microRNAs are small ~22 nucleotide non-coding RNAs that can bind protein coding mRNAs through complimentary base pairing to mediate mRNA decay or translational repression. Because a single microRNA can bind and silence hundreds of genes across diverse signaling pathways they can be developed as powerful therapeutic agents to silence entire disease networks. We have evidence to suggest that the mir-140-5p microRNA that is suppressed by MYCN in neuroblastoma cells expressing high levels of MYCN can when introduced as a synthetic mimic can significantly suppress cell proliferation, clonogenicty of neuroblastoma cell lines and in vivo tumor growth in an orthotopic mouse model of neuroblastoma. Our work is currently focused on developing this microRNA family as an alternative or complement to small molecule inhibitors for cancer treatment.