Regulation of P-glycoprotein by Bajijiasu in vitro and in vivo by activating the Nrf2-mediated signalling pathway

Xin Yang,Guoyan Hu,Lijuan Lv,Ting Liu,Longkai Qi,Guozhan Huang,Dongqing You,Jun Zhao

doi:10.1080/13880209.2019.1582679

Abstract

Context: Bajijiasu (BJJS), a main bioactive compound from Morinda officinalis F.C. How. (Rubiaceae), is widely administered concomitantly with other drugs for treating male impotence, female infertility, fatigue, chronic rheumatism, depression, etc.Objective: This study investigates the regulation of P-glycoprotein (P-gp) by BJJS in vitro and in vivo.Material and methods: HepG2 cells were incubated with BJJS (10, 20 or 40 μM) for 48 h. C57 mice were orally treated with BJJS (25, 50 or 100 mg/kg) for 2 weeks. The protein and mRNA levels of P-gp were measured by using Western blot and real-time PCR, respectively. siNrf2 RNA was used to explore the mediation effects of Nrf2 on the P-gp expression. The efflux activity of P-gp was tested via a flow cytometry.Results: Incubation of HepG2 cells with BJJS at 10, 20, and 40 μM up-regulated the P-gp protein expression by 12.3%, 82.9%, and 134.3%, respectively. Treatment of C57 mice with BJJS at 25, 50 and 100 mg/kg increased the P-gp protein expression by 49.3%, 75.8% and 106.0%, respectively. Incubation of the cells with BJJS at 10, 20 and 40 μM up-regulated the total Nrf2 protein levels by 34.3%, 93.1% and 118.6%, respectively, and also increased the nuclear Nrf2 protein levels by 14.8%, 44.4% and 59.25%, respectively. The total Nrf2 protein levels were increased by 46.3%, 66.5%, and 87.4%, respectively, in the mice exposed to BJJS at 25, 50, and 100 mg/kg. Inhibition of Nrf2 by siRNA diminished the P-gp induction by 25.0%, 33.4%, and 38.7%, respectively, in the cells. In addition, BJJS enhanced the efflux activity of P-gp by 9.6%, 37.1%, and 48.1%, respectively, in the cells.Conclusions: BJJS activates Nrf2 to induce P-gp expression, and enhanced the efflux activity of P-gp. The possibility of potential herb–drug interactions when BJJS is co-administered with other P-gp substrate drugs should be carefully monitored.

Highlights

HepG2 cell line, which is established from human hepatic carcinoma, is a suitable in vitro model and has been widely used to study the regulation of P-gp expression and function of xenobiotic drugs (Rigalli et al 2011; He et al 2014)
We evaluated whether variation in the expression and activity of P-gp induced by BJJS can protect cells from the cytotoxicity produced by doxorubicin, a drug used in cancer chemotherapy and used here as a model P-gp substrate (Rigalli et al 2011; Wu et al 2016) The combined results of this study will help to predict the possibility of potential herb–drug interactions (HDIs) when BJJS is co-administered with other herbal medicines or chemical drugs that are P-gp substrates, thereby providing beneficial guidance for the correct application of MO in clinical practice
The HepG2 cell line, which is established from human hepatic carcinoma, is a suitable in vitro model and has been widely used to study the regulation of P-gp expression and function by xenobiotic drugs (Rigalli et al 2011; He et al 2014)

Summary

Introduction

In traditional Chinese medicine (TCM), MO is frequently used to treat various diseases, including male impotence, female infertility, fatigue, chronic rheumatism, and depression (Song et al 2015). MO has been shown to contribute to improving memory and treating Alzheimer’s disease (AD) (Cai et al 2017; Lee et al 2017; Zhang et al 2018). Bajijiasu (BJJS) (Figure 1(A)), which is one of the main bioactive compounds isolated from MO, possesses various pharmacological activities and therapeutic efficacies (Chen et al 2014; Cai et al 2017; Hong et al 2017)

Objectives

Results

Conclusion