| Background:Hepatocellular carcinoma (HCC) is the fifth most common cancer in men and the ninth most common cancer in women, and it is the second leading cause of cancer related death worldwide. The mechanisms involved in HCC remain unclear. Accumulations of genetic and epigenetic changes are regarded as important mechanisms for many cancers. Aberrant epigenetic changes have been frequently found in human HCC. The Ras-association domain family (RASSF) proteins are associated with Ras-like small GTP binding proteins and participate in a range of cellular processes including cell growth, adhesion, migration, differentiation and apoptosis. The family of genes comprises 10 members that are subdivided into C-terminal (RASSF1-6) and N-terminal (RASSF7-10) RASSF genes. The C-terminal RASSF proteins harbor Ras association domains and Salvador/RASSF/Hippo (SARAH) domains in the C-terminus, whereas the N-terminal RASSF proteins contain Ras association domains in the N-terminus and lack the SARAH domain. RASSFIO is located on chromosome 11p15.2. Loss of heterozygosity (LOH) frequently occurs in this region in several types of cancer. RASSF10 is frequently methylated in many human cancers. Our previous study found that RASSF10 suppresses colorectal cancer growth by activating P53 signaling. In this study, we explored the epigenetic changes and the role of RASSF10 in HCC progression.Objective:To explore the methylation statues of RASSF10 in HCC and evaluate he effects of function of RASSF10 on HCC. To understand the mechanism of RASSF10 in HCC progression, and explore the possibility of methylation of RASSF10 is HCC diagnostic and prognostic biomarker.Material and methods:Ten HCC cell lines (SNU182, SNU387, HBXF344, >NU475, HepG2, BEL7402, LM3, Huh7, PLC/PRF5 and OGY7703).69 cases of primary HCC tissue samles,31 cases of available matched primary HCC and adjacent tissue samples were involved in this study. Semi-quantitative RT-PCR, methylation specific PCR (MSP), bisulfite sequencing (BSSQ), immunohistochemistry (IHC), MTT assay, colony formation assay, flow cytometry and western-blot were employed to analyze the function of RASSF10 in hepatocellular carcinoma cells.Results:Loss of RASSF10 expression and completely methylation in the promoter region were found in SNU387, HBXF344, HepG2, PLC/PRF/5, Huh7, BEL7402, LM3 and QGY7703 cells, and reduced expression and partial methylation were detected in SNU182 and SNU475 cells. Restoration or increasing the expression of RASSF10 was induced by 5-aza-2’-deoxy-cytidine (5-aza) in unexpressed/reduced cells. The expression of RASSF10 was regulated by promoter region methylationin in HCC cells. RASSF10 was methylated in 82.6%(57/69) of primary HCC samples, but no methylation was detected in normal liver tissue samples. Methylation of RASSF10 was significantly associated with tumor size (P< 0.05) and tumor stage (P< 0.05). Restoration of RASSF10 expression suppressed cell proliferation, induced apoptosis and G2/M phase arrest, as well as sensitized cells to docetaxel and activated P53 signaling in HepG2 and QGY7703 cells.Conclusion:RASSF10 is frequently methylated in human HCC and the expression of RASSF10 is regulated by promoter region methylation. Methylation of RASSFIO is associated with tumor size and TNM stage, and it may serve as a docetaxel resistant marker in human HCC. RASSFIO suppresses human HCC growth by activating P53 signaling. |
PDF Full Text Request