Downregulation of MDR1 gene by cepharanthine hydrochloride is related to the activation of c-Jun/JNK in K562/ADR cells.

Li Han,Fang Ma,Jinhua Jiang,Jingmin Zhang,Xiaojuan Guo,Yubing Zhou,Qingduan Wang,Yafeng Wang,Ning Wang

doi:10.1155/2014/164391

Abstract

The purpose of the study was to determine the signal transduction mechanism of cepharanthine hydrochloride (CH) on reversing tumor multidrug resistance. RT-PCR and Western blot analysis were used to determine the effects of CH on the expression of MDR1 mRNA and P-glycoprotein in K562/ADR cells when CH was used alone and combined with SP600125, a JNK inhibitor, to explore the effects of CH on JNK pathway. Western blot analysis was used to determine the effects of CH on c-Jun protein expression and phosphorylation, to explore the regulating effects of CH on c-Jun and phosphorylated c-Jun (p-c-Jun) proteins. Our results showed that the inhibitory effect of CH on MDR1 mRNA increased with the concentrations of CH (5.0, 10.0, and 20.0 μM) and the inhibitory effects of CH on MDR1 mRNA and P-glycoprotein increased with the incubation time of CH (0, 12, 24, 36, and 48 hours). The inhibitory effect was weakened after CH combined with SP600125. The expressions of c-Jun and p-c-Jun proteins increased with the incubation time of CH (0, 6, 12, and 24 hours). These findings suggest that CH downregulated the expressions of MDR1 mRNA and P-glycoprotein in a time and concentration manner; the mechanism may be mediated via activating c-Jun/JNK pathway.

Highlights

Chemotherapy is one of the main treatment strategies for cancer patients currently
In drug-resistant K562/ADR cells, coincubation of cepharanthine hydrochloride (CH) with ADR resulted in a significant increase in the cytotoxicity of ADR; the IC50 dropped drastically from 13.97 ± 0.30 to 1.62 ± 0.10 μM
Researches have advanced greatly in multidrug resistance (MDR), it remains a formidable problem in clinical treatment

Summary

Introduction

Chemotherapy is one of the main treatment strategies for cancer patients currently. It is more and more serious that the multidrug resistance (MDR) occurred in the cancer patients as the anticancer drugs are widely used, which affected the patients’ treatment directly. The overexpression of P-glycoprotein (P-gp), encoded by multidrug resistance gene MDR1, is one of the important mechanisms involved in MDR [1,2,3]. Cepharanthine hydrochloride (Figure 1), manufactured by salification from cepharanthine (CEP), which is a biscoclaurine alkaloid, extracted from Stephania cepharantha Hayata, has a reversed effect involved in multimechanisms from our previous studies [7,8,9]. It is reported that CH has MDR-reversing effect and one of the reversing mechanisms is to inhibit the P-gp expression and function in MDR cancer cells [10, 11]

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Conclusion