucleotide, the guanines were notably effective; xanthosine was also shown to be an active antidote. Confirmation that the drug was producing a state of guanine deprivation was provided by high performance liquid chromatography (HPLC) analysis acid-soluble extracts. A time-dependent fall in the concentrations of GMP and GTP ensued upon exposure to the drug; IMP concentrations increased by .apprx. 15-fold. Pursuant to these findings, an examination was made of the enzymologic steps unique to the biosynthesis of guanine nucleotides in cells exposed to cytotoxic concentrations of the drug. No prominent inhibition of GMP synthetase could be demonstrated in vitro or in culture, but the specific activity of IMP dehydrogenase underwent substantial reductions in both of these cases. HPLC analyses of extracts of cultures exposed to supralethal concentration of the title compound provided evidence of modest anabolism to the 5''-monophosphate among other products; in vitro a chemically synthesized sample of 2-.beta.-D-ribofuranosylthiazole-4-carboxamide-5''-monophosphate was twenty times more potent than the parent nucleoside in inhibiting IMP dehydrogenase. On kinetic analysis, this inhibition was noncompetitive with IMP as the variable substrate.