The Analysis Of Histone Modification And Gene Expression In Human Hepatoma Cell Lines And Normal Liver Cell Lines

Hepatocellular carcinoma(HCC)is a common cancer and one of the leading causes of cancer death worldwide.It has been reported that the changes of histone modifications are closely related to HCC.Therefore studying the pathogenesis of histone modification and finding biomarkers are important for the clinical treatment of HCC.In this paper,the hepatoma cell lines(HepG2)and normal liver cell lines(hepatocyte)were studied.Firstly,we computed and analyzed the histone modifications and gene expression levels in the promoter regions of genes that including genome-wide,highly expressed genes and lowly expressed genes,oncogenes and tumor suppressor genes,the different highly and lowly expressed genes,the oncogenes and tumor suppressor genes of different highly and lowly expressed genes in two kinds of cell lines.The results showed that the histone modification signals with activating gene expression were stronger in tumor cells than that in normal cells,and their signals were also stronger in highly expressed genes than that in lowly expressed genes.Secondly,we calculated the correlation between histone modification and gene expression levels,and the correlation between histone modifications.It was found that the correlations between the histone modification and the gene expression levels were stronger in the oncogenes and tumor suppressor genes of highly and lowly expressed genes,and the correlations between histone modifications were also stronger in the highly and lowly expressed genes than that in the whole genome.Finally,we selected the oncogenes and tumor suppressor genes of different highly and lowly expressed genes,and calculated the histone modification signals of these genes in 80 bins of promoter regions.By comparing with the normal cells,we found some key genes(such as ARHGAP5,CCND1,MALT1,MAP2K1,CHD4,MYD88,PLCG1,MYC etc.)and important histone modifications that might cause HCC.Then we compared the distribution of histone modifications in these key genes for two kinds of cell lines,and located the regions where histone modifications had changed.