MicroRNA-184 inhibits neuroblastoma cell survival through targeting the serine/threonine kinase AKT2. Niamh H. Foley Isabella Bray Amanda Tivnan Kenneth Bryan Derek M. Murphy Patrick G. Buckley Jacqueline Ryan Anne O'Meara Maureen O'Sullivan Raymond L. Stallings 10779/rcsi.10767932.v1 https://repository.rcsi.com/articles/journal_contribution/MicroRNA-184_inhibits_neuroblastoma_cell_survival_through_targeting_the_serine_threonine_kinase_AKT2_/10767932 <p><strong>BACKGROUND: </strong>Neuroblastoma is a paediatric cancer of the sympathetic nervous system. The single most important genetic indicator of poor clinical outcome is amplification of the MYCN transcription factor. One of many down-stream MYCN targets is miR-184, which is either directly or indirectly repressed by this transcription factor, possibly due to its pro-apoptotic effects when ectopically over-expressed in neuroblastoma cells. The purpose of this study was to elucidate the molecular mechanism by which miR-184 conveys pro-apoptotic effects.</p> <p><strong>RESULTS: </strong>We demonstrate that the knock-down of endogenous miR-184 has the opposite effect of ectopic up-regulation, leading to enhanced neuroblastoma cell numbers. As a mechanism of how miR-184 causes apoptosis when over-expressed, and increased cell numbers when inhibited, we demonstrate direct targeting and degradation of AKT2, a major downstream effector of the phosphatidylinositol 3-kinase (PI3K) pathway, one of the most potent pro-survival pathways in cancer. The pro-apoptotic effects of miR-184 ectopic over-expression in neuroblastoma cell lines is reproduced by siRNA inhibition of AKT2, while a positive effect on cell numbers similar to that obtained by the knock-down of endogenous miR-184 can be achieved by ectopic up-regulation of AKT2. Moreover, co-transfection of miR-184 with an AKT2 expression vector lacking the miR-184 target site in the 3'UTR rescues cells from the pro-apoptotic effects of miR-184.</p> <p><strong>CONCLUSIONS:</strong> MYCN contributes to tumorigenesis, in part, by repressing miR-184, leading to increased levels of AKT2, a direct target of miR-184. Thus, two important genes with positive effects on cell growth and survival, MYCN and AKT2, can be linked into a common genetic pathway through the actions of miR-184. As an inhibitor of AKT2, miR-184 could be of potential benefit in miRNA mediated therapeutics of MYCN amplified neuroblastoma and other forms of cancer.</p> 2019-11-22 15:18:00 Apoptosis Blotting Western Cell Line Tumor Gene Expression Gene Expression Regulation Neoplastic Humans MicroRNAs Neuroblastoma Nuclear Proteins Oncogene Proteins Proto-Oncogene Proteins c-akt Reverse Transcriptase Polymerase Chain Reaction Transfection Cancer Genetics