Suggested roles for microRNA in tumors.

MicroRNAs are short non-coding RNA molecules encoded by distinct genes involved in the posttranscriptional regulation of gene expression. Forming part of the epigenetic machinery, microRNAs are involved in several aspects of tumorigenesis. Deregulation of microRNA expression is a common feature of tumors. Overexpressed oncogenic and underexpressed tumor suppressor microRNAs have been described in many different tumors. MicroRNAs are released from tumors that might affect other cells within and outside the tumor. Circulating microRNAs might also be involved in a tumor surveillance mechanism. In this short overview, some important aspects of microRNA in tumors are discussed.