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Proliferative Phenotype (proliferative + phenotype)
Selected AbstractsSerum-free cultured keratinocytes fail to organize fibronectin matrix and possess different distribution of beta-1 integrinsEXPERIMENTAL DERMATOLOGY, Issue 2 2001G. Altankov Abstract: The development of serum free medium formulation for culturing keratinocytes was a breakthrough in achieving a high number of epidermal cells for experimental and therapeutic studies, in particular to support the wound healing process. It is not clear, however, if switching the cells to highly proliferative phenotype may reflect change in other cellular functions important for the wound repair as their adhesive interactions with the extracellular matrix components. Remodelling of the extracellular matrix, particularly of fibronectin plays an essential role for guiding the cells during wound healing. The molecular mechanisms for organization of this provisional fibronectin matrix, however, are still not clear. We found that keratinocytes in serum containing medium, although in fewer numbers than fibroblasts, were able to remove adsorbed fluorescent labelled fibronectin from the substratum and reorganize it in a fibrilar pattern along the cell periphery. After 3 days the secreted fibronectin had also been organized as matrix-like fibers and as clusters deposited on the substratum after migrating cells. In contrast, serum free cultured keratinocytes fail to organize pre-adsorbed fluorescent labelled fibronectin, as well as the secreted fibronectin, although they grow very well under these conditions. Switching the cells to serum containing medium initiates the removal of fluorescent labelled fibronectin from the substratum, however without reorganization in fibrillar pattern. Most likely, these keratinocytes remove fluorescent labelled fibronectin by the expression of proteolytic activity, rather than with the mechanical function of ,1 integrins. The latter were diffusely dispersed in serum containing conditions and tend to organize in focal adhesions in serum free cultured cells. We assumed their transient expression and different affinity state might be important for the keratinocyte migration and matrix assembly mechanism. [source] A mouse model for cystic biliary dysgenesis in autosomal recessive polycystic kidney disease (ARPKD),HEPATOLOGY, Issue 5 2005Markus Moser Autosomal recessive polycystic kidney disease (ARPKD) is an important cause of liver- and renal-related morbidity and mortality in childhood. Recently, PKHD1, the gene encoding the transmembrane protein polyductin, was shown to be mutated in ARPKD patients. We here describe the first mouse strain, generated by targeted mutation of Pkhd1. Due to exon skipping, Pkhd1ex40 mice express a modified Pkhd1 transcript and develop severe malformations of intrahepatic bile ducts. Cholangiocytes maintain a proliferative phenotype and continuously synthesize TGF-,1. Subsequently, mesenchymal cells within the hepatic portal tracts continue to synthesize collagen, resulting in progressive portal fibrosis and portal hypertension. Fibrosis did not involve the hepatic lobules, and we did not observe any pathological changes in morphology or function of hepatocytes. Surprisingly and in contrast to human ARPKD individuals, Pkhd1ex40 mice develop morphologically and functionally normal kidneys. In conclusion,our data indicate that subsequent to formation of the embryonic ductal plate, dysgenesis of terminally differentiated bile ducts occurs in response to the Pkhd1ex40 mutation. The role of polyductin in liver and kidney may be functionally divergent, because protein domains essential for bile duct development do not affect nephrogenesis in our mouse model. Supplementary material for this article can be found on the HEPATOLOGYwebsite (http://www.interscience.wiley.com/jpages/0270-9139/suppmat/index.html). (HEPATOLOGY 2005.) [source] Modulation of VE-cadherin and PECAM-1 mediated cell,cell adhesions by mitogen-activated protein kinasesJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2003Jianqiang Wu Abstract Endothelial cell transition from a differentiated, quiescent phenotype to a migratory, proliferative phenotype is essential during angiogenesis. This transition is dependent on alterations in the balanced production of stimulatory and inhibitory factors, which normally keep angiogenesis in check. Activation of MAPK/ERKs is essential for endothelial cell migration and proliferation. However, its role in regulation of endothelial cell adhesive mechanisms requires further delineation. Here, we show that sustained activation of MAPK/ERKs results in disruption of cadherin-mediated cell,cell adhesion, down-regulation of PECAM-1 expression, and enhanced cell migration in microvascular endothelial cells. Expression of a constitutively active MEK-1 in mouse brain endothelial (bEND) cells resulted in down-regulation of VE-cadherin and catenins expression concomitant with down-regulation of PECAM-1 expression. In contrast, inhibition of MEK-1 restored parental morphology, cadherin/catenins expression and localization. These data are further supported by our observation that sustained activation of MAPK/ERKs in phorbol myristate acetate incubated HUVEC lead to disruption of cadherin-mediate cell,cell interactions and enhanced capillary formation on Matrigel. Thus, sustained activation of MAPK/ERKs plays an important role in disruption of cell,cell adhesion and migration of endothelial cells. J. Cell. Biochem. 90: 121,137, 2003. © 2003 Wiley-Liss, Inc. [source] Common and distinct mechanisms of different redox-active carcinogens involved in the transformation of mouse JB6P+ cellsMOLECULAR CARCINOGENESIS, Issue 7 2008Sun Yang Abstract We transformed JB6P+ cells with prolonged intermittent low-dose UVB radiation or prolonged exposure to low-dose H2O2 or CdCl2. Stable transformation was confirmed by an anchorage-independence assay. The JB6P+ transformants formed more colonies (,six folds) in soft agar as compared to their JB6P+ parent cells and were associated with increased intracellular reactive oxygen species (ROS) levels. Activating protein-1 (AP-1) is a family of transcription factors that are rapidly activated by elevated intracellular ROS levels, and their composition is important in the process of cellular transformation and/or tumor progression. To investigate if carcinogenesis induced by distinct carcinogens was via similar molecular mechanisms in these transformants, gel mobility shift and immunoblot analyses were utilized to determine the distinct AP-1 compositions. Compared to parent JB6P+ cells, the gain of JunB and Fra-1 in AP-1 DNA binding complexes was markedly increased in all transformed cells, which might contribute to a more proliferative phenotype, while loss of Fra-2 occurred in JB6P+/H2O2 and JB6P+/Cd cells. Differential AP-1 components in the transformants suggested that their transformations might be mediated by distinct transcription signalings with distinct AP-1 dimer compositions. However, all three transformants exhibited increased activation of pathways involved in cell proliferation (ERK/Fra-1/AP-1 and JNK/c- jun/AP-1) and anti-apoptosis (Bcl-xl). The development of the JB6P+ transformants (JB6P+/UVB; JB6P+/H2O2; JB6P+/Cd) provides a unique tool to study the mechanisms that contribute to different redox-active carcinogens in a single model. © 2007 Wiley-Liss, Inc. [source] Modulation of cyclin dependent kinase inhibitor proteins and ERK1/2 activity in allylamine-injured vascular smooth muscle cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2004Sarah A. Jones Abstract Chronic oxidative injury by allylamine (AAM) induces proliferative vascular smooth muscle cell (vSMC) phenotypes in the rat aorta similar to those seen in rodent and human atherosclerotic lesions. The proliferative advantage of AAM vSMC compared to control cells is maintained with serial passage of the cells and the advantage is nullified when AAM cells are seeded on a collagen substrate. In this study, we evaluate the potential role of cyclin dependent kinase inhibitors, p27 and p21, and mitogen activated protein (MAP) kinases, ERK1/2, in mediating the proliferative advantage of AAM stressed vSMC over control cells on plastic or collagen substrates. p27 levels in randomly cycling cells were comparable in both cell types irrespective of the substrate. In contrast, basal levels of p21 were 1.9,±,0.3 (P,<,0.05)-fold higher in randomly cycling AAM cells seeded on plastic compared to controls, a difference that was lost on a collagen substrate. Following G0 synchronization, basal levels of both p27 and p21 were higher in AAM cells seeded on plastic compared to controls (1.7,±,0.2 and 2.0,±,0.3-fold, respectively, P,<,0.05), but these differences were lost upon mitogenic stimulation. Pyrrolidine dithiocarbamate (PDTC) decreased p27 and p21 levels in cycling AAM cells relative to controls in a substrate-dependent manner. AAM cells seeded on plastic exhibited enhanced ERK1/2 activation upon mitogenic stimulation; seeding on collagen nullified this advantage. The duration of ERK1/2 activation was prolonged in AAM cells independently of the seeding substrate. We conclude that substrate-dependent acquisition of proliferative phenotypes following repeated cycles of AAM injury correlates with modulation of the cyclin dependent kinase inhibitors, p27 and p21. © 2004 Wiley-Liss, Inc. [source] LIM kinase-2 targeting as a possible anti-metastasis therapyTHE JOURNAL OF GENE MEDICINE, Issue 3 2004Eigo Suyama Abstract Background Metastatic properties of tumors involve movement of cancerous cells from one place to another and tissue invasion. Metastatic cells have altered cell adhesion and movement that can be examined by in vitro chemotaxis assays. The Rho/ROCK/LIM kinase pathway is one of the major signaling pathways involved in tumor metastasis. It is involved in the regulation of the actin cytoskeleton. Using the randomized ribozyme library, we initially found that metastatic human fibrosarcoma cells harboring ribozyme specific for ROCK lose their metastatic properties. In this study, we have determined the effect of ribozymes specific for LIM kinase-2 on metastatic and proliferative phenotypes of human fibrosarcoma cells. Methods We attempted to target LIM kinase-2 (LIMK-2) expression by hammerhead ribozymes (Rz) in human metastatic fibrosarcoma cells. An effective ribozyme was selected based on the expression analysis. Cells were stably transfected with Rz specifically effective for LIMK-2 and were examined for metastatic and proliferative properties. Results Analyses of cellular phenotypes such as cell proliferation, cell migration and colony-forming efficiency revealed that the suppression of LIMK-2 expression in human fibrosarcoma cells limits their migration and dense colony-forming efficiency without affecting cell proliferation rate or viability. Conclusions Specific targeting of metastatic and malignant properties of tumor cells by LIMK-2 ribozyme may serve as an effective therapy for invasive tumors with minimum effect on the surrounding normal cells. Copyright © 2004 John Wiley & Sons, Ltd. [source] | |||||||||||||