Scutellarin mediates cytochrome P450 3A4 and 2C19 expression via pregnane X receptor and constitutive androstane receptor

Background: Breviscapine is a flavonoid extracted from Erigeron breviscapus (Vant.) Hand.-Mazz., and mainly contains scutellarin. Nuclear receptors play important roles in regulating transporter and drug metabolic enzymes. Objective: To investigate the regulatory effects of scutellarin on CYP3A4 and 2C19 in HepG2 and Caco-2 cells based on nuclear receptors PXR and CAR. Methods: The proteins and mRNA levels of CYP3A4 and CYP2C19 treated with scutellarin were detected by Western Blot and RT-qPCR. Using assays of the dual-luciferase reporter, promoter sequences containing hPXR and hCAR protein recognition and binding regulatory elements CYP3A4 and CYP2C19 were inserted upstream of the reporter gene, and the expression vector and the reporter vector were cotransfected into HepG2 and Caco-2 cells. Result: Scutellarin inhibited mRNA of CYP3A4 and PXR, promoted mRNA expression of CYP2C19 and CAR in RT-qPCR results. Western-blot results showed scutellarin inhibited the expression of CYP3A4 and promoted the expression of CYP2C19. The dual-luciferase reporter genes showed that scutellarin enhanced the expression level of CYP2C19 and when its concentration was 40 and 80μmol/L, CYP3A4 is significantly increased. Conclusions: Scutellarin down-regulates CYP3A4 through PXR, and its mechanism may be through up-regulating CAR and binding to PXR to inhibit PXR-mediated expression of CYP3A4. Scutellarin up-regulates CYP2C19 through CAR.