Early targets of miR-34a in neuroblastoma.

Several genes encoding for proteins involved in proliferation, invasion, and apoptosis are known to be direct miR-34a targets. Here, we used proteomics to screen for targets of miR-34a in neuroblastoma (NBL), a childhood cancer that originates from precursor cells of the sympathetic nervous system. We examined the effect of miR-34a overexpression using a tetracycline inducible system in two NBL cell lines (SHEP and SH-SY5Y) at early time points of expression (6, 12, and 24 h). Proteome analysis using post-metabolic labeling led to the identification of 2,082 proteins, and among these 186 were regulated (112 proteins down-regulated and 74 up-regulated). Prediction of miR-34a targets via bioinformatics showed that 32 transcripts held miR-34a seed sequences in their 3'-UTR. By combining the proteomics data with Kaplan Meier gene-expression studies, we identified seven new gene products (ALG13, TIMM13, TGM2, ABCF2, CTCF, Ki67, and LYAR) that were correlated with worse clinical outcomes. These were further validated in vitro by 3'-UTR seed sequence regulation. In addition, Michigan Molecular Interactions searches indicated that together these proteins affect signaling pathways that regulate cell cycle and proliferation, focal adhesions, and other cellular properties that overall enhance tumor progression (including signaling pathways such as TGF-ß, WNT, MAPK, and FAK). In conclusion, proteome analysis has here identified early targets of miR-34a with relevance to NBL tumorigenesis. Along with the results of previous studies, our data strongly suggest miR-34a as a useful tool for improving the chance of therapeutic success with NBL.

A therapeutic approach to treat prostate cancer by targeting Nm23-H1/h-Prune interaction.

Nm23-H1 is a metastasis suppressor gene whose overexpression is associated with both reduced cell motility in various cancers and increased metastatic potential in neuroblastomas, osteosarcomas, and hematological malignances. We previously reported that Nm23-H1 exerts tumor suppressor action in prostate cancer cells and that h-Prune, which is overexpressed in various tumor types, binds Nm23-H1. Moreover, blockage of the Nm23-H1/h-Prune interaction with a competitive permeable peptide (CPP) attenuates migration of breast and neuroblastoma cells. This series of events suggests that the Nm23-H1/h-Prune protein complex regulates cancer progression and that its specific impairment could be a new therapeutic strategy in oncology. We found that CPP leads to inhibition of the AKT/mTORv and NF-kBv signaling pathways and also activates apoptosis. To obtain a proof-of-concept of our hypothesis, we used a xenograft model of prostate cancer to evaluate whether impairment of this complex using CPP results in an anti-tumoral effect. Using a mouse orthotopic model with bioluminescent imaging, we show evidences that CPP reduces prostate cancer metastases formation. In conclusion, CPP being able to impair formation of the h-Prune/Nm23-H1 complex holds promise for the treatment of prostate cancer.