bluuebunny/crossref_metadata_2025_split huggingface dataset:
Substance P‐related antagonists inhibit vasopressin and bombesin but not 5′‐3‐O‐(thio) triphosphate‐stimulated inositol phosphate production in swiss 3T3 cells
Authors: Seckl Michael J. , Newman Richard H. , Freemont Paul S. , Rozengurt Enrique 
Published: February 2005

AbstractThe substance P (SP) analogues [DArg1, DPhe5, DTrp7,9, Leu11] SP (AntD) and [Arg6, DTrp7,9, MePhe8] SP (6–11) (AntG) inhibit the action of many different neuropeptides including SP. These analogues might be useful in the treatment of small cell lung cancer but their mechanism of action is unclear. Here, we analyzed the effect of AntD and AntG on neuropeptide vs. guanosine 5′‐3‐O‐(thio) triphosphate (GTPγS) stimulated inositol phosphate generation in permeabilized Swiss 3T3 cells. AntD inhibited vasopressin and bombesin stimulated inositol phosphate formation (IC50 of 0.75 μM and 2 μM, respectively). Similarly, AntG inhibited vasopressin‐stimulated inositol phosphate generation with an IC50 of 1 μM. Strikingly, neither AntD up to 10 μM nor AntG up to 20 μM was able to inhibit GTPγS‐stimulated inositol phosphate generation. Dose‐response curves of neuropeptide‐induced inositol phosphate generation were dramatically displaced to the right by either 10 μM AntD or 20 μM AntG. However, neither antagonist affected the dose response of GTPγS‐stimulated inositol phosphate generation. Furthermore, 20 μM AntD had no effect on AIF−4‐induced inositol phosphates in COS‐1 cells transfected with Gαq. AntD inhibited [3H]vasopressin binding competitively in intact Swiss 3T3 cells and both AntD and AntG inhibited [3H]vasopressin binding in Swiss 3T3 and rat liver membranes. Scatchard analysis revealed that AntD inhibited vasopressin binding by reducing receptor affinity without affecting receptor number in both intact and membrane preparations of Swiss 3T3 cells. The results strongly suggest that SP analogues AntD and AntG block the action of the Ca2+ mobilizing neuropeptides at the receptor level, rather than inhibiting G protein‐stimulated inositol phosphate production. © 1995 Wiley‐Liss, Inc.
Okadaic acid co‐induces vimentin expression and cell cycle arrest in MPC‐11 mouse plasmacytoma cells
Authors: Giese G. , Wiegers W. , Kubbies M. , Scherbarth A. , Traub P. 
Published: February 2005

AbstractThe effect of the tumor promoter okadaic acid on cell cycle progression and on vimentin expression in MPC‐11 mouse plasmacytoma cells was compared with that of the tumor promoter 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA). Cell cycle progression of asynchronously grown MPC‐11 cells was inhibited by both agents, but, in contrast to the G1 phase arrest caused by TPA, okadaic acid gave rise to G2/M phase and S phase arrest. This effect of okadaic acid was delayed significantly compared to the TPA‐caused arrest. Furthermore, okadaic acid was able to induce vimentin expression to an extent comparable to the TPA response. However, vimentin expression was markedly delayed in okadaic acid‐treated relative to TPA‐treated cells. Another protein phosphatase inhibitor, calyculin A, also induced cell cycle changes and vimentin expression at concentrations at or above 1 × 10−9M. Based on these observations, we suggest an involvement of protein phosphatase 1 (possibly also phosphatase 2A and/or other phosphatases) in both the G2/M cell cycle block and the induction of vimentin expression in MPC‐11 cells by okadaic acid. © 1995 Wiley‐Liss, Inc.
Regulatory action of prolactin on the in vitro growth of CD34+ve human hemopoietic progenitor cells
Authors: Bellone Graziella , Geuna Massimo , Carbone Anna , Silvestri Stefania , Foa Robin , Emanuelli Giorgio , Matera Lina 
Published: February 2005

AbstractThe pituitary hormone prolactin (Prl) is known to act as a local regulator of immune cell function, and Prl‐binding receptors (Prl‐R) have been described to share distinctive features with the members of the newly described cytokine/hemopoietin receptor superfamily. Here we show that the hormone can functionally interact with lineage‐specific hemopoietic factors. When highly purified progenitor cells (CD34+ve) were seeded in semisolid methylcellulose cultures in the presence of interleukin (IL)‐3, granulocyte‐macrophage colony stimulating factor (GM‐CSF), and erythropoietin (Epo), a selective enhancing effect of Prl on the formation of colony forming unit‐granulocyte (CFU‐G) and burst forming unit‐erythroid (BFU‐E) colonies was observed. The effect of the hormone was plotted as a bell shaped curve, with the optimal response at the supraphysiological concentration of 50 ng/ml. Limiting dilution analysis showed that Prl acted directly on hemopoietic progenitors. This was confirmed by the observation on the CD34+ve cells of Prl‐binding sites reacting with the specific monoclonal antibodies (mAbs), U5 and PrR‐7A. Immunoprecipitation of the metabolically labeled CD34+ve cells with the PrR‐7A mAb revealed a structure of 43 kD under reducing conditions. Analysis of the early events associated with the Prl/Prl‐R interaction showed an increased number of cells engaged in DNA and hemoglobin synthesis. Enhanced erythroid differentiation of CD34+ve cells in the presence of Prl was secondary to upmodulation of receptors for the lineage‐specific factor Epo. Together these data demonstrate the existence of a functional interplay between Prl. and hemopoietic factors. © 1995 Wiley‐Liss, Inc.
Induction of autocrine epidermal growth factor receptor ligands in human keratinocytes by insulin/insulin‐like growth factor‐1
Authors: Vardy Daniel A. , Kari Csaba , Lazarus Gerald S. , Jensen Pamela J. , Zilberstein Asher , Plowman Gregory D. , Rodeck Ulrich 
Published: February 2005

AbstractAutocrine activation of the epidermal growth factor (EGF) receptor on keratinocytes has been recognized as an important growth regulatory mechanism involved in epithelial homeostasis, and, possibly, hyperproliferative diseases. Insulin‐like growth factor (IGF)‐1 and insulin have been shown to be paracrine keratinocyte mitogens that bind to the type I IGF receptor which is expressed on actively proliferating keratinocytes in situ. In this report, we demonstrate that IGF‐1/insulin induced production of keratinocyte‐derived autocrine growth factors that bind to the EGF receptor. Increased steady‐state mRNA levels for transforming growth factor alpha (TGF‐α) and for amphiregulin (AR) were observed upon incubation of keratinocytes with mitogenic concentrations of IGF‐1. IGF‐1 also induced production and secretion of TGF‐α and AR proteins as detected by immunoassays. An EGF receptor antagonistic monoclonal antibody abolished the mitogenic effect of IGF‐1 on cultured keratinocytes. These results suggest that stimulation of keratinocyte growth by IGF‐1 requires activation of an EGF receptor‐mediated autocrine loop. © 1995 Wiley‐Liss, Inc.
Hydrocortisone and progesterone regulation of the proliferation, morphogenesis, and functional differentiation of normal rat mammary epithelial cells in three dimensional primary culture
Authors: Darcy Kathleen M. , Shoemaker Suzanne F. , Lee Ping‐Ping H. , Ganis Barbara A. , Ip Margot M. 
Published: February 2005

AbstractThe mechanisms of action of, and resistance to, the steroidal regulators of normal mammary epithelial and breast cancer cell development are only partially understood. A major obstacle to research progress has been the difficulty in supporting physiologically relevant development of normal mammary epithelial cells (MEC) under defined serum‐free conditions. A primary culture system was developed in our laboratory that permits nonfunctional rat MEC to undergo extensive proliferation, functional differentiation, as well as multilobular and lobuloductal branching alveolar morphogenesis. In the studies reported here, the contributions of hydrocortisone and progesterone during the coordinate induction of cellular proliferation, organoid morphogenesis, and functional capacity were assessed. Hydrocortisone (0.1–10 μg/ml) induced alveolar and multilobular branching morphogenesis, suppressed lobuloductal branching morphogenesis, and enhanced casein accumulation. Hydrocortisone also played a role in maintaining alveolar as well as multilobular branching morphogenesis and casein levels. Progesterone (0.01–1 μg/ml) induced cellular proliferation as well as multilobular and lobuloductal branching morphogenesis, and suppressed casein accumulation. At a supraphysiological concentration (10 μg/ml), progesterone inhibited cell growth, alveolar branching morphogenesis, and casein accumulation. MEC cultured without progesterone for up to 1 week retained the ability to respond when subsequently exposed to this steroid. Reversibility studies suggested that progesterone was required for the induction, but not the maintenance of the mitogenic, morphogenic, and lactogenic effects. This physiologically relevant primary culture system can be used to study the factors that regulate steroid responsiveness as well as the cross‐talk between steroid and growth factor receptor signaling pathways in normal MEC and breast cancer cells. © 1995 Wiley‐Liss, Inc.
RB phosphorylation in sodium butyrate‐resistant HL‐60 cells: Cross‐resistance to retinoic acid but not vitamin D3
Authors: Yen Andrew , Varvayanis Susi 
Published: February 2005

AbstractTo examine the potential coupling between inducible cellular changes in RB (retinoblastoma) tumor suppressor protein phosphorylation and ability to G0 growth arrest and differentiate, HL‐60 promyelocytic leukemia cells were cultured in incremental sodium butyrate (NaB) concentrations and thereby made resistant to the growth inhibitory effects of sodium butyrate, which normally induces G0 arrest and monocytic differentiation in wild type HL‐60 cells. The resistant cells were also unable to differentiate in response to NaB, indicating that a regulatory function controlling both G0 growth arrest and differentiation had been affected. The induced resistance was not genetic in origin since the cells regained the ability to G0 arrest and differentiate after being recultured in medium free of sodium butyrate for only three days. The resistant cells had similar cell cycle phase durations as the original wild type cells. The resistant cells retained the ability to both G0 arrest and differentiate in response to 1,25‐dihydroxy vitamin D3 (VD3), normally an inducer of G0 arrest and monocytic differentiation in wild type cells. However, they were cross‐resistant to retinoic acid (RA), another ligand for the same steroid thyroid hormone receptor family, which induces G0 arrest and myeloid differentiation in wild type cells. The ability to G0 arrest and phenotypically differentiate in response to RA were both grossly impaired. Unlike wild type cells which undergo early down‐regulation and then hypophosphorylation of the RB protein when induced to differentiate, in resistant cells, hypophosphorylation of RB in response to NaB was grossly retarded. These changes in RB protein occurred faster when the cells were treated with VD3. In contrast, the changes in RB phosphorylation occurred significantly slower when the cells were treated with RA. The results suggest a coupling between the ability to G0 growth arrest and phenotypically convert and the ability to hypophosphorylate RB. © 1995 Wiley‐Liss, Inc.
Multifunctional phosphatidic acid signaling in mammary epithelial cells: Stimulation of phosphoinositide hydrolysis and conversion to diglyceride
Authors: Imagawa Walter , Bandyopadhyay Gautam , Nandi Satyabrata 
Published: February 2005

AbstractWe have shown previously that phosphatidic acid esterified to polyunsaturated fatty acids is mitogenic for primary cultures of mouse mammary epithelial cells embedded within collagen gels. We hypothesized that this mitogenic competence resulted from the ability of this phospholipid to activate multiple signal transduction pathways in mammary epithelium. A closer examination of this hypothesis was undertaken by examining the effect of exogenous phosphatidic acid on phosphoinositide (PI) hydrolysis and its intracellular metabolism to diglyceride, an activator of protein kinase C. For assays of phosphoinositide‐specific phospholipase C activation, mammary epithelial cells from virgin Balb/c mice were isolated by collagenase dissociation of mammary glands and cultured on the surface of Type I collagen‐coated culture dishes. Phosphatidic acid (PA) stimulated a sustained increase in inositol phosphates and caused inositol phospholipid depletion when added to cells in which inositol phospholipids were prelabeled with 3H‐myoinositol. This effect was specific for PA among phospholipids tested. Neither lineoleic acid, that can be released from PA, nor prostaglandin E2 affected PI hydrolysis. When mammary epithelial cells were cultured inside collagen gels in the presence of exogenous PA or phosphatidylcholine (PC) radiolabeled with 3H‐glycerol, PA was found to persist intracellularly and be dephosphorylated to diglyceride (an activator of protein kinase C) to a greater extent than PC, a nonmitogenic phospholipid. In contrast to PA, epidermal growth factor (EGF) only slightly stimulated PI hydrolysis, showing that these two different growth‐promoting factors do not actively couple to the same signal transduction pathways in mammary epithelial cells. These results show that PA may activate multiple pathways in mammary epithelial cells either directly or via its metabolism to diglyceride. © 1995 Wiley‐Liss, Inc.
Analysis of sequence‐specific binding activity of cis‐elements in human thymidine kinase gene promoter during G1/S phase transition
Authors: Good Lifeng , Chen Jie , Chen Kuang Yu 
Published: February 2005

AbstractExpression of thymidine kinase (TK) gene in normal human diploid cells is both cell cycle and age dependent and appears to be transcriptionally regulated. Several studies have indicated that the G1/S control sequence may reside within the region of about 130 bp upstream of the transcription initiation site. We have previously shown that a trans‐acting factor, CBP/tk (CCAAT binding protein for TK gene), binds to either one of the two inverted CCAAT boxes in a cell cycle‐ and age‐dependent manner (Pang and Chen, 1993, J. Biol. Chem., 268:2909–2916). An upstream 25 bp fragment (−109/−84), containing both Yi‐like and E2F‐like binding sites, has recently been proposed to be essential for the G1/S regulation of human TK gene. To assess the contribution of various cis‐elements in human TK promoter to the G1/S regulation, we have examined the binding activity of these cis‐elements in the nuclear extracts derived from human IMR‐90 cells at low passage number. Our results indicated that no binding activity could be detected using either the 25 bp fragment (−109/−94) or the authentic Yi sequence. However, Yi binding activity was observed in SV‐40 transformed IMR‐90 cells. In contrast, the 28 bp fragment (−91/−64) that contains the distal inverted CCAAT box exhibited a strong binding in serum‐stimulated young IMR‐90 cells. The binding of CBP/tk to the 28 bp fragment was abolished by a single base mutation in the CCAAT box. The CBP/tk binding of the 28 bp fragment could not be displaced by either the 25 bp fragment or the authentic Yi element. A deletion of the 5′‐flanking region of the 28 bp fragment up to 5 bases also abolished the binding activity. The CBP/tk binding in IMR‐90 cells was supershifted by antiserum against NF‐Ya, but not by antiserum made against p107, pRb, cyclin A, p33cdk2, or p34cdc2. Taken together, our results suggest that the G1/S regulatory cis‐element in human TK promoter may be confined only to CBP/tk binding sites. © 1995 Wiley‐Liss, Inc.
Alterations in the molecular response to DNA damage during cellular aging of cultured fibroblasts: Reduced AP‐1 activation and collagenase gene expression
Authors: Choi Augustine M. K. , Pignolo Robert J. , Rhys Colette M. J. Ap , Cristofalo Vincent J. , Holbrook Nikki J. 
Published: February 2005

AbstractTranscriptional activation of c‐fos in response to both serum stimulation and DNA damage requires the serum response element. The inability of in vitro aged or senescent fibroblasts to proliferate in response to serum has been shown to be associated with repressed c‐fos expression and reduced AP‐1 binding activity. In contrast, we have observed similar levels of c‐fos mRNA and protein expression in young (early passage) and old (late passage) cells following their treatment with ultraviolet (UV) irradiation or methyl methanesulfonate (MMS). Thus, the early events in the signal transduction pathway leading to transcriptional activation of c‐fos following DNA damage are distinct from those mediating the gene's expression in response to mitogenic stimulation. Despite normal levels of c‐fos expression, we observed a reduced level of AP‐1 binding activity in old cells relative to young cells treated with UV irradiation or MMS. Reduced AP‐1 binding activity is associated with reduced expression of the AP‐1‐dependent gene, collagenase, in old cells treated with DNA damaging agents. Since other DNA damage‐inducible genes also contain an AP‐1 regulatory element presumed to play a role in their expression, reduced AP‐1 binding activity is likely to have a major impact on the old cell's ability to respond appropriately to DNA damage. © 1995 Wiley‐Liss, Inc.
THP‐1 macrophage membrane‐bound plasmin activity is up‐regulated by transforming growth factor‐β1 via increased expression of urokinase and the urokinase receptor
Authors: Falcone Domenick J. , McCaffrey Timothy A. , Mathew Jean , McAdam Kimberly , Borth Wolfgang 
Published: February 2005

AbstractReceptors for urokinase (uPA) and plasminogen provide a mechanism to direct the cellular activation of plasminogen. The regulation of these receptors is important for several macrophage functions. In these studies, the effect of transforming growth factor‐b̃1 (TGF‐b̃1) on uPA, uPA receptor, and plasminogen receptor expression by human THP‐1 macrophage was examined. TGF‐b̃1 induction of uPA expression by THP‐1 cells was differentiation dependent. Suspension and adherent cultures expressed similar constitutive levels of uPA. Exposure of adherent cells to TGF‐b̃1 led to a dose‐ and time‐dependent increase in uPA activity which was paralleled by an increase in uPA antigen and uPA mRNA. In contrast, uPA expression by suspension cultures was unresponsive to TGF‐b̃1. The differential response exhibited by suspension and adherent THP‐1 cells may reflect differences in their expression of TGF‐b̃1 receptors, since when assayed by crosslinking techniques, suspension cells primarily expressed a 65 kDa receptor; whereas, the adherent cells expressed 65 and 100 kDa receptors. TGF‐b̃1‐induced alterations in uPA receptor expression by adherent THP‐1 cells were examined by quantitating membrane‐bound uPA activity. Membrane‐bound uPA activity increased three‐fold when cells were incubated with TGF‐b̃1. The increase in membrane‐uPA activity expressed by TGF‐b̃1‐treated cells was not due to increased uPA receptor occupancy since incubation of either control or TGF‐b̃1 primed cells with exogenous uPA did not lead to an increase in membrane‐bound uPA activity. Furthermore, immunoreactive uPA receptor was increased in TGF‐b̃1‐treated cells. Following incubation with plasminogen, membrane‐bound plasmin activity increased three‐fold in TGF‐b̃1‐treated cells. However, no change in immunoreactive membrane‐bound plasmin(ogen) was observed. In addition, binding of 125I‐Lys‐plasminogen to THP‐1 cells was not affected by TGF‐b̃1 treatment. We conclude that TGF‐b̃1 stimulates membrane‐bound plasmin activity, without affecting plasminogen receptor expression, through the up‐regulation of uPA and the uPA receptor expression. © 1995 Wiley‐Liss, Inc.
Kinetics of 125I‐PDGF binding and down‐regulation of PDGF receptor in human arterial smooth muscle cell strains during cellular senescence in vitro
Authors: Aoyagi Masaru , Fukai Naomi , Ogami Kazuo , Yamamoto Mari , Yamamoto Kiyotaka 
Published: February 2005

AbstractPlatelet‐derived growth factor (PDGF) is one of the major mitogens in serum to stimulate replication of human smooth muscle cells (SMCs) in culture. Previous studies using human fibroblasts failed to demonstrate changes in the receptor systems for growth factors during cellular senescence. We investigated the kinetics of 125I‐PDGF(‐BB) binding and down‐regulation of the PDGF receptor in three human arterial SMC strains during cellular aging. The number of specific 125I‐PDGF binding sites per cell increased slightly at a population doubling level (PDL) of 60%–80% of life span and then decreased at the PDL above 90%. The number of receptors per cell‐surface area decreased with increasing in vitro age. The apparent Kd for the 125I‐PDGF binding decreased with in vitro senescence. The internalization and degradation of 125I‐PDGF per receptor were significantly reduced in senescent SMCs than young cells. Furthermore, down‐regulation of the PDGF receptor was significantly greater in sensescent SMCs than young cells. Immunoblot studies demonstrated that changes in b̃‐subunit of the PDGF receptor accounted for those in the studies using 125I‐PDGF and that tyrosine phosphorylation of the PDGF receptor was significantly greater in young SMCs than aged cells. Our results suggest that age‐related changes in the receptor systems for PDGF may be important contributors to the failure of DNA synthesis in senescent SMCs. © 1995 Wiley‐Liss, Inc.
On the mechanisms of the growth‐promoting effect of prostaglandins in hepatocytes: The relationship between stimulation of DNA synthesis and signaling mediated by adenylyl cyclase and phosphoinositide‐specific phospholipase C
Authors: Refsnes Magne , Dajani Olav F. , Sandnes Dagny , Thoresen G. Hege , Røttingen John‐Arne , Iversen Jens‐Gustav , Christoffersen Thoralf 
Published: February 2005

AbstractWhile many observations indicate that prostaglandins may act as positive regulators of hepatocyte proliferation, the underlying mechanisms are not known. We have examined some of the signal pathways in the growth response induced by prostaglandins in hepatocytes, with particular focus on adenylyl cyclase and phosphoinositide‐specific phospholipase C. Adult rat hepatocytes were cultured as primary monolayers in serum‐free medium in the presence of EGF and insulin. PGE2 or PGF2α (added 0‐3 h after plating) enhanced the incorporation of [3H]‐thymidine into DNA (measured at 50 h); at 100 γM the stimulation was about threefold. PGI2 and PGD2 also showed significant but smaller stimulatory effects. No significant increase in the level of cyclic AMP (cAMP) was detected in response to any of the prostaglandins. Low concentrations of glucagon (0.1‐10 nM), a potent activator of hepatic adenylyl cyclase, or 8‐bromo‐cAMP (0.1‐10 γM) enhanced the DNA synthesis. When 8‐bromo‐cAMP was used in maximally effective concentrations, no further stimulation was obtained by combining it with glucagon, whereas the effects of PGE2 and 8‐bromo‐cAMP were completely additive. All the prostaglandins also showed additivity with the effect of glucagon on the DNA synthesis. PGE2, PGF2α, PGI2, and PGD2 increased intracellular inositol‐1,4,5‐trisphosphate (InsP3), with a relative order of efficacy roughly corresponding to their activity as stimulators of DNA synthesis. Increases in cytosolic free Ca2+, as measured in single cells, were elicited in a majority of the hepatocytes by all these prostaglandins at 1 γM. Supramaximal concentrations of vasopressin, a strong activator of phospholipase C in hepatocytes, acted additively with PGE2 on the DNA synthesis. Pretreatment of the hepatocytes with a concentration of pertussis toxin that prevented the inhibitory effect of PGE2 on glucagon‐induced cAMP accumulation did not abolish the ability of PGE2 to stimulate the DNA synthesis. The results do not support a role for adenylyl cyclase activation in the stimulatory effect of prostaglandins on hepatocyte growth. While the data are compatible with an involvement of phosphoinositide‐specific phospholipase C in the growth‐promoting effect of prostaglandins in cultured rat hepatocytes, they suggest this may not be the sole mechanism. © 1995 Wiley‐Liss, Inc.