MicroRNAs in breast cancer and breast cancer stem cells and their potential for breast cancer therapy

The discovery of the first miRNA,lin-4,in Caenorhabditis elegans initiated a new era of miRNA biology.Since then,thousands of miRNAs have been identified and annotated,many of which have been shown to play roles in a variety of biological processes,including development,differentiation,apoptosis,proliferation,and cell death.1 Furthermore,growing evidence indicates that miRNA deregulation is a critical cause of cancer formation.The biogenesis,function,and potential application of miRNAs have become active areas of research.With the development of molecular biological technologies,such as northern blotting with radio-labeled probes,cloning,quantitative PCR,serial analysis of gene expression (SAGE)-based techniques,bead-based profiling methods,and oligonucleotide microarrays,2 it is possible to conduct miRNA research precisely and comprehensively.