Epigenetic Changes And The Functional Study Of ZNF545 In Hepatocellular Carcinoma

Background Hepatocellular carcinoma (HCC) is one of the most fatal human malignancies. It is the fifth most common cancer in men and the ninth in women. HCC is the second leading cause of cancer related death. The mechanisms of carcinogenesis and progression in HCC remains to be elucidated. Accumulations of genetic and epigenetic alterations play crucial roles in the development of HCC. Promoter region hypermethylationis frequently found in tumor suppressor genes (TSGs) in HCC. About one-third of Zinc finger proteins (ZFPs) are Kruppel-associated box containing zinc finger proteins (KRAB-ZFPs), which are important to the regulation of cell proliferation, differentiation, apoptosis and tumorigenesis. ZNF545 is a member of the family of KRAB-ZFPs. ZNF545 is located on chromosome 19q13.1, which shows frequent loss of heterozygote (LOH) in several cancer types. ZNF545 is frequently methylated in a few primary tumors. However, the regulation and the function of ZNF545 in HCC remain unclear.Objective The aim of this study is to investigate the epigenetic changes and the function of ZNF545 in human HCC.Methods Nine HCC cell lines (HBX344, SNU449, SMMC-7721, SNU182, SNU387, Huh7, HepG2, LM3, and PLC-PRF-5), one transformed cell lines (LO2), and 62 cases of primary human hepatic cancer samples were involved in this study. Methylation specific PCR (MSP), MTT assay, colony formation transwell assay, western-blot and flow cytometry technique were employed.Results Loss of ZNF545 expression and completely methylation in the promoter region were found in SNU449, SMMC7721, LO2, Huh-7, HepG2 and LM3 cell lines, and reduced expression and partial methylation were detected in SNU182 and PLC-PRF-5 cells. Highly expression and unmethylation in the promoter region were revealed in HBXF344 and SNU387 cells. Restoration or increasing the expression of ZNF545 was induced by 5-aza-2’-deoxy-cytidine (5-AZA) in unexpressed/reduced cells. The expression of ZNF545 was regulated by promoter region methylationin HCC cells. Promoter region hypermethylation was detected in 53.2%(33/62) of primary HCC samples. Restoration of ZNF545 expression suppressed cell proliferation, colony formation, cell invasion and migration in SNU449 and Huh-7 cells. Apoptosis was induced by ZNF545 in SNU449 and Huh-7 cells.In conclusion ZNF545 is frequently methylated in HCC and the expression of ZNF545 is regulated by promoter region methylation. ZNF545 suppresses cell proliferation, invasion, migration and induces apoptosis in human HCC.