DNA Damage Response to the Mdm2 Inhibitor nutlin-3

Biochem Pharmacol. 2010 Feb 15;79(4):565-74. doi: 10.1016/j.bcp.2009.09.020.

Abstract

Mdm2 inhibitors represent a promising class of p53 activating compounds that may be useful in cancer treatment and prevention. However, the consequences of pharmacological p53 activation are not entirely clear. We observed that Nutlin-3 triggered a DNA damage response in azoxymethane-induced mouse AJ02-NM(0) colon cancer cells, characterized by the phosphorylation of H2AX (at Ser-139) and p53 (at Ser-15). The DNA damage response was highest in cells showing robust p53 stabilization, it could be triggered by the active but not the inactive Nutlin-3 enantiomer, and it was also activated by another pharmacological Mdm2 inhibitor (Caylin-1). Quantification of gamma H2AX-positive cells following Nutlin-3 exposure showed that approximately 17% of cells in late S and G2/M were mounting a DNA damage response (compared to a approximately 50% response to 5-fluorouracil). Nutlin-3 treatment caused the formation of double-strand DNA strand breaks, promoted the formation of micronuclei, accentuated strand breakage induced by doxorubicin and sensitized the mouse colon cancer cells to DNA break-inducing topoisomerase II inhibitors. Although the HCT116 colon cancer cells did not mount a significant DNA damage response following Nutlin-3 treatment, Nutlin-3 enhanced the DNA damage response to the nucleotide synthesis inhibitor hydroxyurea in a p53-dependent manner. Finally, p21 deletion also sensitized HCT116 cells to the Nutlin-3-induced DNA damage response, suggesting that cell cycle checkpoint abnormalities may promote this response. We propose that p53 activation by Mdm2 inhibitors can result in the slowing of double-stranded DNA repair. Although this effect may suppress illegitimate homologous recombination repair, it may also increase the risk of clastogenic events.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • DNA Damage / drug effects*
  • DNA Damage / physiology
  • HCT116 Cells
  • Humans
  • Imidazoles / toxicity*
  • Mice
  • Piperazines / toxicity*
  • Proto-Oncogene Proteins c-mdm2 / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-mdm2 / physiology
  • Stereoisomerism
  • Tumor Cells, Cultured

Substances

  • Imidazoles
  • Piperazines
  • nutlin 3
  • Mdm2 protein, mouse
  • Proto-Oncogene Proteins c-mdm2