Loss of type VI collagen in experimental and most spontaneous human fibrosarcomas

Expression of type VI collagen, an adhesive protein of mesenchymal tissues, is significantly down-regulated upon viral transformation of fibroblasts, Likewise, most cell lines derived from spontaneous mesenchymal tumors, incl uding fibrosarcomas, rhabdomyosarcomas, leiomyosarcomas, chondrosarcomas an d liposarcomas, do not synthesize type VI collagen because they are not cap able of expressing all 3 of the polypeptide chains required for the assembl y of a functional heterotrimeric molecule. When injected into nude mice, ne ither fibrosarcoma cells (HT1080) nor rhabdomyosarcoma cells (A204) initiat e the synthesis of type VI collagen, suggesting that the inhibition is not caused by deficiency of a paracrine factor. Immuno-histochemical studies fu rther illustrate that 15 of 17 spontaneous adult fibrosarcomas lack type VI collagen in the tumor stroma, The absence of this important adhesion prote in may contribute to tumorigenicity, invasiveness and/or metastasis of mese nchymal tumor cells. Int J, Cancer 86:331-336, 2000, (C) 2000 Wiley-Liss, I nc.