MicroRNA Promoter Methylation in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide. The beginning and progression of the disease are thought to be determined by combinations of epigenetic and genetic changes that trigger multistep programs of carcinogenesis. In colorectal cancer, epigenetic alterations, in particular promoter CpG island methylation, occur more commonly than genetic mutations. Hyper-methylation contributes to carcinogenesis via inducing transcriptional silencing or down-regulation of tumor suppressor genes. DNA methylation alteration has a high potential for minimally invasive biomarker identification. Genome analysis has confirmed that microRNA expression is deregulated in most cancer types through several mechanisms, including failings in the microRNA biogenesis machinery. Moreover, microRNAs can be dysregulated by abnormal CpG methylation in cancer. Since it is believed that epigenetic changes occur in the early stages of the disease, these changes can be used for the early detection of cancer. In this review, we intend to study the role of microRNA gene promoter methylation in colorectal cancer.