Inhibitory effect of miR-183 on MCM family members

MYCN and HDAC2 jointly repress the transcription of tumor suppressive micro RNA miR-183 in neuroblastoma. Enforced miR-183 expression induces neuroblastoma cell death and inhibits anchorage-independent colony formation and subcutaneous xenograft growth in mice. We here aimed to unravel the miR-183 signaling network and elucidated the role of MYCN mediated transcriptional activation of members of the minichromosome maintenance (MCM) family protein family involving miR-183 . The hexamer protein complex formed by MCM proteins is involved in the initiation and elongation of eukaryotic genome replication, thereby contributing to genomic integrity. Analysis of miR-183 versus negative control transfected neuroblastoma cells identified 85 differentially expressed proteins in a label-free mass spectrometric approach. Six members of the MCM family were found to be lower expressed upon enforced miR-183 expression, and subsequent annotation category enrichment analysis revealed a 14-fold enrichment in the protein module category “MCM”. Down-regulation was confirmed by western blot analysis. MicroRNA target prediction software studies revealed that miR-183 was predicted to directly target several MCMs.