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  • 1
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  Regulation of the extracellular matrix turnover is a crucial process in wound healing and the progress of periodontal disease. It has been proposed that urokinase-type plasminogen activator (uPA), under the control of growth factors or cytokines, provides the proteolytic potential to the accomplishment of these cellular events. Epidermal growth factor (EGF) is one of the growth factors that has been shown to be active in uPA regulation.Methods:  In this study, we have assessed the effect of EGF on uPA expression in primary cultures of human gingival fibroblasts. We also studied the signaling pathways involved in this process and the role of the dietary phytoestrogens curcumin and genistein as potential modulators of this response.Results:  Human gingival fibroblasts expressed a basal uPA activity, which was inhibited by genistein, but not by curcumin. After treatment with 10 ng/ml EGF, uPA production was strongly stimulated. Exposure to genistein and curcumin inhibited EGF-stimulated urokinase production, although only genistein showed a statistically significant inhibitory response. Using more specific inhibitors, we found that the mitogen-activated extracellular kinase and c-Jun N-terminal kinase (JNK) inhibitors PD98059 and SP600125 also blocked the EGF-dependent stimulatory effect. On the other hand, SB203580, inhibitor of the p38 member of mitogen-activated protein kinase family, did not alter this response. In accordance to these findings, EGF stimulated a potent activation of JNK and a mild activation of extracellular signal-regulated kinases 1/2. Finally, EGF stimulated the phosphorylation of its receptor and tyrphostin (AG1478), curcumin and genistein were able to inhibit this stimulatory effect.Conclusions:  These results indicate that EGF constitutes a strong stimuli on uPA expression in human gingival fibroblasts. Our data also shows that EGF-stimulated uPA production involves the activation of the extracellular signal-regulated kinases 1/2 and JNK signaling pathways and might be modulated by the natural phytoestrogens curcumin and genistein.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 61 (1996), S. 18-25 
    ISSN: 0730-2312
    Keywords: osteoblasts ; calvaria ; invasion ; prostate ; PC-3 cells ; differentiation ; metastasis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Bone metastasis is a common event and a major cause of morbidity in prostate cancer patients. After colonization of bone, prostate cells induce an osteoblastic reaction which is not associated with marrow fibrosis (i.e., osteoblast but not fibroblast proliferation). In the present study we test the hypothesis that the tumoral prostatic cell line (PC-3) secretes factors that block the osteoblast differentiation process, resulting in an increase of the relative size of the proliferative cell pool. Our results, using fetal rat calvaria cells in culture, show that conditioned medium from PC-3 cells (PC-3 CM) stimulates osteoblast proliferation and inhibits both alkaline phosphatase (AP) activity (an early differentiation marker) and the mineralization process, measured as calcium accumulation (late differentiation marker). The inhibition of the expression of AP and mineralization depends on the presence of PC-3 CM during the proliferative phase of culture and suggests that both processes occur in a nonsimultaneous fashion. The inhibitory effect of PC-3 CM was not reverted by dexamethasone, which would indicate that prostatic-derived factors and the glucocorticoid do not share a common site of action. Measurement of the proliferative capacity of subcultures from control and treated cells demonstrates that PC-3 CM treatment induces the maintenance of the proliferative potential that characterizes undifferentiated precursor cells. © 1996 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 13 (1995), S. 217-225 
    ISSN: 0263-6484
    Keywords: 5637 tumour bladder cell ; tumoural invasion ; taxol ; estramustrine-phosphate ; microtubules ; proteinase secretion ; u-plasminogen activator ; gelatinase ; conditioned media ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The secretion of proteinases into the extracellular matrix is one of the main features of tumour cells, as related to their invasive behaviour. Considering the role of the microtubule cytoskeleton, and particularly the action of microtubule-associated protein (MAPs) in mediating protein secretion, the effects of the anti-microtubule drugs estramustine and taxol, on the secretion of urokinase-type plasminogen activator (u-PA) and the 72 kDa gelatinase were investigated. Treatment of 5637 bladder carcinoma cells with estramustine and taxol inhibited u-PA secretion into the conditioned medium in a drug concentration-dependent fashion. This inhibition was confirmed by determinations of u-PA enzymatic activities and by measurements of the levels of immunoreactive activator. Studies using gelatin zymograms also showed an inhibition of another tumoural proteinase namely the 72 kDa gelatinase. Time-course uptake experiments showed that estramustine was incorporated into the cells, a process which depended on temperature. On the other hand, immunofluorescence studies indicated that the microtubule network was affected by taxol with the formation of bundles of microtubules at different cell domains. Minor effects were visualized after treatment of the cells with estramustine-phosphate, a drug that blocks primarily the action of microtubule-associated proteins. The studies provide a way to analyse the relationships between u-PA secretion and the integrity of the cytoskeletal network.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 11 (1993), S. 101-105 
    ISSN: 0263-6484
    Keywords: Calcium ; cell proliferation ; calcium blockers ; FDCP-1 cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Blockade of the calcium channel inhibited, in a dose-dependent manner, the proliferation of the IL-3 dependent FDCP-1 cell line and normal murine bone marrow cells. Similar results were obtained by lowering the amount of extracellular calcium using specific chelators or a calcium-free medium. These results suggest that factor-dependent cell proliferation is highly sensitive to fluctuations in the concentration of extracellular calcium.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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