The LncRNA HOTAIR-expression, regulation and function in cancer

Only 2% of transcribed RNAs encode proteins. Whole transcriptome analysis suggests that a predominant number of transcripts synthesized in the cell are non-coding RNAs (ncRNAs). Classical noncoding RNAs comprise housekeeping structural RNAs like transfer RNAs and ribosomal RNAs. More recently, two types of ncRNAs with regulatory function in specialized, cell specific processes have been discovered. They fall into small/short ncRNAs and long non-coding RNAs (lncRNAs). While small ncRNAs typically function in protein translation, lncRNAs seem to be more versatile, abundant at specific developmental stages, and diverse in function. They epigenetically remodel the genome, regulate gene expression, are major scaffolding RNAs within protein complexes, and are often themselves regulated by complex mechanisms. One such lncRNA is HOTAIR, that not only plays key roles in development and body axis patterning but also promotes cancer progression when dysregulated in the adult. This review discusses the multiple molecular functions of HOTAIR with special emphasis on cancer.