| Name | Luca |
| Surname | Colucci-D'Amato |
| Institution | Università degli Studi della Campania Luigi Vanvitelli |
| luca.colucci@unicampania.it | |
| Address | Department of Environmental, Biological, Pharmaceutical Science and Technology, "Luigi Vanvitelli", Caserta, Italy |
Angiogenesis is a phenomenon that includes different processes, such as endothelial cell proliferation, differentiation, and migration, that lead to the formation of new blood vessels and involve several signal transduction pathways. Here we show that the tube formation assay is a simple in vitro method to evaluate the impact of natural products on angiogenesis and to investigate the molecular mechanisms involved. In particular, in the presence of the water extract of Ruta graveolens (RGWE), endothelial cells are no longer able to form a cell-cell network and that the RGWE effects on human umbilical vein endothelial cell (HUVEC) tube formation is abolished by the constitutive activation of MEK.
Glioblastoma (GBM), a high-grade glioma (WHO grade IV), is the most aggressive form of brain cancer. Available treatment options for GBM involve a combination of surgery, radiation and chemotherapy but result in a poor survival outcome. GBM is a high-vascularized tumor and antiangiogenic drugs are widely used in GBM therapy as adjuvants to control abnormal vasculature. Vasculogenic mimicry occurs in GBM as an alternative vascularization mechanism, providing a means whereby GBM can escape anti-angiogenic therapies. Here, using an in vitro tube formation assay on Matrigel, we evaluated the ability of different histone deacetylase inhibitors (HDACis) to interfere with vasculogenic mimicry. We found that vorinostat (SAHA) and MC1568 inhibit tube formation by rat glioma C6 cells. Moreover, at sublethal doses for GBM cells, SAHA, trichostatin A (TSA), entinostat (MS275), and MC1568 significantly decrease tube formation by U87MG and by patient-derived human GBM cancer stem cells (CSCs). The reduced migration and invasion of HDACis-treated U87 cells, at least in part, may account for the inhibition of tube formation. In conclusion, our results indicate that HDACis are promising candidates for blocking vascular mimicry in GBM.
Differential DNA methylation defects of H19/IGF2 are associated with congenital growth disorders characterized by opposite clinical pictures. Due to structural differences between human and mouse, the mechanisms by which mutations of the H19/IGF2 Imprinting Control region (IC1) result in these diseases are undefined. To address this issue, we previously generated a mouse line carrying a humanized IC1 (hIC1) and now replaced the wildtype with a mutant IC1 identified in the overgrowth-associated Beckwith-Wiedemann syndrome. The new humanized mouse line shows pre/post-natal overgrowth on maternal transmission and pre/post-natal undergrowth on paternal transmission of the mutation. The mutant hIC1 acquires abnormal methylation during development causing opposite H19/Igf2 imprinting defects on maternal and paternal chromosomes. Differential and possibly mosaic Igf2 expression and imprinting is associated with asymmetric growth of bilateral organs. Furthermore, tissue-specific imprinting defects result in deficient liver- and placenta-derived Igf2 on paternal transmission and excessive Igf2 in peripheral tissues on maternal transmission, providing a possible molecular explanation for imprinting-associated and phenotypically contrasting growth disorders.
Angiogenesis is a process encompassing several steps such as endothelial cells proliferation, differentiation and migration to form a vascular network, involving different signal transduction pathways. Among these, ERK1/2 signaling mediates VEGF-dependent signaling pathway. Here we report that the water extract of Ruta graveolens (RGWE), widely known as a medicinal plant, is able to impair in a dose-dependent manner, cell network formation without affecting cell viability. Biochemical analysis showed that the major component of RGWE is rutin, unable to reproduce RGWE effect. We found that RGWE inhibits ERK1/2 phosphorylation and that this event is crucial in cell network formation since the transfection of HUVEC with a constitutively active MEK (caMEK), the ERK1/2 activator, induces a robust cell network formation as compared to untransfected and/or mock transfected cells and, more importantly, caMEK transfected cells became unresponsive to RGWE. Moreover, RGWE inhibits VEGF and nestin gene expression, necessary for vessel formation, and the caMEK transfection induces their higher expression. In conclusion, we report that RGWE is able to significantly impair vessels network formation without affecting cell viability, preventing ERK1/2 activation and, in turn, down-regulating VEGF and nestin expression. These findings point to RGWE as a potential therapeutic tool capable to interfere with pathologic angiogenesis.
Tryptophan hydroxylase 2 (TPH2) is the key enzyme in the synthesis of neuronal serotonin. Although previous studies suggest that TPH2 NRSE (neuron-restrictive silencer element) functions as a negative regulator dependent on NRSF (neuron-restrictive silencer factor) activity, the underlying mechanisms are yet to be fully elucidated. Here, we show a detailed analysis of the NRSE-mediated repression of the human TPH2 (hTPH2) promoter activity in RN46A cells, a cell line derived from rat raphe neurons. Quantitative real-time RT-PCR analysis revealed the expression of serotonergic marker genes (Mash1, Nkx2.2, Gata2, Gata3, Lmx1b, Pet-1, 5-Htt, and Vmat2) and Nrsf gene in RN46A cells. Tph1 mRNA is the prevalent form expressed in RN46A cells; Tph2 mRNA is also expressed but at a lower level. Electrophoretic mobility shift assays and reporter assays showed that hTPH2 NRSE is necessary for the efficient DNA binding of NRSF and for the NRSF-dependent repression of the hTPH2 promoter activity. The hTPH2 promoter activity was increased by knockdown of NRSF, or overexpression of the engineered NRSF (a dominant-negative mutant or a DNA-binding domain and activation domain fusion protein). MS-275, a class I histone deacetylase (HDAC) inhibitor, was found to be more potent than MC-1568, a class II HDAC inhibitor, in enhancing the hTPH2 promoter activity. Furthermore, treatment with the ubiquitin-specific protease 7 (USP7) deubiquitinase inhibitors, P-22077 or HBX 41108, increased the hTPH2 promoter activity. Collectively, our data demonstrate that the hTPH2 NRSE-mediated promoter repression via NRSF involves class I HDACs and is modulated by the USP7-mediated deubiquitination and stabilization of NRSF. This article is protected by copyright. All rights reserved.
Progranulin (GRN) gene mutations have been genetically associated with frontotemporal dementia (FTD) and are present in about 23% of patients with familial FTD. However, the neurobiology of this secreted glycoprotein remains unclear. Here, we report the identification of 3 pedigrees of Southern Italian extraction in whom FTD segregates with autosomal dominant inheritance patterns. We present evidence that all the available patients in these 3 familial cases are carrying the rare GRN gene exon 6 deletion g10325_10331delCTGCTGT (relative to nt 1 inNG_007886.1), alias Cys157LysfsX97. This mutation was previously described in 2 sporadic cases but was never associated with familial cases. Our patients demonstrate heterogeneous clinical phenotypes, such as the behavioral variant (bvFTD) in the affected men and the nonfluent/agrammatic variant of primary progressive aphasia (nfvPPA) in the affected woman. Haploinsufficiency was revealed by both quantitative real-time PCR of the gene and protein analyses. These findings provide further support for a previously proposed role for the GRN gene in the genetic etiology of FTD and its phenotypic variability.
We performed ultra-deep methylation analysis at single molecule level of the promoter region of developmentally regulated D-Aspartate oxidase (Ddo), as a model gene, during brain development and embryonic stem cell neural differentiation. Single molecule methylation analysis enabled us to establish the effective epiallele composition within mixed or pure brain cell populations. In this framework, an epiallele is defined as a specific combination of methylated CpG within Ddo locus and can represent the epigenetic haplotype revealing a cell-to-cell methylation heterogeneity. Using this approach, we found a high degree of polymorphism of methylated alleles (epipolymorphism) evolving in a remarkably conserved fashion during brain development. The different sets of epialleles mark stage, brain areas, and cell type and unravel the possible role of specific CpGs in favoring or inhibiting local methylation. Undifferentiated embryonic stem cells showed non-organized distribution of epialleles that apparently originated by stochastic methylation events on individual CpGs. Upon neural differentiation, despite detecting no changes in average methylation, we observed that the epiallele distribution was profoundly different, gradually shifting toward organized patterns specific to the glial or neuronal cell types. Our findings provide a deep view of gene methylation heterogeneity in brain cell populations promising to furnish innovative ways to unravel mechanisms underlying methylation patterns generation and alteration in brain diseases.
Activation of microglia is a central event in the atypical inflammatory response occurring during prion encephalopathies. We report that the prion protein fragment encompassing amino acids 90-231 (PrP90-231), a model of the neurotoxic activity of the pathogenic prion protein (PrP(Sc)), causes activation of both primary microglia cultures and N9 microglial cells in vitro. This effect was characterized by cell proliferation arrest and induction of a secretory phenotype, releasing prostaglandin E2 (PGE2) and nitric oxide (NO). Conditioned medium from PrP90-231-treated microglia induced in vitro cytotoxicity of A1 mesencephalic neurons, supporting the notion that soluble mediators released by activated microglia contributes to the neurodegeneration during prion diseases. The neuroinflammatory role of COX activity, and its potential targeting for anti-prion therapies, was tested measuring the effects of ketoprofen and celecoxib (preferential inhibitors of COX1 and COX2, respectively) on PrP90-231-induced microglial activation. Celecoxib, but not ketoprofen significantly reverted the growth arrest as well as NO and PGE2 secretion induced by PrP90-231, indicating that PrP90-231 pro-inflammatory response in microglia is mainly dependent on COX2 activation. Taken together, these data outline the importance of microglia in the neurotoxicity occurring during prion diseases and highlight the potentiality of COX2-selective inhibitors to revert microglia as adjunctive pharmacological approach to contrast the neuroinflammation-dependent neurotoxicity.
Glioblastoma multiforme is a highly aggressive brain tumor whose prognosis is very poor. Due to early invasion of brain parenchyma, its complete surgical removal is nearly impossible, and even after aggressive combined treatment (association of surgery and chemo- and radio-therapy) five-year survival is only about 10%. Natural products are sources of novel compounds endowed with therapeutic properties in many human diseases, including cancer. Here, we report that the water extract of Ruta graveolens L., commonly known as rue, induces death in different glioblastoma cell lines (U87MG, C6 and U138) widely used to test novel drugs in preclinical studies. Ruta graveolens' effect was mediated by ERK1/2 and AKT activation, and the inhibition of these pathways, via PD98058 and wortmannin, reverted its antiproliferative activity. Rue extract also affects survival of neural precursor cells (A1) obtained from embryonic mouse CNS. As in the case of glioma cells, rue stimulates the activation of ERK1/2 and AKT in A1 cells, whereas their blockade by pharmacological inhibitors prevents cell death. Interestingly, upon induction of differentiation and cell cycle exit, A1 cells become resistant to rue's noxious effects but not to those of temozolomide and cisplatin, two alkylating agents widely used in glioblastoma therapy. Finally, rutin, a major component of the Ruta graveolens water extract, failed to cause cell death, suggesting that rutin by itself is not responsible for the observed effects. In conclusion, we report that rue extracts induce glioma cell death, discriminating between proliferating/undifferentiated and non-proliferating/differentiated neurons. Thus, it can be a promising tool to isolate novel drugs and also to discover targets for therapeutic intervention.
Chemokines and cytokines, primarily known for their roles in the immune and inflammatory response, have also been identified as key components of the neurogenic niche where they are involved in the modulation of neural stem cell proliferation and differentiation. However, a complete understanding of the functional role played in neural differentiation and a comprehensive profiling of these secreted molecules are lacking. By exploiting the multiplexing capability of magnetic bead-based immunoassays, we have investigated the changes of the expression levels of a set of chemokines and cytokines released from the pluripotent neural cell line mes-c-myc A1 following its differentiation from a proliferating phenotype (A1P) toward a neural (A1D) phenotype. We found a subset of molecules exclusively released from A1P, whereas others were differentially detected in A1P and A1D conditioned media. Among them, we identified monocyte chemoattractant protein-1/chemokine ligand 2 (MCP-1/CCL2) as a proneurogenic factor able to affect neuronal differentiation of A1 cells as well as of neuroblasts from primary cultures and to induce the elongation and/or formation of neuritic processes. Altogether, data are suggestive of a main role played by the CCL2/CCR2 signaling pathway and in general of the network of secreted cytokines/chemokines in the differentiation of neural progenitor cells toward a neural fate.