Genetic unmasking of an epigenetically silenced microRNA in human cancer

LB-208MicroRNAs (miRNAs) are small noncoding RNAs that control a wide range of biological functions, such as cellular proliferation, differentiation and apoptosis. About half of the annotated human miRNAs map within fragile regions of chromosomes, associated with different human cancers. Furthermore, it has been shown that they can act as tumour suppressors or oncogenes. It is widely known that the promoter CpG island hypermethylation of tumour suppressor genes is a common event in cancer so we hypothesized that microRNAs could be regulated by epigenetic mechanisms.To address this issue, we analyzed the differential miRNA expression in a colon cancer cell line (HCT-116) and in a derived cell line (HCT-116 DKO, double knock out) in which two major DNA methyltransferases, DNMT1 and DNMT3b, had been genetically disrupted. Among the upregulated miRNAs found in the DNA methylation …