ROLE OF H-RAS IN THE MALIGNANT PROGRESSION OF RAT TRACHEAL EPITHELIAL-CELLS

The effect of an activated H-ras oncogene on the progression of neopla sia was studied in transformed rat tracheal epithelial cells. Nude mou se tumours produced by injection of these cells exhibited a higher fra ction of cells containing the mutant ras gene than did the injected ce lls, while a subclone that lacked the ras mutation was much less tumor igenic than parental cells. Serial passage of one cell line containing a ras mutation resulted in an increase in the fraction of ras-mutated cells, which suggests that, in this line, ras activation may confer a selective advantage in vitro as well. However, this was not seen in a nother ras-containing line, suggesting the importance of alternative p athways in malignant progression of rat tracheal epithelial cells.