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Biomedical subjects

A Albini

Publications and source records attributed to A Albini.

At least 37 records · Page 2Linked to original sources
PubMed2001

Effects of angiostatin gene transfer on functional properties and in vivo growth of Kaposi's sarcoma cells.

Gene transfer delivery of endogenous angiogenesis inhibitors such as angiostatin would circumvent problems associated with long-term administration of proteins. Kaposi's sarcoma (KS), a highly vascular neoplasm, is an excellent model for studying tumor angiogenesis and antiangiogenic agent efficacy. We investigated the effects of angiostatin gene transfer in in vitro and in vivo models of KS-induced neovascularization and tumor growth. A eukaryotic expression plasmid and a Moloney leukemia virus-based retroviral vector for expression of murine angiostatin were generated harboring the angiostatin cDNA with cleavable leader signals under the control of either the strong cytomegalovirus promoter/enhancer or the Moloney leukemia virus long terminal repeat. Angiostatin secretion was confirmed by radioimmunoprecipitation and Western blot analysis. Supernatants of angiostatin-transfected cells inhibited endothelial cell migration in vitro. Stable gene transfer of the angiostatin cDNA by retroviral vectors in KS-IMM cells resulted in sustained angiostatin expression and delayed tumor growth in nude mice, which was associated with reduced vascularization. These findings suggest that gene therapy with angiostatin might be useful for treatment of KS and possibly other highly angiogenic tumors.

Angiostatins↗
PubMed2001

HIV type 1 Tat protein is a survival factor for Kaposi's sarcoma and endothelial cells.

The HIV-1 Tat protein has been directly implicated in the pathogenesis of AIDS-related Kaposi's sarcoma (KS); however, its effects on KS spindle-shaped and endothelial cell apoptosis are largely unexplored. Since susceptibility to apoptosis is relevant for tumor development and response to therapy, we investigated the effects of Tat on KS and endothelial cell survival from apoptosis. The effect of Tat was evaluated in three KS cell lines (KS-imm, KS-C1, and KS-L3) exposed to the chemotherapy agent vincristine, currently used for the treatment of this tumor, and in human umbilical vein-derived endothelial cells (HUVECs) induced to undergo apoptosis by serum withdrawal. Apoptosis was assessed by enzymatic assays, microscopic examination of chromatin and cytoskeleton, evaluation of plasma membrane integrity and subdiploid DNA content, TUNEL assays, and measurement of caspase-3 activity. Tat, in a dose-dependent manner, protected the three KS cell lines and HUVECs from apoptosis induced by vincristine or serum starvation, respectively. This effect appeared to be independent of modulation of Fas, Bcl-2, or Bax expression. In contrast, Tat upregulated Bcl-X(L) expression and induced a relevant decrease in caspase-3 activity in vincristine-treated KS cells. Taken together, these results suggest that the HIV-1 Tat protein may factor KS development and progression by sustaining endothelial and transformed cell survival.

Apoptosis↗
PubMed2001

Multifaceted photoreactivity of 6-fluoro-7-aminoquinolones from the lowest excited states in aqueous media: a study by nanosecond and picosecond spectroscopic techniques.

Nanosecond and picosecond absorption and emission spectroscopic techniques were applied to the investigation of the reactivity from the lowest excited states of some 6-fluoro-7-piperazino-4-quinolone-3-carboxylic acids (FQs) in aqueous media at neutral pH, in the absence and presence of different sodium salts. Following the detection of various transients, we proposed a mechanism for the cleavage of the carbon-fluorine bond that proceeded through different reaction pathways, dependent on the molecular structure and the characteristics of the medium. The drug lomefloxacin (LOM), a 6,8-difluoroquinolone derivative, underwent heterolytic cleavage of the C8-F bond from the excited singlet state. With the 6-monofluoroquinolone norfloxacin (NOR) and the corresponding 1,8-naphthyridinone enoxacin (ENX), the lowest singlet state was not significantly reactive and an important deactivation channel was intersystem crossing (ISC) to the triplet manifold. The lowest triplet state underwent cleavage of the C6-F bond through a solvent mediated process possibly via a cyclohexadienyl anionic adduct. In the presence of sulfite or phosphate buffer a novel defluorination mechanism, induced by electron transfer from the inorganic anions to the FQ triplet state, was observed. The correlation between the transients observed and the final photoproducts in the different media was elucidated.

Anti-Infective Agents↗
PubMed2001

Specific structural determinants are responsible for the antioxidant activity and the cell cycle effects of resveratrol.

Resveratrol (3,4',5-trihydroxy-trans-stilbene) is a natural phytoalexin found in grapes and wine, which shows antioxidant and antiproliferative activities. In this study we have investigated whether these properties are dependent on similar or different structural determinants of the molecule. To this purpose, resveratrol derivatives, in which all or each single hydroxylic function were selectively substituted with methyl groups, were synthesized. Analogues with the stilbenic double bond reduced or with the stereoisometry modified were also investigated. The antioxidant activity of these compounds was evaluated by measuring the inhibition of citronellal thermo-oxidation, or the reduction of 2,2-diphenyl-1-picrylhydrazyl radical. In addition, the protection against lipid peroxidation was determined in rat liver microsomes, and in human primary cell cultures. The antiproliferative activity was evaluated by a clonogenic assay, and by analysis of cell cycle progression and DNA synthesis. The results showed that the hydroxyl group in 4' position is not the sole determinant for antioxidant activity. In contrast, the presence of 4'-OH together with stereoisometry in the trans-conformation (4'-hydroxystyryl moiety) was absolutely required for inhibition of cell proliferation. Enzymatic assays in vitro demonstrated that inhibition of DNA synthesis was induced by a direct interaction of resveratrol with DNA polymerases alpha and delta.

Animals↗
PubMed2001

Tumor gelatinases and invasion inhibited by the green tea flavanol epigallocatechin-3-gallate.

BACKGROUND: Given the association of consumption of green tea with prevention of cancer development, metastasis, and angiogenesis, the effect of the main flavanol present, epigallocatechin-3-gallate (EGCG), on two gelatinases most frequently overexpressed in cancer and angiogenesis (MMP-2 and MMP-9) and on tumor cell invasion and chemotaxis were examined. METHODS: Zymography, Western blotting, and enzyme linked immuoadsorbent assay were used to analyze the effect of EGCG on MMP-2 and MMP-9 activity, whereas its effect on tumor cell invasion and chemotaxis was examined using modified Boyden chamber assays. RESULTS: A Zn2+ chelation-independent, dose-dependent, noncompetitive inhibition by EGCG of both gelatinases was found at concentrations 500 times lower than that reported to inhibit urokinase. Tumor cell invasion of a reconstituted basement membrane matrix, but not chemotaxis, was reduced by 50% with EGCG concentrations equivalent to that in the plasma of moderate green tea drinkers, and 2 orders of magnitude below those of tissue inhibitors of MMPs. Although higher concentrations of EGCG were associated with increased levels of both cell-associated gelatinases and their activator MT1-MMP, no increased gelatinase activation was found, and TIMP-1 and TIMP-2 inhibitors were up-regulated. Finally, concentrations of EGCG active in restraining proliferation and inducing apoptosis of transformed cells were more than 100 times lower than those reported for normal cells. CONCLUSIONS: Epigallocatechin-3-gallate is a potent inhibitor of gelatinases and an orally available pharmacologic agent that may confer the antiangiogenic and antimetastatic activity associated with green tea.

Anticarcinogenic Agents↗
PubMed2001

Nonrandom chromosome changes in Kaposi sarcoma: cytogenetic and FISH results in a new cell line (KS-IMM) and literature review.

The karyotype of a new tumorigenic Kaposi sarcoma (KS)-derived cell line, as defined by cytogenetic and fluorescence in situ hybridization (FISH) analysis is 49,XY,i(1)(q10),i(7)(p10),+i(7) (q10),+der(8)t(8;13)(p11;q11),-13,+del(14)(q22),+der(17)t(1;17)(p13;p13). Our aim was to point out some characteristics and recurrent chromosome changes probably playing a relevant role in the malignant progression of KS, by a comparison of the cytogenetic results obtained in the present study with data from the literature. The interpretation of the cytogenetic results is that KS development occurs by multiple steps: an initial reactive polyclonal cell proliferation is associated with chromosome instability; the cells in a later stage acquire clonal chromosome changes. If many chromosome changes are present, particularly 8q and 1q trisomy, 3p14-->pter deletion, 1p13, 13p14.3, 7q22, 8p11, 13q11, and 19q13 band rearrangements, KS acquires a neoplastic aggressive state.

Chromosome Aberrations↗
PubMed2001

Growth factor supplemented matrigel improves ectopic skeletal muscle formation--a cell therapy approach.

Following damage to skeletal muscle, satellite cells become activated, migrate towards the injured area, proliferate, and fuse with each other to form myotubes which finally mature into myofibers. We tested a new approach to muscle regeneration by incorporating myoblasts, with or without the exogenous growth factors bFGF or HGF, into three-dimensional gels of reconstituted basement membrane (matrigel). In vitro, bFGF and HGF induced C2C12 myoblast proliferation and migration and were synergistic when used together. In vivo, C2C12 or primary i28 myoblasts were injected subcutaneously together with matrigel and growth factors in the flanks of nude mice. The inclusion of either bFGF or HGF increased the vascularization of the gels. Gels supplemented with bFGF showed myogenesis accompanied by massive mesenchymal cell recruitment and poor organization of the fascicles. Samples containing HGF showed delayed differentiation with respect to controls or bFGF, with increased myoblast proliferation and a significantly higher numbers of cells in myotubes at later time points. HGF samples showed limited mesenchymal cell infiltration and relatively good organization of fascicles. The use of both bFGF and HGF together showed increased numbers of nuclei in myotubes, but with bFGF-mediated fibroblast recruitment dominating. These studies suggest that an appropriate combination of basement membrane components and growth factors could represent a possible approach to enhance survival dispersion, proliferation, and differentiation of myogenic cells during muscle regeneration and/or myoblast transplantation. This model will help develop cell therapy of muscle diseases and open the future to gene therapy approaches.

Animals↗
PubMed2001

Effect of HGF-like basic hexapeptides on angiogenesis.

The interaction of glycosaminoglycans (GAG) with peptides relies on noncovalent binding to basic amino acid sequences, for which a minimal requirement is a pentapeptide region in the protein and the sulfated and carboxyl region in the GAG. Since such sequences are present in the heparin-binding angiogenic cytokines, including hepatocyte growth factor (HGF), we have postulated that such small peptides may have biological activity. Two basic peptide regions of the beta chain of HGF (RYRNKH512-516, HHRGK645-649) exhibited significant antiangiogenic activity in vivo in the chorioallantoic membrane assay and showed some antiproliferative activity in vitro on normal human brain microvessel endothelial-but not on anchorage-independent endothelial-cells (Kaposi sarcoma). Basic HIV-TAT peptides and scrambled hexapeptides did not show similar activity, except for KRKRKR, indicating sequence specificity of the phenomena. An HGF-derived basic peptide, HHRGK, modulated tumor-induced angiogenesis in vivo by interfering with the morphogenic, but not with the proliferative, phase of the process. These observations suggest small basic peptides as a new class of angiogenesis modulators.

Allantois↗
PubMed2001

Endothelin receptor blockade inhibits proliferation of Kaposi's sarcoma cells.

Endothelin-1 (ET-1) has been shown to be mitogenic for endothelial and several tumor cells through an autocrine mechanism. In this study we evaluated whether the tumorigenic KS IMM cell line deriving from Kaposi's sarcoma (KS), a highly angiogenic tumor, is susceptible to ET-1 mitogenic activity. By reverse transcriptase-polymerase chain reaction, we detected ET-1 mRNA expression and both ET(A) receptor (ET(A)R) and ET(B)R mRNA transcripts in the KS IMM cells. High concentrations of ET-1 are released from the KS IMM cells and competition-binding studies demonstrated that these cells also express functional ET(A)R and ET(B)R with high affinity for ET-1 and ET-1/ET-3, respectively. Expression of ET-1 and cognate receptors could be detected by immunohistochemical method in vitro, in KS IMM xenograft, and in tissue sections of a human KS lesion. Furthermore ET-1 induces a marked and dose-dependent increase in [3H]thymidine incorporation comparable to that elicited by vascular endothelial growth factor. Addition of both selective ET(B)R antagonist (BQ 788) and ET(A)R antagonist (BQ 123), completely blocked ET-1-induced mitogenic response and reduced the basal growth rate of unstimulated cells, suggesting that both receptors mediated the proliferative signal. Such findings demonstrate that ET-1 participates on KS pathogenesis acting as an autocrine growth factor and that ET-1 receptor antagonists may thus be novel candidates for therapeutic intervention.

Animals↗
PubMed2001

Activation of endothelial cell mitogen activated protein kinase ERK(1/2) by extracellular HIV-1 Tat protein.

Extracellular Tat protein, the transactivating factor of the human immunodeficiency virus type 1 (HIV-1), modulates gene expression, growth, and angiogenic activity in endothelial cells by interacting with the vascular endothelial growth factor (VEGF) receptor-2 (Flk-1/KDR). Recombinant Tat protein, produced as glutathione-S-transferase chimera (GST-Tat), activates mitogen-activated protein kinase (MAPK) ERK(1/2) in human, murine, and bovine endothelial cells whereas GST is ineffective. In bovine aortic endothelial cells, GST-Tat and the 165 amino acid VEGF isoform (VEGF165) induce transient ERK(1/2) phosphorylation with similar potency and kinetics. The synthetic peptide Tat(41-60), but not peptides Tat(1-21) and Tat(71-86), causes ERK(1/2) phosphorylation, thus implicating Tat/KDR interaction in the activation of this signalling pathway. Accordingly, GST-Tat induces ERK(1/2) phosphorylation in KDR-transfected porcine aortic endothelial cells but not in parental cells. MAPK kinase inhibitors PD098059 and U0126 prevent ERK(1/2) phosphorylation by Tat. However, they do not affect the angiogenic activity exerted by Tat in the murine Matrigel plug and chick embryo chorioallantoic membrane assays. Blocking of MAPK kinase activity impairs instead the angiogenic response to VEGF165 and to fibroblast growth factor-2 (FGF-2). Our data demonstrate that ERK(1/2) activation following the interaction of HIV-1 Tat protein with endothelial cell Flk-1/KDR receptor does not represent an absolute requirement for a full angiogenic response to this growth factor that appears to utilize mechanism(s) at least in part distinct from those triggered by other prototypic angiogenic growth factors.

Animals↗
PubMed2001

[Somatostatinergic control of Kaposi's sarcoma growth through the inhibition of angiogenesis].

Somatostatin and its analogs are active in the inhibition of the proliteration of sst receptor positive endocrine neoplasms, however their activity and mechanism in non-endocrine tumors is not clear. Somatostatin effectively inhibited the growth of a Kaposi's sarcoma xenograft in nude mice, yet in vitro the tumor cells did not express any known somatostatin receptors and were not growth inhibited by somatostatin. Histological examination revealed limited vascularization in the somatostatin treated tumors as compared to the controls. Somatostatin was a potent inhibitor of angiogenesis in an in vivo assay. In vitro, somatostatin inhibited endothelial cell growth and invasion. Migration of monocytes, important mediators of the angiogenic cascade, was also inhibited by somatostatin. Both cells types expressed somatostatin receptor mRNAs. These data demonstrate that somatostatin is a potent anti-tumor angiogenesis compound directly affecting both endothelial and monocytic cells. The debated function of somatostatin in tumor treatment and the design of therapeutic protocols should be reexamined considering these data.

Angiogenesis Inhibitors↗
PubMed2000

Human immunodeficiency virus transactivator protein (Tat) stimulates chemotaxis, calcium mobilization, and activation of human polymorphonuclear leukocytes: implications for Tat-mediated pathogenesis.

The extracellular activities of the human immunodeficiency virus (HIV) transactivator protein (Tat) include induction of angiogenesis and stimulation of monocyte migration. Here it is shown that polymorphonuclear leukocytes (PMNL), mostly neutrophils, rapidly invade in response to Tat in vivo and initiate the formation of new vessels. In vitro, Tat was chemotactic for PMNL and induced calcium (Ca(2+)) mobilization. Tat proteins with inactivating substitutions in the arginine-glycine-aspartic acid or basic domain were still active in inducing PMNL migration, whereas Tat peptides mapped the migration and Ca(2+) mobilization activity to a cysteine-rich core domain, previously described as a Tat "chemokine-like" region (peptide CysL(24-51)). Tat and the CysL(24-51) peptide also induced PMNL superoxide production and the release of the angiogenic factors interleukin-8 and vascular endothelial growth factor from PMNL. CysL(24-51) did not induce endothelial cell migration but was angiogenic in vivo. These data indicate that the Tat activity on PMNL is mediated by its chemokine-like region and that PMNL recruitment by Tat is linked to angiogenesis.

Amino Acid Substitution↗
PubMed2000

The combined action of IL-15 and IL-12 gene transfer can induce tumor cell rejection without T and NK cell involvement.

The cooperative antitumor effects of IL-12 and IL-15 gene transfer were studied in the N592 MHC class I-negative small cell lung cancer cell line xenotransplanted in nude mice. N592 cells engineered to secrete IL-15 displayed a significantly reduced tumor growth kinetics, and a slightly reduced tumor take rate, while N592 engineered with IL-12 displayed only minor changes in their growth in nude mice. However, N592 cells producing both cytokines were completely rejected, and produced a potent local bystander effect, inducing rejection of coinjected wild-type tumor cells. N592/IL-12/IL-15 cells were completely and promptly rejected also in NK-depleted nude mice, while in granulocyte-depleted animals a slight delay in the rejection process was observed. Immunohistochemical analyses of the N592/IL-12/IL-15 tumor area in intact nude mice revealed the presence of infiltrating macrophages, granulocytes, and NK cells, and expression of inducible NO synthase and of secondary cytokines such as IL-1beta, TNF-alpha, and IFN-gamma, and at higher levels GM-CSF, macrophage-inflammatory protein-2, and monocyte chemoattractant protein-1. In NK cell-depleted nude mice, numerous macrophages and granulocytes infiltrated the tumor, and a strong expression of macrophage-inflammatory protein-2 and inducible NO synthase was also observed. Finally, macrophages cocultured with N592/IL-12/IL-15 produced NO in vitro, and inhibited tumor cell growth, further suggesting their role as effector cells in this model.

Adjuvants, Immunologic↗
PubMed2000

The alpha 3 beta 1 integrin is associated with mammary carcinoma cell metastasis, invasion, and gelatinase B (MMP-9) activity.

The alpha 3 beta 1 integrin is elevated in several types of metastatic tumor and has been associated with increased migration and invasion. Our analysis of a series of mammary carcinomas of different histotypes and their corresponding metastases demonstrated significantly increased expression of alpha 3 beta 1 in the tumor metastases. We therefore studied alpha 3 beta 1 expression of several human breast carcinoma cell lines and its association with the invasive phenotype. The MDA-MB-231 cell line expressed high levels of the beta1, alpha 2, alpha 3, alpha 5, and alpha 6 integrin subunits along with moderate levels of the alpha v beta 3 integrin. This line was highly migratory and the most invasive using a chemo-invasion assay. In contrast, the other lines tested, MDA-MB-145, MCF-7, and SK-BR-3, showed lower migratory and invasive activity and reduced alpha 3 integrin subunit expression. Metalloproteases capable of degrading collagen IV are necessary for the invasive process. RT-PCR showed that MDA-MB-231 cells expressed MMP-9, but not MMP-2, gelatinase/collagenase IV. Gelatin zymography demonstrated that invading MDA-MB-231 cells released high levels of MMP-9 gelatinase activity. A direct role for this gelatinase in MDA-MB-231 cell invasion was confirmed by inhibition of invasion using the metalloprotease inhibitor Batimastat. Treatment of MDA-MB-231 cells with a function-blocking anti-alpha 3 antibody strongly inhibited migration and invasion. This correlated with a marked reduction in MMP-9 activity produced by MDA-MB-231 cells, suggesting a role for alpha 3 beta 1 ligand binding in cell signaling and regulation of extracellular matrix degradation.

Adult↗
PubMed2000

Effect of protic cosolvents on the photooxygenation of diethyl sulfide

The sluggish (kr < 10kq) photooxygenation of diethyl sulfide in both benzene and other aprotic solvents such as acetone and acetonitrile is made efficient by addition of small amounts of alcohols and, with a much more conspicuous increase, of phenols and carboxylic acids (<<0.1% additive is sufficient in this case). A kinetic analysis shows that the effect is accounted for by interaction of the protic additives with the first formed intermediate, the persulfoxide, in competition with cleavage to the components. The thus obtained rate constants kH linearly correlate with the acid strength of the additives, and the effect is rationalized as a general acid catalysis. Hydrogen bonding of the persulfoxide under this condition accounts in an economic way for the observed data, including co-oxygenation of Ph2SO in mixed solvents.

Journal Article↗
PubMed2000

Kaposi's sarcoma cells of different etiologic origins respond to HIV-Tat through the Flk-1/KDR (VEGFR-2): relevance in AIDS-KS pathology.

Kaposi's sarcoma (KS) is an hyperplastic lesion whose main histological features are typical spindle shaped cells with a mixed endothelial-mesenchymal-macrophage phenotype, an intense vascularization and an inflammatory infiltrate. The etiology of KS appears to be linked to activation of a latent HHV8 infection. Sporadic and iatrogenic KS are slow progressing lesions that can undergo spontaneous regression. In contrast, KS, which is frequently associated with HIV infection, is found in a highly aggressive form in AIDS patients. The HIV-1 Tat has been shown to activate the VEGF receptor KDR in endothelial and KS spindle cells, suggesting this HIV protein could contribute to KS pathogenesis. We used primary 'reactive' KS cell culture from sporadic and epidemic KS, and an immortal KS-line (KS-Imm) isolated in our laboratory from a iatrogenic KS lesion, to verify if Tat-induced cell signaling is able to mediate cellular responses. We demonstrate that KS cells migrated in response to Tat and that VEGF is able to compete with the Tat chemotactic activity towards these cells. A function-blocking anti-KDR antibody was able to abrogate both VEGF and Tat-induced KS chemotactic response, indicating a direct involvement of this receptor. Our data show that HIV-Tat can also activate KS cells derived from sporadic or iatrogenic lesions, suggesting that in AIDS patients Tat could cooperate with VEGF in activation of KDS on KS precursor spindle and endothelial cells, and contribute to the aggressiveness of AIDS-KS lesions.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Structural study of the solid-state photoaddition reaction of arylidenoxindoles

The photochemistry of isomeric 2-furyliden- and benzylidenoxindoles (2H-indol-2-ones) is examined. In solution E-Z isomerization is the only process via the excited singlet state (which fluoresces in glassy solution at 77 K and not at room temperature). In the crystalline state, the two (Z) derivatives are photostable, in accordance with the prediction based on the structural determination of the furylidene derivative, which adopts the unreactive Schmidt's gamma type arrangement. The (E) furylidene derivative (1a) gives efficiently (Phi = 0.3) the head-to-tail dimer, as indicated by the crystal structure, which is of the reactive alpha type, in full accord with the topochemical principles. In contrast, the corresponding benzylidene (1b) derivative reacts sluggishly (Phi < 0. 01) and mainly gives polymers, despite the fact that crystal structure determination shows that it likewise pertains to the alpha type and complies with the topochemical rules. The difference in reactivity is explained on the basis of (i) the twist of the phenyl ring with respect to the indole plane, and (ii) the higher overall cohesion energy and the lower interaction energy between facing molecules, as found from the charge density analysis for the crystals of 1b in comparison to those of 1a. This evidences a further stringent requirement for the occurrence of topochemical photodimerizations.

Journal Article↗