DNA polymerase β mediates protection of mammalian cells against ganciclovir-induced cytotoxicity and DNA breakage

• Published in: Cancer research (Chicago, Ill.) Vol. 61; no. 20; pp. 7399 - 7403
• Main Authors: TOMICIC, Maja T, THUST, Rudolf, SOBOL, Robert W, KAINA, Bernd
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 15.10.2001
• Subjects: Animals; Antineoplastic agents; Biological and medical sciences; Chemotherapy; CHO Cells; Cricetinae; DNA - metabolism; DNA Damage; DNA Polymerase beta - antagonists & inhibitors; DNA Polymerase beta - deficiency; DNA Polymerase beta - metabolism; Enzyme Inhibitors - pharmacology; Fibroblasts - drug effects; Fibroblasts - enzymology; Ganciclovir - metabolism; Ganciclovir - toxicity; Herpes simplex virus; Herpesvirus 1, Human - enzymology; Herpesvirus 1, Human - genetics; Hydroxylamines - pharmacology; Medical sciences; methoxyamine; Mice; Mice, Knockout; Nitriles - pharmacology; Pharmacology. Drug treatments; Thymidine Kinase - genetics; Thymidine Kinase - metabolism; Transfection; Chromosomal aberration; Antineoplastic agent; Acyclic nucleoside; Purine nucleoside; Toxicity; Alphaherpesvirinae; Genotoxicity; Prevention; Ganciclovir; Established cell line; Herpesvirus hominis; Mechanism of action; Repair; Thymidine kinase; Enzyme; Herpesviridae; Transferases; In vitro; Virus; Nucleotidyltransferases; Vertebrata; Chromosome break; Mammalia; Sensitivity resistance; Cell death; Animal; DNA; Lesion; Gene therapy; DNA-directed DNA polymerase; Apoptosis
• ISSN: 0008-5472; 1538-7445

The efficacy of suicide herpes simplex virus-1 thymidine kinase (HSVtk)/ganciclovir (GCV) gene therapy is often limited by intrinsic resistance of tumor cells. Here we show that repair of GCV incorporated in DNA is a factor involved in GCV resistance. A protective role of DNA repair in GCV-induced cell killing is supported by the following findings: (a) GCV-exposed Chinese hamster ovary-HSVtk cells exhibited both reduced repair of GCV and cloning efficiency in the presence of a specific polymerase beta (beta-pol) inhibitor, prunasin; (b) DNA beta-pol-deficient mouse fibroblasts were more sensitive to the cytotoxic, apoptosis-inducing, and genotoxic (DNA breakage and chromosomal aberration-inducing) effects of GCV as compared with wild-type and beta-pol-complemented cell lines; (c) methoxyamine, an inhibitor of beta-pol-dependent short-patch base excision repair, sensitized wild-type and complemented beta-pol cells to GCV, whereas it had no effect on the sensitivity of beta-pol-null cells to GCV. Because methoxyamine-mediated sensitization of beta-pol wild-type and beta-pol-complemented cells to GCV did not reach the level of null cells, we suggest that both beta-pol-dependent short- and long-patch base excision repair are involved in protection of cells to GCV. Some implications for HSVtk/GCV gene therapy are being discussed.