bluuebunny/crossref_metadata_2025_split huggingface dataset:
K vitamins, PTP antagonism, and cell growth arrest
Authors: Carr Brian I. , Wang Ziqiu , Kar Siddhartha 
Published: October 2002

AbstractThe main function of K vitamins is to act as co‐factors for γ‐glutamyl carboxylase. However, they have also recently been shown to inhibit cell growth. We have chemically synthesized a series of K vitamin analogs with various side chains at the 2 or 3 position of the core naphthoquinone structure. The analogs with short thio‐ethanol side chains are found to be more potent growth inhibitors in vitro of various tumor cell lines. Cpd 5 or [2‐(2‐mercaptoethanol)‐3‐methyl‐1,4‐naphthoquinone] is one of the most potent. The anti‐proliferation activity of these compounds is antagonized by exogenous thiols but not by non‐thiol antioxidants. This suggests that the growth inhibition is mediated by sulfhydryl arylation of cellular glutathione and cysteine‐containing proteins and not by oxidative stress. The protein tyrosine phosphatases (PTP) are an important group of proteins that contain cysteine at their catalytic site. PTPs regulate mitogenic signal transduction and cell cycle progression. PTP inhibition by Cpd 5 results in prolonged tyrosine phosphorylation and activation of several kinases and transcription factors including EGFR, ERK1/2, and Elk1. Cpd 5 could activate ERK1/2 either by signaling from an activated EGFR, which is upstream in the signaling cascade, or by direct inhibition of ERK1/2 phosphatase(s). Prolonged ERK1/2 phosphorylation strongly correlates with Cpd 5‐mediated growth inhibition. Cpd 5 can also bind to and inhibit the Cdc25 family of dual specific phosphatases. As a result, several Cdc25 substrates (Cdk1, Cdk2, Cdk4) involved in cell cycle progression are tyrosine phosphorylated and thereby inhibited by its action. Cpd 5 could also inhibit both normal liver regeneration and hepatoma growth in vivo. DNA synthesis during rat liver regeneration following partial hepatectomy, transplantable rat hepatoma cell growth, and glutathione‐S‐transferase‐pi expressing hepatocytes after administration of the chemical carcinogen diethylnitrosamine, are all inhibited by Cpd 5 administration. The growth inhibitory effect during liver regeneration and transplantable tumor growth is also correlated with ERK1/2 phosphorylation induced by Cpd 5. Thus, Cpd 5‐mediated inhibition of PTPs, such as Cdc25 leads to cell growth arrest due to altered activity of key cellular kinases involved in signal transduction and cell cycle progression. This prototype K vitamin analog represents a novel class of growth inhibitor based upon its action as a selective PTP antagonist. It is clearly associated with prolonged ERK1/2 phosphorylation, which is in contrast with the transient ERK1/2 phosphorylation induced by growth stimulatory mitogens. © 2002 Wiley‐Liss, Inc.
Role for cellular Src kinase in myoblast proliferation
Authors: Rosoff William J. , Swope Sheridan L. 
Published: October 2002

AbstractIn this study, a role for cellular Src in muscle cell proliferation and differentiation was investigated. Pharmacological inhibition of Src‐class kinases repressed proliferation and promoted differentiation of the C2C12 muscle cell line, even when the cells were cultured under growth‐inducing conditions of high serum. Pharmacological inhibition of Src‐class kinases also affected cellular components that regulate proliferation and differentiation in muscle; cyclin D1 levels were reduced while, myogenin was increased. Suppression of cyclin D1 and enhancement of myogenin levels also occurred upon expression of a dominant negative Src, corroborating a role for Src kinases in regulating proliferation and differentiation. Inhibition of Src‐family kinases also blocked fibroblast growth factor (FGF) induced proliferation but, notably, did not reverse the effect of FGF to inhibit differentiation. Evidence for the Src‐class kinase Src in myoblast mitogenesis was obtained by determining the pattern of protein expression and activity for this kinase. Under all conditions examined, Src's expression and enzymatic activity were high in cultures of myoblasts and down‐regulated during differentiation. Importantly, Src's activity was rapidly stimulated by mitogen‐containing serum and attenuated when myoblasts were switched to low serum‐containing differentiation medium. These data indicate that Src is important for maintaining muscle cell proliferation. J. Cell. Physiol. 193: 328–339, 2002. © 2002 Wiley‐Liss, Inc.
Antibodies to high‐density lipoprotein and β2‐glycoprotein I are inversely correlated with paraoxonase activity in systemic lupus erythematosus and primary antiphospholipid syndrome
Authors: Delgado Alves J. , Ames P. R. J. , Donohue S. , Stanyer L. , Noorouz‐Zadeh J. , Ravirajan C. , Isenberg D. A. 
Published: October 2002

AbstractObjectiveTo determine the prevalence of anti–high‐density lipoprotein (anti‐HDL) antibodies and to establish a possible relationship between anti‐HDL, anticardiolipin antibodies (aCL), anti–β2‐glycoprotein I (anti‐β2GPI), and paraoxonase (PON) activity in patients with systemic lupus erythematosus (SLE) and primary antiphospholipid syndrome (APS).MethodsThirty‐two patients with SLE and 36 with primary APS were enrolled in a cross‐sectional study. Twenty age‐ and sex‐matched healthy subjects were used as controls. Serum levels of IgG and IgM aCL, anti‐β2GPI, and antiprothrombin antibodies and IgG anti‐HDL were measured by enzyme‐linked immunosorbent assay. Total cholesterol, HDL cholesterol, HDL2, and HDL3 were determined by standard enzymatic techniques. PON activity was assessed by quantification of nitrophenol formation, and total antioxidant capacity (TAC) by chemiluminescence.ResultsLevels of total HDL, HDL2, and HDL3 were reduced in patients with SLE compared with controls (mean ± SD 0.51 ± 0.3, 0.37 ± 0.3, and 0.14 ± 0.1 mmoles/liter, respectively, versus 1.42 ± 0.9, 1.01 ± 0.7, and 0.40 ± 0.2). Patients with SLE and primary APS had higher titers of anti‐HDL antibodies and lower PON activity than controls. In the SLE population, PON activity was inversely correlated with IgG anti‐HDL titers (r = −0.48, P = 0.005) whereas in the primary APS population, IgG anti‐β2GPI was the only independent predictor of PON activity (r = −0.483, P = 0.003). In the SLE group, anti‐HDL was inversely correlated with TAC (r = −0.40, P < 0.02), and PON activity was positively correlated with TAC (r = 0.43, P < 0.02).ConclusionIgG anti‐HDL and IgG anti‐β2GPI antibodies are associated with reduced PON activity in patients with SLE and primary APS. Since the physiologic role of PON is to prevent low‐density lipoprotein oxidation with its attendant atherogenic effects, the reported interactions may be relevant to the development of atherosclerosis in SLE and primary APS.
Interactions of antimitotic peptides and depsipeptides with tubulin
Authors: Hamel Ernest 
Published: October 2002

AbstractTubulin is the target for an ever increasing number of structurally unusual peptides and depsipeptides isolated from a wide range of organisms. Since tubulin is the subunit protein of microtubules, the compounds are usually potently toxic to mammalian cells. Without exception, these (depsi)peptides disrupt cellular microtubules and prevent spindle formation. This causes cells to accumulate at the G2/M phase of the cell cycle through inhibition of mitosis. In biochemical assays, the compounds inhibit microtubule assembly from tubulin and suppress microtubule dynamics at low concentrations. Most of the (depsi)peptides inhibit the binding of Catharanthus alkaloids to tubulin in a noncompetitive manner, GTP hydrolysis by tubulin, and nucleotide turnover at the exchangeable GTP site on β‐tubulin. In general, the (depsi)peptides induce the formation of tubulin oligomers of aberrant morphology. In all cases tubulin rings appear to be formed, but these rings differ in diameter, depending on the (depsi)peptide present during their formation. Published 2002 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 66: 142–160, 2002
Three‐dimensional fibroblast–tumor cell interaction causes downregulation of RACK1 mRNA expression in breast cancer cells in vitro
Authors: Seidl Paula , Huettinger Robert , Knuechel Ruth , Kunz‐Schughart Leoni A. 
Published: October 2002

AbstractFibroblasts are the most abundant stromal cell type in desmoplastic ductal invasive breast tumors, are a substrate of tumor cell invasion and modify tumor cell behavior. However, the complex interaction between tumor cells and fibroblasts remains incompletely understood. Our aim was to identify candidate genes in tumor cells that are affected by fibroblasts and to reveal new molecules involved in this heterologous interaction. To reflect the in vivo situation, a 3‐D multicellular spheroid coculture model of breast tumor cells and fibroblasts was combined with cell separation technology (MACS and FACS) and molecular analyses, including RAP‐PCR, semiquantitative RT‐PCR and reverse Northern blotting. Three tumor cell lines (BT474, T47D and MCF‐7) with different invasive potential were applied in coculture with normal skin and/or breast tumor‐derived fibroblasts. With the techniques mentioned, 18 different bands in the tumor cDNA band pattern of mono‐ as opposed to cocultures were identified. One of the mRNAs is considered worth further analysis: rack1. Rack1 mRNA was reproducibly suppressed in tumor cells following interaction with fibroblasts. Downregulation was recorded in all tumor cell lines and for cocultures with both types of fibroblast. This indicates a general regulatory mechanism between epithelial tumor cells and fibroblasts, which may be an interesting tumor cell differentiation–independent target for therapy. © 2002 Wiley‐Liss, Inc.
Deletion of chromosomal region 6q14‐16 in prostate cancer
Authors: Verhagen Paul C.M.S. , Hermans Karin G.L. , Brok Mariel O. , van Weerden Wytzke M. , Tilanus Marcel G.J. , de Weger Roel A. , Boon Tom A. , Trapman Jan 
Published: October 2002

AbstractA detailed analysis of chromosome 6 in DNAs from prostate cancers was performed, to define a region for subsequent search for cancer genes. DNA from 4 prostate cancer cell lines and 11 xenografts was used for CGH and whole‐chromosome allelotyping with polymorphic microsatellite markers. Loss of proximal 6q was studied in more detail by high‐density allelotyping of xenografts, cell lines and 19 prostate tumour specimens from TURP. Seven of 15 xenografts and cell lines showed deletion of proximal 6q by CGH. Gain of 6q was found in 2 samples. Six samples showed 6p gain, and 1 had 6p loss. Allelotyping results were consistent with CGH data in 11 of 15 DNAs. In LNCaP and DU145 cells, CGH showed 6p loss and 6q loss, respectively, but 2 allelic bands were detected for many polymorphic markers on these chromosome arms. These apparent discrepancies might be explained by aneuploidy. In cell line TSU, allelotyping demonstrated chromosome 6 deletion, which was not clearly detected by CGH, indicating loss of 1 copy of chromosome 6 followed by gain of the retained copy during progressive tumour growth. Loss of heterozygosity was detected in 9 of 19 TURP specimens. Combining all data, we found a common minimal region of loss at 6q14‐16 with a length of 8.6 Mbp flanked by markers D6S1609 and D6S417. One hundred and twenty‐three STSs, ESTs, genes and candidate genes mapping in this interval were used to screen xenografts and cell lines for HDs, but none was detected. In summary, chromosome region 6q14‐16 was deleted in approximately 50% of the prostate cancer specimens analysed. The high percentage of loss underscores the importance of genes within this region in prostate cancer growth. © 2002 Wiley‐Liss, Inc.
Effect of the vascular endothelial growth factor receptor‐2 antibody DC101 plus gemcitabine on growth, metastasis and angiogenesis of human pancreatic cancer growing orthotopically in nude mice
Authors: Bruns Christiane J. , Shrader Marissa , Harbison Matthew T. , Portera Charles , Solorzano Carmen C. , Jauch K.‐W. , Hicklin Daniel J. , Radinsky Robert , Ellis Lee M. 
Published: October 2002

AbstractVascular endothelial growth factor (VEGF) is the major pro‐angiogenic factor for most tumors. VEGF expression has been shown to be associated with a poor prognosis in human pancreatic cancer. The purpose of our study was to determine the effect of blockade of VEGF receptor‐2 activity with or without gemcitabine on tumor growth and metastasis in an orthotopic model of human pancreatic cancer in nude mice. Therapy with gemcitabine or DC101, a VEGF receptor‐2 antibody, resulted in a significant reduction of primary pancreatic tumor growth compared to untreated controls. The combination of DC101 and gemcitabine inhibited primary pancreatic tumor growth and lymphatic metastasis to a greater degree than either agent alone. Treatment with DC101 decreased vessel counts and increased the area of hypoxic tumor tissue compared to controls. Immunofluorescent double staining for apoptotic endothelial cells demonstrated a significant increase in the number apoptotic endothelial cells 24 days after initiation of therapy with DC101 plus gemcitabine. DC101 plus gemcitabine also increased tumor cell death and decreased tumor cell proliferation in pancreatic tumors. These findings indicate that blockade of VEGF receptor activation interferes with the survival of tumor endothelial cells, resulting in a reduction of primary pancreatic tumor growth in nude mice. Furthermore, the data demonstrate that anti‐VEGF receptor‐2 therapy potentiates the tumoricidal effect of gemcitabine in this model. Anti‐VEGF receptor‐2 therapy in combination with gemcitabine may be a novel therapeutic approach for advanced pancreatic cancer. © 2002 Wiley‐Liss, Inc.
Overexpression of integrin αv promotes human osteosarcoma cell populated collagen lattice contraction and cell migration
Authors: Levinson Howard , Hopper James E. , Ehrlich H. Paul 
Published: October 2002

AbstractCells attach and interact with the extracellular matrix (ECM) through heterodimeric αβ integrin receptors. Specifically, the promiscuous αvβ3 integrin and the α2β1 integrin receptors engage numerous matrix components to influence cell adhesion, cell motility, and matrix organization. However, the role of αv integrin mediating cell–collagen interactions is not clear. In the in vitro cell populated collagen lattice (PCL), a model of cell–matrix interaction, integrin receptors play a role in lattice contraction. To elucidate αv integrins' effects on cell–collagen interactions, human osteosarcoma (HOS) cells were transfected with αv integrin (αv‐pcDNA 3.1+). Control HOS cells were transfected with pcDNA 3.1+ vector alone. HOS‐αv cell PCLs contracted to a greater degree than control HOS cell PCLs (P ≤ 0.0001). RT‐PCR revealed that HOS‐αv cells express both β1 and β3 integrins, indicating that αv has the potential to form a partnership with either β1 or β3 integrin. The αvβ3 specific inhibitory antibody LM609 significantly retarded HOS‐αv cell PCL contraction (P ≤ 0.001), suggesting that αvβ3 promotes enhanced HOS‐αv cell PCL contraction. When plated on plastic, control HOS cells show greater elongation compared to HOS‐αv cells. In addition, HOS‐αv cells migrated faster and to a greater degree than control HOS cells (P ≤ 0.0001). The possibility that enhanced HOS‐αv cell migration and HOS‐αv cell PCL contraction was caused by increased myosin ATPase activity was examined. HOS‐αv cells showed less myosin ATPase activity than control HOS cells, by an ATP cell contraction bioassay. The enhancement of HOS‐αv cell migration and lattice contraction appears unrelated to increased myosin ATPase activity. © 2002 Wiley‐Liss, Inc.
Mechanisms regulating the expression, self‐maintenance, and signaling‐function of the bradykinin B2 and B1 receptors
Authors: Prado Gregory N. , Taylor Linda , Zhou Xiaofeng , Ricupero Dennis , Mierke Dale F. , Polgar Peter 
Published: October 2002

AbstractBradykinin (BK) is a potent short‐lived effector belonging to a class of peptides known as kinins. It participates in inflammatory and vascular regulation and processes including angioedema, tissue permeability, vascular dilation, and smooth muscle contraction. BK exerts its biological effects through the activation of the bradykinin B2 receptor (BKB2R) which is G‐protein‐coupled and is generally constitutively expressed. Upon binding, the receptor is activated and transduces signal cascades which have become paradigms for the actions of the Gαi and Gαq G‐protein subunits. Following activation the receptor is then desensitized, endocytosed, and resensitized. The bradykinin B1 (BKB1R) is a closely related receptor. It is activated by desArg10‐kallidin or desArg9‐BK, metabolites of kallidin and BK, respectively. This receptor is induced following tissue injury or after treatment with bacterial endotoxins such as lipopolysacharide or cytokines such as interleukin‐1 or tumor necrosis factor‐α. In this review we will summarize the BKB2R and BKB1R mediated signal transduction pathways. We will then emphasize the relevance of key residues and domains of the intracellular regions of the BKB2R as they relate to modulating its function (signal transduction) and self‐maintenance (desensitization, endocytosis, and resensitization). We will examine the features of the BKB1R gene promoter and its mRNA as these operate in the expression and self‐maintenance of this inducible receptor. This communication will not cover areas discussed in earlier reviews pertaining to the actions of peptide analogs. For these we refer you to earlier reviews (Regoli and Barabé, 1980, Pharmacol Rev 32:1–46; Regoli et al., 1990, J Cardiovasc Pharmacol 15(Suppl 6):S30–S38; Regoli et al., 1993, Can J Physiol Pharmacol 71:556–557; Marceau, 1995, Immunopharmacology 30:1–26; Regoli et al., 1998, Eur J Pharmacol 348:1–10). J. Cell. Physiol. 193: 275–286, 2002. © 2002 Wiley‐Liss, Inc.
Innervation of the carotid body: Immunohistochemical, denervation, and retrograde tracing studies
Authors: Ichikawa Hiroyuki 
Published: October 2002

AbstractThis review presents information about multiple neurochemical substances in the carotid body. Nerve fibers around blood vessels and glomus cells within the chemoreceptive organ contain immunoreactivities (IR) for tyrosine hydroxylase (TH), calcitonin gene‐related peptide (CGRP), substance P (SP), galanin (GAL), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), calretinin (CR), calbindin D‐28k (CB), parvalbumin (PV), and nitric oxide synthase (NOS). Parasympathetic neurons scattered around the carotid body contain VIP, choline acetyltransferase, and vanilloid receptor 1‐like receptor. In the mammalian carotid body, transection of the carotid sinus nerve (CSN) causes the absence or decrease of CGRP‐, SP‐, and NOS‐immunoreactive (IR) nerve fibers, whereas all NPY‐IR nerve fibers disappear after removal of the superior cervical ganglion. Most VIP‐IR nerve fibers disappear but a few persist after sympathetic ganglionectomy. In addition, the CSN transection appears to cause the acquisition of GAL‐IR in originally immunonegative glomus cells and nerve fibers within the rat carotid body. On the other hand, 4%, 25%, 17%, and less than 1% of petrosal neurons retrogradely labeled from the rat CSN contain TH‐, CGRP‐, SP‐, and VIP‐IR, respectively. In the chicken carotid body, many CGRP‐ and SP‐IR nerve fibers disappear after vagus nerve transection or nodose ganglionectomy. GAL‐, NPY‐, and VIP‐IR nerve fibers mostly disappear after removal of the 14th cervical ganglion of the sympathetic trunk. The origin and functional significance of the various neurochemical substances present in the carotid body is discussed. Microsc. Res. Tech. 59:188–195, 2002. © 2002 Wiley‐Liss, Inc.
Halofuginone inhibition of COL1A2 promoter activity via a c‐Jun–dependent mechanism
Authors: McGaha Tracy L. , Kodera Takao , Spiera Harry , Stan Alexandru C. , Pines Mark , Bona Constantin A. 
Published: October 2002

AbstractObjectiveThe naturally occurring compound halofuginone has been shown to antagonize collagen synthesis by fibroblasts both in vitro and in vivo. We previously demonstrated that this inhibitory property was related to the ability of halofuginone to disrupt transforming growth factor β signal transduction. The present study further analyzed the ability of halofuginone to affect transcription factors that can regulate type I collagen gene expression by examining its effect on c‐Jun, the negative regulator of collagen gene transcription.MethodsThe phosphorylation state of c‐Jun in the presence of halofuginone was examined via direct Western blotting, and the transcriptional activity of the activator protein 1 (AP‐1) binding element via electrophoretic mobility shift assay and luciferase reporter assay. We determined whether the effect of halofuginone on collagen synthesis was dependent on the presence of c‐Jun by ectopic expression of a wild‐type or dominant‐negative c‐Jun construct in the presence of halofuginone and assaying α2(I) collagen promoter strength via luciferase reporter assay. The effect of halofuginone on α2(I) collagen message levels in fibroblasts when wild‐type or dominant‐negative c‐Jun was overexpressed was determined. We also determined whether halofuginone had an effect on the phosphorylation state of c‐Jun in the skin of TSK/+ mice via immunohistochemistry.ResultsTreatment of fibroblasts with 10−8M halofuginone enhanced basal and mitogen‐mediated phosphorylation of c‐Jun in culture. This elevated phosphorylation of c‐Jun correlated with enhanced DNA binding and transcriptional activation of an AP‐1 complex consisting of c‐Jun and Fos but lacking the c‐Jun antagonist JunB. Overexpression of c‐Jun enhanced in a dose‐dependent manner the ability of halofuginone to inhibit the activity of a luciferase reporter construct under control of the −3200‐bp to +54‐bp COL1A2 promoter, whereas the expression of a dominant‐negative c‐Jun construct abolished this effect. Northern blotting showed that overexpression of c‐Jun enhanced the ability of halofuginone to reduce collagen α2(I) messenger RNA levels in fibroblasts, whereas expression of the dominant‐negative c‐Jun abolished this effect. Topical administration of a halofuginone‐containing cream for 20 days to TSK mice, which spontaneously develop dermal fibrosis, greatly increased the phosphorylated form of c‐Jun in the skin; this was followed by a decrease in skin thickness and type I collagen messenger RNA expression.ConclusionOur findings illustrate the powerful down‐regulatory property of c‐Jun toward type I collagen and establish that halofuginone exerts its effect on collagen synthesis in a c‐Jun–dependent manner.