LIMITED INVASIVE CAPACITY OF PLT PLUS RAS TRANSFORMED RAT FIBROSARCOMA CELLS EFFECTIVE IN EXPERIMENTAL METASTASIS

Nine cell lines were isolated after cotransfection of rat embryo fibro blasts with polyomavirus large-T (plt) and T24-ras oncogenes. Five of these lines were highly tumorigenic following subcutaneous injection, but differed in their metastatic and in vitro invasive properties. Two cell lines, expressing low levels of ras mRNA, showed low capacity fo r experimental metastasis. Three cell lines, expressing high levels of ras mRNA, were tumorigenic and showed high capacity for experimental metastasis. High expression of interstitial collagenase, stromelysin a nd 92 kDa type IV collagenase was observed in the highly metastatic ce ll lines. Immunochemical analysis revealed that these cell lines expre ssed apparently wild-type p53 protein. Furthermore, the level of a 43 kDa/pI 5,44 polypeptide was elevated and the levels of a series of 41 to 43 kDa acidic polypeptides were decreased in the metastatic cells. Within this panel of transformed cell lines, high capacity for experim ental metastasis did not correlate with high chemoinvasive capacity in the reconstituted basal membrane assay. The limited invasive propensi ty could not be attributed to low chemotactic or adhesive capacity. We conclude that in vitro invasion does not correlate with experimental metastasis in this model system.