Deregulated DNA polymerase beta strengthens ionizing radiation-induced nucleotidic and chromosomal instabilities.
DNA polymerase beta (Pol beta) is an error-prone enzyme which has been found to be overexpressed in several human tumors. By using a couple of recombinant CHO cells differing only from the exogenous expression of Pol beta, we showed here that cells overexpressing Pol beta are much more sensitive to IR treatments by increasing apoptosis. We also found that the surviving cells displayed an hypermutator phenotype which could be explained by different pathways involving Pol beta, such as (i) an increased capacity to incorporate into DNA the mutagenic dGTP analog, 8-oxo-dGTP, one of the most abundant purine-derived nucleotides exposed to gamma-irradiation, (ii) the induction of IR-induced DNA breaks and (iii) accumulation of chromosome aberrations induced by radiation. Alteration of Pol beta expression in irradiated cells thus appears to strengthen both cell death and genetic changes associated with a malignant phenotype. These data provide new insights into the cellular response to radiations and the associated carcinogenic consequences.
Fréchet
Mathilde
M
IPBS - CNRS UMR 5089, groupe Instabilité Génétique et Cancer, 'Labellisée Ligue Contre le Cancer', 205 route de Narbonne, 31077 Toulouse cedex, France.
Canitrot
Yvan
Y
Bieth
Anne
A
Dogliotti
Eugenia
E
Cazaux
Christophe
C
Hoffmann
Jean-Sébastien
JS
D000818:Animals; D017209:Apoptosis; D016466:CHO Cells; D002869:Chromosome Aberrations; D006224:Cricetinae; D004249:DNA Damage; D019951:DNA Polymerase beta / Q000378:metabolism*; D003848:Deoxyguanine Nucleotides / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D007700:Kinetics; D009154:Mutation; D011836:Radiation Tolerance; D011839:Radiation, Ionizing; D015854:Up-Regulation
D003848:Deoxyguanine Nucleotides; C078206:8-oxodeoxyguanosine triphosphate; D019951:DNA Polymerase beta