TY - JOUR T1 - The Effect of 5-Fluorouracil on the Synthesis and Methylation of Low Molecular Weight Nuclear RNA in L1210 Cells JF - Molecular Pharmacology JO - Mol Pharmacol SP - 245 LP - 249 VL - 17 IS - 2 AU - ROBERT I. GLAZER AU - KATHLEEN D. HARTMAN Y1 - 1980/03/01 UR - http://molpharm.aspetjournals.org/content/17/2/245.abstract N2 - The effect of 5-fluorouracil on the synthesis, methylation and its incorporation into low molecular weight nuclear RNA was studied in L1210 cells in vitro. 5-Fluorouracil was incorporated into high molecular weight, 5 S and 4 S nuclear RNA at a linear rate for 2 hr following an initial lag period. Drug concentrations of 1 x 10-5 to 1 x 10-4 M did not have a marked effect on the incorporation of [3H]adenosine into 5 S and 4 S nuclear RNA; however, the synthesis of high molecular weight nuclear RNA was inhibited 10-60% depending on the length of time of labeling and the drug concentration. 5-Fluorouracil impaired the methylation of 4 S nuclear RNA in a dose-dependent manner and affected high molecular weight nuclear RNA to a lesser extent. 5-Fluorouracil at 1 x 10-4 M inhibited the methylation of eight methylated nucleosides in 4 S nuclear RNA, but at 5 x 10-5 M preferentially affected 7-methylguanosine, N2, N2-dimethylguanosine and 5-methyluridine. These results indicate that the methylation of 4 S nuclear RNA is impaired by 5-fluorouracil at concentrations of drug which do not significantly impair its transcription. ACKNOWLEDGMENT The authors wish to thank Mrs. Margaret Green for help in the preparation of this manuscript. ER -