DNA strand damage product analysis provides evidence that the tumor cell-specific cytotoxin tirapazamine produces hydroxyl radical and acts as a surrogate for O2
DNA strand damage product analysis provides evidence that the tumor cell-specific cytotoxin tirapazamine produces hydroxyl radical and acts as a surrogate for O2
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DOI：
10.1021/ja074432m
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发表时间：
2007-10-24
影响因子：
15
通讯作者：
Gates, Kent S.
中科院分区：
文献类型：
--
作者：
Chowdhury, Goutam;Junnotula, Venkatraman;Gates, Kent S.
化合物3-氨基-1，2，4-苯并三嗪1，4-二氧化物（替拉扎明，TPZ）是一种临床上有前途的抗癌剂，可选择性杀死实体瘤中发现的贫氧（缺氧）细胞。人们早就知道，在缺氧条件下，TPZ会导致DNA链损伤，这是由双链体DNA的脱氧核糖磷酸骨架上的氢原子提取引发的，但这一过程背后的确切化学机制仍不清楚。在这里，我们详细描述了TPZ介导的链损伤所产生的糖衍生产品的特性。我们发现TPZ在缺氧条件下对双链DNA的作用产生5-亚甲基-2-呋喃酮（6）、3 '-磷酸乙醇酸酯（7）、丙二醛等价物（8或9）和糠醛（10）。这些结果提供了证据表明，TPZ介导的链损伤是通过从双螺旋中脱氧核糖糖的最受阻（C1 '）和最少受阻（C4'和C5 '）位置夺取氢原子而产生的。观察到的产物与羟基自由基产生的产物相同。进行了额外的实验，以更好地了解TPZ产生所观察到的DNA损伤产物的化学途径。与先前的工作表明TPZ可以在DNA损伤反应中取代分子氧一致，发现在厌氧条件下，TPZ与DNA 2 '-寡脱氧核苷酸中离散的光生C1'-racical反应干净地产生2-cleoxyribonolactone损伤（5），作为5-亚甲基-2-呋喃酮（6）的前体。总体而言，这些结果提供了关于暴露于TPZ后面临细胞修复，转录和复制机制的DNA损伤的化学结构的见解，并提供了与TPZ介导的链切割相关的化学机制的新信息。
The compound 3-amino-1,2,4-benzotriazine 1,4-dioxide (tirapazamine, TPZ) is a clinically promising anticancer agent that selectively kills the oxygen-poor (hypoxic) cells found in solid tumors. It has long been known that, under hypoxic conditions, TPZ causes DNA strand damage that is initiated by the abstraction of hydrogen atoms from the deoxyribose phosphate backbone of duplex DNA, but exact chemical mechanisms underlying this process remain unclear. Here we describe detailed characterization of sugar-derived products arising from TPZ-mediated strand damage. We find that the action of TPZ on duplex DNA under hypoxic conditions generates 5-methylene-2-furanone (6), oligonucleoticle 3'-phosphoglycolates (7), malondialdehyde equivalents (8 or 9), and furfural (10). These results provide evidence that TPZ-mediated strand damage arises via hydrogen atom abstraction from both the most hindered (C1') and least hindered (C4' and C5') positions of the deoxyribose sugars in the double helix. The products observed are identical to those produced by hydroxyl radical. Additional experiments were conducted to better understand the chemical pathways by which TPZ generates the observed DNA-damage products. Consistent with previous work showing that TPZ can substitute for molecular oxygen in DNA damage reactions, it is found that, under anaerobic conditions, reaction of TPZ with a discrete, photogenerated C1'-raclical in a DNA 2'-oligodeoxynucleotide cleanly generates the 2-cleoxyribonolactone lesion (5) that serves as the precursor to 5-methylene-2-furanone (6). Overall, the results provide insight regarding the chemical structure of the DNA lesions that confront cellular repair, transcription, and replication machinery following exposure to TPZ and offer new information relevant to the chemical mechanisms underlying TPZmediated strand cleavage.