Studies on the effect of homo-aza-steroidal ester of p-bis (2-chloroethyl) amino phenyl acetic acid in Ehrlich ascites tumor cells

The effect of a homo-aza-steroidal ester (ASE) on the incorporation of radioactive precursor to DNA of Ehrlich ascites tumor (EAT) cells has been investigated. We found that treatment of cells with 80 micrograms/ml of ASE for 2 hours causes an inhibition of the incorporation of 3H-thymidine to DNA by 71%. This is partly because ASE affects the radioactive thymidine pool in the cell. The DNA from EAT cells after centrifugation in CsCl is shifted to higher densities when ASE is present throughout the experiment. This density shift was not observed when ASE was incubated only in the growth medium of the cells.