[Mechanism of various degrees of tumor sensitivity to olivomycin]

Efficiency and duration of suppression of the synthesis of low-polymer (4S) and ribosomal (18S and 28S) fractions of total RNA due to exposure of the cells of Ehrlich's carcinoma and Zajdela's hepatoma to olivomycin were studied. The tumors differed in their sensitivity to the antibiotic. The efficiency of the rRNA synthesis inhibition by olivomycin on its addition to the cells of Ehrlich's carcinoma and Zajdela's hepatoma in vitro was of the same order. Study on the kinetics of rRNA synthesis after addition of olivomycin showed that the maximum inhibition of rRNA synthesis in the cells of Ehrlich's carcinoma was achieved 1 hour after the drug addition. After 2 hours the inhibition level returned to normal. The most efficient inhibition of rRNA synthesis in the cells of Zajdela's hepatoma was observed 2 hours after addition of the drug. The inhibition level in this case did not return to normal after 24 hours. It is concluded that tumor sensitivity to olivomycin is determined by the duration of the affection of the DNA template activity during the synthesis of RNA.