ROLE OF METHYLATED NUCLEIC ACIDS IN CARCINOGENESIS

The methylating potencies toward RNA and DNA increase several fold in animal tumors and human leukemia and other malignancies, and the levels of methylated components of nucleic acids are greater in the affected tissues than those found in corresponding normal tissues. The increased urinary excretion of methylated purines occurs in human leukemia and in experimental animal tumors. Several neoplasms synthesize S-adenosylmethionine, an active methyl donor required for the methylation process. The cultured tumor cells possess increased levels of methylated nucleic acids and the necessary methylating enzymes. Several molecular mechanisms of carcinogenesis are discussed in the light of these findings. © 1969.