Effect of azacytidine in SV40-infected BSC-1 cells.

5-Azacytidine (5-AzaCR) reduced significantly the levels of ribosomal 28S and 18S RNAs in the cytoplasm of uninfected and simian virus 40 (SV40)-infected BSC-1 cells. The percent inhibition of ribosomal RNAs was correlated to both the dose of AzaCR and the time of exposure. In SV40-infected cultures treated with 200 microgram/ml AzaCR, a portion of the total cytoplasmic radioactivity was observed to sediment as 19S and 16S by sucrose gradient analysis. The 19S and 16S peaks represented in part the viral-specific RNA species. This result was due to the drastic reduction (70--75%) of ribosomal RNAs in the cytoplasm of infected cultures.