MicroRNA and colorectal cancer.

Colorectal cancer is still the third most common cancer in the world. Its carcinogenesis has been extensively studied at a molecular point of view, and has recently entered the era of microRNAs, a class small non-coding RNAs that post-transcriptionally regulate gene expression and control various cellular mechanisms. Because they control biological processes that are implicated in carcinogenesis (as developmental transitions, organ morphology, apoptosis and cell proliferation), microRNAs have been linked to cancer development, and these molecules have been recently studied as new potential biomarkers to better characterise tumour prognosis and to predict response to the different active chemotherapy. This review summarizes the potential roles of microRNAs as potential biomarkers for colorectal cancer diagnosis, prognosis and drug-response prediction. Through the literature there is evidence that some microRNA could be used as biomarkers in colorectal cancer; however, there are some discrepancies amongst the different studies. These differences could partially due to heterogeneity between the different series associated with tumour stage, tumour location, genetic background of the tumours and technical issues. More progress is needed before microRNAs can be used in clinical practice. Accumulation of further data will allow to determine the most relevant microRNAs as biomarkers and also to better understand their role in colorectal carcinogenesis.