Raucy Judy L
California Toxicology Research Institute, Carlsbad, California 92009, USA.
Drug Metab Dispos. 2003 May;31(5):533-9. doi: 10.1124/dmd.31.5.533.
Human CYP3A4 metabolizes a majority of clinically important substrates at variable rates. Accounting for these unpredictable rates is the wide variation noted in expression of this enzyme that is due, in part, to xenobiotic exposure. We used primary cultures of human hepatocytes from 17 individuals to assess the inducibility of CYP3A4 mRNA by prototypical inducers, dietary flavonoids, and botanicals. Those agents producing the greatest mRNA accumulation were 10 microM RIF (699 +/- 307% of control levels) 100 microM phenytoin (707 +/- 188% of control), 1 mM phenobarbital (536 +/- 207% of control), and 100 microM omeprazole (404 +/- 8% of control). Various concentrations of RIF were found to exhibit a typical dose-response curve for CYP3A4 mRNA content. A reporter gene assay using the human pregnane X receptor (hPXR) and promoter regions of CYP3A4 transiently transfected into HepG2 cells, exhibited inductive properties by the aforementioned therapeutics that were similar to those observed in hepatocytes. Several flavonoids including quercetin, resveratrol, and curcumin were also examined for their ability to induce CYP3A4 in human hepatocytes. Only quercetin produced accumulation of CYP3A4 mRNA (230 +/- 73% of control). When examined in a reporter gene assay, this flavonoid exhibited negligible increases in luciferase activity suggesting that quercetin induced CYP3A4 by mechanisms that may not involve PXR. We also examined the effects of herbals on CYP3A4 expression in human hepatocytes. Grapeseed extract, ginseng, silymarin, and kava-kava produced 270 +/- 73, 155 +/- 83, 100 +/- 10, and 386 +/- 185% of control CYP3A4 mRNA, respectively. Of these botanicals only kava-kava produced enhanced luciferase activity (11.6 +/- 2.1 fold above DMSO treated cells). Such results indicate that kava-kava required PXR to mediate CYP3A4 induction. Collectively, results demonstrated that several botancials induce CYP3A4, suggesting the potential for drug-herbal interactions.
人类CYP3A4以可变速率代谢大多数临床上重要的底物。这种酶表达的广泛差异导致了这些不可预测的速率，部分原因是异生素暴露。我们使用来自17名个体的人肝细胞原代培养物，评估原型诱导剂、膳食类黄酮和植物药对CYP3A4 mRNA的诱导能力。产生最大mRNA积累的药物是10 microM利福平（对照水平的699±307%）、100 microM苯妥英（对照的707±188%）、1 mM苯巴比妥（对照的536±207%）和100 microM奥美拉唑（对照的404±8%）。发现不同浓度的利福平对CYP3A4 mRNA含量呈现典型的剂量反应曲线。使用人孕烷X受体（hPXR）和瞬时转染到HepG2细胞中的CYP3A4启动子区域进行的报告基因分析显示，上述治疗药物具有诱导特性，与在肝细胞中观察到的相似。还检测了几种类黄酮，包括槲皮素、白藜芦醇和姜黄素在人肝细胞中诱导CYP3A4的能力。只有槲皮素导致CYP3A4 mRNA积累（对照的230±73%）。在报告基因分析中检测时，这种类黄酮的荧光素酶活性增加可忽略不计，这表明槲皮素通过可能不涉及PXR的机制诱导CYP3A4。我们还研究了草药对人肝细胞中CYP3A4表达的影响。葡萄籽提取物、人参、水飞蓟宾和卡瓦分别产生对照CYP3A4 mRNA的270±73%、155±83%、100±10%和386±185%。在这些植物药中，只有卡瓦增强了荧光素酶活性（比用二甲基亚砜处理的细胞高11.6±2.1倍）。这些结果表明卡瓦需要PXR来介导CYP3A4的诱导。总体而言，结果表明几种植物药可诱导CYP3A4，提示存在药物与草药相互作用的可能性。
