Stimulation of dihydrofolate reductase promoter activity by antimetabolic drugs.
Stimulation of dihydrofolate reductase promoter activity by antimetabolic drugs.
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抗代谢药物刺激二氢叶酸还原酶启动子活性。
DOI：
10.1073/pnas.88.19.8572
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发表时间：
1991
影响因子：
11.1
通讯作者：
Azizkhan,JC
中科院分区：
文献类型：
--
作者：
Eastman,HB;Swick,AG;Schmitt,MC;Azizkhan,JC
二氢叶酸还原酶(DHFR；EC 1.5.1.3)是叶酸代谢过程中合成嘌呤、胸苷和甘氨酸所必需的。甲氨蝶呤(MTX)是一种竞争性抑制DHFR的药物，虽然已有多个研究报道了MTX对DHFR基因转录的诱导作用，但尚无研究检测MTX对DHFR基因转录的影响。我们用瞬时表达实验检测了甲氨蝶呤和其他DNA合成抑制剂对dhfr转录的影响。MTX以浓度依赖的方式刺激从含有150个碱基对5‘的仓鼠DHFR启动子构建体到转录开始的瞬时表达。加入四氢叶酸或次黄嘌呤加胸腺嘧啶核苷可阻止对MTX反应的启动子诱导，提示MTX的刺激是通过抑制这些代谢物而产生的。此外，另外两种抗代谢药物--氟代脱氧尿苷和羟基脲--也以浓度依赖的方式刺激DHFR启动子。相比之下，通过抑制DNA聚合酶α来阻止细胞生长的aphidiclin对dhfr启动子没有影响。讨论了这些结果与化疗药物交叉耐药和基因扩增过程的潜在相关性。
Dihydrofolate reductase (DHFR; EC 1.5.1.3) is required in folate metabolism for the synthesis of purines, thymidine, and glycine. Although there have been several reports of induction of DHFR enzyme by methotrexate (MTX), a drug that competitively inhibits DHFR, there are no studies reported that examine the effect of MTX on DHFR gene transcription. We have examined the effect of MTX and other inhibitors of DNA synthesis on DHFR transcription using a transient expression assay. MTX stimulates transient expression in a concentration-dependent manner from a hamster DHFR promoter construct containing 150 base pairs 5' to the start of transcription. Addition of either tetrahydrofolate or hypoxanthine plus thymidine prevents the promoter induction in response to MTX, suggesting that stimulation by MTX results from inhibition of these metabolites. Furthermore, two other antimetabolic drugs--fluorodeoxyuridine and hydroxyurea--also stimulate the DHFR promoter in a concentration-dependent manner. In contrast, aphidicolin, which blocks cell growth through inhibition of DNA polymerase alpha, has no effect on the DHFR promoter. The potential relevance of these results to cross-resistance to chemotherapeutic agents and to the process of gene amplification is discussed.