Determination of apoptosis, uracil incorporation, DNA strand breaks, and sister chromatid exchanges under conditions of thymidylate deprivation in a model of BER deficiency
| Autor: | Michael D. Wyatt, Sondra H. Berger, Li Li, Ellen E. Connor |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Poly Adenosine Diphosphate Ribose
Time Factors DNA Repair DNA repair Apoptosis Sister chromatid exchange Thiophenes Biology Biochemistry Thymidylate synthase Cell Line Mice chemistry.chemical_compound Null cell medicine Animals Humans Uracil Uracil-DNA Glycosidase Cells Cultured DNA Polymerase beta Pharmacology Dose-Response Relationship Drug Thymidylate Synthase Base excision repair Fibroblasts Embryo Mammalian Molecular biology chemistry Quinazolines biology.protein Sister Chromatid Exchange Raltitrexed DNA DNA Damage medicine.drug |
| Zdroj: | Biochemical Pharmacology. 70:1458-1468 |
| ISSN: | 0006-2952 |
| DOI: | 10.1016/j.bcp.2005.08.016 |
| Popis: | Thymidylate synthase (TS) is an important target of several chemotherapeutic agents. During TS inhibition, dTTP levels decrease with a subsequent increase in dUTP. Uracil incorporated into the genome is removed by base excision repair (BER). BER has been hypothesized to play a role in the response to thymidylate deprivation, despite a lack of direct evidence. We previously found that beta-pol null murine fibroblasts were approximately six-fold more resistant than wild-type cells to raltitrexed, a folate-based inhibitor specific for TS. In this study, a number of endpoints were determined to understand the influence of BER and beta-pol during raltitrexed treatment. Raltitrexed induced apoptosis in wild-type cells to a greater extent than in beta-pol null cells. A PARP inhibitor decreased the sensitivity to raltitrexed, although the extent was not different between wild-type and beta-pol null cells. No evidence was seen for extensive strand break formation that preceded apoptosis, although raltitrexed induced more sister chromatid exchanges in wild-type cells. Increased levels of uracil in DNA were detected following treatment in wild-type and beta-pol null cells. However, uracil levels were only approximately two-fold higher in DNA from treated cells compared to untreated. Uracil DNA glycosylase activity was slightly higher in beta-pol null cells, although not sufficiently different to explain the difference in sensitivity to raltitrexed. Taken together, the data suggest that the sensitivity of the wild-type cells to raltitrexed is not associated with activation of PARP-1 dependent BER, extensive uracil incorporation into DNA and persistent strand breaks, but rather with changes suggestive of DNA recombination. |
| Databáze: | OpenAIRE |
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