Relationship between Differential Hepatic microRNA Expression and Decreased Hepatic Cytochrome P450 3A Activity in Cirrhosis

Background and Aim
Liver cirrhosis is associated with decreased hepatic cytochrome P4503A (CYP3A) activity but the pathogenesis of this phenomenon is not well elucidated. In this study, we examined if certain microRNAs (miRNA) are associated with decreased hepatic CYP3A activity in cirrhosis.
Methods
Hepatic CYP3A activity and miRNA microarray expression profiles were measured in cirrhotic (n=28) and normal (n=12) liver tissue. Hepatic CYP3A activity was measured via midazolam hydroxylation in human liver microsomes. Additionally, hepatic CYP3A4 protein concentration and the expression of CYP3A4 mRNA were measured. Analyses were conducted to identify miRNAs which were differentially expressed between two groups but also were significantly associated with lower hepatic CYP3A activity.
Results
Hepatic CYP3A activity in cirrhotic livers was 1.7-fold lower than in the normal livers (0.28 ± 0.06 vs. 0.47 ± 0.07mL* min-1*mg protein-1 (mean ± SEM), P=0.02). Six microRNAs (miR-155, miR-454, miR-582-5p, let-7f-1*, miR-181d, and miR-500) had >1.2-fold increase in cirrhotic livers and also had significant negative correlation with hepatic CYP3A activity (range of r = -0.44 to -0.52, P <0.05). Notably, miR-155, a known regulator of liver inflammation, had the highest fold increase in cirrhotic livers (2.2-fold, P=4.16E-08) and significantly correlated with hepatic CYP3A activity (r=-0.50, P=0.017). The relative expression (2-ΔΔCt mean ± SEM) of hepatic CYP3A4 mRNA was significantly higher in cirrhotic livers (21.76 ± 2.65 vs. 5.91 ± 1.29, P=2.04E-07) but their levels did not significantly correlate with hepatic CYP3A activity (r=-0.43, P=0.08).
Conclusion
The strong association between certain miRNAs, notably miR-155, and lower hepatic CYP3A activity suggest that altered miRNA expression may regulate hepatic CYP3A activity.

研究背景与目的
肝硬化与肝细胞色素P4503A（cytochrome P4503A, CYP3A）活性降低相关，但该现象的发病机制尚未完全阐明。本研究旨在探讨部分微小RNA（microRNAs, miRNA）是否与肝硬化患者的肝细胞CYP3A活性降低存在关联。

研究方法
本研究检测了肝硬化组（n=28）与正常肝组织对照组（n=12）中的肝细胞CYP3A活性及miRNA芯片表达谱。肝细胞CYP3A活性通过人肝微粒体中的咪达唑仑羟化试验进行测定。此外，本研究还检测了肝细胞CYP3A4蛋白浓度及CYP3A4信使核糖核酸（mRNA）的表达水平。通过分析筛选出两组间差异表达，且与肝细胞CYP3A活性降低显著相关的miRNA。

研究结果
肝硬化患者的肝细胞CYP3A活性较正常肝组织降低1.7倍（0.28 ± 0.06 vs. 0.47 ± 0.07 mL·min⁻¹·mg⁻¹蛋白，均值±标准误（SEM），P=0.02）。共筛选出6种在肝硬化组织中表达量升高超过1.2倍的miRNA，分别为miR-155、miR-454、miR-582-5p、let-7f-1*、miR-181d及miR-500，且上述miRNA均与肝细胞CYP3A活性呈显著负相关（相关系数r范围为-0.44至-0.52，P<0.05）。值得注意的是，作为已知的肝脏炎症调控因子，miR-155在肝硬化组织中的表达增幅最高（2.2倍，P=4.16×10⁻⁸），且与肝细胞CYP3A活性显著相关（r=-0.50，P=0.017）。肝硬化组织中肝细胞CYP3A4 mRNA的相对表达量（2-ΔΔCt均值±标准误）显著高于正常肝组织（21.76 ± 2.65 vs. 5.91 ± 1.29，P=2.04×10⁻⁷），但该表达水平与肝细胞CYP3A活性无显著相关性（r=-0.43，P=0.08）。

研究结论
部分miRNA（尤其是miR-155）与肝细胞CYP3A活性降低之间存在强相关性，这提示miRNA表达异常可能参与调控肝细胞CYP3A活性。