MiR-199a-3p enhances cisplatin sensitivity of cholangiocarcinoma cells by inhibiting mTOR signaling pathway and expression of MDR1.

Qiang Li,Linjun Mo,Xuefeng Xia,Wei Chen,Liang Tao,Jie Ji,Jianghui Ma

doi:10.18632/oncotarget.16834

Abstract

Several studies have reported reduced miRNA-199a-3p (miR-199a-3p) in different human malignancies, however, little is known about miR-199a-3p in cholangiocarcinoma cells. In this study, we demonstrate the essential role and mechanism of miR-199a-3p in regulating cisplatin sensitivity in cholangiocarcinoma cell lines. Using a CCK-8 cell counting assay we found that expression of miR-199a-3p was positively correlated with cisplatin sensitivity in cholangiocarcinoma cell lines. MiR-199a-3p overexpression could decrease the proliferation rate and increase apoptosis of cholangiocarcinoma cells in the presence of cisplatin, while miR-199a-3p inhibition had the opposite effect. Further study demonstrated that mTOR was the target gene of miR-199a-3p, and that miR-199a-3p mimics could inhibit expression of mTOR, which consequently reduced the phosphorylation of its downstream proteins 4EBP1 and p70s6k. Rescue experiments proved that miR-199a-3p could increase the cisplatin sensitivity of cholangiocarcinoma cell lines by regulating mTOR expression. Moreover, we also found that miR-199a-3p overexpression could reduce cisplatin induced MDR1 expression by decreasing the synthesis and increasing the degradation of MDR1, thus enhancing the effectiveness of cisplatin in cholangiocarcinoma. In conclusion, miR-199a-3p could increase cisplatin sensitivity of cholangiocarcinoma cell lines by inhibiting the activity of the mTOR signaling pathway and decreasing the expression of MDR1.

Highlights

As a bile duct epithelium cancer, cholangiocarcinoma is the second most common primary hepatic malignancy after hepatocellular carcinoma, and accounts for 10–20% of primary liver cancers [1, 2]
Gemcitabine plus cisplatin was associated with a significant survival advantage compared with gemcitabine alone in patients with locally advanced or metastatic cholangiocarcinoma cancer, suggesting that gemcitabine plus cisplatin is the standard regimen for advanced cholangiocarcinoma cancer [6, 23,24]
Recent studies have reported that miR-199a-3p plays an important role in suppressing cell proliferation and migration in various tumors, such as prostate cancer [27], colorectal cancer [28], breast cancer [29], glioma [30], osteosarcoma [31] and pancreatic ductal adenocarcinoma [32]

Summary

Introduction

As a bile duct epithelium cancer, cholangiocarcinoma is the second most common primary hepatic malignancy after hepatocellular carcinoma, and accounts for 10–20% of primary liver cancers [1, 2]. Even amongst those able to undergo radical resection, the recurrence risk is high and the 5-year overall survival is only 30% [3]. Our previous studies revealed that inhibition of mTOR suppresses human gallbladder carcinoma cell proliferation and enhances the cytotoxicity of 5-fluorouracil (5-FU) by regulating MDR1 expression [10]. Little is known about the role of mTOR in cholangiocarcinoma

Methods

Results

Conclusion