Batt A M, Siest G, Oesch F
Carcinogenesis. 1984 Sep;5(9):1205-6. doi: 10.1093/carcin/5.9.1205.
Two microsomal epoxide hydrolases of the rat liver were found to be differentially regulated in hyperplastic nodules. Whilst the activity for substrates of the well-known microsomal epoxide hydrolase with a broad substrate specificity (EHb), benzo[a]pyrene 4,5-oxide and androstene oxide (16 alpha, 17 alpha-epoxyandrosten-3-one), was greatly (approximately 5-fold) increased in the nodule microsomes and moderately (approximately 2-fold) increased in the surrounding tissue, that for the substrate of the novel microsomal epoxide hydrolase, cholesterol 5 alpha,6 alpha-oxide (EHch) remained unchanged. Since both enzymes convert endogenous steroid epoxides but with distinct structural features, this differential regulation may indicate a role of endogenous steroid epoxide(s) of a defined structure during hepatocarcinogenesis. Alternatively, this differential regulation may serve as a marker during hepatocarcinogenesis.
大鼠肝脏中的两种微粒体环氧化物水解酶在增生性结节中受到不同的调节。具有广泛底物特异性的著名微粒体环氧化物水解酶（EHb）对底物苯并[a]芘4,5-氧化物和雄烯氧化物（16α,17α-环氧雄甾-3-酮）的活性，在结节微粒体中大幅增加（约5倍），在周围组织中适度增加（约2倍），而新型微粒体环氧化物水解酶对底物胆固醇5α,6α-氧化物（EHch）的活性则保持不变。由于这两种酶都能转化内源性甾体环氧化物，但具有不同的结构特征，这种差异调节可能表明特定结构的内源性甾体环氧化物在肝癌发生过程中发挥作用。或者，这种差异调节可能作为肝癌发生过程中的一个标志物。
