Background: MetastamiRs have momentous clinical relevance and have been correlated with disease progression in many tumors. In this study, we identified neuroblastoma metastamiRs exploiting unique mouse models of favorable and high-risk metastatic human neuroblastoma. Further, we related their deregulation to the modulation of target proteins and established their association with clinical outcomes.
Results: Whole genome miRNA microarray analysis identified 74 metastamiRs across the manifold of metastatic tumors. RT-qPCR on select miRNAs validated profile expression. Results from bio-informatics across the ingenuity pathway, miRCancer, and literature data-mining endorsed the expression of these miRNAs in multiple tumor systems and showed their role in metastasis, identifying them as metastamiRs. Immunoblotting and TMA-IHC analyses revealed alterations in the expression/phosphorylation of metastamiRs' targets, including ADAMTS-1, AKT1/2/3, ASK1, AURKβ, Birc1, Birc2, Bric5, β-CATENIN, CASP8, CD54, CDK4, CREB, CTGF, CXCR4, CYCLIN-D1, EGFR, ELK1, ESR1, CFOS, FOSB, FRA, GRB10, GSK3β, IL1α, JUND, kRAS, KRTAP1, MCP1, MEGF10, MMP2, MMP3, MMP9, MMP10, MTA2, MYB, cMYC, NF2, NOS3, P21, pP38, PTPN3, CLEAVED PARP, PKC, SDF-1β, SEMA3D, SELE, STAT3, TLR3, TNFα, TNFR1, and VEGF in aggressive cells ex vivo and in a manifold of metastatic tumors in vivo. miRNA mimic (hsa-miR-125b, hsa-miR-27b, hsa-miR-93, hsa-miR-20a) and inhibitor (hsa-miR-1224-3p, hsa-miR-1260) approach for select miRNAs revealed the direct influence of the altered metastamiRs in the regulation of identified protein targets. Clinical outcome association analysis with the validated metastamiRs' targets corresponded strongly with poor overall and relapse-free survival.
Conclusions: For the first time, these results identified a comprehensive list of neuroblastoma metastamiRs, related their deregulation to altered expression of protein targets, and established their association with poor clinical outcomes. The identified set of distinctive neuroblastoma metastamiRs could serve as potential candidates for diagnostic markers for the switch from favorable to high-risk metastatic disease.