title: Adhesive defect in extracellular matrix tenascin-X-null fibroblasts: a possible mechanism of tumor invasion.
abstract: Extracellular matrix tenascin-X (TNX)-null mice, generated by disruption of the Tnx gene, display augmented invasion and metastasis of B16-BL6 melanoma tumor cells due to increased activities of matrix metalloproteinase (MMP)-2 and MMP-9. In this study, we investigated cell-matrix and cell-cell adhesions using TNX-null fibroblasts and wild-type fibroblasts. TNX-null fibroblasts exhibited a decreased attachment to fibronectin compared with that of wild-type fibroblasts. B16 melanoma cells were cocultured with wild-type or TNX-null fibroblasts, and the adhesion of B16 melanoma to the fibroblasts was assessed. B16 melanoma cells on wild-type fibroblasts proliferated and spread out in a horizontal direction, whereas those on TNX-null fibroblasts overlapped each other rather than migrating horizontally. These overlapping B16 melanoma cells on TNX-null fibroblasts peeled off faster than those on wild-type fibroblasts. To determine whether the decreased cell-matrix and cell-cell adhesions on TNX-null fibroblasts were due to increased MMP activity, the activities of MMPs in wild-type and TNX-null fibroblasts were compared by gelatinolytic assays. The analysis of MMPs from conditioned media demonstrated that almost the same levels of MMP activities were detected between wild-type and TNX-null fibroblasts. However, contrary to our expectations the activities of MMPs from conditioned media of B16 melanoma cells cocultured on TNX-null fibroblasts were rather reduced than those of B16 melanoma cells cocultured on wild-type. We concluded that the absence of TNX in the extracellular environment might play an important role in enhancement of the detachment of B16 melanoma cells.
authors.affiliation: Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
authors.forename: Takeharu
authors.initials: T
authors.lastname: Minamitani
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Ariga
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000235:genetics; D018920:Coculture Techniques / Q000379:methods; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D008546:Melanoma, Experimental / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008813:Mice, Inbred ICR; D018345:Mice, Knockout; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D019063:Tenascin / Q000172:deficiency* / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: D019063:Tenascin; C081865:tenascin X