The effect of nitrogen mustard treatment on the cesium chloride density gradient patterns of the DNA from Ehrlich ascites tumor cells, sensitive and resistant to the agent, was studied. Exposure of sensitive cells to methybis(β-chloroethyl)amine (HN2) reduced the amount of DNA that banded in a cesium chloride density gradient and resulted in a greater proportion of the DNA appearing as a DNA-protein complex. In contrast, exposure of HN2-resistant Ehrlich cells to this agent had little effect on the DNA density gradient profile and less protein bound DNA was observed. The results obtained suggest that the resistance of these cells to HN2 may be related to the function and properties of the cell membrane.
This investigation was supported by USPHS Grant No. CA 05831 from the National Cancer Institute.