Competing roles of cytochrome p450 1A1/1B1 and aldo-keto reductase 1A1 in the metabolic activation of (±)-7,8-dihydroxy-7,8-dihydro-benzo[a]pyrene in human bronchoalveolar cell extracts
Competing roles of cytochrome p450 1A1/1B1 and aldo-keto reductase 1A1 in the metabolic activation of (±)-7,8-dihydroxy-7,8-dihydro-benzo[a]pyrene in human bronchoalveolar cell extracts
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DOI：
10.1021/tx0497245
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发表时间：
2005-02-01
影响因子：
4.1
通讯作者：
Penning, TM
中科院分区：
文献类型：
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作者：
Jiang, H;Shen, YM;Penning, TM
（+/-）-7，8-二羟基-7，8-二氢苯并[α]芘（BP-7，8-二醇），一种源自苯并[a]芘（BP）的近似致癌物，需要进一步的代谢活化来发挥其致癌作用。涉及两种主要途径，这些途径涉及（+/-）-反式-7，8-二羟基-9 α，10 α-L-环氧-7，8，9，P450 1A 1/P450 1B 1（NADPH依赖性单加氧酶）催化的10-四氢苯并[α]芘（抗BPDE）或人醛酮还原酶AKR 1A 1和AKR 1C 1-AKR 1C 4 [NAD（P）（H）依赖性氧化还原酶]催化的苯并[α]芘-7，8-二酮（BP-7，8-二酮）形成。这两种途径对PAH激活的相对贡献尚不清楚。在这项研究中，BP-7，8-二醇代谢研究在人支气管肺泡H358细胞提取物。亲本H358细胞不组成型表达P450 1A 1/P450 1B 1或AKR，但通过用2，3，7，8-四氯-二苯并-p-二恶英（TCDD）诱导以表达P450 1A 1/P450 1B 1或通过稳定转染以表达AKR 1A 1（醛还原酶）来操纵。AKR 1A 1转染子的TCDD诱导提供了表达两种途径的细胞系。来自亲本H358细胞加TCDD的提取物（P450诱导）产生亲电性抗BPDE，其水解为苯并[α]芘四氢四醇（BP-四醇），源自AKR 1A 1转染细胞的提取物（AKR 1A 1表达）产生反应性和氧化还原活性的BP-7，8-二酮，其作为其单体被原位捕获。（硫醚）偶联物，并且来自AKR 1A 1转染子加TCDD（P450 1A 1/P450 1B 1和AKR 1A 1的共表达）的提取物产生抗BPDE和BP-7，8-二酮。采用不同的NADPH：NAD（+）比例研究了P450 1A 1/P450 1B 1和AKR 1A 1对BP-7，8-二醇的竞争激活作用。具有相对较高浓度的NADPH的系统有利于通过P450 1A 1/P450 1B 1形成抗BPDE，而具有较高浓度的NAD（+）的系统有利于通过AKR 1A 1形成BP-7，8-二酮。在模拟细胞氧化还原状态的条件下，10 μ M NADPH和1 mM NAD（+），形成等量的BP-四醇和BP-7，8-二酮。这表明P450 1A 1/P450 1131和AKR 1A 1在BP-7，8-二醇的代谢活化中起竞争作用，BP-7，8-二醇活化的主导途径取决于细胞的氧化还原状态。这些模型系统提供了一种细胞环境，其中可以比较由任一途径形成的显性DNA加合物/损伤。
(+/-)-7,8-Dihydroxy-7,8-dihydrobenzo[alpha]pyrene (BP-7,8-diol), a proximate carcinogen derived from benzo [a] pyrene (BP) requires further metabolic activation to exert its carcinogenic effects Two principal pathways have been implicated, and these involve either the formation of (+/-)-trans-7,8-dihydroxy-9alpha, 10alpha-L-epoxy-7,8,9,10-tetrahydrobenzo [alpha] pyrene (anti-BPDE) catalyzed by P450 1A1/P450 1B1 (NADPH-dependent monoxygenases) or the formation of benzo[alpha]pyrene-7,8-dione (BP-7,8-dione) catalyzed by human aldo-keto reductases AKR1A1 and AKR1C1-AKR1C4 [NAD(P)(H)-dependent oxidoreductases]. The relative contributions of the two pathways to PAH activation are unknown. In this study, BP-7,8-diol metabolism was studied in human bronchoalveolar H358 cell extracts. Parental H358 cells do not constitutively express P450 1A1/P450 1B1 or AKRs but were manipulated by induction with 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) to express P450 1A1/P450 1B1 or by stable transfection to express AKR1A1 (aldehyde reductase). TCDD induction of AKR1A1 transfectants provided a cell line that expressed both pathways. Extracts derived from parental H358 cells plus TCDD (P450 induction) produced electrophilic anti-BPDE, which hydrolyzed to benzo[alpha]pyrene tetrahy-drotetrols (BP-tetrols), extracts derived from AKR1A1-transfected cells (AKR1A1 expression) produced reactive and redox-active BP-7,8-dione, which was trapped in situ as its mono(thioether) conjugate, and extracts derived from AKR1A1 transfectants plus TCDD (coexpression of P450 1A1/P450 1B1 and AKR1A1) produced both anti-BPDE and BP-7,8-dione. The competing activation of BP-7,8-diol by P450 1A1/P450 1B1 and AKR1A1 was studied with varied NADPH:NAD(+) ratios. The system with a relatively higher concentration of NADPH favored formation of anti-BPDE via P450 1A1/P450 1B1, while the system with the higher concentration of NAD(+) favored formation of BP-7,8-dione via AKR1A1 Under conditions that mimic the cellular redox state, 10muM NADPH and 1 mM NAD(+), equal amounts of BP-tetrols and BP-7,8-dione were formed. This suggests that P450 1A1/P450 1131 and AKR1A1 play competing roles in the metabolic activation of BP-7,8-diol and that the dominant pathway of BP-7,8-diol activation depends on the redox state of the cells. These model systems provide a cellular context in which the dominant DNA adducts/lesions formed by either pathway may be compared.