Bioactivation of mitomycin antibiotics by aerobic and hypoxic Chinese hamster ovary cells overexpressing DT-diaphorase
Bioactivation of mitomycin antibiotics by aerobic and hypoxic Chinese hamster ovary cells overexpressing DT-diaphorase
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DOI：
10.1016/0006-2952(96)00143-8
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发表时间：
1996-06-28
影响因子：
5.8
通讯作者：
Sartorelli, AC
中科院分区：
文献类型：
--
作者：
Belcourt, MF;Hodnick, WF;Sartorelli, AC
DT-黄递酶催化丝裂霉素C（MC）和卟啉霉素（FOR）的双电子还原反应。许多细胞系，过表达DT心肌黄酶和敏感的丝裂霉素保护这些药物的需氧细胞毒性的DT-心肌黄酶抑制剂dicumarol。然而，这种相对非特异性抑制剂的细胞保护特性在缺氧条件下消失。为了确定DT-心肌黄酶在丝裂霉素生物活化和活细胞毒性中的作用，将大鼠肝脏DT-心肌黄酶cDNA转染中国仓鼠卵巢细胞。MC在氧合和缺氧条件下与亲本细胞的毒性相等。相反，在有氧条件下，FOR对这些细胞的毒性低于MC，但在缺氧条件下，FOR的毒性明显高于MC。两个DT-心肌黄酶转染的克隆显示DT-心肌黄酶活性增加126-和133倍以上的亲本细胞。丝裂霉素生物还原涉及的其他氧化还原酶的活动是不变的。MC是更有毒的DT-心肌黄酶转染线比亲本细胞; MC的转染线的毒性是类似的空气和缺氧。FOR也是更有毒的DT-心肌黄酶升高的克隆比父母的细胞在含氧条件下。然而，在缺氧条件下，FOR对转染克隆的毒性与亲本细胞的毒性没有变化。研究结果牵连DT-心肌黄酶在活细胞中的丝裂霉素生物活化，但表明，这种酶也没有：有助于MC或FOR在空气和缺氧的差异毒性。
DT-Diaphorase catalyzes a two-electron reduction of mitomycin C (MC) and porfiromycin (FOR) to reactive species. Many cell lines that overexpress DT diaphorase and are sensitive to the mitomycins are protected from the aerobic cytotoxicity of these drugs by the DT-diaphorase inhibitor dicumarol. The cytoprotective properties of this relatively non-specific inhibitor, however, vanish under hypoxic conditions. To ascertain the role of DT-diaphorase in mitomycin bioactivation and cytotoxicity in living cells, a rat liver DT-diaphorase cDNA was transfected into Chinese hamster ovary cells. MC was equitoxic to the parental cells under oxygenated and hypoxic conditions. In contrast, FOR was less toxic than MC to these cells under aerobic conditions, but significantly more toxic than MC under hypoxia. Two DT-diaphorase-transfected clones displayed increases in DT-diaphorase activity of 126- and 133-fold over parental cells. The activities of other oxidoreductases implicated in mitomycin bioreduction were unchanged. MC was more toxic to both DT-diaphorase-transfected lines than to parental cells; the toxicity of MC to the transfected lines was similar in air and hypoxia. FOR was also more toxic to the DT-diaphorase-elevated clones than to parental cells under oxygenated conditions. Under hypoxia, however, the toxicity of FOR to the transfected clones was unchanged from that of parental cells. The findings implicate DT-diaphorase in mitomycin bioactivation in living cells, but suggest that this enzyme does nor: contribute to the differential toxicity of MC or FOR in air and hypoxia.