MicroRNA and Breast Cancer

MicroRNAs (miRNAs) are a group of short non-coding RNAs which regulate protein-coding gene expression and often actbypairing withcomplementarysequences in the 3’ UTR of multiple target mRNA. MicroRNAs were discovered in 1993 and play very important and broad roles in different organisms. It was initially thought that the genes encoding miRNAswere located in intergenic regions. However، recent analyses of miRNA gene locations showed that the most of mammalian miRNA genes are located in defined transcription units (TUs) and transcribed by RNA polymerase II. Transcription product must be processed to become mature miRNA and ultimately effectson gene expression. The miRNA deregulation in breast cancer was first reported in 2005. Epigenetic، chromosomal changes، polymorphismsoradefect inproteinprocessing are the mechanismsthat maybecausingthelack ofproperexpression of mi RNA in cancers. In fact، these RNAs may act as oncogene or tumor suppressor. Scientistsarenow tryingtomakethediagnosis andclassificationofcancer usingmiRNA، and arealso usedinthe treatment. They have alsoachievedinthesefieldsto succeed.