Long noncoding RNA, the methylation of genomic elements and their emerging crosstalk in hepatocellular carcinoma.

The epigenetic mechanism that incorporates DNA methylation alterations, histone modifications, and non-coding RNA expression has been identified as a major characteristic in distinguishing physiological and pathological settings of cancers including hepatocellular carcinoma (HCC), the third leading cause of mortality related cancer. The advance in methylation modification of chromatin elements (for both genomic DNA and histone tails) and the emerging roles of long noncoding RNA (lncRNA) have given us a better understanding of molecular mechanisms underlying HCC. Recently, methods like genome-wide lncRNA profiling and histone hallmark detection were reported to discover mass tumor-associated lncRNAs epigenetically deregulated by differential chromosome modification, mainly by genomic DNA and histone methylation. Therefore, aberrant methylation modification of certain particular lncRNA genes could be crucial events correlating with unfavorable outcomes in HCC. In addition, amount of lncRNAs could act as a manipulator for DNA methylation or a scaffold for histone modification to affect key signaling pathways in hepatocarcinogenesis. This suggests that methylation modification of chromatin elements may have functional crosstalk with lncRNA. Here, we aim to outline the emerging role of the methylation and lncRNA, and their crosstalk of molecular mechanism.