Abolfazl Nosrati Tirkani - Department Of Medical Biochemistry, School Of Medicine, Mashhad University Of Medical Sciences, Mashhad, Iran
Dadiaa Boroumand - Department Of Biochemistry, Faculty Of Medicine, Mashhad University Of Medical Sciences, Mashhad, Iran
Maliheh Ahmadinejad - Department Of Biotechnology, Faculty Of Agriculture, University Of Zabol, Zabol, Iran
Daryush Hamidi Alamdari - Biochemistry And Nutrition Research Center, Faculty Of Medicine, Mashhad University Of Medical Sciences, Mashhad, Iran

Breast cancer is the second cancer-related death, the most common carcinoma among womenworldwide, developing about 1.6 million people in 2015 and 230,000 new cases will be added eachyear. According to histological studies, breast cancer is divided into non-invasive and invasivecarcinoma, both of them subdivided in ductal and lobular. Diverse risk factors are involved inbreast cancer progression, among them genetic background is known as an unchangeable risk factorand used as a marker for early diagnosis and/or prognosis. Several studies have shown thederegulation of microRNAs and genomic changes in human breast cancer. Also, it has been proventhat a number of microRNAs express differently in breast tumor. MicroRNAs (miRNAs) are a class ofsingle-strained non-coding RNA molecules containing 20-22 nucleotides which have a key role inpost-transcriptional gene expression regulation. The miRNAs which are found in organized nucleuscontaining DNA, generally transcribed by RNA polymerase II and III that characterized by thehairpin structure. The function of miRNAs in human is complicated and largely unknown. ThemiRNAs are involved in biological activities such as cell cycle regulation and bacterial division, celldevelopment and differentiation and inactivation of human X-chromosome. Deregulation ofmiRNAs and related enzymes severally described in onset, progression, and diagnosis of diseasesand cancers.In different cancers, the miRNAs play the main role in tumor secretion and initiation,tumor cell division and metastasis. In breast cancer, the platform of miRNAs is different with thehealthy group and between breast cancer sub-types with clinical implications. A number of miRNAsexpression are associated with tumor sub-type and coordinated with stage and severance of thecarcinoma. In this regard, this paper will focus on the role of microRNAs in breast cancer prognosisand diagnosis and will review the possible changes in the expression platforms of microRNAs whichare clinically correlated with breast cancer. It has been confirmed that miRNAs play a key role invarious cancers including breast cancer, by regulation expression of a wide range of genes of a cell.Therefore, a comprehensive perspective of possible changes in the expression platforms ofmicroRNAs and their roles in breast cancer progression will greatly aid in early detection andmanagement of breast cancer.