COMPARATIVE-STUDY OF THE EFFECT OF 1-METH YL-1-NITROSOUREA AND 1,3-DIMETHYL-1-NITROSOUREA ON DNA OF TUMOR-CELLS IN-VITRO AND IN-VIVO BY THEMETHOD OF ALKALI ELUTION

DNA damage of the tumor cells was studied by the method of alkali elut ion from filters after introduction of 1-methyl-1-nitrosourea (MNU) an d 1,3-dimethyl-1-nitrosourea (DMNU) to mice with Ehrlich ascites carci noma or after treatment of the cultivated cells with these drugs. DNA was essayed fluorometrically using DAPI. The degree of DNA damage was characterized by the constant of the alkali elution rate (K-ae), which was estimated according to the anamorphism of the kinetic curves of e lution. It was shown that in the case of MNU application the tumor cel l DNA was damaged to a greater extent than in the case of DMNU applica tion. K-ae increased with the concentration of drugs. A correlation wa s established between the antitumor activity of the drug (k), K-ae, an d the number of chromosome defects per cell (gaps, deletions, microfra gments, ring chromosomes, and translocations). This suggests that Ic i s due both to DNA damage and chromosome defects.