Chemoprotective gene transfer II: multilineage in vivo protection of haemopoiesis against the effects of an antitumour agent by expression of a mutant human O6-alkylguanine-DNA alkyltransferase

Gene Ther. 1998 Jun;5(6):842-7. doi: 10.1038/


Murine bone marrow cells were transduced ex vivo with a retrovirus encoding an O6-benzylguanine (O6-beG) insensitive, double mutant form of the human DNA repair protein O6-alkylguanine-DNA alkyltransferase (hATPA/GA). In animals reconstituted with the transduced bone marrow, about 50% of cells in the multipotent spleen colony-forming cells (CFU-S) and lineage restricted granulocyte-macrophage (GM-CFC) haemopoietic progenitor populations were found to be carrying the transgene and this correlated with the frequency of bone marrow cells and spleen colonies which stained positive for hATPA/GA by immunocyto-chemistry. Expression of hATPA/GA was associated with significant in vivo protection of both CFU-S (P = 0.001) and GM-CFC (P < 0.024) against the toxicity of the antitumour methylating agent, temozolomide, given in combination with O6-beG. Expression of hATPA/GA also led to a reduction in the frequency of combined O6-beG/temozolomide-induced micronuclei seen in polychromatic erythrocytes (P < 0.003). This study is the first to demonstrate in vivo protection of multipotent haemopoietic progenitors against the toxic and clastogenic effects of an O6-alkylating agent in the presence of O6-beG. It also represents the first report of reduced clastogenesis as a consequence of expression of an O6-beG-resistant ATase. In the accompanying article we report hATPA/GA-mediated resistance of human CD34+ haemopoietic progenitors to combined O6-beG/O6-alkylating agent toxicity. Together these two reports suggest that a gene therapy strategy whereby protection of normal haemopoietic tissue may be combined with O6-beG-mediated tumour sensitisation may be efficacious in achieving an increase in therapeutic index.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents, Alkylating / toxicity*
  • Bone Marrow Cells
  • Cell Survival
  • Dacarbazine / analogs & derivatives*
  • Dacarbazine / toxicity
  • Gene Expression
  • Gene Transfer Techniques*
  • Genetic Vectors*
  • Male
  • Mice
  • Mice, Inbred Strains
  • O(6)-Methylguanine-DNA Methyltransferase / genetics*
  • Polymerase Chain Reaction
  • Retroviridae*
  • Spleen / cytology
  • Stem Cells*
  • Temozolomide


  • Antineoplastic Agents, Alkylating
  • Dacarbazine
  • O(6)-Methylguanine-DNA Methyltransferase
  • Temozolomide