Evaluation of Drug-metabolizing enzyme activity and-drug interaction in paitients with hepatic disease

研究了肝细胞癌（HCC）和转移癌（MC）患者手术标本中细胞色素P450介导的肝脏药物代谢能力。7例HCC患者和4例MC患者捐献肝脏样本。每个肝脏样本，显然是正常的部分，用于药物代谢酶活性的评估。采用常规方法制备微粒体分数。从白种人脑死亡患者中提取的人肝微粒体作为参比酶源。采用典型底物高效液相色谱法测定微粒体细胞色素P450 （CYP）酶活性，CYP1A2（咖啡因、乙氧基再间芬）、2C9（华法林）、2C19（甲苯妥英）、2D6（布呋喃醇）、2E1（氯唑氮酮）和3A4（睾酮、咪达唑仑）酶活性。与混合微粒体CYP活性相比，HCC和MC中每种CYP酶的活性变化从2到5倍不等。此外，HCC和MC肝样品中各CYP酶的平均活性与汇总的微粒体CYP活性相比，大多数CYP酶的活性非常相似。然而，CYP2C19在HCC和MC中的酶活性与池状微粒体相比都很低。为了阐明CYP2C19在肝病患者中低活性表达的机制，我们分析了6例新患者肝脏样本的遗传谱和s -甲苯托因4′-羟基化活性。对CYP2C19基因外显子4和外显子5进行分析，6例患者中有3例外显子5突变，6例患者中有3例外显子4野生型杂合。另有3例外显子5为野生型纯合子。Mephenytoin 4′-羟化活性与基因型密切相关，5外显子纯合子的野生型患者活性正常，5外显子突变纯合子的3例患者活性较低。考虑到这些结果，肝病患者CYP2C19活性低是由于外显子5上CYP2C19基因的遗传缺陷所致。一般来说，20%到25%的人群CYP2C19基因缺陷，然而，在我们的结果中，在肝病患者中观察到相当高的酶缺乏症频率。这些结果可能提示CYP2C19缺乏是肝癌和/或肝硬化等肝脏疾病的危险因素之一。少

Hepatic drug-metabolizing capacity mediated by cytochrome P450 is assayed in human surgical samples obtained from hepatocellular carcinoma (HCC) and metastatic cancer (MC) patients. Liver samples were donated from seven of HCC and four of MC patients. Each liver samples, apparently normal part, was used for the evaluation of drug metabolizing enzyme activity. Microsomal fraction was prepared by conventional method. Human pooled hepatic microsome from Caucasian brain death patients was employed as a reference enzyme source. Microsomal cytochrome P450 (CYP) enzyme activity, CYP1A2 (Caffeine, Ethoxyresorfin), 2C9 (Warfarin), 2C19 (Mephenytoin), 2D6 (Bufuralol), 2E1 (Chlorzoxazone) and 3A4 (Testosterone, Midazolam), were analysed by using typical substrates HPLC method was employed for the determination of each enzyme activity. CYP enzymes activity was variated from 2 to 5 fold in each CYP enzymes in both HCC and MC compared with pooled microsome CYPs activity. Furthermore, mean activity o … More f each CYP enzymes activity in HCC and MC liver samples compared with pooled microsomal CYP activities were quite similar in most of CYP enzymes. In CYP2C19, however, enzyme activity was quite low in both HCC and MC compared with pooled microsome. To clarify the mechanism of the expressed low activity of CYP2C19 in patient with hepatic disease, genetic profile and S-Mephenytoin 4'-hydroxylation activity in six of new patient's liver samples were analysed. Exon 4 and Exon 5 of CYP2C19 gene was analysed and all of patients has heterozygous for wild type and mutation in Exon 4 and three of 6 patients bad homozygous for mutation of Exon 5.Other 3 patients had wild type homozygous for Exon 5. Mephenytoin 4'-hydroxrylation activity was well correlated to genotype and normal level of the activity was observed in patients who has wild type homozygous in Exon 5 and quite low activity in 3 samples which has the homozygous for the mutation in Exon 5. These results in to consideration, low activity of CYP2C19 in patients with liver disease was due to the genetic deficiency of CYP2C19 gene on Exon 5.In general, 20 to 25% of again populations are genetically deficient of CYP2C19, however, in our results, quite high frequency of the enzyme deficiency was observed in patients with liver disease. These results may indicating that CYP2C19 deficiency reflect the one of the risk factor of liver disease such as hepatic cancer and/or liver cirrhosis. Less