[Effect of N-nitroso-N-methylurea on DNA and RNA synthesis in cells of liver and spleen tumors in leucosis L-1210].

During the development of leucosis a progressively retarded incorporation of 2-C14-thymidine and C14-uridine into DNA and RNA of a separate tumor cell and an active incorporation of 2-C14-thymidine into DNA of hepatic and splenic cells were observed. Repeated injections of NMU (20 mg/Kg X 5) in tumor-bearing animals result in a twice increase of life terms in mice and suppression of total tumor cells growth. The observed therapeutic effect is related with deep inhibition of DNA and RNA synthesis in leucosis L-1210 cells, while DNA synthesis in hepatic and splenic cells is only insignificantly suppressed (compared with the normal level typical for intact animals), but RNA synthesis in these organs is actually not involved.