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  • tissue inhibitors of metalloproteinases  (2)
  • chemically modified tetracyclines  (1)
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  • 1
    ISSN: 1573-7276
    Schlagwort(e): glioblastoma multiforme ; invasion ; matrix ; metalloproteinases ; metastasis ; tissue inhibitors of metalloproteinases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Tissue inhibitors of metalloproteinases (TIMPs) are negative regulators of matrix metalloproteinases (MMPs) which degrade major components of the extracellular matrix. The aberrant expression of TIMPs is believed to represent an important modulating factor in the invasive capacity of human tumors. In the present study we analyzed the expression of TIMPs in human brain tumor tissue samples by an enzyme-linked immunosorbent assay (ELISA) and by Northern blotting analysis. Quantitation of TIMP-1 and TIMP-2 by ELISA demonstrated low levels of TIMP-1 and TIMP-2 proteins in glioblastomas, and moderate levels in anaplastic astrocytomas compared with normal brain tissues low-grade gliomas and metastatic tumors (renal and breast carcinomas and melanomas). Northern blot analysis of TIMP-1 transcripts demonstrated higher expression in meningioma, normal brain tissues and other metastatic tumors than in anaplastic astrocytoma and glioblastoma. Two distinct transcripts of 1.0 and 3.5 kb were observed for TIMP-2 mRNA in normal brain tissue and in tumor extracts. In addition, TIMP-2 mRNA expression was lower in glioblastoma and anaplastic astrocytoma than in meningioma, normal brain tissues and metastatic tumors. These findings suggest that down-regulation of both TIMP-1 and TIMP-2 contributes significantly to the invasive potential of human glioblastoma multiforme and anaplastic astrocytomas.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1573-7276
    Schlagwort(e): invasion ; metalloproteinases ; metastasis ; tissue inhibitors of metalloproteinases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Basement membrane forms widespread barriers to tumor invasion. It has been shown that tumor-secreted, basement membrane-degrading enzymes, namely metalloproteinases (MMPs) play an important role in tumor invasion and metastasis. In this study, we determined the enzymatic activity, content, and mRNA of both the 72 kDa (MMP-2) and 92 kDa (MMP-9) MMPs in primary cultures of human giant-cell tumor of bone (GCT)in vitro and in tissue extracts (in vivo). Gelatin zymography showed the presence of lytic bands at Mr 121000, 92000, and 72000, and these enzymatic activities were inhibited by EDTA, an inhibitor of MMPs. Western blots with antibodies specific for MMP-2 and MMP-9 confirmed the presence of MMP-2 and MMP-9 bothin vitro andin vivo, but GCT cells at late passage showed only MMP-2. Northern blots using labeled cDNA probes specific for these molecules revealed the presence of 3.1 kb transcript for MMP-2 and a 2.9 kb transcript for MMP-9. Using specific antibodies to 72 kDa and 92 kDa type IV collagenases, we studied their cellular distribution by immunohistochemical means. Stronger immunoreactivity was found for 92 kDa type IV collagenase than 72 kDa type IV collagenase in the giant cells. It appears, therefore, that MMP-9 may play an important role in the malignant behavior of GCTs and suggests a potential therapeutic role for protease inhibitors in attempting to minimize the invasive behavior of GCTs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1573-7276
    Schlagwort(e): chemically modified tetracyclines ; invasion ; matrix metalloproteinases ; melanoma ; metastasis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Recent work has shown that chemically modified tetracyclines (CMTs) are potent inhibitors of matrix metal-loproteinase (MMP) activity, both in vitro and in vivo, which is distinct from their antimicrobial activities (Golub et al. Crit Rev Oral Biol Med, 2, 297-321, 1991; Ryan et al. Curr Opin Rheumatol, 8, 238-47, 1996). The process of tumor cell invasion requires MMP-mediated degradation of extracellular matrix barriers as a key step in the metastasic cascade. In this study, we examined the effect(s) of doxycycline and CMTs on extracellular levels of gelatinase A and B activity from a highly invasive and metastatic human melanoma cell line C8161, and correlated these observations with changes in the cells' biological behavior in an in vitro invasion assay and in an in vivo SCID mouse model. The results indicate that coincident with the ability of these compounds to differentially suppress extracellular levels of gelatinase activity, C8161 cells treated with doxycycline, CMT-1, CMT-3, or CMT-6 were less invasive in vitro in a dose-dependent manner (3-50 mg/ml). Furthermore, data derived from the in vivo model indicate that SCID mice dosed orally with CMT-1 or CMT-3 contained a reduced number of lung metastases following i.v. injection of C8161 cells via tail vein inoculation. These observations suggest that careful screening of different CMTs could lead to the identification of compounds which suppress the formation and magnitude of metastases associated with certain cancers, and if used as an adjunct to other treatment regimes, lead to greater efficacy in the treatment of metastatic cancers. © Rapid Science 1998
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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