The role of histone H3 lysine 9 trimethylation modification on cholangiocarcinoma moleculor mechanism

Abstract

Objective To study the effect of histone H3 lysine 9 trimethylation(H3K9me3) modification on cholangiocarcinoma moleculor mechanism. Methods 9 cases cholangiocarcinoma tissue and 5 cases normal extrahepatic bile duct tissue were collected.Chromatin immunoprecipitation linked to microarrays(ChIP-chip) was adopted to profile the variations of histone H3K9me3 in genome-wide in cholangiocarcinoma cell and normal extrahepatic bile duct cell.CHIP-quantitative polymerase chain reaction(qPCR) was used to validate the microrray results.mRNA expression analysis of 6 selected genes by real-time quantitative reverse transcriptase-polymerase chain reaction(RT -qPCR) was performed to confirm the correlations between H3K9me3 and gene expression. Results 67(35 increased and 32 decreased) gene displayed significant histone H3K9me3 differences were found in tumor cell compared with normal extrahepatic bile duct cell.In bile duct cancer tissues, six selected oncogenes[calcium binding protein A2(S100A2), anaphase-promoting complex subunit 2 (ANAPC2), myeloid translocation gene on chromosome 16(CBFA2T3), Rho GTPase activating protein 4 isoform 2(ARHGAP),Rap guanine nucleotide exchange factor 3 isoform(RAPGEF3), protein kinase C alpha(PRKCA)]H3K9me3 modifications level were:(3. 51±3. 51)%,(8. 45± 0. 16)%,(0. 89±0. 27)%,(0. 66±0. 22)%,(0. 04±0. 01)%,(5. 21±1. 53)%, there was a statistically significant difference compared with normal bile duct cells.It was the Pearson correlation between selected genes expression and H3K9Me3 modification(r=-0. 539)in the turmor cell. Conclusion Compared with normal extrahepatic bile duct cell,there are significant changes in many genes of cholangiocarcinoma cell about histone H3K9Me3 profiling.And resulting in a number of related oncogenes and tumor suppressor genes expression change. Key words: Histone H3 lysine 9 trimethylation; Microarray; Chromatin immunoprecipitation; Cholangiocarcinoma