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Estrogen-related receptor γ is upregulated in liver cancer and its inhibition suppresses liver cancer cell proliferation via induction of p21 and p27

Experimental & Molecular Medicine 2016년 48권 3호 p.9 ~ p.9

김지현(Kim Ji-Hyun) - Kyungpook National University School of Medicine Department of Internal Medicine
최연경(Choi Yeon-Kyung) - Kyungpook National University School of Medicine Department of Internal Medicine
변준규(Byun Jun-Kyu) - Kyungpook National University Hospital Leading-edge Research Center for Drug Discovery and Development for Diabetes and Metabolic Disease
김미경(Kim Mi-Kyung) - Keimyung University School of Medicine Department of Internal Medicine
강유나(Kang Yu-Na) - Keimyung University School of Medicine Department of Pathology
김성헌(Kim Seong-Heon) - Daegu-Gyeongbuk Medical Innovation Foundation New Drug Development Center
이승우(Lee Sung-Woo) - Daegu-Gyeongbuk Medical Innovation Foundation New Drug Development Center
장병국(Jang Byoung-Kuk) - Keimyung University School of Medicine Department of Internal Medicine
박근규(Park Keun-Gyu) - Kyungpook National University School of Medicine Department of Internal Medicine

Abstract

Orphan nuclear receptor estrogen-related receptor γ (ERRγ) regulates cell growth and tumorigenesis in various cancers. However, the clinical relevance of ERRγ to hepatocellular carcinoma (HCC) remains unclear. Here we examined the clinical significance of ERRγ in HCC and its potential as a therapeutic target. ERRγ levels in tissues from completely resected specimens from 190 HCC patients were examined immunohistochemically and their association with clinical stage and pathological grade was analyzed. Small interfering RNA (siRNA)-mediated knockdown of ERRγ (siRNA-ERRγ) or an ERRγ inverse agonist, GSK5182, were also used to examine the effects of ERRγ inhibition on the proliferation and growth of a human hepatoma cell line, PLC/PRF/5. Immunohistochemical analysis revealed that tumor tissues showed higher levels of ERRγ-positivity than adjacent non-tumor lesions. Tumors showing high levels of ERRγ immunoreactivity also had advanced tumor node metastasis (TNM) and Barcelona Clinic Liver Cancer stages and a higher Edmondson?Steiner grade. In addition, high-level expression of ERRγ in tumors of advanced TNM stage correlated with poorer overall survival. Treatment of PLC/PRF/5 cells with siRNA-ERRγ or GSK5182 inhibited proliferation through G1 arrest, increased expression of p21 and p27 and decreased expression of phosphorylated retinoblastoma protein. GSK5182-induced reactive oxygen species also suppressed the proliferation of PLC/PRF/5 cells. The present study showed that ERRγ expression is clinically significant in HCC; therefore, it can be considered a biomarker for HCC diagnosis. Moreover, the results provide a rationale for the use of ERRγ inhibitors such as GSK5182 as potential therapeutic agents.