DNA-PK: the major target for wortmannin-mediated radiosensitization by the inhibition of DSB repair via NHEJ pathway

J Radiat Res. 2003 Jun;44(2):151-9. doi: 10.1269/jrr.44.151.

Abstract

The effect of wortmannin posttreatment was studied in cells derived from different species (hamster, mouse, chicken, and human) with normal and defective DNA-dependent protein kinase (DNA-PK) activity, cells with and without the ataxia telangiectasia (ATM) gene, and cells lacking other regulatory proteins involved in the DNA double-strand break (DSB) repair pathways. Clonogenic assays were used to obtain all results. Wortmannin radiosensitization was observed in Chinese hamster cells (V79-B310H , CHO-K1), mouse mammary carcinoma cells (SR-1), transformed human fibroblast (N2KYSV), chicken B lymphocyte wild-type cells (DT40), and chicken Rad54 knockout cells (Rad54-/-). However, mouse mammary carcinoma cells (SX9) with defects in the DNA-PK and chicken DNA-PK catalytic subunit (DNA-PKcs) knockout cells (DNA-PKcs-/-/-) failed to exhibit wortmannin radiosensitization. On the other hand, SCID mouse cells (SC3VA2) exposed to wortmannin exhibited significant increases in radiosensitivity, possibly because of some residual function of DNA-PKcs. Moreover, the transformed human cells derived from AT patients (AT2KYSV) and chicken ATM knockout cells (ATM-/-) showed pronounced wortmannin radiosensitization. These studies demonstrate confirm that the mechanism underlying wortmannin radiosensitization is the inhibition of DNA-PK, but not of ATM, thereby resulting in the inhibition of DSB repair via nonhomologous endjoining (NHEJ).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androstadienes / pharmacology*
  • Animals
  • Cells, Cultured
  • Chickens
  • Cricetinae
  • Cricetulus
  • DNA / drug effects*
  • DNA Damage / drug effects*
  • DNA Repair*
  • DNA-Activated Protein Kinase
  • DNA-Binding Proteins*
  • Humans
  • Mice
  • Mice, SCID
  • Nuclear Proteins
  • Protein-Serine-Threonine Kinases / drug effects*
  • Radiation-Sensitizing Agents / pharmacology*
  • Wortmannin

Substances

  • Androstadienes
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Radiation-Sensitizing Agents
  • DNA
  • DNA-Activated Protein Kinase
  • PRKDC protein, human
  • Protein-Serine-Threonine Kinases
  • Wortmannin