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  • 1
    ISSN: 0730-2312
    Keywords: extracellular matrices (ECMs) ; bFGF ; NGF ; HGF and KGF ; growth factors (GFs) ; human prostate cancer model ; prostate cancer-bone interaction ; stromal-epithelial interaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A human prostate cancer model was established by inoculating a prostate specific antigen (PSA)-producing LNCaP cell line with either prostate or bone fibroblasts. Alternatively, this human prostate cancer model can also be established by inoculating LNCaP cell with growth factor(s) (GFs) and extracellular matrix (ECM) immobilized on Gelfoam®. The resulting LNCaP tumors were used to evaluate PSA production and excretion athymic hosts. This model was also employed to examine the biochemical nature of mesenchymal cell-derived growth-promoting protein(s) and to assess the efficacy of potential chemotherapeutic agents. Because of the propensity of human prostate cancer to metastasize to the bone, this study defined a 1.0 M NaCI-eluted fraction, MS1, from the conditioned medium of a bone stromal cell line (MS) by heparin-affinity column chromatography. The growth-promoting activity was assayed both in vivo (e.g., tumor formation) and in vitro (e.g., soft agar colony formation). We found that the growth-promoting activity was trypsin-and heat-sensitive, and partially degraded by acid and dithiothreitol. Immunochemical studies indicated that the polyclonal antibody raised against MS1 blocked the growth-promoting effect elicited by the bone-conditioned media. This growth-promoting factor was found to be immunochemically dissimilar to KGF, HGF, and bFGF. However, addition of bFGF, HGF and NGF, but not a FGF, TGFβ, IGF1, IGF2, PDGF, EGF, TGFα and KGF, stimulated anchorage-independent growth of prostate cells, a condition closely parallel to tumor formation in vivo. We found that the MS1 fraction also contained fibronectin and tenascin but not laminin or collagen IV. None of the ECM proteins induced soft agar colony formation by normal prostate epithelial cells. Therefore, it is possible that the ECM protein(s) may potentiate the tumor-inducing activity of locally produced GFs. © 1992 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0730-2312
    Keywords: cell adhesion ; arg-gly-asp amino acid sequence ; VLA proteins ; integrin superfamily ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The Very Late Activation Antigen (VLA) proteins are a family of five related heterodimers, which also are part of the integrin superfamily of cell adhesion molecules. Except for the identification of VLA-5 as a fibronectin receptor structure, the functions of the VLA proteins have remained unclarified. In this paper, immuno-precipitation experiments with both anti-α and anti-β subunit antibodies showed that the previously identified cell adhesion receptor for collagen, extracellular matrix receptor II (ECMRII), is equivalent to VLA-2. At the same time a previously described multispecific cell adhesion receptor for collagen, fibroncclin, and laminin (ECMRI) has been shown to be identical to VLA-3. Although the mAb 12F1 and P1H5 both recognized VLA-2 (ECMRII), they appeared to define distinct epitopes on the α2 subunit. On the other hand, the mAb PIB5 and J143 recognized the α3 subunit of VLA-3 (ECMRI) at or near the same site. Consistent with the collagen receptor functions of VLA-2 (ECMRII) and VLA-3 (ECMRI), anti-VLA β antiserum blocked cell attachment to collagen.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0730-2312
    Keywords: butyrate ; isobutyramide ; prostate cancer ; LNCaP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Progression to androgen independence remains the main obstacle to improving survival and quality of life in patients with advanced prostate cancer. Induction of differentiation may serve as a rational basis for prevention of progression to androgen independence by modulating gene expression activated by castration or upregulated during androgen-independent progression. The objectives of this study were to characterize the in vitro effects of sodium butyrate on human prostate cancer cell growth, PSA gene expression, and differentiation in the LNCaP tumor model and to determine whether tumor progression in vivo is delayed by isobutyramide, an orally bioavailable butyrate analogue with a longer half-life. The effects of isobutyramide on LNCaP tumor growth and serum PSA levels in both intact and castrate male mice were compared to controls. At concentrations 〉 1 mM, butyrate induced dose-dependent changes towards a more differentiated phenotype, G1 cell cycle arrest, and an 80% decrease in LNCaP cell growth rates. PSA gene expression was increased threefold by butyrate, indicative of differentiation-enhanced gene expression. The half-life of isobutyramide in athymic mice was determined by gas chromatography to be 4 h. During a 4 week period in intact-placebo mice, tumor volume and serum PSA increased 4.1- and 6.6-fold, respectively, compared to twofold and 2.7-fold increases in tumor volume and serum PSA in intact-treated mice. During a 7 week period in castrate-placebo mice, tumor volume and serum PSA levels increased 2.4-fold and fourfold, respectively, compared to a 50% reduction in tumor volume and a twofold increase in serum PSA above nadir levels in castrate mice treated with adjuvant isobutyramide. Isobutyramide treatment induced pronouced morphological changes in LNCaP tumor cells, with loss of defined nucleoli and dispersion of chromatin distribution. LNCaP tumor PSA mRNA levels actually increased threefold, indicative of differentiation-enhanced gene expression. This study demonstrates that butyrate causes LNCaP cell cycle arrest and increased PSA gene expression, both indicative of differentiation. The combination of castration and adjuvant isobutyramide was synergistic in delaying tumor progression. Decreased tumor cell proliferation and increased PSA gene expression induced by isobutyramide results in disconcordant changes in serum PSA and tumor volume and reduces the utility of serum PSA as a marker of response to therapy. J. Cell. Biochem. 69:271-281, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 71 (1998), S. 63-73 
    ISSN: 0730-2312
    Keywords: integrin ; activation epitopes ; ligand binding ; focal adhesions ; cytoplasmic domains ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The anti-integrin β1 MAb 15/7 sometimes may be a reporter of integrin activation or ligand occupancy. However, certain β1 tail deletions eliminate ligand binding despite inducing maximal constitutive 15/7 expression [Puzon-Mclaughlin et al. (1996): J Biol Chem 271:16580-16585]. Here we describe β1 tail mutations (e.g., double point mutations [D759L/F763L, F766L/E769L], or replacement of the β1 tail by the β5 tail) that prevent rather than induce constitutive appearance of the 15/7 epitope. Despite variable losses of constitutive 15/7 epitope, these mutants all retained a similar inducible 15/7 epitope component as seen upon incubation with GRGDSP peptide ligand. In addition, constitutive 15/7 expression did not correlate with integrin localization into focal adhesions. In conclusion, we show for the first time for a fully functional integrin that specific mutations within the β1 tail can down-regulate the constitutive appearance of an extracellular conformation defined by MAb 15/7. Because this regulation occurs away from the ligand binding site and does not correlate with responsiveness to integrin ligand, cell adhesion, or localization into focal adhesions, a novel type of conformational regulation is suggested. J. Cell. Biochem. 71:63-73, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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