Breast cancer stem cells programs: enter the (non)-code.

Breast tumors exhibit a hierarchical cellular organization driven by several subpopulations of cancer stem cells (CSCs). These breast CSC subpopulations are able to infinitely self-renew and to differentiate, giving rise to tumor heterogeneity. Accumulating evidence show that breast CSCs resist conventional therapies and i`nitiate tumor relapse. The development of anti-CSCs therapies may therefore greatly improve patient survival. A better elucidation of molecular circuitries involved in stemness would offer new relevant targets. Noncoding RNAs, especially microRNAs and long noncoding RNAs, are regulators of cell identity and are notably found deregulated in breast CSCs. This review will focus on noncoding RNAs involved in CSCs biology during breast cancer initiation, maintenance, therapeutic resistance and metastatic progression. Potential clinical applications using noncoding RNAs as biomarkers or therapies will be discussed.