Differential Effects of 5‐bromodeoxyuridine on B16 Mouse Melanoma Cells

Abstract

The effects of 5-bromodeoxyuridine (BrdU) on BI6 mouse melanoma were studied and the following results were obtained. 1) Melanogenesis of cells was completely inhibited by BrdU.2) Tyrosinase activity was reduced linearly with time by BrdU, but cytochrome c oxidase was not affected.3) The polysome profile from controls and that from BrdU-treated cells resembled each other when assayed at 260nm. However, the radioactivity in polysomes in the treated cells was about 30-40% ofthat in the control, when pulse labeled with radioactive uridine. 4) Polysomal RNAs were fractionated into poly(A)-containing and non-poly(A)-containing RNA with the use of poly(U)-Sepharose, and both types of RNA were examined by polyacrylamide gel electrophoresis. No significant differences were detected between the control and the BrdUtreated cells in either type of RNA.5) The effects of BrdU are specific for melanogenesis and the differences in polysomal RNAs might be too small to detect in our experiments. Immunoprecipitation of mRNAs for melanosomal proteins will be necessary to detect persuasive differences.