TR4 nuclear receptor suppresses HCC cell invasion via downregulating the EphA2 expression

Ren’an Jin,Xiujun Cai,Gonghui Li,Liang Shi,Junjie Xu,Chawnshang Chang,Hui Lin

doi:10.1038/s41419-018-0287-5

Abstract

Early studies indicated that testicular nuclear receptor 4 (TR4) could function as a suppressor in the transcriptional regulation of the HBV core gene expression, which might then influence the development of hepatocellular carcinoma (HCC). The direct linkage between TR4 and HCC progression, however, remained unclear. Here, via a human clinical sample survey, we found that 13 of the 18 HCC patients studied had lower TR4 expression in metastatic lesions than in matched primary HCC lesions, suggesting that TR4 may play a negative role in HCC metastasis. Results from in vitro cell migration/invasion studied confirmed that TR4 could suppress HCC cell migration/invasion. Mechanism dissection revealed that TR4 might function through downregulating ephrin type-A receptor 2 (EphA2) expression at the transcriptional level via direct binding to the TR4REs located on the 5′ promoter of EphA2 to suppress HCC cell migration/invasion. Targeting the EphA2 via EphA2-siRNA partially reversed the enhanced HCC cell migration/invasion with confirmed TR4 knockdown. Notably, results from preclinical studies using in vivo mouse model with orthotopic xenograft of HCC LM3 cells also confirmed the in vitro findings. Taking these findings together, preclinical studies using multiple in vitro HCC cell lines and an in vivo mouse model all led to the conclusion that TR4 may function as a suppressor of HCC metastasis and that targeting this newly identified TR4-EphA2 signaling may improve our ability to suppress HCC metastasis.

Highlights

Hepatocellular carcinoma (HCC) is one of the most common and lethal malignant tumors, accounting for 70–90% of primary liver cancers [1,2,3]
German Immunoreactive Score (IRS) was calculated to measure the protein levels, and the results revealed that 13 patients had lower testicular nuclear receptor 4 (TR4) expression in metastatic lesions than in their matched primary HCC lesions, while such levels in the other 5 patients were equal, with significant difference (P = 0.014)
As metastatic tissues are difficult to extract without the contamination of normal tissues or primary HCC tissues, we compared TR4 expression between normal liver tissues and primary HCC tissues, and the results showed lower expression of TR4 in primary HCC tissues (P = 0.043; Fig. 1e)

Summary

Introduction

Hepatocellular carcinoma (HCC) is one of the most common and lethal malignant tumors, accounting for 70–90% of primary liver cancers [1,2,3]. The common risk factors for HCC are chronic hepatitis B virus (HBV) infection, hepatitis C virus infection, consumption of food contaminated with aflatoxin, obesity, type 2 diabetes, non-alcoholic fatty liver disease, cirrhosis related to heavy alcohol consumption, and smoking [3]. The standard treatments for HCC include surgical resection, liver transplantation, local ablation therapy, transhepatic arterial chemotherapy and embolization, and systemic treatment. Surgical resection, liver transplantation, and local ablation therapy are considered as curative treatments [5, 6], which are suitable for early-

Methods

Results

Conclusion