Reversing multidrug resistance in hepatocellular carcinoma cells by inhibiting extracellular signal-regulated kinase/mitogen-activated protein kinase signaling pathway activity.

Xiaomin Wang,Siyuan Chen,Chao Pan,Yali Wang,Wenwen Ruan

doi:10.3892/ol.2014.2521

Abstract

The aim of the present study was to evaluate whether downregulation of extracellular signal-regulated kinase 1/2 (ERK1/2) is involved in conventional reversal methods and whether the inhibitors of the ERK signaling pathway reverse multidrug resistance (MDR) in hepatocellular carcinoma (HCC) cells. The sensitivities of SMMC7721 and BEL7402, and the MDR SMMC7721/Adriamycin (ADM) and BEL7402/ADM HCC cell lines to ADM were evaluated by CellTiter-Glo® luminescent cell viability assay through calculating the half maximal inhibitory concentration (IC50) of ADM. In addition, the expression levels of ERK1/2 and phosphorylated (p)ERK1/2 were determined by western blot analysis subsequent to treatment of the cells with PD98059, an MEK inhibitor, or sorafenib, a multikinase inhibitor. The results revealed that the ADM IC50 for the SMMC7721/ADM cells was 16.44 times higher than that of the SMMC7721 cells (P<0.05), and the ADM IC50 for the BEL7402/ADM cells was 20.34 times higher than that of the BEL7402 cells (P<0.05). Following treatment with PD98059 or sorafenib, the expression levels of pERK1/2 in the MDR cells decreased in a dose-dependent manner. Subsequent to treatment with 5 μM PD98059, the ADM IC50 values for the SMMC7721/ADM and BEL7402/ADM cells were reduced to 0.8±0.056 and 1.583±0.284 μg/ml, respectively. Following treatment with 2.5 μM sorafenib, the ADM IC50 values for the SMMC7721/ADM and BEL7402/ADM cells were reduced to 0.264±0.049 and 1.099±0.135 μg/ml, respectively. Subsequent to incubation with 4 μg/ml cyclosporine A (CsA), a classic MDR reversal agent, the ADM IC50 values in the SMMC7721/ADM and BEL7402/ADM cells were reduced to 0.349±0.023 and 0.427±0.039 μg/ml, respectively. CsA treatment also increased the expression levels of pERK1/2 without affecting the total ERK1/2 levels. Therefore, the inhibition of ERK signaling pathway activity may be an important method to reverse the MDR of HCC cells, but is not unique.

Highlights

Hepatocellular carcinoma (HCC) is the third most common cause of cancer‐related mortality worldwide, with high recurrence and a low five‐year survival rate [1]
In addition to surgical intervention, systemic chemotherapy has a significant role in HCC treatment, for patients with advanced HCC [29]
Identifying safe and efficient reversal agents is of vital importance for treating advanced‐stage HCC patients

Summary

Introduction

Hepatocellular carcinoma (HCC) is the third most common cause of cancer‐related mortality worldwide, with high recurrence and a low five‐year survival rate [1]. The recurrence may be as high as 50% after two years [4]. Chemotherapy is used as an adjuvant post‐operative treatment, with the aim of reducing tumor recurrence. Conventional systemic chemotherapy has shown only minor effectiveness with response rates of

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