MicroRNA regulatory network in human colorectal cancer.

Epigenetic modifications include DNA methylation, histone modifications, and noncoding RNAs containing microRNAs (miRNA). miRNAs are small noncoding RNAs that are 21 to 25 nt in length; they downregulate gene expression during cell development, cell proliferation, cell differentiation, and apoptosis. They play a critical role in human carcinogenesis. Presently, evidences show that miRNAs participate as oncogenic miRNAs or tumor suppressors in the developmental and physiological processes of human colorectal cancer (CRC). Disturbed miRNA expression may be attributable to a mechanism involving multiple factors. In this review, we focus on the colorectal miRNA expression profile and further discuss the miRNA regulatory network involved in the tumorigenesis of human CRC. We, thus, hope to open up new avenues for anticancer therapy based on the epigenetic regulation of miRNA.