bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased content of chondroitin sulfate proteoglycan in human colorectal carcinoma metastases compared with the primary tumor as determined by an anti‐chondroitin‐sulfate monoclonal antibody
Authors: Yamori Takao , Ota David M. , Cleary Karen R. , Irimura Tatsuro 
Published: December 2004

AbstractTo determine if the amount of chondroitin sulfate proteoglycan (CSPG) in human colorectal tumor tissue correlates with the tumor's aggressiveness we immunochemically determined the CSPG levels in colorectal carcinomas at different stages. A total of 50 specimens—4 polyps, 15 stage B tumors, 9 stage C tumors, 12 stage D tumors, 7 liver metastases, and 3 lymph node metastases—were examined. Tumor tissues were extracted with 4 M guanidine hydrochloride containing protease inhibitors. The extracts were serially diluted and blotted onto nitrocellulose membranes. Reactivity of a chondroitin sulfate‐specific mouse monoclonal antibody (CS‐56) was determined by biotinylated goat antimouse Ig and avidin‐biotin‐peroxidase complex. After comparing tissues from tumors at different stages (classified by the presence or absence of metastasis), we could not find a positive or negative correlation between the amount of CSPG in primary colorectal carcinoma tissues and the tumor's metastatic potential. However, the metastatic foci in the liver or lymph node contained higher amounts of CSPG than the primary tumors did. Immunohistochemical staining of colon carcinoma tissue with CS‐56 revealed that CSPG is predominantly localized in fibrotic portions in the tumor tissues. Two‐year follow‐up studies indicated that a high level of CSPG in primary tumors was not predictive of recurrence.
Inhibition of metastatic potential by fucosidase: An NMR study identifies a cell surface metastasis marker
Authors: Wright Lesley C. , May George L. , Gregory Patricia , Dyne Marlen , Holmes Kerry T. , Williams Philip G. , Mountford Carolyn E. 
Published: December 2004

AbstractNMR spectroscopy is able to detect subtle changes to the surface chemistry of cells. We have previously shown that high‐resolution 1H NMR methods can identify tumor cells with the capacity to metastasize, and we now report that the long T2 relaxation value (500–800 ms) observed in metastatic rat mammary adenocarcinoma cells is removed by treatment with fucosidase. Two‐dimensional scalar‐correlated NMR (COSY) spectra of fucosidase‐treated cells show that a cross peak, consistent with scalar coupling between the methyl and methinè groups on fucose and usually associated with malignancy and metastatic ability, is absent. Metastases were observed in only two out of ten rats injected subcutaneously with enzyme‐treated cells compared to eight out of ten with untreated cells. NMR studies on isolated cellular lipids identified the long T2 relaxation value only in the ganglioside fraction. This fraction accounts for 51% of the total 14C‐labelled fucose incorporated into the cells. We propose that fucogangliosides are an indicator of metastatic potential in rats. The observation that a cell surface metastasis marker has an NMR signal with a characteristically long relaxation value has important consequences for the future use of magnetic resonance imaging and spectroscopy in the cancer clinic.
Cell surface heparan sulfate proteoglycan and the neoplastic phenotype
Authors: Iozzo Renato V. 
Published: December 2004

AbstractCell surface proteoglycans are strategically positioned to regulate interactions between cells and their surrounding environment. Such interactions play key roles in several biological processes, such as cell recognition, adhesion, migration, and growth. These biological functions are in turn necessary for the maintenance of differentiated phenotype and for normal and neoplastic development. There is ample evidence that a special type of proteoglycan bearing heparan sulfate side chains is localized at the cell surface in a variety of epithelial and mesenchymal cells. This molecule exhibits selective patterns of reactivity with various constituents of the extracellular matrix and plasma membrane, and can act as growth modulator or as a receptor. Certainly, during cell division, membrane constituents undergo profound rearrangement, and proteoglycans may be intimately involved in such processes. The present work will focus on recent advances in our understanding of these complex macromolecules and will attempt to elucidate the biosynthesis, the structural diversity, the modes of cell surface association, and the turnover of heparan sulfate proteoglycans in various cell systems. It will then review the multiple proposed roles of this molecule, with particular emphasis on the binding properties and the interactions with various intracellular and extracellular elements. Finally, it will focus on the alterations associated with the neoplastic phenotype and will discuss the possible consequences that heparan sulfate may have on the growth of normal and transformed cells.
Tissue‐specific analogues of erythrocyte protein 4.1 retain functional domains
Authors: Anderson Richard A. , Correas Isabel , Mazzucco Charles , Castle J. David , Marchesi Vincent T. 
Published: December 2004

AbstractAnalogues of the human erythroid membrane skeletal component protein 4.1 have been identified in perfused rat tissues and human T and B lymphocyte cell lines, olyclonal antibodies were used which are specific for all domains of protein 4.1, the spectrin‐actin‐promoting 8‐Kd peptide, the membrane‐binding 30‐Kd domain, and the 50‐Kd domain. Antibody reactivity, by Western blotting of tissue homogenates, shows reactivity with proteins varying in molecular weight from 175 Kd to 30 Kd. Further, these protein 4.1 analogues appear to be expressed in a tissue‐specific fashion. Of the analogues detected there appear to be at least three classes: analogues containing all erythroid protein 4.1 domains, analogues containing all domains but with modified antigenic epitopes, and analogues containing only some domains. Chemical cleavage at cysteine linkages indicates that in analogues containing the 30‐Kd region the location of cysteine is highly conserved. This datum suggests that in nonerythroid 4.1 isoforms of higher molecular weight the additional protein mass is added to the amino terminal end (30 Kd end).
Relationship of pseudopod extension to chemotactic hormone‐induced actin polymerization in amoeboid cells
Authors: Hall Anne L. , Schlein Anthony , Condeelis John 
Published: December 2004

AbstractAggregation‐competent amoeboid cells of Dictyostelium discoideum are chemotactic toward cAMP. Video microscopy and scanning electron microscopy were used to quantitate changes in cell morphology and locomotion during uniform upshifts in the concentration of cAMP. These studies demonstrate that morphological and motile responses to cAMP are sufficiently synchronous within a cell population to allow relevant biochemical analyses to be performed on large numbers of cells.Changes in cell behavior were correlated with F‐actin content by using an NBD‐phallacidin binding assay. These studies demonstrate that actin polymerization occurs in two stages in response to stimulation of cells with extracellular cAMP and involves the addition of monomers to the cytochalasin D‐sensitive (barbed) ends of actin filaments. The second stage of actin assembly, which peaks at 60 sec following an upshift in cAMP concentration, is temporally correlated with the growth of new pseudopods. The F‐actin assembled by 60 sec is localized in these new pseudopods.These results indicate that actin polymerization may constitute one of the driving forces for pseudopod extension in amoeboid cells and that nucleation sites regulating polymerization are under the control of chemotaxis receptors.
Insulin and IGF‐1 receptors contain covalently bound palmitic acid
Authors: Magee A. I. , Siddle K. 
Published: December 2004

AbstractWe have studied the biosynthesis of the insulin receptor in a human hepatoma cell line, HepG2. As previously reported, these cells synthesize a disulphide–bonded α2 β2 tetrameric insulin receptor. Labelling of HepG2 cells with [3H]palmitate or [3H]myristate followed by immunoprecipitation with a polyclonal antireceptor antibody revealed the incorporation of palmitate, but not myristate, into the β‐subunit and αβ‐precursor of the receptor in a hydroxylamine‐sensitive linkage. The extracellular α‐subunit was not labelled, demonstrating the specificity of incorporation. Acylation of the insulin receptor was an early event as judged by fatty acid incorporation into the αβ‐precursor and prevention by protein synthesis inhibitors. Pulse‐chase studies demonstrated the expected processing of the αβ‐precursor to mature α‐ and β‐subunits, but no evidence for preferential turnover of the fatty acid moiety was found. The site of acylation appears to be in the transmembrane or cytoplasmic domain since proteolytic treatment of intact cells produced a truncated β‐subunit still containing label. Binding studies showed that HepG2 cells contain approximately half as many insulin‐like growth factor‐1 receptors as insulin receptors, raising the possibility that this receptor may also be acylated. Indeed, immunoprecipitation with the antiinsulin receptor serum of MDCK cells expressing IGF‐1 receptors, but not insulin receptors, revealed bands corresponding to the αβ‐precursor, α‐ and β‐subunits, of which the αβ‐precursor and β‐subunits incorporated [3H]palmitate but the α‐subunit did not.
A search for EGF‐elicited degradation products of the EGF receptor
Authors: Stoscheck Christa M. , Gates Ronald E. , King Lloyd E. 
Published: December 2004

AbstractEpidermal growth factor (EGF) induces the degradation of EGF receptors in both human foreskin fibroblasts and A‐431 cells. Similar degradation products of 125I‐EGF covalently linked to its receptor appeared at the same times in both A‐431 cells and fibroblasts when the cells were exposed to a concentration of 10 ng/ml EGF. Although the products between the two cell types differed in molecular weight, this was at least partly caused by an actual difference in the receptor proteins from the two cell types (as shown by partial proteolysis) rather than from different pathways of receptor degradation. However, when EGF receptors were biosynthetically labeled, no receptor degradation products could be observed, even when the receptor was labeled with radioactive mannose or phosphate, molecules which would predominantly label the outside or inside face of the receptor, respectively. At 20°C, degradation of the receptor slowed and a 150,000‐dalton degradation product was observed. This degradation product has previously been observed in cell homogenates produced in the presence of calcium, mediated by calpain. Thus, calpain may play a role in the intracellular degradation of the EGF receptor.
Epidermal growth factor‐stimulated DNA synthesis requires an influx of extracellular calcium
Authors: Hill Timothy D. , Kindmark Henrik , Boynton Alton L. 
Published: December 2004

AbstractThe dependency of normal cell proliferation on adequate extracellular Ca2+ levels was further investigated by determining the role of Ca2+ influx in epidermal growth factor (EGF)‐induced rat liver epithelial (T51B) cell DNA synthesis. Fura‐2‐loaded T51B cells responded with an increase in [Ca2+]i to EGF (5–50 ng/ml) that was blocked by low (25 μM) extracellular Ca2+ or by pretreatment with 50 μM La3+ to inhibit plasma membrane Ca2+ flux. Confluent T51B cells treated for 24 h with EGF (0.1–50 ng/ml) dose‐dependently incorporated [3H]‐thymidine into cell nuclei. Low extracellular Ca2+ or addition of La3+ prevented the EGF stimulated rise in labeled nuclei, indicating that a movement of Ca2+ into the cell was required for DNA synthesis. This was supported by our findings that bradykinin, which induced a rise in [Ca2+]i by opening plasma membrane Ca2+ channels in T51B cells (but not A23187, thrombin or ATP, which raise [Ca2+]i primary through mobilization of intracellular Ca2+ stores), potentiated DNA synthesis stimulated by submaximal doses of EGF. Potentiation of the action of EGF by the tumor promoter 12‐0‐tctradecanoyl‐phorbol‐13‐acetatc (TPA), indicates that activation of protein kinase C and an influx of Ca2+ share a common mechanism for initiating DNA synthesis.
Defection of minor immunological differences among human “universal‐type” alkaline phosphatases
Authors: Goseki Masae , Oida Shinichiro , Sasaki Satoshi 
Published: December 2004

AbstractTwo clones of monoclonal antibodies against swine alkaline phosphatase (ALPase; orthophosphoric monoester phosphohydrolase, alkaline optimum, EC 3.1.3.1), which were useful in distinguishing human kidney and bone ALPases from liver ALPase, were successfully raised in mice. On the other hand, polyclonal antibody cross‐reacted not only with human kidney ALPase but also with all other human universal type ALPases. The difference in cross‐reactivitiy of monoclonal and polyclonal antibodies may be caused by the specific antigenicity of human enzymes. The monoclonal antibodies were able to recognize minor heterogeneity that could not be distinguished by their enzymatic properties. The present monoclonal antibody preparations will be utilized for clinical as well as basic investigations to detect minor heterogeneity among universal‐type ALPases.
Activation and membrane binding of carboxypeptidase E
Authors: Fricker Lloyd D. 
Published: December 2004

AbstractCarboxypeptidase E (CPE) is a Carboxypeptidase B‐like enzyme that is thought to be involved in the processing of peptide hormones and neurotransmitters. Soluble and membrane‐associated forms of CPE have been observed in purified secretory granules from various hormone‐producing tissues. In this report, the influence of membrane association on CPE activity has been examined. A substantial amount of the membrane‐associated CPE activity is solubilized upon extraction of bovine pituitary membranes with either 100 mM sodium acetate buffer (pH 5.6) containing 0.5% Triton X‐100 and 1 M NaCl, or by extraction with high pH buffers (pH > 8). These treatments also lead to a two‐ to threefold increase in CPE activity. CPE extracted from membranes with either NaCl/Triton X‐100 or high pH buffers hydrolyzes the dansyl‐Phe‐Ala‐Arg substrate with a lower Km than the membrane‐associated CPE. The Vmax of CPE present in extracts and membrane fractions after the NaCl/Triton X‐100 treatment is twofold higher than in untreated membranes. Treatment of membranes with high pH buffers does not affect the Vmax of CPE in the soluble and particulate fractions. Pretreatment of membranes with bromoacetyl‐D‐arginine, an active site‐directed irreversible inhibitor of CPE, blocks the activation by NaCl/Triton X‐100 treatment. Thus the increase in CPE activity upon extraction from membranes is probably not because of the conversion of an inactive form to an active one, but is the result of changes in the conformation of the enzyme that effect the catalytic activity.
Characterization of tumors produced by signal peptide‐basic fibroblast growth factor‐transformed cells
Authors: Rogelj Snezna , Weinberg Robert A. , Fanning Paul , Klagsbrun Michael 
Published: December 2004

AbstractBasic fibroblast growth factor (bFGF) is found in a variety of cells and tissues. We have previously shown that bFGF is a transforming growth factor, but only when fused to a signal peptide (sp‐bFGF). Cells expressing the native bFGF are tumorigenic in nude mice only, where the tumors form at a low frequency and grow very slowly as compared to sp‐bFGF tumors. The cells transformed by the sp‐bFGF growth factor gene cause rapidly growing tumors within 10 days in 100% of syngeneic and nude mice. In nude mice, the tumors are highly vascularized, while the vascularization in immunocompetent syngeneic mice is not as prominent. The syngeneic mice have a characteristic humoral immune response to sp‐bFGF tumors, which differs from that mounted against ras‐induced tumors. The ability of bFGF to induce tumorigenicity is significant in view of the recent discoveries of three new oncogenes: hst, int‐2, and an oncogene from a human colon cancer. In addition to homology with FGF, the proteins encoded by these oncogenes all have a potential signal peptide at the protein's amino terminus, suggesting a mode of action analogous to that of our artificial signal peptide‐bFGF (sp‐bFGF) transforming growth factor model system.
Transforming growth factor‐β1 enhances the suppression of human hematopoiesis by tumor necrosis factor‐α or recombinant interferon‐α
Authors: Sing Garwin K. , Keller Jonathan R. , Ellingsworth Larry R. , Ruscetti Francis W. 
Published: December 2004

AbstractThe effects of transforming growth factor‐β1 (TGF‐β1) on human hematopoiesis were evaluated in combination with two other regulatory cytokines, namely, recombinant human tumor necrosis factor‐α (TNF‐α) and recombinant human interferon‐α (rIFN‐α). Combinations of TNF‐α and TGF‐β1 resulted in a synergistic suppression of colony formation by erythroid progenitor cells (BFU‐E) and an additive suppression of granulocyte‐macrophage (CFU‐GM) and multipotential (CFU‐GEMM) progenitor cells. In addition, TGF‐β1 synergized with rIFN‐α to suppress CFU‐GM formation, while the combined suppressive effects of both cytokines on CFU‐GEMM and BFU‐E were additive. When TGF‐β1 was tested with TNF‐α or IFN‐α on granulocyte/macrophage colony‐stimulating factor (GM‐CSF)‐stimulated bone marrow cells in a 5‐day proliferation assay, the antiproliferative effects of TGF‐β1 and TNF‐α were additive, while those with TGF‐β1 and rIFN‐α were synergistic. A similar pattern was seen in the suppression of the myeloblastic cell line KG‐1 where TGF‐β1 in combination with TNF‐α resulted in an additive suppression while inhibition by TGF‐β1 and IFN‐α was synergistic.These results demonstrate for the first time the cooperative effects between TGF‐β and TNF‐α and IFN‐α in the suppression of hematopoietic cell growth, raising the possibility that TGF‐β might be used in concert with TNF‐α or IFN‐α in the treatment of various myeloproliferative disorders.
Phosphatidylinositol‐specific phospholipase C From Bacillus cereus: Improved purification, amino acid composition, and amino‐terminal sequence
Authors: Volwerk Johannes J. , Wetherwax Peter B. , Evans Loreene M. , Kuppe Andreas , Griffith O. Hayes 
Published: December 2004

AbstractPhosphatidylinositol‐specific phospholipase C was purified in a 27% yield from the culture medium of Bacillus cereus by a combination of ammonium sulfate precipitation and ion‐exchange and hydrophobic interaction chromatography. The purified enzyme was free of other phospholipase C‐type activities and exhibited a high specific activity of approximately 1,300 units/mg. Amino acid composition analysis and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis indicated a molecular weight of about 35 kDa. The sequence of the first 29 N‐terminal amino acids was also determined.
Modulation of mitogenic activity and cellular binding of basic fibroblast growth factor by basic proteins
Authors: Dauchel M. C. , Courty J. , Mereau A. , Barritault D. 
Published: December 2004

AbstractPolycationic molecules were studied either for their ability to displace the binding of basic fibroblast growth factor (bFGF) to high‐ and low‐affinity membrane interaction sites and/or to modulate bFGF‐induced proliferation of fibroblasts. Heparin‐binding polypeptides, such as polylysine, protamine, histones, and thrombin‐displaced [125I]bFGF bound to bovine brain membrane receptors. The most displacing polypeptides were those with the strongest affinity to heparin. Two of these polypeptides, protamine and polylysine, inhibited (at 5 μM) by more than 90% the mitogenic effect induced by bFGF on Chinese hamster lung fibroblast cells (CCL39). At the same dose, no effect was observed with basic proteins that do not bind to heparin, such as cytochrome C and lysozyme. An interesting observation was that protamine at 1 μM potentiated by 1.5‐fold the mitogenic activity of bFGF, while it acted as an inhibitor at higher concentration.
Growth factor modulation of melanoma growth stimulatory activity mRNA expression in human malignant melanoma cells correlates with cell growth
Authors: Bordoni R. , Thomas G. , Richmond A. 
Published: December 2004

AbstractThis report demonstrates that the expression of melanoma growth stimulatory activity (MGSA) mRNA can be modulated in a positive fashion in the Hs294T human melanoma cell line by PDGF and MGSA. There is close correlation between MGSA expression and the pattern of cell growth in Hs294T cells.
Phospholipase A2‐mediated release of arachidonic acid in stimulated guinea pig alveolar macrophages: Interaction with lipid mediators and cyclic AMP
Authors: Kadiri Chakir , Masliah Joëlle , Bachelet Maria , Vargaftig B. Boris , Béréziat Gilbert 
Published: December 2004

AbstractThe stimulation of cultured guinea pig alveolar macrophages by the chemotactic peptide N‐formyl‐L‐methionyl‐L‐leucyl‐L‐phenylalanine, or by the phospholipid inflammatory mediator platelet activating factor (PAF) induced an increase in arachidonic acid release and its cyclooxygenase products. This release, which was mimicked by the association of threshold concentrations of the calcium ionophore A 23187 and of the protein kinase C activator tetradecanoyl phorbol acetate arose mainly from diacyl‐ and alkyl‐acyl‐phosphatidylcholine and phosphatidylinositol. Using [1 14C]arachidonic acid‐labeled membranes as an endogenous substrate as well as dioleoyl‐phosphatidyl [14C]ethanolamine as an exogenous substrate, we showed that phospholipase A2 activity of stimulated macrophages increases upon stimulation. Treatment of macrophages by prostaglandin E2 decreased the arachidonic acid release elicited by the chemotactic peptide and PAF. Furthermore, prostaglandin E2 increased and PAF decreased the cellular content in cyclic AMP. From these results we suggest that an initial stimulation of alveolar macrophages by a bacterial signal initiates the sequential activation of a phospholipase C and of phospholipase A2, leading to the release of PAF and eicosanoids. These mediators may in turn modulate the cell response by increasing or decreasing cyclic AMP, Ca2+, or diacyglycerol macrophage content.