Recent advances in the field of RNA research have provided compelling evidence 
implicating microRNA (miRNA) and long non-coding RNA molecules in many diverse 
and substantial biological processes, including transcriptional and 
post-transcriptional regulation of gene expression, genomic imprinting, and 
modulation of protein activity. Thus, studies of non-coding RNA (ncRNA) may 
contribute to the discovery of possible biomarkers in human cancers. Considering 
that the response to chemotherapy can differ amongst individuals, researchers 
have begun to isolate and identify the genes responsible. Identification of 
targets of this ncRNA associated with cancer can suggest that networks of these 
linked to oncogenes or tumor suppressors play pivotal roles in cancer 
development. Moreover, these ncRNA are attractive drug targets since they may be 
differentially expressed in malignant versus normal cells and regulate 
expression of critical proteins in the cell. This review focuses on ncRNAs that 
are differently expressed in malignant tissue, and discusses some of challenges 
derived from their use as potential biomarkers of tumor properties.