ABSTRACT
Colorectal cancer (CRC) is the third most common type of cancer worldwide, currently representing the most common gastrointestinal cancer with 13% of all malignant tumors. MicroRNAs (miRNAs) are small non-coding RNAs that repress the translation of target genes. Since their discovery, they have been shown to play an important role in the development of cancer, since they can act as tumor suppressors or oncogenes. A literature review was performed in different databases such as Medline, PubMed, Cochrane, nature, Wolters Kluwer, ScienceDirect, Scopus, SpringerLink, Wiley Online Library. Studies were included from 2003 to 2018. Colorectal cancer presents genetic heterogeneity, because it can develop in different ways, the pathway through which cancer occurs depends on the gene initially altered. The aberrant expression of microRNAs is implicated in the development of colorectal cancer and its progression. Three existing steps in the maturation of the microRNAs have been identified: 1) transcription of the pri-miRNA, 2) cleavage in the nucleus to form the pre-miRNA and 3) a final excision in the cytoplasm to form the mature microRNA. It has been discovered that miRNAs have an impact on cell proliferation, apoptosis, stress response, maintenance of stem cell potency and metabolism, all important factors in the etiology of cancer. The data analyzed in this article highlights the importance of the study of microRNAs in colorectal cancer, however, for the carcinogenic process, progression, therapeutic management and prognosis, more multicenter randomized clinical trials are needed with a detailed analysis.