Cytoskeletal-induced alterations in the adhesion of HT-1080 fibrosarcoma cells to extracellular matrix

We have investigated the adhesion of the human fibrosarcoma cell line, HT-1 080, transfected with glial fibrillary acidic protein (GFAP) to a variety o f extracellular matrix macromolecules (ECM) including collagen type IV, lam inin, and fibronectin. The GFAP-transfectants demonstrated altered adhesive ness to extracellular matrix substrates when compared to controls. GFAP-pos itive, heavy metal-induced fibrosarcoma cells were more adherent to plastic and collagen type IV than were the parental or uninduced cells. In contras t, GFAP-positive fibrosarcoma cells were less adherent to laminin- or fibro nectin-coated dishes than controls. Time course adhesion studies over 9 day s showed that the heavy metal-induced fibrosarcoma cells progressively beca me more adherent to collagen type IV and less adherent to laminin- or fibro nectin-coated dishes than did uninduced cells. However, with the removal of heavy metal from the medium, the HT-1080 fibrosarcoma cells were restored to their original adhesive potential. By phase microscopy, uninduced and in duced MT-1080 cells demonstrated different morphological features and remai ned viable in an anchorage-dependent fashion on collagen type IV as a subst rate. By way of contrast, GFAP-induced MT-1080 cells were not particularly viable in monolayer culture and readily detached from laminin as a substrat e. The expression of beta1 integrin in GFAP-positive fibrosarcoma cells was decreased following heavy metal induction by Western blot analyses. In con trast, the expression of alpha2 integrin was increased whereas alpha5 integ rin was unchanged in MT-1080 cells following the induction of GFAP. Gelatin zymography showed that 72 kDa collagenase was less expressed in GFAP-induc ed clones than in controls. Our data suggest that the forced expression of the intermediate filament, GFAP, in MT-1080 cells may modulate cell adhesio n to different ECM substrates through alterations in expression of integrin s.