Metastatic ability and expression of c-fos oncogene in cell clones of a spontaneous rat mammary tumor.

It was found that cell clones c1-2, cl-2r, c1-3, c1-4 and c1-6 of a spontaneous rat mammary tumor, c-SST-2, exhibit different degrees of metastatic ability: c1-2, c1-3, c1-6 were highly metastatic, while c1-2r and c1-4 were weakly metastatic. The expression of several oncogenes in these clones was examined. The amounts of myc mRNA in the clones were nearly the same. Expression of N-ras mRNA was higher in c1-2r and c1-4 than in c1-2, c1-3 and c1-6. On the other hand, the amounts of fos mRNA in the weakly metastatic clones were markedly lower than those in the highly metastatic clones. These results suggest that fos oncogene plays a role in the high metastatic ability of c-SST-2.