Drug resistance via radixin-mediated increase of P-glycoprotein membrane expression during SNAI1-induced epithelial-mesenchymal transition in HepG2 cells

Abstract

Objectives Epithelial–mesenchymal transition (EMT) plays a role in cancer metastasis as well as in drug resistance through various mechanisms, including increased drug efflux mediated by P-glycoprotein (P-gp). In this study, we investigated the activation mechanism of P-gp, including its regulatory factors, during EMT in hepatoblastoma-derived HepG2 cells. Methods HepG2 cells were transfected with SNAI1 using human adenovirus serotype 5 vector. We quantified mRNA and protein expression levels using qRT-PCR and western blot analysis, respectively. P-gp activity was evaluated by uptake assay, and cell viability was assessed by an MTT assay. Key findings P-gp protein expression on plasma membrane was higher in SNAI1-transfected cells than in Mock cells, although there was no difference in P-gp protein level in whole cells. Among the scaffold proteins such as ezrin, radixin and moesin (ERM), only radixin was increased in SNAI1-transfected cells. Uptake of both Rho123 and paclitaxel was decreased in SNAI1-transfected cells, and this decrease was blocked by verapamil, a P-gp inhibitor. The reduced susceptibility of SNAI1-transfected cells to paclitaxel was reversed by elacridar, another P-gp inhibitor. Conclusions Increased expression of radixin during SNAI1-induced EMT leads to increased P-gp membrane expression in HepG2 cells, enhancing P-gp function and thereby increasing drug resistance.

Slug Mediates MRP2 Expression in Non-Small Cell Lung Cancer Cells

“…In our previous study using HCC827 cells, overexpression of Snail induced an increase in P-gp activity through an increase in Msn protein [ 14 ]. Moreover, MRP2 is often regulated by Rdx in liver cancer [ 17 , 18 ], breast cancer cell lines [ 19 ], and the gastrointestinal tract [ 20 ]. Furthermore, previous studies have shown that Rdx modulates MRP2 activity in A549 lung cancer cell lines [ 21 , 22 ].…”