Study On The Function And Mechanism Of DNA Methylation-regulated Long Non-coding RNAs In Hepatocellular Carcinoma

We study on the function and mechanism of DNA methylation-regulated longnon-coding RNAs in hepatocellular carcinoma.Liver cancer is one of the most common cancer in the world and also the mostcommon cause of cancer-related death. The disease is a serious threat to humanhealth.The pathogenesis of liver cancer is complicated. Classic genetics has provideda firm foundation for our understanding of carcinogenesis. As we have known that theactivation of proto-oncogene and the mutation of anti-oncogene are key reasons forcarcinogenesis. However, in reacent years, abnormal changes in epigenetics are alsobelieved to play key role in the course of HCC.The activation of oncogene and theinactivation of tumor suppressor genes, caused by genetic or epigenetic modifications,will lead to the malignant transformation of cells. Usually, epigenetic alterations isalways an early onset at the preneoplastic stage.Recent reports have emphasized thatepigenetic modifications, especially hypomethylation of proto-oncogene andhypermethylation of tumor suppression gene, might play crucial roles in the initiationof cancer. However, the detail mechanism of abnormal DNA hypomethylationremains unknown.LncRNAs are a class of non-coding RNAs transcripts longer than200nucleotides. These non-coding RNAs are involved in genomic imprinting,transcription, post-transcriptional processing, chromatin modification, proteinfunction regulation and other important signal transduction regulation.As we haveknown, diverse epigenetic modifications can influence each other. Several reportshave declared that DNA methylation and microRNA play coaction inhepatocarcinogenesis. We want to clarify whether some lncRNAs also participatehepatocarcinogenesis with the control of DNA methylation.In the present study, hepatoma carcinoma cell were demethylated. After thelncRNAs microarray analysis the candidate lncRNAs were screened as genes that,based on their expression level, CpG island in promoter, transcription factor bindingsite, conservation between human and mouse. Several lncRNAs were selected andvalidated the expression of these lncRNAs in expanded samples of transgenic andwild-type mice livers of different age and sex by real-time quantitative PCR. After theanalyse of DNA methylation, lncRNA AY927547was selected as the candidatelncRNA for functional studies, due to its down-regulation in hepatoma cell lines andtissues.To further declare the relationship between lncRNA and tumor phenotype, AY927547were over expressed and downregulated by siRNA in vitro.The resultsshowed that AY927547can effectively inhibit the proliferation and migration ofhepatoma cells.Meanwhile, with RNA-pulldown and RNA immunoprecipitationanalysis, pyruvate kinase M2were detected. AY927547could combine with PKM2protein and inhibit its activity.Our results confirmed that lncRNA AY927547were regulated by modification ofDNA methylation and play crucial role in hepatocarcinogenesis. It is an importantsupplement to the mechanisms of HBV-HCC tumorigenesis and transfer network.This allowing us to better clarify the occurance of HCC, so as to get early finding,early diagnose, and early prevention to improve the survival rate of HCC.Furthermore,the tumor suppressor role of lncRNA-AK927547in hepatoma growth and metastasisprovides us new ideas and target for the treatment HCC. The results of this studyprovide a rational support for treatment of HBV-related HCC with epigenetictherapies of synthetic lncRNAs.