Overexpression of DNA polymerase beta sensitizes mammalian cells to 2',3'-deoxycytidine and 3'-azido-3'-deoxythymidine. NLM AIDSLINE Important note: Information in this article was accurate in 1997. The state of the art may have changed since the publication date.

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Overexpression of DNA polymerase beta sensitizes mammalian cells to 2',3'-deoxycytidine and 3'-azido-3'-deoxythymidine.

Cancer Res. 1997 Jan 1;57(1):110-6. Unique Identifier : AIDSLINE MED/97141792
Bouayadi K; Hoffmann JS; Fons P; Tiraby M; Reynes JP; Cazaux C; Laboratoire de Microbiologie et de Genetique, Universite Paul; Sabatier, Toulouse, France.

Abstract: Mammalian DNA polymerase beta is a DNA repair enzyme expressed constitutively at a low level. In vitro, purified DNA polymerase Pol) beta incorporates the nucleotide analogues 2'-3' deoxycytidine (ddC)-triphosphate and 3'-azido-3'-deoxythymidine AZT)-triphosphate into DNA, causing chain termination. We have tested the possibility of enhancing the cytotoxicity of these chain terminators against mammalian cells by increasing the level of Pol beta. Chinese hamster ovary AA8 and murine melanoma B16 cell lines were stably transfected with rat pol beta cDNA under the control of a viral enhancer/promoter. We found that overexpression of Pol beta sensitized the cells to ddC and AZT. To confirm the role of this polymerase in this process, we prepared cell extracts from the control and Pol beta overexpressing Chinese hamster ovary cell lines and tested in vitro their capacity to incorporate ddC-triphosphate and AZT-triphosphate into DNA. We found that inhibition of DNA replication by both chain terminators was more pronounced when extracts from pol beta-transfected cells were used, providing a direct evidence of the involvement of Pol beta in the sensitization process. In addition, we showed that cotransfection with bacterial or viral thymidine/thymidylate kinase genes enhanced the Pol beta-mediated cytotoxicity of AZT, suggesting that phosphorylation and polymerization activities might be combined to potentiate their respective effects. These observations may be useful for improving therapeutic efficiency of DNA chain terminators.
Keywords: *Deoxycytidine/PHARMACOLOGY *DNA Polymerase I/METABOLISM *DNA Replication/DRUG EFFECTS *Neoplasm Proteins/METABOLISM *Zidovudine/PHARMACOLOGYKWDdeoxycytidine/pharmacologyKWDdnapolymerasei/metabolismKWDdnareplication/drugeffectsKWDneoplasmproteins/metabolismKWDzidovudine/pharmacology
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