Molecular and Cellular Changes in Breast Cancer and New Roles of lncRNAs in Breast Cancer Initiation and Progression

Breast cancer is not just one disease but many variations on a theme, comprising a variety of molecular subtypes with distinct etiologies, cellular origins, treatment strategies, and prognoses. Like mRNAs and microRNAs (miRNAs), long noncoding RNAs (lncRNAs) differ dramatically in expression across breast cancer subtypes and can be used for classification. While there has been considerable emphasis on miRNAs, our knowledge is still in its infancy about the role of lncRNAs that comprise the majority of the mammalian transcriptome. In this chapter, we will review the critical functions that lncRNAs play in breast cancer development and metastatic progression. We will conclude with a discussion of current and future approaches for RNA-targeted therapeutic intervention.