Tenascin-C is expressed by human glioma in vivo and shows a strong association with tumor blood vessels

Abstract

The extracellular matrix (ECM) protein tenascin-C (TN-C) is upregulated within glioma tissues and cultured glioma cell lines. TN-C possesses a multi-modular structure and a variety of functional properties have been reported for its domains. We describe five novel monoclonal antibodies identifying different domains of TN-C. The epitopes for these antibodies were investigated by using recombinantly expressed fibronectin type III domains of TN-C. The biological effects of TN-C fragments on glioma cell proliferation and adhesion were analyzed. The expression pattern of TN-C in human glioma tissue sections and in glioma cell lines was studied with the novel library of monoclonal antibodies. The immunocytochemical analyses of the established human glioma cell lines U-251-MG, U-373-MG and U-87-MG revealed distinct staining patterns for each antibody. Robust expression of TN-C was found within the tumor mass of surgery specimens from glioblastoma. In many cases, the expression of this ECM molecule was clearly associated with blood vessels, particularly with microvessels. Three of the new antibodies highlighted individual TN-C-expressing single cells in glioma tissues. The effect of TN-C domains on glioma cells was examined by a BrdU-proliferation assay and an adhesion assay. Short fragments of constitutively expressed TN-C-domains did not exert significant effects on the proliferation of glioma cells, whereas the intact molecule increased cell division rates. In contrast, the long fragment TNfnALL containing all of the FNIII domains of TN-C decreased proliferation. Additionally, we found strong differences between the adhesion-influencing properties of the recombinant fragments on glioma cells.