bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification of a cell growth factor from a human lung cancer cell line: Its relationship with ferritin
Authors: Kikyo Nobuaki , Hagiwara Koichi , Fujisawa Michio , Kikyo Nobuko , Yazaki Yoshio , Okabe Tetsuro 
Published: February 2005

AbstractWe have purified a cell growth factor from a human lung cancer cell line, T3M‐30, which was established in a protein‐free chemically defined medium. The factor, designated carcinoma‐derived growth factor (CD‐GF), stimulated proliferation of a variety of cells, including human leukemia cells, HL‐60, and melanoma cells, SK‐28. Half‐maximum stimulation by the purified CD‐GF was achieved at a concentration of 40 ng/ml. In the purified CD‐GF, two major protein bands of 24 kDa and 22 kDa were identified on a SDS polyacrylamide gel. The partial amino acid sequences of the 24 kDa protein were determined from two peptide fragments obtained by V8 protease treatment. The partial sequences were identical to those of heavy chain of human ferritin. The activity of the purified CD‐GF was coprecipitated completely with a monoclonal antibody to heavy chain of ferritin. Ferritin has been considered to inhibit cell growth. However, human heart ferritin was capable of stimulating the growth of HL‐60 cells. These results suggest that CD‐GF is related to feritin and ferritin is a growth factor of HL‐60 leukemia cells. © 1994 Wiley‐Liss, Inc.
Interaction of high‐molecular‐weight basic fibroblast growth factor with endothelium: Biological activity and intracellular fate of human recombinant Mr 24,000 bFGF
Authors: Gualandris A. , Urbinati C. , Rusnati M. , Ziche M. , Presta M. 
Published: February 2005

AbstractThe single‐copy gene of human basic fibroblast growth factor (bFGF) encodes four co‐expressed isoforms, with an apparent molecular weight (Mr) of 24kD, 22.5 kD, 22kD, and 18kD, co‐translated from a single mRNA. As a tool for the study of the role exerted by the different bFGF isoforms in the biology of endothelial cells, human recombinant 24‐kD bFGF was produced and purified from transformed Escherichia coli cells. To this purpose, the novel CUG start codon present in human bFGF cDNA and responsible for the synthesis of 24‐kD bFGF was mutagenized to the classic AUG start codon. Transient expression of the mutagenized cDNA in simian COS‐1 cells, followed by immunolocalization and subcellular fractionation, resulted in the synthesis of high levels of 24‐kD bFGF, which localizes in the cell nucleus as an intact protein. When the same 24‐kD bFGF, cDNA was expressed in E. coli, the recombinant protein was purified to homogeneity by heparin‐Sepharose and ion‐exchange chromatography. Recombinant 24‐kD bFGF was similar to recombinant 18‐kD bFGF in receptor‐binding activity and in inducing cell proliferation, plasminogen activator production, and chemotactic movement in cultured endothelial cells. In agreement with the in vitro observations, 24‐kD bFGF and 18‐kD bFGF exerted a similar angiogenic response when assayed in vivo in the rabbit cornea. Experiments performed with the radiolabeled molecule demonstrated that 24‐kD bFGF has an intrinsic ability to bind to high‐affinity receptors when added to endothelial GM 7373 cell cultures. Receptor‐bound 24‐kD bFGF is internalized within the cell and associates with the nucleus with kinetics similar to 13‐kD bFGF. Internalized 24‐kD bFGF is first processed to the 18‐kD form via a chloroquine‐insensitive pathway and then to smaller fragments into the lysosomal compartment. At variance with the data obtained in transfected COS‐1 cells, only limited amounts of exogenous internalized 24‐kD bFGF associates with the nucleus in the intact form, mostly of the nuclear‐bound molecule being represented by the processed 18‐kD protein and by smaller degradation products. In conclusion, human recombinant 24‐kD bFGF exerts a biological response in endothelial cells similar to 18‐kD bFGF both in vitro and in vivo. Our data point to a different intracellular behavior of the high‐molecular‐weight bFGF isoform when added exogenously to cultured cells or when produced endogenously in transfected cells. © 1994 Wiley‐Liss, Inc.
Proliferation and differentiation of rat adipose precursor cells in chemically defined medium: Differential action of anti‐adipogenic agents
Authors: Vassaux Georges , Négrel Raymond , Ailhaud Gérard , Gaillard Danielle 
Published: February 2005

AbstractPrimary rat adipose precursor cells, maintained in the minimal chemically defined medium (ITT medium) able to promote differentiation, have been used to investigate the ability of several agents to modulate their proliferation and their differentiation. Fetuin and fibroblast growth factor (FGF), which exhibited a strong and a weak mitogenic activity, respectively, do not significantly affect the proportion of differentiated cells as indicated by glycerol‐3‐phosphate dehydrogenase (GPDH) activity values. In contrast, carbaprostacyclin (cPGI2), a stable analogue of prostacyclin, behaves as a true adipogenic factor leading to a 4 to 5‐fold increase in GPDH‐specific activities with no significant effect on cell growth. Submaxillary gland kallikrein (SMGK), transforming growth factor‐β (TGF‐β) and tumor necrosis factor‐α (TNF‐α) behave as growth‐promoting agents but at the same time elicit a dose‐dependent inhibition of differentiation. Epidermal growth factor (EGF) and prostaglandin F2α (PGF2α) do not show any effect on cell proliferation at concentrations which exert a maximal inhibitory action on differentiation. Upon removal of EGF from the culture medium, complete resumption of differentiation occurs, whereas upon removal of PGF2α or SMGK, complete resumption only takes place when differentiation is triggered by cPGl2. Upon removal of TNF‐α, a partial resumption of differentiation is observed, whereas no subsequent differentiation is observed upon TGF‐β removal. These results emphasize the adipogenic, nonmitogenic role of cPGl2 and also allow the distinction between the various adipogenic/mitogenic factors which affect adipose cell differentiation. © 1994 Wiley‐Liss, Inc.
IGF‐II is more active than IGF‐I in stimulating L6A1 myogenesis: Greater mitogenic actions of IGF‐I delay differentiation
Authors: Ewton Diana Z. , Roof Suzette L. , Magri Karen A. , McWade Frank J. , Florini James R. 
Published: February 2005

AbstractMitogens are generally thought to inhibit myogenesis, and many cell biologists have found it hard to interpret observations that the insulin‐like growth factors (IGSs) stimulate bothe proliferation and differentiation of muscle cells in culture. Our previous studies suggested that the Type I IGF receptor mediates these actions. However, IGF‐II and insulin treatment caused myoblasts to differentiate much more extensively, suggesting that more complex mechanism; may be involved. Here we present evidence that the greater mitogenic activity of IGF‐l (compared to IGF‐ll and insulin) delays L6A 1 myoblast differentiation. Under conditions in which the mitogenicactions of IGDD‐l are suppressed, the stimulation of myogenesis by IGF‐I approached that by IGF‐II:; (1) in L6A1 cultures plated at a higher cell density; (2) in L6A1 cultured in which cell proliferation was inhibited by cytosine arabinoside or aphidicilin; and (3) in cultures of primary human muscle cells, which exhibit a smaller mitogenic responseee to IGF‐I. Further Further evidenceee that the Type Ireceptor plays a major role in relaying the signal for differentiation was obtained by suing IGF‐I and IGF‐II analogs. Analogs which have reduced affinity for the Type I receptor showed a dramatic decrease in activity, while an analog with increased affinity for the Type II receptor was no more active than native IGF‐I. Our results indicate that both mitogenic and myogenic actions of IGF‐I are mediated by the Type I receptor. We conclude that IGF‐I delays the onset of myogenesis as a result of its mitogenic actions, and only subsequenlty stimulates myogenesis. These observations reconcile the apparent conflict between our results with the IGFs and other investigator' reports of effects of other mitogens. © 1994 Wiley‐Liss, Inc.
Expression and phosphorylation of NHE1 in wild‐type and transformed human and rodent fibroblasts
Authors: McSwine Rebecca L. , Babnigg Gyorgy , Musch Mark W. , Chang Eugene B. , Villereal Mitchel L. 
Published: February 2005

AbstractActivation and phosphorylation of the Na+/H+ exchanger occurs with a diverse group of mitogens such as phorbol myristate acetate (PMA), epidermal growth factor (EGF), thrombin and serum (Sardet et al., 1990, Science, 247:723‐‐726). Some of these growth factors have been shown to differentially activate the Na+/H+ exchanger in various fibroblasts (Etscheid et al., 1990, Am. J. Physiol., 259:C549‐‐C556; Muldoon, L. L., et al., 1987, Am. J. Physiol., 253:C219‐‐C229). However, alterations in the expression and phosphorylation of NHE1 in various fibroblasts has not been examined with respect to a potential mechanism of differential activation of the exchanger. To pursue this question, a novel antibody, anti‐XB17, directed to the cytoplasmic tail of NHE1 was characterized and then utilized to examine the expression of NHE1 protein and the level of phosphorylation of the serum stimulated exchanger in human embryonic lung fibroblasts (WI‐38), SV40‐transformed WI‐38, and nontransformed human foreskin fibroblasts (HSWP) cells. The level of mRNA expressed in these cells was also examined. Results indicate that the parental cell lines and other nontransformed fibroblasts express NHE1. Although the transformed cell lines express NHE1 mRNA in approximately similar abundance to the parental lines, they contain decreased quantity of NHE1 exchanger/mg membrane protein as recognized by anti‐XB17 Ab. The mechanism that results in the apparent decrease in NHE1 protein levels in the transformed cells is not known. Also, the SV40‐transformed cells express and exchanger with a higher apparent molecular weight. The WI‐38 cells demonstrate phosphorylation of NHE1 in response to mitogenic stimulation. Although the nontransformed HSWP cells have a high level of Na+/H+ exchanger protein, they do not show a significant increase in phosphorylation following serum stimulation, when examined by immunoprecipitation, and analysis on 1‐D gels. However, subsequent studies of tryptic phosphopeptides from the immunoprecipitated exchanger reveal that serum‐stimulated phosphorylation of one tryptic peptide does occur but may be masked in the first dimension by differential phosphorylation of other tryptic peptides that are more heavily phosphorylated in unstimulated cells. © 1994 Wiley‐Liss, Inc.
Bombesin stimulates the in vitro growth of a human gastric cancer cell line
Authors: Bold Richard J. , Lowry Patrick S. , Ishizuka Jin , Battey James F. , Townsend Courtney M. , Thompson James C. 
Published: February 2005

AbstractBombesin (BBS) and its mammalian equivalent, gastrin‐releasing peptide (GRP) exhibit diverse biological functions, including that of a neurotransmatter, a regulator of gastrointestinal hormone release, and a trophic factor for various normal and neoplastic tissues. Bombesin stimulates the growth of normal cells of the stomach, pancreas, and bronchial epithelium as well as cells in breast cancer, gastrinoma, and small cell lung cancer. The purpose of this study was to determine whether BBS regulates the growth of a human gastric cancer cell line (SIIA) in vitro, and if so, to examine the mechanisms of signal‐transduction that are involved. We found that BBS stimulated the growth of SIIA cells in vitro. The GRP receptor antagonists, BIM 26189 and BIM 26226, had no effect on growth of SIIA cells. Although these antagonists blocked the BBS‐induced increase of [Ca2+]i, they failed to block the growth‐stimulatory effect of BBS. BBS stimulated intracellular tyrosine phosphorylation of multiple proteins, with a predominant protein of apparent molecular weight of 125 kDa. Inhibition of intracellular tyrosine kinases by tyrphostin blocked the growth‐stimulatory effect of BBS on SIIA cells. These results indicate that BBS exerts its trophic effect on SIIA cells through a receptor(s) linked to tyrosine kinase pathway, but not to the phospholipase C (PLC) pathway. © 1994 Wiley‐Liss, Inc.
Selective effects of the PKC inhibitors Ro 31‐8220 and CGP 41 251 on PMN locomotion, cell polarity, and pinocytosis
Authors: Keller H. U. , Niggli V. 
Published: February 2005

AbstractUsing two newly synthesized inhibitors, Ro 31‐8220 and CGP 41 251, of protein kinase C (PKC), we analyzed: (1) how distinct PMN functions (shape changes, locomotion, pinocytosis) are regulated, and (2) the role of protein phosphorylation and PKC in this process. We were able to transform: (1) resting PMNs into locomoting cells using fNLPNTL, (2) locomoting cells into non‐locomoting highly pinocytic cells using PMA, and (3) PMA‐stimulated cells showing marked pinocytosis into locomoting or into resting cells using Ro 31‐8220. It is thus possible to selectively manipulate PMN function (resting state, locomotion, marked pinocytosis), indicating that there are different regulatory pathways. It was not possible to induce locomotion and marked pinocytosis simultaneously, indicating crosstalk between pathways. Ro 31‐8220 inhibited PMA‐induced shape changes (nonpolar cells) and pinocytosis, but not fNLPNTL‐induced shape changes (polarity) and pinocytosis. At higher concentrations, Ro 31‐8220 alone elicited cell polarity and chemokinesis, indicating that a constitutively active protein kinase is involved in maintaining the spherical shape of resting PMNs. Functional effects of another PKC inhibitor, CGP 41 251, on neutrophil function were strikingly different. CGP 41 251 selectively inhibited fNLPNTL‐induced polarity and locomotion (but not colchicine or Ro 31‐8220‐induced polarity), and it failed to inhibit PMA‐induced, stimulated pinocytosis and shape changes. Although the effects of Ro 31‐8220 vs. CGP 41 251 on PMN function were strikingly different, the inhibition of profiles for constitutive and for fNLPNTL‐ or PMA‐induced protein phosphorylation in intact PMNs showed only small differences, which could not yet be conclusively related to cell function. © 1994 Wiley‐Liss, Inc.
Calcium influences sensitivity to growth inhibition induced by a cell surface sialoglycopeptide
Authors: Betz Natalie A. , Fattaey Heideh K. , Johnson Terry C. 
Published: February 2005

AbstractWhile studies concerning mitogenic factors have been an important area of research for many years, much less is understood about the mechanisms of action of cell surface growth inhibitors. We have purified an 18 kDa cell surface sialoglycopeptide growth inhibitor (CeReS‐18) which can reversibly inhibit the proliferation of diverse cell types. The studies discussed in this article show that three mouse keratinocyte cell lines exhibit sixtyfold greater sensitivity than other fibroblasts and epithelial‐like cells to CeReS‐18‐induced growth inhibition. Growth inhibition induced by CeReS‐18 treatment is a reversible process, and the three mouse keratinocyte cell lines exhibited either single or multiple cell cycle arrest points, although a predominantly G0/G1 cell cycle arrest point was exhibited in Swiss 3T3 fibroblasts. The sensitivity of the mouse keratinocyte cell lines to CeReS‐18‐induced growth inhibition was not affected by the degree of tumorigenic progression in the cell lines and was not due to differences in CeReS‐18 binding affinity or number of cell surface receptors per cell. However, the sensitivity of both murine fibroblasts and keratinocytes could be altered by changing the extracellular calcium concentration, such that increased extracellular calcium concentrations resulted in decreased sensitivity to CeReS‐18‐induced proliferation inhibition. Thus the increased sensitivity of the murine keratinocyte cell lines to CeReS‐18 could be ascribed to the low calcium concentration used in their propagation. Studies are currently under way investigating the role of calcium in CeReS‐18‐induced growth arrest. The CeReS‐18 may serve as a very useful tool to study negative growth control and the signal transduction events associated with cell cycling. © 1994 Wiley‐Liss, Inc.
Activation of TNF‐R1 receptor in the presence of copper kills TNF resistant CEM leukemic T cells
Authors: Wada H. Garrett , Fok Katherine S. , Fendly Brian M. , Chiang Nancy Y. , Sussman Howard H. 
Published: February 2005

AbstractThe cytotoxic effects of TNF on malignant cells are known to be mediated through high affinity surface receptors. The precise mechanism by which transformed cells are selectively killed by the activation of these receptors is yet unknown, but several intracellular signaling pathways are known to be involved. Phospholipase A2 activation by TNF‐α has been shown to be important in the transduction of signals leading to cell death. We have used monitoring of extracellular acidification rate as a measure of cellular metabolism to follow the early time course of TNF effects on a human leukemic T cell line (CEM‐SS cells). CEM‐SS cells were relatively resistant to TNF cell killing but TNF caused an early stimulation of metabolism within 2‐4 hr, followed by a suppression of metabolic activity occurring over 20 hr. In contrast, a TNF sensitive subclone of CEM cells (C1Ca) showed a rapid and dramatic decrease in metabolic activity corresponding to cytotoxicity within 18 hr. It was discovered that cupric o‐phenanthroline markedly potentiated the effects of TNF on the resistant CEM‐SS cells leading to cell death. This observation was specific for copper because ferric o‐phenanthroline was without effect at the same concentration. The copper cytotoxic effect was shown to be mediated through the TNF‐R1 receptor and independent of phospholipase A2 signaling. © 1994 Wiley‐Liss, Inc.
Immunolocalization of mitochondrial 3‐hydroxy‐3‐methylgutaryl CoA synthase in rat liver
Authors: Royo Teresa , Pedragosa Maria J. , Ayté José , Gil‐Gómez Gabriel , Vilaró Senén , Hegardt Fausto G. 
Published: February 2005

AbstractWe report the preparation of specific polyclonal antibodies raised against two synthetic peptides deduced from the cDNA sequence for the rat liver mitochondrial 3‐hydroxy‐3‐methylglutaryl Coenzyme A (HMG‐CoA) synthase gene. Immunoelectron microscopy using these antibodies on hepatic cryoultrathin sections confirms the mitochondrial localization of this protein in hepatocytes. Immunofluorescence microscopy on frozen sections of adult rat liver revealed fluorescence inside all hepatocytes, with no evidence of zonation, indicating that ketogenesis may not be limited to specific regions of rat liver but is extended to all hepatocytes. © 1995 Wiley‐Liss, Inc.
Tumor necrosis factor reduces proteoglycan synthesis in cultured endothelial cells
Authors: Ramasamy S. , Lipke D. W. , McClain C. J. , Hennig B. 
Published: February 2005

AbstractTumor necrosis factor (TNF)‐induced disruption of vascular endothelial barrier function may be due in part to alterations in proteoglycan metabolism. To test this hypothesis, confluent endothelial cell monolayers were exposed for 24 h to 500 or 1,000 U of TNF per mililiter of culture medium together with 20 μCi Na2 35SO4. HPLC anion‐exchange separation of proteoglycans secreted into media of control as well as TNF‐treated cultures revealed one major peak (representing 95% of total radioactivity) and one minor peak (representing 5% of total radioactivity), which eluted at 0.6 and 0.9 M NaCl, respectively. One single peak was obtained from control as well as TNF‐treated endothelial cell monolayers and eluted at 1.2 M NaCl. TNF treatment did not change the total quantity of radioactive proteoglycans secreted into the media but significantly decreased the amount of proteoglycans in endothelial cell monolayers. However, TNF treatment did not alter the size or glycosaminoglycan (GAG) composition of the proteoglycans either in the media or in the cell monolayers. In addition, mRNA levels of specific proteoglycans, perlecan and biglycan, were measured upon TNF treatment, using Northern analysis. TNF treatment caused a dose‐dependent decrease in mRNA levels for the biglycan in endothelial cultures. These results suggest that TNF decreases production of proteoglycans and alters normal endothelial cell proteoglycan metabolism which may be sufficient to impair endothelial barrier function. © 1995 Wiley‐Liss, Inc.
New CD44 splice variants associated with human breast cancers
Authors: Iida Naoko , Bourguignon Lilly Y. W. 
Published: February 2005

AbstractChanges in the CD44 variant (CD44v) isoforms on the cell surface have been correlated with tumor metastasis. In this study we have examined the expression of CD44 variant isoforms in human breast carcinoma samples by a variety of techniques including immunohistochemistry, reverse transcriptase‐polymerase chain reaction (RT‐PCR), and nucleotide sequencing. Using RT‐PCR, we have determined that normal human breast tissue contains primarily the CD44 epithelial (CD44E) form and very little CD44 standard (CD44s) form. However, metastatic breast carcinomas appear to overxpress both the CD44E and CD44s forms and also display multiple new species of CD44 variant isoforms. Histocytochemical staining using anti‐CD44 antibody (recognizing a common determinant of the CD44 class of glycoproteins) confirms that the CD44 molecules are overexpressed and preferentially located in metastatic breast cancer tissues. Nucleotide sequencing analyses indicate that at least four new CD44 variant isoforms (i. e., displaying unique splicing via the insertion or the deletion of exons 7, 10, 11, and 14) may be closely associated with human metastatic breast cancers. These newly described CD44 variant isoforms may be useful for monitoring the progression of human breast cancer metastasis. © 1995 Wiley‐Liss, Inc.
Multiple sites of vanadate and peroxovanadate action in Xenopus oocytes
Authors: Barnes David M. , Sykes Destiny B. , Shechter Yoram , Miller David S. 
Published: February 2005

AbstractIn Xenopus laevis oocytes, the insulin mimics, vanadate and peroxovandates (PV), stimulated the uptake of 3H‐2‐deoxyglucose and incorporation of 35S‐methionine into protein. For both hexose transport and protein synthesis, peroxovandates (produced by reacting vandate and H2O2) were at least as potent as vandate. Microinjection of peroxovandates into the oocytes stimulated 2‐deoxyglucose uptake. However, methionine incorporation was not stimulated by microinjection of peroxovanadate or vanadate solutions. Consistent with these results and with the possibility that vandate and peroxovandates enter the cell on a phosphate transporter, raising the medium phosphate concentration from 1 mM to 10 mM blocked vanadate‐stimulated hexose transport and partially reduced peroxovanadates stimulation of hexose transport. Increased medium phosphate did not reduce stimulation of protein synthesis by either effector. Taken together, these data indicate that vanadate/peroxovanadates act at both intracellular and extracellular sites. Action at the former stimulates hexose uptake and action at the latter, protein synthesis. © 1995 Wiley‐Liss, Inc.This artilce is a US Government work and, as such, is in the public domain in the United States of America.