TUMORIGENIC AND METASTATIC PROPERTIES OF 2 RAS-ONCOGENE TRANSFECTED RAT FIBROSARCOMA CELL-LINES DEFECTIVE IN C-JUN

We here report the spontaneous loss of both homologues of the c-jun ge ne in two cell lines, isolated after transfection of rat embryo fibrob lasts with single ras-oncogenes. These cells lines (designated A14 and B25) grow rapidly in vitro, have transformed morphologies and are inv asive through reconstituted basal membranes. Both c-jun defective cell lines were found to be tumorigenic and metastatic in athymic mice. Lo ss of c-jun was paralleled by a dramatic decrease in interstitial coll agenase expression, whereas stromelysin mRNA expression in c-jun(-) A1 4 and B25 cells was similar to that observed in c-jun(+) transformed c ell lines. Transient transfection experiments using reporter plasmids showed that stromelysin promoter activity in A14 cells was severely im paired by a point mutation in the -71 to -65 AP-1 motif, and was inhib ited by a Jun dominant negative mutant. Gel mobility shift studies dem onstrated the presence of a factor in A14 nuclear extracts capable of binding the stromelysin TRE. This factor bound JunB, JunD and Fos anti bodies. Our findings suggest that c-Jun is not required for the tumori genic and metastatic potential of vas-transformed fibrosarcoma cells, and that AP-1 protein(s) lacking c-Jun are capable of activating the s tromelysin gene promoter.