Phorbol ester abrogates up-regulation of DNA polymerase beta by DNA-alkylating agents in Chinese hamster ovary cells

J Biol Chem. 1995 Jul 7;270(27):16402-8. doi: 10.1074/jbc.270.27.16402.


Mammalian DNA polymerase beta (beta-pol), a DNA repair polymerase, is known to be constitutively expressed in cultured cells, but treatment of cells with the DNA-alkylating agents MNNG or methyl methanesulfonate has been shown to up-regulate beta-pol mRNA level. To further characterize this response, we prepared a panel of monoclonal antibodies and used one of them to quantify beta-pol in whole cell extracts by immunoblotting. We found that treatment of Chinese hamster ovary cells with either DNA-alkylating agent up-regulated the beta-pol protein level 5-10-fold. This induction appeared to be secondary to DNA alkylation, as induction was not observed with a genetically altered cell line overexpressing the DNA repair enzyme O6-methylguanine-methyltransferase. We also found that 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment of wild type Chinese hamster ovary cells increased expression of beta-pol protein (approximately 10-fold). Any interrelationship between this TPA response and the DNA-alkylation response was studied by treatment with combinations of MNNG and TPA. The beta-pol up-regulation observed with MNNG treatment was abrogated by TPA, and conversely the up-regulation observed with TPA treatment was abrogated by MNNG.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alkylating Agents / pharmacology*
  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal
  • CHO Cells
  • Cricetinae
  • DNA Damage*
  • DNA Polymerase I / biosynthesis*
  • DNA Polymerase I / genetics
  • DNA Polymerase I / immunology
  • DNA Repair
  • Drug Antagonism
  • Epitope Mapping
  • Immunoblotting
  • Methyl Methanesulfonate / pharmacology
  • Methylnitronitrosoguanidine / pharmacology
  • Molecular Sequence Data
  • Rats
  • Signal Transduction
  • Tetradecanoylphorbol Acetate / pharmacology*
  • Up-Regulation / drug effects*


  • Alkylating Agents
  • Antibodies, Monoclonal
  • Methylnitronitrosoguanidine
  • Methyl Methanesulfonate
  • DNA Polymerase I
  • Tetradecanoylphorbol Acetate