Expression of genes involved in absorption, distribution, metabolism and excretion (ADME) of drugs is collectively impaired during pathophysiological conditions such as cholestasis and inflammation. The mechanism of coordinated ADME gene downregulation remains unclear. In our previous study strongly elevated levels of microRNAs (miRNA) miR-21, miR-34a, and miR-130b in cholestatic liver and of miR-21 and miR-130b during inflammation were observed. Using HepaRG cells, which retain many functional characteristics of human hepatocytes, we investigated the potential of these miRNAs to downregulate ADME genes. Cells were transfected with the corresponding miRNA mimics, chemically modified double-stranded RNAs that mimic endogenous miRNAs, followed by mRNA profiling by quantitative RT-PCR. Enzyme activities of six cytochromes P450 (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP3A4) were determined with a liquid chromatography-tandem mass spectrometric cocktail assay. While miR-21 and miR-34a showed little effects, transfection of miR-130b lead to significantly lower expression of nuclear receptors CAR and FXRa, the CYPs 1A1, 1A2, 2A6, 2C8, 2C9, and 2C19, as well as GSTA2. Furthermore, miR-130b negatively affected activity levels of all measured P450s by more than 40%. Reporter gene assays employing the CYP2C9 3'UTR confirmed direct regulation by miR-130b. These data support miR-130b as a potential negative regulator of drug metabolism by directly and/or indirectly affecting the expression of several ADME genes. This may be of relevance in pathophysiological conditions such as cholestasis and inflammation, which are associated with increased miR-130b expression.

 

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