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Isolation, Propagation, and Prion Protein Expression During Neuronal Differentiation of Human Dental Pulp Stem Cells

Bioethical issues related to the manipulation of embryonic stem cells have hindered advances in the field of medical research. For this reason, it is very ...

Sabina Universitas - Rieti University Hub

Sapienza University of Rome

Several studies demonstrated that cannabinoids reduce tumor growth, inhibit angiogenesis, and decrease cancer cell migration. As these molecules are well tolerated, it would be interesting to investigate the potential benefit of newly synthesized compounds, binding cannabinoid receptors (CBRs). In this study, we describe the synthesis and biological effect of 2-oxo-1,8-naphthyridine-3-carboxamide derivative LV50, a new compound with high CB2 receptor (CB2R) affinity. We demonstrated that it decreases viability of Jurkat leukemia cells, evaluated by Trypan Blue and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), but mainly induces a proapoptotic effect. We observed an increase of a hypodiploid peak by propidium iodide staining and changes in nuclear morphology by Hoechst 33258. These data were confirmed by a significant increase of Annexin V staining, cleavage of the nuclear enzyme poly(ADP-ribose)-polymerase (PARP), and caspases activation. In addition, in order to exclude that LV50 non-specifically triggers death of all normal leukocytes, we tested the new compound on normal peripheral blood lymphocytes, excluding the idea of general cytotoxicity. To characterize the involvement of CB2R in the anti-proliferative and proapoptotic effect of LV50, cells were pretreated with a specific CB2R antagonist and the obtained data showed reverse results. Thus, we suggest a link between inhibition of cell survival and proapoptotic activity of the new compound that elicits this effect as selective CB2R agonist.

Anti-Proliferative Properties and Proapoptotic Function of New CB2 Selective Cannabinoid Receptor Agonist in Jurkat Leukemia Cells.

Human Dental Pulp Stem Cells (hDPSCs) represent a type of adult mesenchymal stem cells that have the ability to differentiate in vitro in several lineages such as odontoblasts, osteoblasts, chondrocytes, adipocytes and neurons. In the current work, we used hDPSCs as the experimental model to study the role of recombinant prion protein 23⁻231 (recPrP) in the neuronal differentiation process, and in the signal pathway activation of ERK 1/2 and Akt. We demonstrated that recPrP was able to activate an intracellular signal pathway mediated by extracellular-signal-regulated kinase 1 and 2 (ERK 1/2) and protein kinase B (Akt). Moreover, in order to understand whether endogenous prion protein (PrP) was necessary to mediate the signaling induced by recPrP, we silenced PrP, demonstrating that the presence of endogenous PrP was essential for ERK 1/2 and Akt phosphorylation. Since endogenous PrP is a well-known lipid rafts component, we evaluated the role of these structures in the signal pathway induced by recPrP. Our results suggest that lipid rafts integrity play a key role in recPrP activity. In fact, lipid rafts inhibitors, such as fumonisin B1 and MβCD, significantly prevented ERK 1/2 and Akt phosphorylation induced by recPrP. In addition, we investigated the capacity of recPrP to induce hDPSCs neuronal differentiation process after long-term stimulation through the evaluation of typical neuronal markers expression such as B3-Tubulin, neurofilament-H (NFH) and growth associated protein 43 (GAP43). Accordingly, when we silenced endogenous PrP, we observed the inhibition of neuronal differentiation induced by recPrP. The combined data suggest that recPrP plays a key role in the neuronal differentiation process and in the activation of specific intracellular signal pathways in hDPSCs.

Cellular and Molecular Mechanisms Mediated by recPrP Involved in the Neuronal Differentiation Process of Mesenchymal Stem Cells.

Therapies against glioblastoma (GBM) show a high percentage of failure associated with the survival of glioma stem cells (GSCs) that repopulate treated tumours. Forced differentiation of GSCs is a promising new approach in cancer treatment. Erythropoietin-producing hepatocellular (Eph) receptors drive tumourigenicity and stemness in GBM. We tested GLPG1790, a first small molecule with inhibition activity versus inhibitor of various Eph receptor kinases, in preclinical GBM models using in vitro and in vivo assays. GLPG1790 rapidly and persistently inhibited Ephrin-A1-mediated phosphorylation of Tyr and Ser, completely blocking EphA2 receptor signalling. Similarly, this compound blocks the ephrin B2-mediated EphA3 and EphB4 tyrosine phosphorylation. This resulted in anti-glioma effects. GLPG1790 down-modulated the expression of mesenchymal markers CD44, Sox2, nestin, octamer-binding transcription factor 3/4 (Oct3/4), Nanog, CD90, and CD105, and up-regulated that of glial fibrillary acidic protein (GFAP) and pro-neural/neuronal markers, βIII tubulin, and neurofilaments. GLPG1790 reduced tumour growth in vivo. These effects were larger compared to radiation therapy (RT; U251 and T98G xenografts) and smaller than those of temozolomide (TMZ; U251 and U87MG cell models). By contrast, GLPG1790 showed effects that were higher than Radiotherapy (RT) and similar to Temozolomide (TMZ) in orthotopic U87MG and CSCs-5 models in terms of disease-free survival (DFS) and overall survival (OS). Further experiments were necessary to study possible interactions with radio- and chemotherapy. GLPG1790 demonstrated anti-tumor effects regulating both the differentiative status of Glioma Initiating Cells (GICs) and the quality of tumor microenvironment, translating into efficacy in aggressive GBM mouse models. Significant common molecular targets to radio and chemo therapy supported the combination use of GLPG1790 in ameliorative antiglioma therapy.

The Small Molecule Ephrin Receptor Inhibitor, GLPG1790, Reduces Renewal Capabilities of Cancer Stem Cells, Showing Anti-Tumour Efficacy on Preclinical Glioblastoma Models.

Stefano Martellucci

Laboratory of Experimental Medicine and Environmental Pathology

Sabina Universitas - Rieti University Hub

Isolation, Propagation, and Prion Protein Expression During Neuronal Differentiation of Human Dental Pulp Stem Cells

Stefano Martellucci

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Laboratory of Experimental Medicine and Environmental Pathology

Sabina Universitas - Rieti University Hub

Isolation, Propagation, and Prion Protein Expression During Neuronal Differentiation of Human Dental Pulp Stem Cells

Laboratory of Experimental Medicine and Environmental Pathology