bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of Smad4 in the FaDu cell line partially restores TGF‐beta growth inhibition but is not sufficient to regulate fibronectin expression or suppress tumorigenicity
Authors: Hummer B. Timothy , Bartlett Christopher , Henry Erin , Weissman Bernard E. 
Published: January 2003

AbstractMutations of the Smad4 gene, a member of a group of TGF‐β signal transduction components, occur in several types of cancer suggesting that its inactivation significantly affects TGF‐β responsiveness in these tumors. To further investigate the role of Smad4 with respect to TGF‐β signaling and carcinogenesis, we re‐expressed the Smad4 gene in the Smad4‐deficient cancer cell line FaDu by microcell‐mediated chromosome transfer (MMCT) and retroviral infection to closely approximate physiological protein levels. The Smad4‐expressing FaDu clones were then evaluated for TGF‐β responsiveness to assess the role of Smad4 in TGF‐β‐induced growth inhibition and target gene regulation. We found that the re‐expression of the Smad4 gene by either method partially restored TGF‐β responsiveness in FaDu cells with respect to both growth inhibition and expression of p21WAF1/CIP1 and p15INK4B. However, only the microcell hybrids showed growth retardation in organotypic raft culture and an enhanced ability to upregulate fibronectin. In contrast, the re‐expression of Smad4 by either method failed to suppress tumorigenicity. These results suggest that in addition to a homozygous deletion of Smad4, FaDu cells contain additional defects within the TGF‐β signaling pathway, thereby limiting the extent of TGF‐β responsiveness upon Smad4 re‐expression and perhaps accounting for the inability to induce p15INK4B to a high level. They also demonstrate the advantages of providing a physiological extracellular environment, when assessing TGFβ responsiveness. © 2003 Wiley‐Liss, Inc.
Dissociation of focal adhesion kinase and paxillin tyrosine phosphorylation induced by bombesin and lysophosphatidic acid from epidermal growth factor receptor transactivation in Swiss 3T3 cells
Authors: Salazar Eduardo Perez , Hunger‐Glaser Isabel , Rozengurt Enrique 
Published: January 2003

AbstractTyrosine phosphorylation of the nonreceptor tyrosine kinase p125 focal adhesion kinase (FAK) and the adapter protein paxillin is rapidly increased by multiple agonists, including bombesin (BOM) and lysophosphatidic acid (LPA), through heptahelical G protein‐coupled receptors (GPCRs). The pathways involved remain incompletely understood. The experiments presented here were designed to test the role of epidermal growth factor receptor (EGFR) transactivation in the rapid increase of tyrosine phosphorylation of FAK and paxillin induced by GPCR agonists. Our results show that treatment with the selective EGFR tyrosine kinase inhibitor AG 1478, at concentrations that completely blocked the increase in tyrosine phosphorylation of these proteins induced by EGF, did not affect the stimulation of tyrosine phosphorylation of either FAK or paxillin induced by multiple GPCR agonists including LPA, BOM, vasopressin, bradykinin, and endothelin. Similar results were obtained when Swiss 3T3 cells were treated with another highly specific inhibitor of the EGF receptor kinase activity, PD‐158780. Collectively, our results clearly dissociate EGFR transactivation from the tyrosine phosphorylation of FAK and paxillin induced by multiple GPCR agonists. © 2002 Wiley‐Liss, Inc.
α‐Lipoic acid induces p27Kip‐dependent cell cycle arrest in non‐transformed cell lines and apoptosis in tumor cell lines
Authors: Mark Karyn van de , Chen James S. , Steliou Kosta , Perrine Susan P. , Faller Douglas V. 
Published: January 2003

Abstractα‐Lipoic acid is a naturally‐occurring co‐factor found in a number of multi‐enzyme complexes regulating metabolism. We report here that α‐lipoic acid induces hyperacetylation of histones in vivo and has differential effects on the growth and viability of normal versus transformed cell lines. The human tumor cell lines FaDu and Jurkat, as well as a Ki‐v‐Ras‐transformed Balb/c‐3T3 murine mesenchymal cell line, all initiated apoptosis following exposure to α‐lipoic acid. In contrast, treatment of non‐transformed cell lines with α‐lipoic acid resulted only in reversible cell cycle arrest in G0/G1. Treatment with butyrate, another short‐chain fatty acid, induced a G0/G1 arrest in both transformed and non‐transformed cell lines. α‐Lipoic acid caused a post‐translational elevation in the levels of the cyclin‐dependent kinase inhibitor p27Kip1. Studies using p27Kip1‐deficient MEF cells demonstrated that p27Kip1 was required for the α‐lipoic acid‐mediated cell cycle arrest. The mechanism of apoptosis was independent of Fas‐mediated signaling, as α‐lipoic acid‐treated Jurkat cell mutants deficient in Fas or FADD retained sensitivity to apoptosis. The differential selectivity of the pro‐apoptotic effects of α‐lipoic acid for transformed cells supports its potential use in the treatment of neoplastic disorders. © 2003 Wiley‐Liss, Inc.
Role of CTGF/HCS24/ecogenin in skeletal growth control
Authors: Takigawa Masaharu , Nakanishi Tohru , Kubota Satoshi , Nishida Takashi 
Published: January 2003

AbstractConnective tissue growth factor/hypertrophic chondrocyte‐specific gene product 24 (CTGF/Hcs24) is a multifunctional growth factor for chondrocytes, osteoblasts, and vascular endothelial cells. CTGF/Hcs24 promotes the proliferation and maturation of growth cartilage cells and articular cartilage cells in culture and hypertrophy of growth cartilage cells in culture. The factor also stimulates the proliferation and differentiation of cultured osteoblastic cells. Moreover, CTGF/Hcs24 promotes the adhesion, proliferation, and migration of vascular endothelial cells, as well as induces tube formation by the cells and strong angiogenesis in vivo. Because angiogenesis is critical for the replacement of cartilage with bone at the final stage of endochondral ossification and because gene expression of CTGF/Hcs24 predominates in hypertrophic chondrocytes in the physiological state, a major physiological role for this factor should be the promotion of the entire process of endochondral ossification, with the factor acting on the above three types of cells as a paracrine factor. Thus, CTGF/Hcs24 should be called “ecogenin: endochondral ossification genetic factor.” In addition to hypertrophic chondrocytes, osteoblasts activated by various stimuli including wounding also express a significantly high level of CTGF/Hcs24. These findings in conjunction with in vitro findings about osteoblasts mentioned above suggest the involvement of CTGF/Hcs24 in intramembranous ossification and bone modeling/remodeling. Because angiogenesis is also critical for intramembranous ossification and bone remodeling, CTGF/Hcs24 expressed in endothelial cells activated by various stimuli including wounding may also play important roles in direct bone formation. In conclusion, although the most important physiological role of CTGF/Hcs24 is ecogenin action, the factors also play important roles in skeletal growth and modeling/remodeling via its direct action on osteoblasts under both physiological and pathological conditions. © 2003 Wiley‐Liss, Inc.
HES and HERP families: Multiple effectors of the notch signaling pathway
Authors: Iso Tatsuya , Kedes Larry , Hamamori Yasuo 
Published: January 2003

AbstractNotch signaling dictates cell fate and critically influences cell proliferation, differentiation, and apoptosis in metazoans. Multiple factors at each step—ligands, receptors, signal transducers and effectors—play critical roles in executing the pleiotropic effects of Notch signaling. Ligand‐binding results in proteolytic cleavage of Notch receptors to release the signal‐transducing Notch intracellular domain (NICD). NICD migrates into the nucleus and associates with the nuclear proteins of the RBP‐Jκ family (also known as CSL or CBF1/Su(H)/Lag‐1). RBP‐Jκ, when complexed with NICD, acts as a transcriptional activator, and the RBP‐Jκ‐NICD complex activates expression of primary target genes of Notch signaling such as the HES and enhancer of split [E(spl)] families. HES/E(spl) is a basic helix‐loop‐helix (bHLH) type of transcriptional repressor, and suppresses expression of downstream target genes such as tissue‐specific transcriptional activators. Thus, HES/E(spl) directly affects cell fate decisions as a primary Notch effector. HES/E(spl) had been the only known effector of Notch signaling until a recent discovery of a related but distinct bHLH protein family, termed HERP (HES‐related repressor protein, also called Hey/Hesr/HRT/CHF/gridlock). In this review, we summarize the recent data supporting the idea of HERP being a new Notch effector, and provide an overview of the similarities and differences between HES and HERP in their biochemical properties as well as their tissue distribution. One key observation derived from identification of HERP is that HES and HERP form a heterodimer and cooperate for transcriptional repression. The identification of the HERP family as a Notch effector that cooperates with HES/E(spl) family has opened a new avenue to our understanding of the Notch signaling pathway. © 2003 Wiley‐Liss, Inc.
Chemical sympathectomy‐induced changes in TH‐, VIP‐, and CGRP‐immunoreactive fibers in the rat mandible periosteum: Influence on bone resorption
Authors: Cherruau M. , Morvan F.O. , Schirar A. , Saffar J.L. 
Published: January 2003

AbstractThe expression of neurotransmitter receptors by bone cells supports the concept that the nervous system is a regulator of bone metabolism. The discrimination of the respective roles of the sensory and sympathetic nervous systems requires evidence of topographic relationships between the corresponding fibers and the cells involved in bone turnover, in vivo. In this study, the influence of the sympathetic system on bone resorption was assessed by using a synchronized model of cortical resorption along the mandible. The sympathetic system was destroyed by daily injections of guanethidine (40 mg/kg) for 25 days; a resorption wave was induced on day 21. The distribution of periosteal tyrosine‐hydroxylase (TH)‐, vasoactive intestinal polypeptide (VIP)‐, and calcitonin gene‐related peptide (CGRP)‐immunoreactive (IR) fibers was studied by compartmentalizing the periosteum. Most fibers were located in the distal, non‐osteogenic compartment. TH‐IR fibers were located perivascularly, VIP‐IR fibers were gathered at the boundary with the osteogenic compartment, and CGRP‐IR fibers were scattered. Sympathectomy decreased the number of TH‐ and VIP‐IR fibers and increased the number of CGRP‐IR fibers, without changing their topography. After the injection of Fast blue, a retrograde fluorescent marker, over the periosteum, fluorescent neuronal cell bodies were found in the superior cervical ganglion (SCG). Many neurons were TH‐IR and very few were VIP‐IR. Sympathectomy decreased the numbers of fluorescent and TH‐IR cell bodies. It also decreased the number of preosteoclasts and osteoclasts, which had a drastic effect on the cortical bone surface, as assessed by scanning electron microscopy. These data indicate that VIP‐IR fibers have a strategic position close to the most peripheral and less differentiated, osteogenic cells, pointing to a functional relationship. As poorly differentiated osteogenic cells support preosteoclast differentiation, VIP‐IR fibers may be involved in this process, as suggested by the smaller number of preosteoclasts in sympathectomized rats. Although VIP is predominantly a parasympathetic mediator, it seemed to be conveyed by sympathetic fibers, as shown by the marked effect of guanethidine treatment. Nevertheless, these fibers did not originate from the SCG, contrary to TH‐IR fibers. © 2003 Wiley‐Liss, Inc.
Role of PP2A in the regulation of p38 MAPK activation in bovine aortic endothelial cells exposed to cyclic strain
Authors: Lee Taeseung , Kim Sang Joon , Sumpio Bauer E. 
Published: January 2003

AbstractWe have previously reported that cyclic strain results in rapid phosphorylation of p38 mitogen activated protein kinase (MAPKs). The aim of this study was to examine the role of protein phosphatase type 2A (PP2A) in regulating p38 MAPK activation in bovine aortic endothelial cells exposed to cyclic strain. In this study, we demonstrate that the catalytic subunit of PP2A is tyrosine phosphorylated by cyclic strain, resulting in inhibition of phosphatase activity. Okadaic acid, an inhibitor of PP2A at lower concentrations increased phosphorylation of p‐38. Phospho‐p38 MAPK physically associated with the catalytic subunit, PP2Ac. Phospho‐p38 MAPK was dephosphorylated by purified PP2Ac in cell lysates, but if pretreated with okadaic acid, phospho‐p38 MAPK was maintained. Taken together, our result suggests that PP2A plays a regulatory role in p38 MAPK activation in endothelial cells exposed to cyclic strain. J. Cell. Physiol. 194: 349–355, 2003. © 2003 Wiley‐Liss, Inc.
Pathophysiological implications of stroma pattern formation in uveal melanoma
Authors: Clarijs Ruud , Ruiter Dirk J. , de Waal Robert M.W. 
Published: January 2003

AbstractClinical outcome of cancer patients is mainly determined by the rate of metastasis and, also by primary tumor growth. Formation of extracellular matrix and interactions of neoplastic and non‐neoplastic (host) cells in solid tumors have been shown to be essential for these processes. One result of such interactions is the outgrowth of new blood vessels from existing ones, angiogenesis, to provide the tumor tissue with oxygen and nutrients. It is assumed that the neovascular bed also facilitates the escape of metastatic cells from the primary lesions. In addition, recent reports suggested the existence of blood‐conducting channels lined by melanoma cells (so‐called “vascular channels”) accompanied by depositions of extracellular matrix patterns in cutaneous and uveal melanoma. Since the presence of these matrix structures has been negatively associated with prognosis, we hypothesize that they play a role in melanoma outgrowth or metastasis. In this review, we will discuss the morphological and functional properties of the extracellular matrix patterns in that may underlie these clinical phenomena. © 2003 Wiley‐Liss, Inc.
Cancer/testis‐associated genes: Identification, expression profile, and putative function
Authors: Zendman Albert J.W. , Ruiter Dirk J. , Van Muijen Goos N.P. 
Published: January 2003

AbstractCancer/testis‐associated genes (CTAs) are a subgroup of tumor antigens with a restricted expression in testis and malignancies. During the last decade, many of these immunotherapy candidate genes have been discovered using various approaches. Most of these genes are localized on the X‐chromosome, often as multigene families. Methylation status seems to be the main, but not the only regulator of their specific expression pattern. In testis, CTAs are exclusively present in cells of the germ cell lineage, though there is a lot of variation in the moment of expression during different stages of sperm development. Likewise, there is also a lot of heterogeneity in the expression of CTAs in melanoma samples. Clues regarding functionality of CTAs for many of these proteins point to a role in cell cycle regulation or transcriptional control. Better insights in the function of these genes may shed light on the link between spermatogenesis and tumor growth and could be of use in anti‐tumor therapies. This review outlines the CTA family and focuses on their expression and putative function during male germ cell development and melanocytic tumor progression. © 2003 Wiley‐Liss, Inc.
HPV16 E6 and E7 oncoproteins regulate Notch‐1 expression and cooperate to induce transformation
Authors: Weijzen Sanne , Zlobin Andrei , Braid Mike , Miele Lucio , Kast W. Martin 
Published: January 2003

AbstractNotch receptor signaling has been implicated in cellular transformation. Notch‐1 receptor expression is increased during the progression from cervical intraepithelial lesions (CIN) to invasive cervical carcinoma. Moreover, the main cellular localization of Notch‐1 protein changes from cytoplasmic to nuclear with the transition from CIN III to microinvasive carcinoma. Since the E6 and E7 proteins encoded by human papilloma virus (HPV) are a causative agent of cervical carcinoma, this study determined whether E6 and E7 protein expression causes the observed upregulation in Notch‐1 expression. Mouse and human primary cell lines were transfected with HPV16 E6 and E7 and Notch‐1 expression and activity were analyzed. We show that Notch‐1 expression and activity are upregulated by E6 and E7 independently. This was due to both transcriptional and post‐transcriptional mechanisms. A protein involved in Notch processing, Presenilin‐1 (PS‐1), was also upregulated by E6 and E7. In the presence of E6 and E7, Notch‐1 protein expression is localized in the cytoplasm. Downregulation of Notch‐1 expression in a human cervical carcinoma cell line expressing E6/E7 caused striking inhibition of proliferation in vitro and tumorigenicity in vivo. These data suggest that E6‐ and E7‐mediated upregulation of Notch signaling may contribute to disruption of regular cell growth in cervical cancer. © 2003 Wiley‐Liss, Inc.
Cl− channel blockers inhibit transition of quiescent (G0) fibroblasts into the cell cycle
Authors: Zheng Ya‐Juan , Furukawa Tetsushi , Tajimi Kimitaka , Inagaki Nobuya 
Published: January 2003

AbstractModulation of ion permeability during the cell cycle is one of the key events in cell cycle progression. We have compared the effects of K+ and Cl− channel blockers on the cell cycle in synchronous and asynchronous NIH3T3 cells. The Cl− channel blocker 5‐N‐2‐(3‐phenylpropylamino) benzoic acid (NPPB; 0.2 mM) inhibited entry into S phase in synchronous cells but not in asynchronous cells, while the K+ channel blocker 4‐aminopyridine (4‐AP) showed similar inhibitory effects in both conditions. In NIH3T3 cells synchronized by serum deprivation/replenishment, G0‐to‐G1 transition occurred within 8 h after serum addition, and the G1/S checkpoint at 10–14 h. NPPB applied only at 0–8 or 8–14 h after serum addition inhibited entry into S phase. Cl− permeability measured as 125I efflux increased at 4 and 10 h after serum addition. Ki‐67‐negative cells, which represent quiescent G0 phase cells, progressively decreased in number until 8 h after serum addition. The Cl− channel blockers (NPPB and 4,4′‐diisothiocyanatostilbene‐2,2′‐disulfonic acid [DIDS]) but not the K+ channel blocker (4‐AP) significantly decreased the rate of reduction in number of Ki‐67‐negative cells. These data indicate that an increase in Cl− permeability plays an important role in reentry of quiescent cells into the proliferating phase, in addition to the known effects on passage through the G1/S checkpoint. © 2003 Wiley‐Liss, Inc.
Subcellular localization of Photofrin® determines the death phenotype of human epidermoid carcinoma A431 cells triggered by photodynamic therapy: When plasma membranes are the main targets
Authors: Hsieh Ya‐Ju , Wu Chih‐Ching , Chang Cheng‐Jen , Yu Jau‐Song 
Published: January 2003

AbstractPhotodynamic therapy (PDT) is a kind of photochemo‐therapeutic treatment that exerts its effect mainly through the induction of cell death. Distinct types of cell death may be elicited by different PDT regimes. In this study, the mechanisms involved in the death of human epidermoid carcinoma A431 cells triggered by PDT with Photofrin® (a clinically approved photosensitizer) were characterized. Photofrin distributes dynamically in A431 cells; the plasma membranes and Golgi complex are the main target sites of Photofrin after a brief (3 h) and prolonged (24 h) incubation, respectively. Cells with differentially localized Photofrin displayed distinct death phenotypes in response to PDT. The effects of PDT on cells with plasma membrane‐localized Photofrin were further studied in details. Cells stopped proliferating post PDT at Photofrin dose >7 μg/ml, and at higher dose (28 μg/ml) plasma membrane disruption and cell swelling were observed immediately after PDT. Dramatic alterations of several important signaling events were detected in A431 cells post Photofrin®‐PDT, including (i) immediate formation of reactive oxygen species (ROS), (ii) rapid activation of c‐Jun N‐terminal kinase, (iii) delayed activation of caspase‐3 and cleavage of polyADP‐ribose polymerase and p21‐activated kinase 2, and (iv) loss of mitochondrial membrane potential. Intriguingly, the characteristics of typical apoptosis such as phosphatidylserine externalization and DNA fragmentation were not detected in the cell death process caused by this PDT regime. In conclusion, our results show that when plasma membranes are the main targets, Photofrin‐PDT can lead to instant ROS formation and subsequent activation of downstream signaling events similar to those elicited by many apoptotic stimuli, but the damage of plasma membranes renders the death phenotype more necrosis like. © 2003 Wiley‐Liss, Inc.
Structural and functional aspects of Bufo americanus spermatozoa: Effects of inactivation and reactivation
Authors: Kouba Andrew J. , Vance Carrie K. , Frommeyer Mark A. , Roth Terri L. 
Published: January 2003

AbstractVery little is known about the effects of manipulating toad sperm activity in vitro, and such information is important in the development of a genetic resource bank for bufonid species. The specific objectives of this study were to: 1) identify the optimal inactivation and reactivation solutions for toad spermatozoa colleted in urine; 2) establish the length of time toad spermatozoa can be exposed to an inactivation buffer and still resume motility upon reactivation; 3) evaluate the consequence of inactivation on specific sperm characteristics; and 4) characterize the sperm mitochondria vesicle (MV) and its relationship to motility. Reactivated sperm motility was similar after inactivation in either Simplified Amphibian Ringers (SAR) solution or DeBoer's (DB) solution. Diluting the buffer by 80% with water provided the best method for reactivating sperm. Dilutions with NaCl solutions (10–50 mM) produced inferior results. SAR‐inactivated spermatozoa could remain suspended up to 4 hr and still regain 25% of initial motility upon reactivation in water. Compared to the controls, sperm motility was greater (P<0.01) over time for samples treated with SAR, although forward progression was significantly lower. Furthermore, SAR treatment resulted in sperm samples with a greater number of viable, morphologically normal, and intact MVs over time. Electron microscopy and fluorescent staining confirmed that the toad sperm's MV contains a large number of active mitochondria with very few other cytoplasmic structures. Nearly all spermatozoa exhibiting motility had an intact MV, and dissociation of this structure was clearly related to motility loss. In conclusion, toad spermatozoa can be effectively inactivated and reactivated by varying the osmolality of the external solutions and, although sperm forward progression is reduced, all other characteristics are well maintained. Moreover, the increased number of spermatozoa with intact MV after inactivation suggests the process may help preserve this important structure. J. Exp. Zool. 295A:172–182, 2003. © 2003 Wiley‐Liss, Inc.