Benedetta Nicolini

Selective apoptosis of monocytes and monocyte-derived DCs induced by bortezomib (Velcade)

Bortezomib, a proteasome inhibitor, has shown immunosuppressive activity in animal models of GVHD. In this study, we evaluated the effects of Bortezomib on the survival of monocytes, a major circulating source of DCs. PBMCs or purified CD14+ monocytes were cultured for 24 h with Bortezomib (0.1–100 ng/ml). Apoptosis was demonstrated on the basis of detection of phosphatydilserine. Bortezomib induced a significant dose-dependent depletion (P=0.008) of monocytes in PBMC preparations, with <1% CD14+ cells remaining at doses ⩾5 ng/ml. Moreover, Bortezomib decreased the survival of purified monocytes within 24 h (P=0.004) (n=6). Monocyte loss was due to apoptosis (effective dose 50%, ED50, 1–10 ng/ml). In addition, both immature and mature monocyte-derived DC underwent apoptosis following exposure to Bortezomib. Kinetic experiments showed that apoptosis increased at 16 h through 24 h of culture. However, short term (4 h) incubation with Bortezomib irreversibly committed monocytes to undergo apoptosis at 24, 72 and 144 h. Instead, Bortezomib induced no apoptosis of purified CD19+ B, CD3+ T lymphocytes and CD34+ progenitor cells (ED50 >50 ng/ml). The inhibitory effect of Bortezomib on professional APCs, such as monocytes and DCs, suggests its possible use in GVHD prophylaxis.

Novel PLA microspheres with hydrophilic and bioadhesive surfaces for the controlled delivery of fenretinide

Abstract Novel polylactide (PLA) microspheres endowed with hydrophilic and bioadhesive surfaces as injectable formulations for the controlled release of fenretinide were prepared, using a novel technique based on the co-precipitation of PLA with gelatin, at the interface of a liquid dispersion formed by the addition of N-methylpyrrolidone containing PLA and dextrin (DX), towards an aqueous solution of gelatin (G). The resulting PLA–G–DX microspheres were compared with others prepared by the same technique using polylactide-co-glycolide (PLGA), with or without DX, and with or without phosphatidylcholine. Of the different systems, the PLA–G–DX microspheres had the best morphological, dimensional and functional characteristics. They had the highest drug loading, and their drug release was the most efficient over time without any burst effect. Their in vitro anti-tumoural activity was strongly enhanced with respect to the pure fenretinide. This paralleled the increased drug concentration inside the cells due to their marked bioadhesion to the tumour cell membranes as indicated by scanning electron microscope images.

Synthetic polyamines activating autophagy: Effects on cancer cell death

The ability of symmetrically substituted long chain polymethylene tetramines, methoctramine (1) and its analogs 2-4 to kill cancer cells was studied. We found that an elevated cytotoxicity was correlated with a 12 methylene chain length separating the inner amine functions (6-12-6 carbon backbone), together with the introduction of diphenylethyl moieties on the terminal nitrogen atoms (compound 4) of a tetramine backbone. Compound 4 triggered dissipation of mitochondrial transmembrane potential and increased intracellular peroxide levels, leading to a caspase-independent HeLa cell death associated with a rapid activation of autophagy. The antioxidant N-acetylcysteine inhibited cell death and activation of autophagy, indicating a link between oxidative stress and autophagy. Autophagy was rapidly triggered even by tetramines 2 and 3, indicating that is related to their polyamine structure. Autophagy did not protect HeLa cells against cytotoxicity elicited by compound 4. The present study shows that, by modifications of the methoctramine structure, it is possible to design polyamine derivatives highly cytotoxic against tumor cells and that the appropriate design of molecules bearing polyamine-like structures leads to powerful inducers of autophagy.

Combined inhibition of the EGFR/AKT pathways by a novel conjugate of quinazoline with isothiocyanate

Epidermal growth factor receptor inhibitors (EGFR-TKIs) represent a class of compounds widely used in anticancer therapy. An increasing number of studies reports on combination therapies in which the block of the EGFR-TK activity is associated with inhibition of its downstream pathways, as PI3K-Akt. Sulforaphane targets the PI3K-Akt pathway whose dysregulation is implicated in many functions of cancer cells. According to these considerations, a series of multitarget molecules have been designed by combining key structural features derived from an EGFR-TKI, PD168393, and the isothiocyanate sulforaphane. Among the obtained molecules 1-6, compound 6 emerges as a promising lead compound able to exert antiproliferative and proapoptotic effects in A431 epithelial cancer cell line by covalently binding to EGFR-TK, and reducing the phosphorylation of Akt without affecting the total Akt levels.

Gelatin crosslinked with dehydroascorbic acid as a novel scaffold for tissue regeneration with simultaneous antitumor activity

A porous scaffold was developed to support normal tissue regeneration in the presence of residual tumor disease. It was prepared by gelatin crosslinked with dehydroascorbic acid (DHA). A physicochemical characterization of the scaffold was carried out. SEM and mercury porosimetry revealed a high porosity and interconnection of pores in the scaffold. Enzymatic degradation provided 56% weight loss in ten days. The scaffold was also evaluated in vitro for its ability to support the growth of normal cells while hindering tumor cell development. For this purpose, primary human fibroblasts and osteosarcoma tumor cells (MG-63) were seeded on the scaffold. Fibroblasts attached the scaffold and proliferated, while the tumor cells, after an initial attachment and growth, failed to proliferate and progressively underwent cell death. This was attributed to the progressive release of DHA during the scaffold degradation and its cytotoxic activity towards tumor cells.

Quinazoline based α1-adrenoreceptor antagonists with potent antiproliferative activity in human prostate cancer cell lines

New α1-adrenoreceptor (α1-AR) antagonists related to prazosin and doxazosin were synthesized by replacing piperazine ring with (S)- or (R)-3-aminopiperidine. Binding studies indicated that the S configuration at the 3-C position of the piperidine ring is crucial for an optimal interaction of the compounds at all three α1-AR subtypes. Quinazolines 9 and 10, bearing a quinone ring on the lateral chain, exhibited also potent antiproliferative activity in LNCaP androgen-sensitive prostate cancer cell lines, higher than that of doxazosin. Compound 10 increased apoptosis, in terms of DNA fragmentation, without triggering cell necrosis. The prooxidant activity found in compound 10 may underlie its ability to inhibit cell proliferation in synergy with the effect mediated by α1-AR antagonism. Due to its better biological profile compared to doxazosin for LNCaP cell line, compound 10 might be a valuable lead compound for the design of new prostate antitumor agents.

Human hematopoietic CD34+ progenitor cells induce natural killer cell alloresponses via NKG2D activation

Human CD34+ cells cross-interact with allogeneic T lymphocytes. In this study we addressed the interaction between CD34+ cells and allogeneic natural killer (NK) cells. Purified NK cells were cultured with allogeneic KIR-permissive CD34+ or CD14+ blood cells, obtained from HLA group C homozygous donors, or with high-dose interleukin-2. A cytotoxicity assay was used to test the ability of NK cells to lyse NK-sensitive K562 or NK-resistant Daudi cells. Cytofluorometric assays were employed to assess cell phenotype and cytokine release. CD34+ cells induced greater lysis of K562 (p = 0.02) and Daudi cells (p = 0.01) than monocytes. CD34 cell stimulation resulted in upregulation of CD69 and CD25 on NK cells and in the production of interferon γ and tumor necrosis factor α. NK activation by CD34+ cells was inhibited by an anti-NKG2D antibody. However, NKG2D ligands such as MIC (MHC class I chain)-A/B and ULBP (UL16 binding protein)-1/3 were not detected on CD34+ cells. Cross-talk between NK and CD34+ cells also induced the upregulation of CD40 and CD86 co-stimulatory molecules on CD34+ cells. Our study indicates a direct NKG2D-dependent stimulatory effect of human CD34+ cells on allogeneic NK cells. These findings may be relevant to the NK-mediated rejection effect in HLA-mismatched hematopoietic stem cell transplantation.

DMP1 and DSP localization during in vitro odontoblast like cell differentiation

The aim of this study was to analyze the temporal and spatial localization of dentin matrix protein 1 (DMP1) and dentin sialoprotein (DSP) in human dental pulp cells differentiated in vitro towards odontoblast-like cells. Following to a notable injury to the tooth, the odontoblasts die and a new generation of odontoblast-like cells differentiate from pulp progenitor cells [1]. They are responsible for the secretion of the reparative dentin matrix. In this study, morphological changes and the analysis of DMP1 and DSP were investigated starting from human dental pulp cells differentiated in vitro. Alizarin red staining, transmission and scanning electron microscopy in combination with Real Time PCR and immunofluorescence techniques were performed to demonstrate the odontoblast-differentiated phenotype and the specific expression and localization of DMP1 and DSP. The results showed a gradual calcium deposition to demonstrate a mineralization matrix. Electron microscopy analysis showed fibroblast-like cells characterized by a large number of mitochondria and a developed rough endoplasmic reticulum and Golgi apparatus involved in intense protein synthesis. A large extracellular matrix was detectable in which collagen type I fibers were detected. The DMP1 and DSP showed low expression and nuclear localization at the beginning of the odontoblast-like cell differentiation. After 21 days, elevated cytoplasm expression was detectable for both odontogenic markers.