MicroRNAs in Epithelial Mesenchymal Transition and Breast Cancer Progression

Breast cancer remains a serious public health issue despite early diagnosis and aggressive treatment. This chapter discusses the molecular mechanism by which epithelial mesenchymal transition (EMT) occurs and its implication for metastasis. The chapter also discusses how the different subsets, including cancer stem cells, contribute to cancer evasion and resistance, through dormancy. Included in the discussion are studies on mesenchymal stem cells as protection for the cancer cells from immune clearance. We reviewed the growing information on microRNA (miRNA) in the cellular mechanisms of EMT and its role in facilitating metastasis and/or dormancy of the cancer cells. Overall, this chapter provides a “snapshot” of EMT and miRNA in breast cancer dormancy and metastasis.