bluuebunny/crossref_metadata_2025_split huggingface dataset:
Down‐modulation of epidermal growth factor receptor accompanies TNF‐induced differentiation of the DiFi human adenocarcinoma cell line toward a goblet‐like phenotype
Authors: Novotny‐Smith C. L. , Zorbas M. A. , McIsaac A. M. , Irimura T. , Boman Bruce M. , Yeoman L. C. , Gallick G. E. 
Published: February 2005

AbstractAlthough the biologic response modifier tumor necrosis factor‐alpha (TNF) is a known differentiation Inducer in hematopoietic cells, its role in differentiation of other tissue types has yet to be elucidated. In the studies presented here, TNF treatment of the human rectal adenocarcinoma cell line, DiFi, elicits characteristics of early stage differentiating, mucin‐producing colonocytes. Not only are TNF‐treated DiFi cells growth‐inhibited by TNF, but they also display a unique morphology. Additionally, TNF treatment of DiFi cells enhances > fivefold the expression of high molecular weight mucin glycoproteins, as measured by [125I]‐wheat germ agglutinin (WGA) binding and the human milk fat globule‐1 (HMFG‐1) anti‐MUC1 antibody reactivity. The induction of these differentiation characteristics correlates with novel alterations in epidermal growth factor receptor (EGF‐R). Following 5‐day TNF treatment of DiFi cultures, EGF receptor levels, kinase autophosphorylation activity, and receptor tyrosine phosphorylation are reduced by > fourfold. The establishment of a model system in which goblet‐like cell characteristics and alterations in a growth factor receptor can be induced in vitro may be potentially useful in studying the underlying mechanisms of colonic epithelial cell proliferation and differentiation. © 1993 Wiley‐Liss, Inc.
Different patterns of apoptosis of HL‐60 cells induced by cycloheximide and camptothecin
Authors: Li Jianping Gong Xun , Darzynkiewicz Zbigniew 
Published: February 2005

AbstractCells of the human promyelocytic HL‐60 line, when treated with a variety of antitumor agents in the presence of the protein synthesis inhibitor cycloheximide (CHX), or with CHX alone, rapidly undergo apoptosis (“active cell death”). It is presumed, therefore, that such cells are “primed” to apoptosis in that no new protein synthesis is required for induction of their death. We have studied apoptosis of HL‐60 cells triggered by the DNA topoisomerase I inhibitor camptothecin (CAM) in the absence and presence of CHX and apoptosis induced by CHX alone. Two different flcw cytometric methods were used, each allowing us to relate the apoptosis‐associated DNA degradation to the cell cycle position. Apoptosis induced by CAM was limited to S phase cells, e.g., at a CAM concentration of 0.15 μM, nearly 90% of the S phase cells underwent apoptosis after 4 h. In contrast, apoptosis triggered by CHX was indiscriminate, affecting all phases of the cycle: ∼40% of the cells from each phase the cycle underwent apoptosis at 5 μM CHX concentration. When CAM and CHX were added together, the pattern of apoptosis resembled that of cycloheximide alone, namely, cells in all phases of the cycle in similar proportion were affected. Thus, CHX, while itself inducing apoptosis of a fraction of cells, protected the S phase cells against apoptosis triggered by CAM. Because CHX (5 μM) did not significantly affect the rate of cell progression through S phase, the observed protective effect was most likely directly related to inhibition of protein synthesis, rather than to its possible indirect effect on DNA replication. Furthermore, whereas apoptosis (DNA degradation) triggered by CAM was prevented by the serine protease inhibitor N‐tosyl‐L‐lysylchloromethyl ketone (TLCK), this process was actually potentiated by this inhibitor when induced by CHX. The present data indicate differences in mechanism of apoptosis triggered by CAM (and perhaps other antitumor drugs) as compared with CHX. Apoptosis caused by CHX may be unique in that it may not involve new protein synthesis. These data are compatible with the assumption that the loss of a hypothetical, rapidly turning over suppressor of apoptosis may be the trigger of apoptosis of HL‐60 cells treated with CHX, whereas de novo protein synthesis is required when apoptosis is triggered by other agents. © 1993 Wiley‐Liss, Inc.
Cell cycle activity and expression of prohibitin mRNA
Authors: Roskams A. Jane I. , Friedman Varda , Wood Carla M. , Walker Lisa , Owens Garrison A. , Stewart David A. , Altus Michael S. , Danner David B. , Liu Xiao‐Tie , McClung J. Keith 
Published: February 2005

AbstractProhibitin, a novel intracellular antiproliferative protein, blocks entry into the S phase of the cell division cycle when its mRNA is microinjected into normal fibroblasts or HeLa cells. To learn more about the interaction between prohibitin and the cell cycle, we studied the effect of microinjecting prohibitin mRNA at different points during the transition from G0 to S phase and analyzed prohibitin mRNA and protein levels in different parts of the cell cycle. The antiproliferative activity of microinjected prohibitin mRNA is high in G0/G1 and falls as cells approach S phase. Prohibitin mRNA and protein levels are high in G1, fall with S phase, rise again in G2, and fall in M. Together, these findings suggest that endogenous prohibitin contributes to the control of the G1 to S transition in cycling cells in a complex manner, which involves both a transcriptional and posttranslational mechanism. © 1993 Wiley‐Liss, Inc.
Transforming growth factor‐beta, basic fibroblast growth factor, and platelet‐derived growth factor‐BB interact to affect proliferation of clonally derived porcine satellite cells
Authors: Cook Douglas R. , Doumit Matthew E. , Merkel Robert A. 
Published: February 2005

AbstractTransforming growth factor beta‐1 (1GF‐β) stimulated porcine satellite cell proliferation in basal serum‐free medium by 25%, but inhibited growth in serumcontaining medium by 58%. The effect of TGF‐β on cell proliferation in serumfree medium was examined in combination with the following human recombinant growth factors: platelet‐derived growth factor‐BB (PDGF), basic fibroblast growth factor (FGF), insulin‐like growth factor I (IGF‐I), and epidermal growth factor (EGF). TGF‐β inhibited PDGF‐stimulated proliferation, enhanced FGF‐stimulated proliferation, and had no effect on proliferation stimulated by IGF‐I. The response of satellite cells to EGF and TGF‐β in serum‐free medium was not different than TGF‐β alone. TGF‐β depressed proliferation stimulated by the following combinations of two growth factors: PDGF and IGF‐I, PDGF and EGF, PDGF and FGF, and IGF‐I and EGF. In combination with IGF‐I and FGF, TGF‐β did not affect proliferation. TGF‐β inhibited proliferation stimulated by the combination of PDGF, EGF, and IGF‐I, but had no effect on proliferation stimulated by combinations of three growth factors that included FGF. FGF stimulated proliferation in Minimum Essential Medium containing 10% porcine serum (MEM‐10% PS) by 13% above control. When the combination of TGF‐β and FGF was added to MEM‐10% PS, a 78% increase in proliferation was observed. Polyclonal antihuman PDGF‐AB (this form neutralizes PDGF‐AA, AB, and BB) reduced proliferation in MEM‐10% PS by 44%. The combination of TGF‐β and anti‐PDGF‐AB reduced proliferation by 59%, indicating the effects were not additive. These data indicate that: (1) FGF and TGF‐β interact to increase proliferation of clonally derived porcine satellite cells, and (2) the inhibitory effect of TGF‐β on proliferation of clonally derived porcine satelite cells can be primarily attributed to a reduction in the mitogenic effects of PDGF. © 1993 Wiley‐Liss, Inc.
Fibroblast growth factor, epidermal growth factor, insulin‐like growth factors, and platelet‐derived growth factor‐BB stimulate proliferation of clonally derived porcine myogenic satellite cells
Authors: Doumit Matthew E. , Cook Douglas R. , Merkel Robert A. 
Published: February 2005

AbstractClonally derived cultures of porcine skeletal muscle satellite cells were developed. The mitogenic effects of basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), insulin‐like growth factors (IGF‐I and ‐II), and platelet‐derived growth factors (PDGF‐AA and ‐BB) were examined. Individually, bFGF, IGFs, and PDGF‐BB stimulated proliferation of porcine satellite cells grown in basal serum‐free medium or Minimum Essential Medium containing 2% fetal bovine serum (MEM‐2% FBS). EGF stimulated proliferation in MEM‐2% FBS, but neither EGF nor PDGF‐AA, were mitogenic when added to serum‐free medium. The interactions among bFGF, [GF, IGF‐I], and PDGF‐BB were examined in serum‐free medium, using growth factor concentrations shown in dose‐response experiments to induce maximal proliferative responses (10 ng/ml bFGF, EGF and PDGF‐BB, and 50 ng/ml IGF‐I). The combination of bFGF and IGF‐I dramatically increased proliferation, and IGF‐I also synergized with EGF to increase proliferation. EGF, IGF‐I and bFGF interacted with PDGF‐BB to stimulate proliferation. With the exception of EGF and bFGF, combinations of two growth factors typically resulted in greater than additive responses. Simultaneous exposure of satellite cells to bFGF, PDGF‐BB, EGF, and IGF‐I produced a fivefold increase in DNA compared to cells grown in basal serum‐free medium. Elimination of EGF did not reduce the mitogenic response, yet removal of IGF‐I, bFGF, or PDGF‐BB reduced proliferation by ∼40, 20, and 10%, respectively. These mitogens are likely physiological regulators of porcine satellite cell activity. © 1993 Wiley‐Liss, Inc.
C‐FMS dependent HL‐60 cell differentiation and regulation of RB gene expression
Authors: Yen Andrew , Forbes Mary E. , Varvayanis Susi , Tykocinski Mark L. , Groger Richard K. , Platko Joseph D. 
Published: February 2005

AbstractThe dependence of induced myelomonocytic cell differentiation, and regulation of the RB tumor suppressor gene during this process, on the c‐fms gene product, the CSF‐1 lymphokine receptor, was determined in HL‐60 promyelocytic leukemia cells. Adding a monoclonal antibody with specificity for the c‐fms gene product to cells treated with various inducers of myelomonocytic or macrophage differentiation, including retinoic acid and 1,25‐dihydroxy vitamin D3, inhibited the rate of differentiation. During the period of inducer treatment usually preceding onset of differentiation, longer periods of antibody exposure caused greater inhibition of differentiation. In a stable HL‐60 transfectant overexpressing the CSF‐1 receptor at the cell surface due to a constitutively driven c‐fms trans gene, the rate of differentiation was enhanced compared to the wild type cell, consistent with a positive regulatory role for the CSF‐1 receptor. The anti‐fms antibody caused much less inhibition of differentiation in the transfectants than in wild type cells, consistent with a larger number of receptors causing reduced sensitivity. During the induced metabolic cascade leading to differentiation, the typical early down regulation of RB gene expression was inhibited by the antibody. The antibody itself caused an increase in RB expression per cell, which offset the decrease normally caused by differentiation inducers (1,25‐dihydroxy vitamin D3 and retinoic acid). The changes in RB expression preceded changes in the RB protein to the hypophosphorylated state. Most of the RB protein in proliferating cells was phosphorylated and no significant accumulation of hypophosphorylated RB protein occurred until after onset of GO arrest. Thus the metabolic cascade leading to myelomonocytic differentiation of HL‐60 cells appears to be driver by a function of the c‐fms protein. Inhibiting that process by attacking this receptor impedes differentiation and also compromises the early down regulation of RB tumor suppressor gene expression which normally precedes differentiation. These findings provide additional support for a potential role for down regulating RB expression in promoting cell differentiation, and suggest the possibility that RB may be either a target or intermediate mediator of CSF‐1 actions. © 1993 Wiley‐Liss, Inc.
Relative roles of Na+/H+ exchange and vacuolar‐type H+ ATPases in regulating cytoplasmic pH and function in murine peritoneal macrophages
Authors: Swallow Carol J. , Grinstein Sergio , Sudsbury Rae A. , Rotstein Ori D. 
Published: February 2005

AbstractTwo distinct mechanisms have been shown to mediate cytoplasmic pH (pH i) recovery in acid‐loaded peritoneal macrophages (Mψs): Na+/H+ exchange and H+ extrusion by vacuolar‐type (V‐type) H+ ATPases. The present studies examined the relative roles of these two systems in maintaining pHi and cell function. Measurements of Mψ pHi and superoxide (O2−) production in response to stimulation with 12‐O‐tetradecanoyl phorbol 13‐acetate (TPA) were made at physiological or acidic extracellular pH (pHo) levels. The V‐type H+ ATPase inhibitor, bafilomycin A1, and potent Na+/H+ exchange inhibitor, N‐ethyl‐N‐propylamino amiloride (EPA), were used to examine the contributions of these ion transporters to pHi regulation and cell function. At pHo 7.35, the complementary activities of the Na+/H+ antiport and the V‐type H+ ATPase mediate pHi homeostasis. At pHo 6.7, maintenance of pHi depends primarily on H+ ATPase activity: bafilomycin A1 reduced pHi from 6.8±0.02 in control cells to 6.59±0.01 (P<0.01) while EPA was without effect. The functional importance of V‐type H+ ATPase‐activity in preserving pHi homeostasis at acidic extracellular oH levels was reflected by the impairment of O2− production at pHo 6.70 when H+ ATPase activity was inhibited: bafilomycin A1 reduced O2− production from 13.9±1.0 to 9.3±0.6 nmoles/106 cells/40 min, in control and bafilomycin A1‐treated cells, respectively (P≤0.05), while EPA had no effect. In subsequent studies, pHi was independently manipulated using the ionophore nigericin. Lowering pHi from 6.80 to 6.60 reduced O2− production from 15.3±1.8 to 9.8±1.6 nmoles/106 cells/40 min (P≤0.05), indicating that the cytoplasmic acidification resulting from inhibition of H+ ATPases at low pHo could account for the associated impairment of O2− production. In a more profoundly acidic environment (pHo 6.35), H+ ATPases remained active in regulating pHi, but could not preserve a sufficiently physiological pHi to supprt respiratory burst activity. V‐type H+ ATPases constitute the dominant mechanism by which the pHi of peritoneal Mψs is maintained in an acidic extracellular environment. © 1993 Wiley‐Liss, Inc.
Effects of mitogens and co‐mitogens on the formation of small‐cell colonies in primary cultures of rat hepatocytes
Authors: Mitaka Toshihiro , Norioka Ken‐Ichi , Nakamura Toshikazu , Mochizuki Yohichi 
Published: February 2005

AbstractColonies of small hepatocytes appeared after the culture of primary adult rat hepatocytes for 4 days in serum‐free Dulbecco's modified Eagle's medium containing 10 mM nicotinamide and 10 ng/ml of epidermal growth factor (EGF), acidic and basic fibroblast growth factors (FGF), hepatocyte growth factor (HGF), or transforming growth factor‐α (TGF‐α). Every colony consisted of cells that each had a single nucleus and a higher nucleus/cytoplasm ratio than surrounding hepatocytes, and immunocytochemically the cells induced by any mitogen were stained with albumin, transferrin, cytokeratin‐8 and ‐18. But these cells expressed neither cytokeratin‐7 nor‐19. When 6 × 105 cells were plated on 35‐mm dishes, about 15 colonies per 1,000 attached cells were observed in the cultures treated with EGF, HGF, and TGF‐α. Although FGFs could also induce colonies, their number was less than half of the number induced by EGF. Furthermore, the numbers of colonies induced by the combinations of EGF + HGF, EGF + TGF‐α, and HGF + TGF‐α were not different from those of the colonies induced by each mitogen alone. To examine the ability of co‐mitogenic factors to induce small‐cell colonies, angiotensin‐II, insulin‐like growth factor‐I, norepinephrine, tumor necrosis factor, and vasopressin were used. In the cells cultured without EGF, these co‐mitogens neither stimulated DNA synthesis nor induced colonies. On the other hand, in cells cultured with both EGF and each co‐mitogen, although the DNA synthesis of the hepatocytes was enhanced, the number of colonies detected was not significantly different from the number which EGF alone could induce. These results showed that the small‐cell colonies in primary cultures of rat hepatocytes were inducible by EGF, HGF, TGF‐α, or FGFs and that the co‐mitogens did not influence the formation of the small‐cell colonies. © 1993 Wiley‐Liss, Inc.
Lipid synthesis and secretion by primary cultures of rat mammary epithelial cells
Authors: Rohlfs Elizabeth M. , Louie Dexter S. , Zeisel Steven H. 
Published: February 2005

AbstractLipid synthesis and secretion was measured in primary rat mammary epithelial cells cultured on basement matrix in medium supplemented with lactogenic hormones. The cells grew and differentiated to form alveolar‐like structures reminiscent of lactating mammary gland. They synthesized abundant triacylglycerol, containing fatty acids characteristic of rat milk (C10:O‐C14:0), using 14C‐glucose, 14C‐oleic acid or 14C‐glycerol as precursors. Basal levels of triacylglycerol secretion were measured using 14C‐oleic acid labeling; 1.3±0.3% of the labeled cellular triacylglycerol was secreted into the medium in 24 hours. Secreted lipid droplets were surrounded by a bilayer membrane with an electron‐dense inner coat characteristic of fat globules secreted by the mammary gland. The rate of triglycerol secretion was increased to 998±98% of control (P<0.01) by the addition of phorbol 12‐myristate 13‐acetate (PMA) in combination with staurosporine, a protein kinase inhibitcn. Several other protein kinase inhibitors, when combined with PMA, also markedly stimulated secretion. Effective protein kinase inhibitors included sphingosine (has diverse cellular effects including the inhibition of protein kinase C; 13‐fold increase in secretion), and KT5823 (a cGMP dependent protein kinase inhibitor; 5‐fold increase). KT5720 (a cAMP‐dependent protein kinase inhibitor) did not alter secretion. Kinase inhibitors were effective only in the presence of a phorbol ester. 4α‐phorbol‐12,13‐didecanoate, a phorbol ester which does not activate protein kinase C (PKC), could substitute for PMA. Lipid release was not mediated by disruption of cell‐cell tight junctions, as EGTA did not release lipid. Based on these observations we suggest that two signals are needed to enable or stimulate lipid secretion in cultured rat mammary epithelial cells: (1) inhibition of a protein kinase and (2) a PKC‐independent effect of phorbol ester. We have, for the first time, characterized a cell culture model suitable for studying lipid synthesis and secretion by mammary epithelial cells. © 1993 Wiley‐Liss, Inc.
Superoxide‐mediated lysis of erythrocytes: The role of colloid‐osmotic forces
Authors: Zhou Ming‐Jie , Petty Howard R. 
Published: February 2005

AbstractAlthough superoxide anions are a well‐known mediator of cytotoxicity, their mechanism of target cell lysis is not clearly understood. In the present study we have used an exogenous source of superoxide to study erythrocyte cytolysis. RBC lysis was studied in buffers containing the cations Li+, Na+, K+, Rb+, and Cs+; superoxide anions were produced and available in these buffers. During this model superoxide‐dependent cytolytic process, erythrocytes underwent a shape change from biconcave disk to sphere as shown by scanning electron microscopy. Soret band transmitted light microscopy has confirmed this shape change and shown that it precedes cytosolic oxidation. This evidence is consistent with a colloid‐osmotic type lytic mechanism. Erythrocyte lysis was studied by 51Crrelease and light scattering methods. Superoxide‐mediated target cytolysis was characterized by: (1) a sigmoidal dose‐response curve and (2) a lag time in cytolysis after superoxide addition in kinetic light scattering experiments. The efficacy of cytolysis followed the rank order Cs+ > Rb+ > Na+, Li+ > sucrose = raffinose, which provides additional support for a colloid‐osmotic lytic mechanism. Furthermore, the rank order potency correlates with the cations' hydration numbers. We suggest that oxidative events trigger the formation of colloid‐osmotic pores ∼I nm in diameter. © 1993 Wiley‐Liss, Inc.
Flow cytometry reveals different lag times in rapid cytoplasmic calcium elevations in human neutrophils in response to N‐formyl peptide
Authors: Elsner Jörn , Norgauer Johannes , Dobos Gustav J. , Emmendörffer Andreas , Schöpf Erwin , Kapp Alexander , Roesler Joachim 
Published: February 2005

AbstractFlow cytometric analyses were performed to study intracellular single‐cell calcium transients ([Ca2+]i) in suspended human neutrophils during the initial phase of N‐formyl peptide stimulation. Thereby, two neutrophil populations became apparent. Early maximally Ca2+‐responding (high fluorescence) neutrophils and not‐yet Ca2+‐responding (low fluorescence) neutrophils, but no neutrophils with intermediate levels of [Ca2+]i, were detected. Within 7 s the number of low fluorescence neutrophils decreased and the number of high fluorescence neutrophils increased maximally. This suggests that [Ca2+]i transients occurred abruptly in individual neutrophils within a time interval below 1 s. At lower N‐formyl peptide concentrations the lag times of individual neutrophils and the interval time of maximal activation of the [Ca2+]i‐responding neutrophil population increased, however the percentage of [Ca2+]i‐responding cells decreased. Surprisingly, no influence of the N‐formyl peptide concentration on the [Ca2+]i‐induced fluorescence signal of the individual cell was observed: it was always in an almost maximal range or not responding. In parallel, binding studies performed with fluorescein‐labeled N‐formyl peptide revealed that the heterogeneity of [Ca2+]i‐responding cells cannot be explained by different receptor occupancy. In summary, this study demonstrates that [Ca2+]i transients induced by N‐formyl peptides in suspended individual human neutrophils occur very rapidly in an almost “all‐or‐none manner” and that the mean increasing fluorescence signal of a calcium indicator within a whole neutrophil population results from varying lag times of the individual cells, rather than from the mean simultaneous progress of many cells. © 1993 Wiley‐Liss, Inc.
Human T lymphocytes synthesize the 92 kDa type IV collagenase (gelatinase B)
Authors: Weeks Benjamin S. , Schnaper H. William , Handy Michael , Holloway Eva , Kleinman Hynda K. 
Published: February 2005

AbstractIn order for T cells to exit the circulatory system, traverse the endothelial basement membrane, and arrive in target tissues, these cells must attach to and degrade basement membrane proteins. 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) has been shown to stimulate lymphoid cell adhesion to basement membrane components. We have used TPA to study the ability of human lymphoid cells to secrete type IV collagenases, enzymes capable of degrading basement membrane proteins. Here, we found that human primary T cells and H‐9 lymphoid cells synthesize the 92 kDa type IV collagenase (gelatinase B) and TPA stimulates the synthesis and secretion of this protease. Peak TPA‐stimulated gelatinase B secretion and mRNA accumulation were observed 9 hours after TPA treatment, while the peak adhesion to type IV collagen was observed only 3 hours after TPA treatment. The protein kinase C inhibitor, H‐7, inhibited TPA‐stimulated gelatinase B secretion. Both the primary T cells and H‐9 lymphoid cells also expressed the mRNA for the tissue inhibitor of metalloproteinase‐1 (TIMP‐1). These data demonstrate that TPA ‐ stimulated lymphoid cells adhere to type IV collagen and subsequently synthesize and secrete gelatinase B and TIMP‐1. We conclude that lymphoid cell extravasation may involve cellular employment of adhesion mechanisms prior to degradation of the matrix, which is similar to the process of extravasation used by metastatic cells. © 1993 Wiley‐Liss, Inc.