Transformation of rodent immortalized and embryo cells by oncogenes. II. Rat embryo fibroblasts (REF).

Rat embryo fibroblasts were transformed by co-transfer of two plasmids carrying the oncogenes ras and myc, respectively. In contrast to immortalized cells gene transfer of ras alone was not sufficient for transformation of rat embryo cells. Embryo cells transformed by both oncogenes showed an altered morphology and produced colonies in soft agar. Cell lines were established from transformation foci. These cells are characterized by a high proliferation capacity, they expressed the oncogenes ras and myc and produced regressing tumors in syngeneic newborn rats. Oncogene expression was demonstrated by in situ and blot hybridization. A cell line was established from a rat tumor induced by oncogene transformed cells. This cell line, designated FTD5, showed in addition to an increased expression of the transferred oncogenes ras and myc an elevated expression of the cellular oncogene fos.