Oncogene and MDR1 gene expression in rat rhabdomyosarcoma sublines of different metastatic potential.

The expression of various protooncogenes (myc, Ki-ras, Ha-ras, erbB, fms, sis, jun and fos) and a gene implicated in multidrug resistance (mdr1) was investigated in cell sublines, isolated from a rat rhabdomyosarcoma cell line, and in the corresponding tumors induced by injection of these cells into syngeneic rats. These cell lines and tumors, selected or not by treatment with chlorozotocin (Czt) or adriamycin (Adr), differed in their tumorigenicities and metastatic potentials. Our results showed that 1) an increased expression of some protooncogenes could be correlated with the metastatic potential of tumors; 2) such a correlation was not observed in the cultured cells from which these tumors were derived; 3) mdr1 expression, similarly to that of protooncogenes, was correlated with metastatic potential in all tumors except the Adr-selected tumors.