title: Matrix metalloproteinase(s) mediate(s) NO-induced dissociation of beta-catenin from membrane bound E-cadherin and formation of nuclear beta-catenin/LEF-1 complex.
abstract: Modulation of the adenomatous polyposis coli (APC)-beta-catenin pathway by inflammatory mediators and extracellular matrix may be important in colon carcinogenesis. We have recently shown that nitric oxide (NO) induces the accumulation of cytosolic beta-catenin and subsequent formation of the nuclear beta-catenin/lymphocyte enhancing factor (LEF)-1 complex in conditionally immortalized young mouse colonic epithelial (YAMC) cells. In the present study, we explored the mechanism(s) through which NO exerts its effect on cytosolic beta-catenin accumulation and nuclear beta-catenin/LEF-1 complex formation. We found that NO-induced degradation of the membrane bound E-cadherin at tight junctions. Using an anti-E-cadherin antibody specific for its extracellular domain, we detected a 50kDa degradation fragment of E-cadherin (120 kDa) from the culture medium conditioned by YAMC cells exposed to the NO-releasing drug, NOR-1, for 4 and 24 h. As beta-catenin is normally bound to transmembrane E-cadherin and thus anchored to the cytoskeleton structure, the degradation of E-cadherin induced by NO may cause dissociation of beta-catenin from membrane bound E-cadherin. This was demonstrated by the detection of beta-catenin accumulation in the soluble cytosolic fractions in YAMC after exposure to NO-releasing drugs. Furthermore, the degradation of E-cadherin and the release of beta-catenin to cytosol were accompanied by the formation of nuclear beta-catenin/LEF-1 complex, demonstrating the dissociation of beta-catenin from E-cadherin may be responsible for the activation of beta-catenin/LEF-1 transcription complex. Co-treatment with NO donors and broad-spectrum matrix metalloproteinase (MMP) inhibitors TIMP-1 (100 ng/ml), GM6001 (10 micro M) and GM1489 (10 micro M) abolished the degradation of E-cadherin induced by NO as demonstrated by western blot analysis. These MMP inhibitors also blocked the cytosolic accumulation of beta-catenin and nuclear formation of beta-catenin/LEF-1 complex. The sum effect of MMP inhibitors demonstrated that NO-induced activation of MMP may cause the degradation of E-cadherin and the subsequent dissociation of beta-catenin, thereby contributing to the cytosolic accumulation of beta-catenin and nuclear formation of beta-catenin/LEF-1 complex.
authors.affiliation: Metabolism and Cancer Susceptibility Section, Basic Research Laboratory, Center for Cancer Research, NCI-Frederick, MD, USA.
authors.forename: Jay M
authors.initials: JM
authors.lastname: Mei
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Borchert
authors.forename: Steven P
authors.initials: SP
authors.lastname: Donald
authors.forename: James M
authors.initials: JM
authors.lastname: Phang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004151:Dipeptides / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051821:Lymphoid Enhancer-Binding Factor 1; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D051176:beta Catenin
chemical_list: C495267:CTNNB1 protein, mouse; D015820:Cadherins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D004151:Dipeptides; D004791:Enzyme Inhibitors; C497574:Lef1 protein, mouse; D051821:Lymphoid Enhancer-Binding Factor 1; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D019715:Tissue Inhibitor of Metalloproteinase-1; D015534:Trans-Activators; D014157:Transcription Factors; D051176:beta Catenin; D009569:Nitric Oxide; D020782:Matrix Metalloproteinases