Long Noncoding RNA Function and Expression in Cancer Regulatory RNAs

In the last decades, medical research has mainly focused on the 2% of the human genome that serve as blueprint for proteins, assuming that the noncoding sequences were irrelevant and would neither contain significant information nor be of functional importance. However, 70% of the human genome are transcribed into RNA; therefore, the genome contains much more noncoding information than coding, which is present in the cell as noncoding RNA (ncRNA). Some of these ncRNAs are highly expressed, specifically regulated and evolutionarily conserved arguing in favor of their functional significance. Long ncRNAs (lncRNAs) have been shown to regulate gene expression at various levels including chromatin modification, transcription, and posttranscriptional processing. Here, we review recent advances in ncRNA research for examples such as XIST , H19 , MALAT1 , HOTAIR , and GAS5 . Many lncRNAs show differential expression patterns that correlate with diagnosis or prognosis in multiple tumor entities and can, thus, serve as an extensive source of new biomarkers. Moreover, these lncRNAs are functionally important and can provide novel insights into the mechanisms underlying tumor development and might serve as new targets in cancer therapy.