人肝脏微粒体在体外对丝裂霉素C的代谢

丝裂霉素C（mitomycin C，MMC）是一种醌类DNA烷化剂，是生物还原活性物的代表之一，也是临床常用的化疗药物，被广泛用于治疗膀胱癌、乳腺癌、头颈部癌、非小细胞肺癌等。作为MMC与肝脏药物代谢酶相互作用的两个方面，作者曾发表了MMC对肝脏3种细胞色素P450同工酶活性影响的报道。已往关于MMC代谢酶学的研究材料主要使用动物肝脏微粒体及纯化酶、体外肿瘤细胞系和／或肿瘤组织，而人肝脏药物代谢酶对MMC代谢的研究尚未见报道。本实验用体外方法初步研究了人肝脏微粒体对MMC的代谢作用。

Metabolism of mitomycin C by human liver microsomes in vitro

To provide the profiles of metabolism of mitomycin C (MMC) by human liver microsomes in vitro, MMC was incubated with human liver microsomes, then the supernatant component was isolated and detected by HPLC. Types of metabolic enzymes were estimated by the effect of NADPH or dicumarol (DIC) on metabolism of MMC. Standard, reaction, background control (microsomes was inactivated), negative control (no NADPH), and inhibitor group (adding DIC) were assigned, the results were analyzed by Graphpad Prism 4. 0 software. Reaction group compared with background control and negative control groups, 3 NADPH-dependent absorption peaks were additionally isolated by HPLC after MMC were incubated with human liver microsomes. Their retention times were 10. 0, 14. 0, 14. 8 min ( named as Ml, M2, M3) , respectively. Their formation was kept as Sigmoidal dose-response and their Km were 0. 52 (95% CI, 0. 40 - 0.67) mmol x L(-1), 0. 81 (95% CI, 0. 59 - 1. 10) mmol x L(-1), 0. 54 (95% CI, 0. 41 -0. 71) mmol x L(-1) , respectively. The data indicated that the three absorption peaks isolated by HPLC were metabolites of MMC. DIC can inhibit formation of M2, it' s dose-effect fitted to Sigmoidal curve and it' s IC50 was 59. 68 (95% CI, 40. 66 - 87. 61) micromol x L(-1) , which indicated DT-diaphorase could take part in the formation of M2. MMC can be metabolized by human liver microsomes in vitro, and at least three metabolites of MMC could be isolated by HPLC in the experiment, further study showed DT-diaphorase participated in the formation of M2.