MicroRNAs in neuroblastoma: small-sized players with a large impact.

Neuroblastoma, a malignant embryonal tumor of the sympathetic nervous system, is the most common solid extracranial malignancy of childhood and accounts for 15 % of all childhood cancer deaths. The biological behavior of neuroblastoma is extensively heterogeneous, ranging from spontaneous regression to rapid progression despite multimodal aggressive therapy. Although the molecular basis of neuroblastoma has received considerable attention over the past decade, elucidating the mechanisms for the aggressive progression of neuroblastoma is needed for improving the efficacy of treatment. miRNAs (microRNAs) are small non-coding RNA molecules generally 19-22 nucleotides in length. miRNAs regulate 60 % of human gene expression at the post-transcriptional level by targeting regions of sequence complementarity on the 3'-untranslated regions (3'-UTRs) of specific mRNAs. miRNAs can either cause degradation of mRNAs or can inhibit their translation and therefore play major roles in normal growth and development. miRNA dysregulation has oncogenic or tumor-suppressive functions in virtually all forms of cancer, including neuroblastoma. The present review highlights the current insights on dysregulated miRNAs in neuroblastoma and on their roles in the diagnosis, prognosis, and treatment of this malignancy. As a rapidly evolving field of basic and biomedical sciences, miRNA research holds a great potential to impact on the management of neuroblastoma.