Marianeve Carotenuto

MiR-34a Targeting of Notch Ligand Delta-Like 1 Impairs CD15+/CD133+ Tumor-Propagating Cells and Supports Neural Differentiation in Medulloblastoma

Background Through negative regulation of gene expression, microRNAs (miRNAs) can function as oncosuppressors in cancers, and can themselves show altered expression in various tumor types. Here, we have investigated medulloblastoma tumors (MBs), which arise from an early impairment of developmental processes in the cerebellum, where Notch signaling is involved in many of the cell-fate-determining stages. Notch regulates a subset of MB cells that have stem-cell-like properties and can promote tumor growth. On the basis of this evidence, we hypothesized that miRNAs targeting the Notch pathway can regulate these phenomena, and can be used in anti-cancer therapies. Methodology/Principal Findings In a screening of potential targets within Notch signaling, miR-34a was seen to be a regulator of the Notch pathway through its targeting of Notch ligand Delta-like 1 (Dll1). Down-regulation of Dll1 expression by miR-34a negatively regulates cell proliferation, and induces apoptosis and neural differentiation in MB cells. Using an inducible tetracycline on-off model of miR-34a expression, we show that in Daoy MB cells, Dll1 is the first target that is regulated in MB, as compared to the other targets analyzed here: Cyclin D1, cMyc and CDK4. MiR-34a expression negatively affects CD133+/CD15+ tumor-propagating cells, then we assay through reverse-phase proteomic arrays, Akt and Stat3 signaling hypo-phosphorylation. Adenoviruses carrying the precursor miR-34a induce neurogenesis of tumor spheres derived from a genetic animal model of MB (Patch1+/- p53-/-), thus providing further evidence that the miR-34a/Dll1 axis controls both autonomous and non autonomous signaling of Notch. In vivo, miR-34a overexpression carried by adenoviruses reduces tumor burden in cerebellum xenografts of athymic mice, thus demonstrating an anti-tumorigenic role of miR-34a in vivo. Conclusions/Significance Despite advances in our understanding of the pathogenesis of MB, one-third of patients with MB remain incurable. Here, we show that stable nucleic-acid-lipid particles carrying mature miR-34a can target Dll1 in vitro and show equal effects to those of adenovirus miR-34a cell infection. Thus, this technology forms the basis for their therapeutic use for the delivery of miR-34a in brain-tumor treatment, with no signs of toxicity described to date in non-human primate trials.

Norcantharidin impairs medulloblastoma growth by inhibition of Wnt/β-catenin signaling

Medulloblastoma is one of the leading causes of morbidity and mortality in pediatric cancer. Wnt-active tumors, an independent molecular subgroup in medulloblastoma, are characterized by a distinct pattern of genomic aberrations. We assessed the anticancer activity of cantharidin and norcantharidin against medulloblastoma, as cell lines in vitro and in athymic nude mice in vivo. Cantharidin and norcantharidin treatment impaired the growth of DAOY and UW228 medulloblastoma cells and promoted the loss of β-catenin activation and the β-catenin nuclearization linked to N-cadherin impairment in vitro. Intra-peritoneal administration of norcantharidin inhibited the growth of intra-cerebellum tumors in orthotopic xenograft nude mice. Analysis of the xenograft tissues revealed enhanced neuronal differentiation and reduced β-catenin expression. Our findings suggest that norcantharidin has potential therapeutic applications in the treatment of medulloblastoma as a result of its ability to cross the blood–brain barrier and its impairment of Wnt-β-catenin signaling.

PRUNE is crucial for normal brain development and mutated in microcephaly with neurodevelopmental impairment

Zollo et al. report that mutations in PRUNE1, a phosphoesterase superfamily molecule, underlie primary microcephaly and profound global developmental delay in four unrelated families from Oman, India, Iran and Italy. The study highlights a potential role for prune during microtubule polymerization, suggesting that prune syndrome may be a tubulinopathy.

MicroRNA 199b-5p delivery through stable nucleic acid lipid particles (SNALPs) in tumorigenic cell lines.

MicroRNA (miR)-199b-5p has been shown to regulate Hes-1, a downstream effector of the canonical Notch and noncanonical SHH pathways, whereby it impairs medulloblastoma (MB) cancer stem cells (CSCs) through a decrease in the CD133+/CD15+ cell population. Here, we have developed stable nucleic acid lipid particles (SNALPs) that encapsulate miR-199b-5p. The efficacy of the miR-199b-5p delivery by these SNALPs is demonstrated by significant impairment of Hes-1 levels and CSC markers in a range of different tumorigenic cell lines: colon (HT-29, CaCo-2, and SW480), breast (MDA-MB231T and MCF-7), prostate (PC-3), glioblastoma (U-87), and MB (Daoy, ONS-76, and UW-228). After treatment with SNALP miR-199b-5p, there is also impairment of cell proliferation and no signs of apoptosis, as measured by caspases 3/7 activity and annexin V fluorescence cell sorter analyses. These data strengthen the importance of such carriers for miRNA delivery, which show no cytotoxic effects and provide optimal uptake into cells. Thus, efficient target downregulation in different tumorigenic cell lines will be the basis for future preclinical studies.

Neuroblastoma tumorigenesis is regulated through the Nm23-H1/h-Prune C-terminal interaction

Nm23-H1 is one of the most interesting candidate genes for a relevant role in Neuroblastoma pathogenesis. H-Prune is the most characterized Nm23-H1 binding partner, and its overexpression has been shown in different human cancers. Our study focuses on the role of the Nm23-H1/h-Prune protein complex in Neuroblastoma. Using NMR spectroscopy, we performed a conformational analysis of the h-Prune C-terminal to identify the amino acids involved in the interaction with Nm23-H1. We developed a competitive permeable peptide (CPP) to impair the formation of the Nm23-H1/h-Prune complex and demonstrated that CPP causes impairment of cell motility, substantial impairment of tumor growth and metastases formation. Meta-analysis performed on three Neuroblastoma cohorts showed Nm23-H1 as the gene highly associated to Neuroblastoma aggressiveness. We also identified two other proteins (PTPRA and TRIM22) with expression levels significantly affected by CPP. These data suggest a new avenue for potential clinical application of CPP in Neuroblastoma treatment.

Epilepsy in the setting of full trisomy 18: A multicenter study on 18 affected children with and without structural brain abnormalities

This paper reports on the clinical aspects, electroencephalographic (EEG) features, and neuroimaging findings in children with full trisomy 18 and associated epilepsy, and compares the evolution and outcome of their neurological phenotype. We retrospectively studied 18 patients (10 males and 8 females; aged 14 months to 9 years) with full trisomy 18 and epilepsy. All patients underwent comprehensive assessment including neuroimaging studies of the brain. We divided patients into two groups according to neuroimaging findings: (Group 1) 10 patients harboring structural brain malformations, and (Group 2) 8 patients with normal brain images. Group 1 had a significantly earlier age at seizure onset (2 months) compared to Group 2 (21 months). The seizure semiology was more severe in Group 1, who presented multiple seizure types, need for polytherapy (80% of patients), multifocal EEG abnormalities and poorer outcome (drug resistant epilepsy in 90% of patients) than Group 2 who presented a single seizure type, generalized or focal, and non‐specific EEG pattern; these patients were successfully treated with monotherapy with good outcome. Imaging revealed a wide and complex spectrum of structural brain abnormalities including anomalies of the commissures, cerebellar malformations, cortical abnormalities, and various degrees of cortical atrophy. Epilepsy in full trisomy 18 may develop during the first months of life and can be associated with structural brain malformations. Patients with brain malformations can show multiple seizure types and can frequently be resistant to therapy with antiepileptic drugs.

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-β, 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.

Mapping Functional Interaction Sites of Human Prune C‐Terminal Domain by NMR Spectroscopy in Human Cell Lysates

Get well prune: The C-terminal third domain of h-prune is largely unfolded and involved in relevant protein-protein interactions, particularly with Nm23-H1 (see figure), GSK-3β and gelsolin. This study shows that protein functions mediated by protein-protein interactions can be accurately followed in cell lysates by using fast NMR spectroscopy, which could be easily used for a very efficient NMR drug-discovery strategy.

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.