RACK1 promotes hepatocellular carcinoma cell survival via CBR1 by suppressing TNF-α-induced ROS generation.

Silei Zhou,Huanling Cao,Chunmei Hou,Yuanfang Ma,Xinying Li,Jiyan Zhang,Yawei Zhao,Qingyang Wang

doi:10.3892/ol.2016.5339

Abstract

It has been reported that intracellular accumulation of reactive oxygen species (ROS) has a significant role in tumor necrosis factor (TNF)-α-induced cell apoptosis and necrosis; however, the key molecules regulating ROS generation remain to be elucidated. The present study reports that knockdown of endogenous receptor for activated C kinase 1 (RACK1) increases the intracellular ROS level following TNF-α or H2O2 stimulation in human hepatocellular carcinoma (HCC) cells, leading to promotion of cell death. Carbonyl reductase 1 (CBR1), a ubiquitous nicotinamide adenine dinucleotide phosphate-dependent enzyme, is reported to protect cells from ROS-induced cell damage. The present study reports that RACK1 is a regulator of CBR1 that interacts with and sustains the protein stability of CBR1. Overexpression of CBR1 reverses the enhanced cell death due to RACK1 knockdown. Taken together, the results of the present study suggest that RACK1 protects HCC cells from TNF-α-induced cell death by suppressing ROS generation through interacting with and regulating CBR1.

Highlights

Escape from tumor necrosis factor (TNF)‐α‐induced cell apoptosis and necrosis is of importance in tumor development [1,2,3].Key words: receptor for activated C kinase 1, carbonyl reductase 1, reactive oxygen species, cell death, tumor necrosis factor‐α, hepatocellular carcinomaThis process is regulated by a number of intracellular signaling pathways, including c‐jun N‐terminal kinase (JNK) and IκB kinase (IKK), as well as reactive oxygen species (ROS) [4,5]
The present study initially investigated the correlation between receptor for activated C kinase 1 (RACK1) and TNF‐α‐induced cell death in SMMC7721 cells
A total of 48 h later, the cells were treated with 10 ng/ml TNF‐α with or without 10 μg/ml CHX for 24 h, followed by cell death assay with Annexin‐V and propidium iodide (PI) double staining

Summary

Introduction

Escape from tumor necrosis factor (TNF)‐α‐induced cell apoptosis and necrosis is of importance in tumor development [1,2,3] This process is regulated by a number of intracellular signaling pathways, including c‐jun N‐terminal kinase (JNK) and IκB kinase (IKK), as well as reactive oxygen species (ROS) [4,5]. Evidence has indicated that RACK1 protects from oxidative stress‐induced cell death in various types of cells, including fission yeasts [13], shrimp cells [14], neurons [15], HeLa cells [16] and HL60 cells [17] Such a role for RACK1 has not been reported in HCC cells to the best of our knowledge. It was reported that overexpression of exogenous CBR1 in HCC cells reverses enhanced cell death upon silencing of endogenous RACK1, which indicated that RACK1 may have a pivotal role in sustaining the protein stability of CBR1

Methods

Results

Conclusion