Document Detail

Toxicity of camptothecin to Chinese hamster cells containing 5-hydroxymethyl-2'-deoxyuridine in their DNA.
MedLine Citation:
PMID:  7739616     Owner:  NLM     Status:  MEDLINE    
5-Hydroxymethyl-2'-deoxyuridine (hmdUrd) is incorporated into the DNA of V79 Chinese hamster cells as an analogue of thymidine. Incorporated residues are then recognized and excised by hmUra-DNA glycosylase (hmUDG). The removal of large numbers of hmUra residues and subsequent strand breakage is cytotoxic, as has been demonstrated by our finding that a mutant cell line, which is deficient in this enzyme, is resistant to hmdUrd (Boorstein et al., 1992a). In order to determine whether topoisomerase I plays a role in hmUDG initiated base excision repair, V79 cells and repair deficient V79mut1 cells were exposed to combinations of hmdUrd and the topoisomerase I inhibitors camptothecin (CPT), CPT-11, and beta-lapachone. Treatment of V79 cells with hmdUrd followed by non-toxic concentrations of camptothecin or CPT-11 showed significant enhancement of the baseline cytotoxicity of the hmdUrd alone. In contrast, camptothecin and CPT-11 had no effect in combination with hmdUrd in the V79mut1 cells. Non-toxic concentrations of beta-lapachone, which inhibits topoisomerase I by a different mechanism than camptothecin and CPT-11, produced no synergistic toxicity in V79 cells. Neither camptothecin nor CPT-11 inhibited removal of hmdUrd from hmdUrd treated cells, nor did they affect hmdUrd-induced poly(ADP-ribose) synthesis. Camptothecin did not alter the cell cycle distribution of either hmdUrd treated cells or untreated cells at concentrations sufficient to cause synergistic toxicity with hmdUrd. Results from our study indicate that the utility of topoisomerase I inhibitors may be enhanced by sensitizing cells with hmdUrd initiated repair activity which arrests cells in S-phase and produces DNA lesions that are further converted into lethal damage by camptothecin.
L J Mi; L N Chiu; E Mahl; R J Boorstein
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Mutation research     Volume:  336     ISSN:  0027-5107     ISO Abbreviation:  Mutat. Res.     Publication Date:  1995 May 
Date Detail:
Created Date:  1995-06-08     Completed Date:  1995-06-08     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0400763     Medline TA:  Mutat Res     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  293-305     Citation Subset:  IM    
Department of Pathology, New York University Medical Center, NY, USA.
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MeSH Terms
Antibiotics, Antineoplastic / toxicity
Antineoplastic Agents / pharmacology*
Camptothecin / analogs & derivatives,  toxicity*
Cell Cycle / drug effects
Cell Line / drug effects
DNA Repair / drug effects,  physiology*
DNA Topoisomerases, Type I / antagonists & inhibitors*
Dose-Response Relationship, Drug
Drug Synergism
Lung / cytology
Naphthoquinones / toxicity
Poly(ADP-ribose) Polymerases / antagonists & inhibitors,  biosynthesis
S Phase
Thymidine / analogs & derivatives*,  metabolism,  toxicity
Grant Support
Reg. No./Substance:
0/Antibiotics, Antineoplastic; 0/Antineoplastic Agents; 0/Naphthoquinones; 100286-90-6/irinotecan; 4707-32-8/beta-lapachone; 50-89-5/Thymidine; 5116-24-5/5-hydroxymethyl-2'-deoxyuridine; 7689-03-4/Camptothecin; EC Polymerases; EC Topoisomerases, Type I

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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