Transient adenoviral N-methylpurine DNA glycosylase overexpression imparts chemotherapeutic sensitivity to human breast cancer cells.
In an effort to improve the efficacy of cancer chemotherapy by intervening into the cellular responses to chemotherapeutic change, we have used adenoviral overexpression of N-methylpurine DNA glycosylase (MPG or ANPG/AAG) in breast cancer cells to study its ability to imbalance base excision repair (BER) and sensitize cancer cells to alkylating agents. Our results show that MPG-overexpressing cells are significantly more sensitive to the alkylating agents methyl methanesulfonate, N-methyl-N'-nitro-N-nitrosoguanidine, methylnitrosourea, dimethyl sulfate, and the clinical chemotherapeutic temozolomide. Sensitivity is further increased through coadministration of the BER inhibitor methoxyamine, which covalently binds abasic or apurinic/apyrimidinic (AP) sites and makes them refractory to subsequent repair. Methoxyamine reduction of cell survival is significantly greater in cells overexpressing MPG than in control cells, suggesting a heightened production of AP sites that, if made persistent, results in increased cellular toxicity. We further explored the mechanism of MPG-induced sensitivity and found that sensitivity was associated with a significant increase in the number of AP sites and/or single-strand breaks in overexpressing cells, confirming a MPG-driven accumulation of toxic BER intermediates. These data establish transient MPG overexpression as a potential therapeutic approach for increasing cellular sensitivity to alkylating agent chemotherapy.
Herman B. Wells Center for Pediatric Research, 1044 West Walnut, Building R4, Room 302C, Indianapolis, IN 46202, USA.
Mikael
M
Rinne
David
D
Caldwell
Mark R
MR
Kelley
D000256:Adenoviridae / Q000235:genetics*; D000477:Alkylating Agents / Q000494:pharmacology; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000628:therapy*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D020552:Comet Assay; D045647:DNA Glycosylases / Q000737:chemistry / Q000235:genetics*; D004260:DNA Repair; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006801:Humans; D006898:Hydroxylamines / Q000737:chemistry; D007150:Immunohistochemistry; D008741:Methyl Methanesulfonate / Q000737:chemistry; D008769:Methylnitronitrosoguanidine / Q000737:chemistry; D008770:Methylnitrosourea / Q000494:pharmacology; D009841:Oligonucleotides / Q000737:chemistry; D012680:Sensitivity and Specificity; D013463:Sulfuric Acid Esters / Q000494:pharmacology; D000077204:Temozolomide; D013997:Time Factors
D000477:Alkylating Agents; D018906:Antineoplastic Agents, Alkylating; D006898:Hydroxylamines; D009841:Oligonucleotides; D013463:Sulfuric Acid Esters; D008769:Methylnitronitrosoguanidine; D008770:Methylnitrosourea; D003606:Dacarbazine; C005214:methoxyamine; D008741:Methyl Methanesulfonate; D045647:DNA Glycosylases; C007482:dimethyl sulfate; D000077204:Temozolomide