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  • 1
    ISSN: 1573-4986
    Keywords: HT-29 cells ; mucins ; aryl-glycosides ; O-glycosylation ; sialyltransferases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We have analysed the mucins synthesized by the HT-29 MTX cell subpopulation, derived from the HT-29 human colon carcinoma cells through a selective pressure with methotrexate (Lesuffleuret al., 1990,Cancer Res 50: 6334–43), in the presence of benzyl-N-acetyl-α-galactosaminide (GalNAcα-O-benzyl), which is a potential competitive inhibitor of the β1,3-galactosyltransferase that synthesizes the T-antigen. The main observation was a 13-fold decrease in the sialic acid content of mucins after 24 h of exposure to 5mm GalNAcα-O-benzyl. This effect was accompanied by an increased reactivity of these mucins to peanut lectin, testifying to the higher amount of T-antigen. The second observation was a decrease in the secretion of the mucins by GalNAcα-O-benzyl treated cells. The decrease in mucin sialyation was achieved through thein situ β-galactosylation of GalNAcα-O-benzyl into Galβ1–3GalNAcα-O-benzyl, which acts as a competitive substrate of Galβ1–3GalNAc α2,3-sialyltransferase, as shown by the intracellular accumulation of NeuAcα2–3Galβ1–3GalNAcα-O-benzyl in treated cells.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7276
    Keywords: metalloproteinases ; breast cancer cells ; invasiveness ; tissue inhibitors of metalloproteinases ; synthetic inhibitors of metalloproteinases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Several matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) were studied in highly invasive (MDA-MB-231) and slightly invasive (MCF-7, T47D, BT-20) breast cancer cell lines. Investigations were carried out at the protein level and/or at the mRNA level, either in cells cultured as monolayers on plastic, or in cells seeded on a thin layer of Matrigel basement membrane matrix. Analysis of MMP expression by RT-PCR showed expression of MMP-1, MMP-3, and MMP-13 in highly invasive MDA-MB-231 cells, but not in slightly invasive cell lines. The extracellular secretion of MMP-1 and MMP-3 by MDA-MB 231 cells could be also shown by ELISA. TIMP-1 and TIMP-2 mRNAs were found in all cell lines, however, the extracellular secretion of both TIMPs was much higher in MDA-MB-231 cells than in the other cell lines. When the cells were cultured on Matrigel matrix, MMP-9 expression was induced in MDA-MB-231 cells only, as assessed by RT-PCR and zymography experiments. The invasive potential of MDA-MB-231 cells evaluated in vitro through Matrigel was significantly inhibited by the MMP inhibitor BB-2516, by 25% and 50% at the concentrations of 2 × 10−6M and 10−5M, respectively. In conclusion, our data show that highly invasive MDA-MB-231 cells but not slightly invasive T47D, MCF-7 and BT-20 cells express MMP-1, MMP-3, MMP-9 and MMP-13. MMP-9 which is specifically up-regulated by cell contact to Matrigel, may play a key role in the invasiveness of MDA-MB-231 cells through basement membranes.
    Type of Medium: Electronic Resource
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