Normal cells and malignant cells transfected with the HRas oncogene have the same heat sensitivity in culture.

Mouse embryo cells (C3H 10T1/2) were transfected with a plasmid (pAL8A) containing the HRas oncogene and neomycin resistance gene. Five transfected cell clones were isolated and established as cell lines, and these showed neomycin resistance. Two of these cell lines expressed a normal morphology while three showed a transformed morphology. Four of the cell lines produced tumours in nude mice. Flow cytometry measurements showed that exponentially growing cell cultures of the five transfected cell lines had the same cell cycle distribution as the normal parental cell line. The sensitivity to hyperthermia of the five transfected cell lines was the same as that of the normal cell line for temperatures ranging from 42.0 to 45.0 degrees C. Thus in these studies we found no difference in the thermal sensitivity of normal and malignant cells transfected by the Hras oncogene.