MicroRNA: A New Player in Breast Cancer Development

Breast cancer is the leading cause of death in women in North America. The etiology of breast cancer is complex, and genetic background and environmental factors are believed to contribute to the complexities. Over the past decades, a large body of literature has demonstrated that gene expression profile may be a useful tool to define the signature of cancer and predict the prognosis or response to treatment. Recently, microRNA (miRNA) expression profile calls a great attention to define various types of cancers. miRNAs are small non-coding RNAs that bind to the 3 ' untranslated region of target mRNAs and down-regulate their translation to protein or degrade the mRNAs. miRNAs play critical roles in many different cellular processes including metabolism, apoptosis, differentiation, and development. They are also linked to human diseases, including cancer. In this paper, we discuss the recent miRNA studies in breast cancer and provide a summary of the literatures focusing on miRNA signalling pathways and their potential involvement in breast cancer development