Maria Turco

IKKγ protein is a target of BAG3 regulatory activity in human tumor growth

BAG3, a member of the BAG family of heat shock protein (HSP) 70 cochaperones, is expressed in response to stressful stimuli in a number of normal cell types and constitutively in a variety of tumors, including pancreas carcinomas, lymphocytic and myeloblastic leukemias, and thyroid carcinomas. Down-regulation of BAG3 results in cell death, but the underlying molecular mechanisms are still elusive. Here, we investigated the molecular mechanism of BAG3-dependent survival in human osteosarcoma (SAOS-2) and melanoma (M14) cells. We show that bag3 overexpression in tumors promotes survival through the NF-κB pathway. Indeed, we demonstrate that BAG3 alters the interaction between HSP70 and IKKγ, increasing availability of IKKγ and protecting it from proteasome-dependent degradation; this, in turn, results in increased NF-κB activity and survival. These results identify bag3 as a potential target for anticancer therapies in those tumors in which this gene is constitutively expressed. As a proof of principle, we show that treatment of a mouse xenograft tumor model with bag3siRNA-adenovirus that down-regulates bag3 results in reduced tumor growth and increased animal survival.

Kinetic modelling of nitric oxide reduction over a high-surface area V2O5-TiO2 catalyst

Abstract Selective nitric oxide reduction over a high-surface area V2O5-TiO2 catalyst was studied in the range 200–350°C, at different initial NH3/NO ratios and contact times, in the presence of excess oxygen. The experimental conversion-time data were compared with different kinetic models developed on the basis of information from the literature. In the temperature range examined, the results are consistent with a reaction mechanism involving the formation of a relatively stable nitrosamidic intermediate. At the highest temperatures, this reaction mechanism can degenerate into an Eley-Rideal mechanism. At T > 250°C, the inhibiting effect of water on the overall reaction rate was also quantitatively explained in terms of competitive adsorption on the active sites.

Decomposition of Hydrogen Peroxide on MnO2/TiO2 Catalysts

Catalysts containing 2-10 wt% MnO 2 supported on TiO 2 were examined for H 2 O 2 decomposition. Catalysts were prepared by impregnation of a high TiO 2 surface area. X-ray defraction patterns, scanning electron micrographs, and surface area measurements gave evidence of a uniform distribution of the active phase on the support surface and of the absence of segregated manganese oxides phases. Temperature programmed reduction measurements showed the presence, beside MnO 2 , of different Mn oxides species formed by interaction between the active phase and the support surface. The MnO 2 reducibility increased, whereas the mean oxidation state of manganese decreased with increasing manganese content. Catalytic tests were performed in a batch reactor with 50 or 70% concentration H 2 O 2 solutions. Catalytic activity was very high at the beginning of the tests and decreased with time, reaching a final constant value that increased with manganese content. Kinetic constants, evaluated assuming a first-order reaction rate, were comparable or higher than those of similar manganese-based catalysts. An optimal MnO 2 content was found, corresponding to the quite complete surface monolayer coverage. A reaction mechanism involving an Mn 4 + -Mn 3 + redox couple has been proposed.

High-mobility group A1 proteins are overexpressed in human leukaemias

High-mobility group A (HMGA) proteins are non-histone nuclear proteins that bind DNA and several transcription factors. They are involved in the regulation of chromatin structure and function. HMGA protein expression is low in normal adult tissues, but abundant during embryonic development and in several human tumours. Rearrangements of the HMGA genes have been frequently detected in human benign tumours of mesenchymal origin, e.g. lipomas, lung hamartomas and uterine leiomiomas. HMGA proteins have been implicated in the control of cell growth and differentiation of the pre-adipocytic cell line 3T3-L1. In an attempt to better understand the role of HMGA1 proteins in haematological neoplasias and in the differentiation of haematopietic cells, we have investigated their expression in human leukaemias and in leukaemic cell lines induced to terminal differentiation. Here we report HMGA1 overexpression in most fresh human leukaemias of different origin and in several leukaemic cell lines. Moreover, differentiation of three cell lines towards the megakaryocytic phenotype was associated with HMGA1 protein induction, whereas induction of erythroid and monocytic differentiation generally resulted in reduced HMGA1 expression.

Nuclear Factor-κB Regulates Inflammatory Cell Apoptosis and Phagocytosis in Rat Carrageenin-Sponge Implant Model

In the present study we investigated whether apoptosis and phagocytosis are regulated by nuclear factor (NF)-kappaB in a model of chronic inflammation. The subcutaneous implant of lambda-carrageenin-soaked sponges elicited an inflammatory response, characterized by a time-related increase of leukocyte infiltration into the sponge and tissue formation, which was inhibited by simultaneous injection of wild-type oligodeoxynucleotide decoy to NF-kappaB. Molecular and morphological analysis performed on infiltrated cells demonstrated: 1) an inhibition of NF-kappaB/DNA binding activity; 2) an increase of polymorphonuclear leukocyte apoptosis correlated either to an increase of p53 or Bax and decrease of Bcl-2 protein expression; and 3) an increase of phagocytosis of apoptotic polymorphonuclear leukocytes by macrophages associated with an increase of transforming growth factor-beta1 and decrease of tumor necrosis factor-alpha as well as nitrite/nitrate production. Our results, showing that blockade of NF-kappaB by oligodeoxynucleotide decoy increases inflammatory cell apoptosis and phagocytosis, may contribute to lead to new insights into the mechanisms governing the inflammatory process.

Vanadium oxide catalysts supported on laser-synthesized titania powders: Characterization and catalytic activity in the selective reduction of nitric oxide

Abstract Laser-activated pyrolysis was applied to the synthesis of ultrafine TiO2, producing a non porous monocrystalline material in anatase phase with high specific surface area and uniform particle size. This powder was used as support for the preparation of vanadia catalysts with different compositions by wet impregnation. The pure TiO2 and the vanadia catalysts were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform IR, X-ray photoelectron spectroscopy, ammonia temperature-programmed desorption and were tested in the reaction of nitric oxide reduction by ammonia. It has been proposed that two different VOx species formed in the submonolayer region: a VIV containing species which prevails up to 6 wt.-% V2O5 and a VV containing species which develops from 6 wt.-% V2O5 up to monolayer completion. The structure of these species has been hypothesized. A reaction scheme has been proposed to interpret the catalytic activity for the selective catalytic reduction (SCR) of NOx. The selectivity of catalysts for nitrogen is related to the prevalence of the VIV containing species.

β-Hairpin Peptide That Targets Vascular Endothelial Growth Factor (VEGF) Receptors DESIGN, NMR CHARACTERIZATION, AND BIOLOGICAL ACTIVITY

VEGF receptors have been the target of intense research aimed to develop molecules able to inhibit or stimulate angiogenesis. Based on the x-ray structure of the complex placental growth factor-VEGF receptor 1D2, we designed a VEGF receptor-binding peptide reproducing the placental growth factor β-hairpin region Gln87–Val100 that is involved in receptor recognition. A conformational analysis showed that the designed peptide adopts the expected fold in pure water. Moreover, a combination of NMR interaction analysis and cell binding studies were used to demonstrate that the peptide targets VEGF receptors. The VEGF receptor 1D2-interacting residues were characterized at the molecular level, and they correspond to the residues recognizing the placental growth factor sequence Gln87–Val100. Finally, the peptide biological activity was characterized in vitro and in vivo, and it showed a VEGF-like behavior. Indeed, the peptide activated VEGF-dependent intracellular pathways, induced endothelial cell proliferation and rescue from apoptosis, and promoted angiogenesis in vivo. This compound is one of the few peptides known with proangiogenic activity, which makes it a candidate for the development of a novel peptide-based drug for medical applications in therapeutic angiogenesis.

TPD study of NH3 adsorbed by different phases of zirconium phosphate

Abstract Thermodesorption of NH 3 has been used to measure the acidity of α-zirconium hydrogen phosphate and different phases obtained from this material by thermal treatments. It was found that samples treated at temperatures lower than 300 °C, consisting of hydrated or anhydrous α-phases, adsorbed an amount of ammonia corresponding almost to neutralization of all acidic -POH groups and formation of a well-characterized diammonium phase. Samples treated at t ≥ 400 °C, in which partial or total condensation of interlayer -POH groups occurred, showed a strongly reduced capacity for adsorption of NH 3 , because of the formation of P-O-P bridges between layers which hindered diffusion of NH 3 . After pretreatment of Zr hydrogen phosphate at 600 °C, the TPD spectrum of ammonia adsorbed at room temperature showed only the signal of NH 3 adsorbed by surface -POH sites, indicating that its interaction with internal sites was now precluded. From the shape of the TPD curves from these samples information on the strength of surface acidic sites was deduced.

CD40 and B Chronic Lymphocytic Leukemia Cell Response To Fludarabine: The Influence of NF-kB/Rel Transcription Factors On Chemotherapy-Induced Apoptosis

The levels of tumour necrosis factor receptor (TNF-R) superfamily members can be altered in lymphoid leukemias, indicating a possible role of such molecules in the biology of these neoplasias. In B chronic lymphocytic leukemia cells, the CD40/CD40L system has been shown to be effective in inhibiting the apoptotic response to fludarabine. The modulation of apoptosis relied on the CD40- induced activity of NF-B/Rel transcription factors. The anti- apoptotic effect of CD40 was abolished using a phosphorothioate B decoy oligodeoxynucleotide. These findings illustrate an example of the biological activity of TNF-R- like molecules in leukemias. They also show the influence of NF-B/Rel activity on leukemic cell response to apoptogenic agents.

BAG3 protein is induced during cardiomyoblast differentiation and modulates myogenin expression.

Dear Editor, In the program of cardiomyoblast differentiation, induction of proteins that protect cardiomyocytes from stretch and load stress-induced apoptosis has a relevant role. Indeed, cardiomyocytes are intrinsically resistant to apoptosis, due in part to high levels of endogenous caspase inhibitors, anti-apoptotic Bcl-2 proteins and the pro-survival kinase Akt. Among proteins that sustain cardiomyocyte survival, a role is assigned to BAG3. This is a co-chaperone of the heat shock protein (Hsp) 70 that is constitutively present in myocytes and a few other normal cell types, while its expression is induced by a variety of stressful stimuli in leukocytes and other cells; on the other hand, some neoplastic cells constitutively express BAG3, that plays an anti-apoptotic role. Indeed, in osteosarcoma or melanoma cells, BAG3 interferes with the Hsp70mediated delivery of the IKK regulatory subunit, IKKγ to proteasome, thereby sustaining IKKγ intracellular levels, NFκB activation and cell survival. Furthermore, in another neoplastic cell type, i.e., glioblastoma, BAG3 protein retains the antiapoptotic protein BAX in cell cytosol, impeding its translocation to mitochondria and apoptosis triggering (unpublished results). Therefore BAG3 appears to sustain cell survival by more than one mechanism and indeed it can interact with several molecular partners, through its BAG, WW or Pro-rich domains. Mice with homozygous disruption of bag3 gene develop postnatally a fulminant cardiomyopathy characterized by noninflammatory myofibrillar degeneration with BAG3 protein is induced during cardiomyoblast differentiation and modulates myogenin expression