Alpha-hydroxylation of tamoxifen and toremifene by human and rat cytochrome P450 3A subfamily enzymes.
Alpha-hydroxylation of tamoxifen and toremifene by human and rat cytochrome P450 3A subfamily enzymes.
复制标题
人类和大鼠细胞色素 P450 3A 亚家族酶对他莫昔芬和托瑞米芬进行 α-羟基化。
DOI：
10.1021/tx0300131
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发表时间：
2003
影响因子：
4.1
通讯作者：
Shibutani,Shinya
中科院分区：
文献类型：
--
作者：
Kim,SungYeon;Suzuki,Naomi;SantoshLaxmi,YR;Rieger,Robert;Shibutani,Shinya
在接受他莫昔芬（TAM）治疗的乳腺癌患者和接受他莫昔芬化学预防治疗的健康女性中观察到患子宫内膜癌的风险增加。在服用TAM的妇女的子宫内膜中检测到TAM-DNA加合物（Shibutani，S.，等人（2000）Carcinogenesis 21，1461 - 1467），并且主要通过α-羟基他莫昔芬（α-OHTAM）的O-磺化形成。为了探索TAM的遗传毒性机制，将TAM与多种人细胞色素P450酶之一孵育，即，P450 1A 1、1A 2、1B 1、2A 6、2B 6、2C 8、2C 9、2C 18、2C 19、2D 6、2 E1、3A 4、3A 5、3A 7、4A 11、4F 2、4F 3A或4F 3B，并使用HPLC/UV分析和真实标准品鉴别代谢产物。在18种人P450酶中，P450 3A 4产生大量的α-OHTAM。当检测一些大鼠P450酶时，P450 3A 2也催化TAM的α-羟基化。同样，人P450 3A 4和大鼠P450 3A 1和3A 2将托瑞米芬（TOR，氯化TAM类似物）转化为α-羟基托瑞米芬（α-OHTOR）。通过串联质谱证实了这些P450酶形成α-OHTAM和α-OHTOR。只有P450 3A亚家族酶能够α-羟基化TAM和TOR。虽然这些酶形成的α-OHTOR远高于α-OHTAM，但已知TOR的遗传毒性远低于TAM。结果支持我们提出的TOR的较低遗传毒性是由于羟基类固醇磺基转移酶对α-OHTOR的有限O-磺化，导致DNA加合物的形成不良（Shibutani，S.，等人（2001）Cancer Res.61，3925 - 3931）。
An increased risk of developing endometrial cancer is observed in breast cancer patients treated with tamoxifen (TAM) and in healthy women undergoing TAM chemoprevention therapy. TAM−DNA adducts were detected in the endometrium of women taking TAM (Shibutani, S., et al. (2000)Carcinogenesis21, 1461−1467) and are formed primarily throughO-sulfonation of α-hydroxytamoxifen (α-OHTAM). To explore the genotoxicic mechanisms of TAM, TAM was incubated with one of multiple human cytochrome P450 enzymes, i.e., P450 1A1, 1A2, 1B1, 2A6, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, 3A4, 3A5, 3A7, 4A11, 4F2, 4F3A, or 4F3B, in a NADPH regenerating system, and the metabolites were identified using HPLC/UV analysis with authentic standards. Among the 18 human P450 enzymes, P450 3A4 generated a significant amount of α-OHTAM. When some rat P450 enzymes were examined, P450 3A2 also catalyzed α-hydroxylation of TAM. Similarly, human P450 3A4 and rat P450 3A1 and 3A2 converted toremifene (TOR, a chlorinated TAM analogue) to α-hydroxytoremifene (α-OHTOR). The formation of α-OHTAM and α-OHTOR by these P450 enzymes was confirmed by tandem mass spectroscopy. Only the P450 3A subfamily enzymes are able to α-hydroxylate TAM and TOR. Although the formation of α-OHTOR by these enzymes was much higher than that of α-OHTAM, TOR is known to be much less genotoxic than TAM. The results support our proposed mechanism that the lower genotoxicity of TOR is due to limitedO-sulfonation of α-OHTOR by hydroxysteroid sulfotransferases, resulting in the poor formation of DNA adducts (Shibutani, S., et al. (2001)Cancer Res.61, 3925−3931).