The bioreductive drug, AQ4N, is metabolized under hypoxic conditions and has been shown to enhance the antitumor effects of radiation and chemotherapy drugs. We have investigated the role of cytochrome P450 3A4 (CYP3A4) in increasing the metabolism of AQ4N using a gene-directed enzyme prodrug therapy (GDEPT) strategy. RIF-1 murine tumor cells were transfected with a mammalian expression vector containing CYP3A4 cDNA. In vitro AQ4N metabolism, DNA damage, and clonogenic cell kill were assessed following exposure of transfected and parental control cells to AQ4N. The presence of exogenous CYP3A4 increased the metabolism of AQ4N and significantly enhanced the ability of the drug to cause DNA strand breaks and clonogenic cell death. Cotransfection of CYP reductase with CYP3A4 showed a small enhancement of the effect in the DNA damage assay only. A single injection of CYP3A4 into established RIF-1 murine tumors increased the metabolism of AQ4N, and when used in combination with radiation, three of nine tumors were locally controlled for >60 days. This is the first demonstration that CYPs alone can be used in a GDEPT strategy for bioreduction of the cytotoxic prodrug, AQ4N. AQ4N is the only CYP-activated bioreductive agent in clinical trials. Combination with a GDEPT strategy may offer a further opportunity for targeting radiation-resistant and chemo-resistant hypoxic tumor cells.

中文翻译：

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使用细胞色素P450 3A4与AQ4N组合进行生物还原GDEPT。

生物还原药物AQ4N在低氧条件下被代谢，并且已显示出可以增强放射和化学疗法药物的抗肿瘤作用。我们已经研究了细胞色素P450 3A4（CYP3A4）在使用基因定向酶前药治疗（GDEPT）策略增加AQ4N代谢中的作用。用含有CYP3A4 cDNA的哺乳动物表达载体转染RIF-1鼠肿瘤细胞。在将转染的和亲本对照细胞暴露于AQ4N之后，评估了体外AQ4N代谢，DNA损伤和克隆细胞杀死。外源CYP3A4的存在增加了AQ4N的代谢，并显着增强了该药物引起DNA链断裂和克隆细胞死亡的能力。CYP还原酶与CYP3A4的共转染仅在DNA损伤试验中显示出较小的增强作用。向成熟的RIF-1鼠肿瘤中单次注射CYP3A4会增加AQ4N的代谢，当与放射线结合使用时，九种肿瘤中的三种会局部控制> 60天。这是第一个证明，CYP可以单独用于GDEPT策略中以生物还原细胞毒性前药AQ4N。在临床试验中，AQ4N是唯一的CYP活化生物还原剂。与GDEPT策略组合可能为靶向抗辐射和抗化学性的低氧肿瘤细胞提供进一步的机会。这是第一个证明，CYP可以单独用于GDEPT策略中以生物还原细胞毒性前药AQ4N。在临床试验中，AQ4N是唯一的CYP活化生物还原剂。与GDEPT策略组合可能为靶向抗辐射和抗化学性的低氧肿瘤细胞提供进一步的机会。这是第一个证明，CYP可以单独用于GDEPT策略中以生物还原细胞毒性前药AQ4N。在临床试验中，AQ4N是唯一的CYP活化生物还原剂。与GDEPT策略组合可能为靶向抗辐射和抗化学性的低氧肿瘤细胞提供进一步的机会。