Document Detail

Determinants of cytotoxicity with prolonged exposure to fluorouracil in human colon cancer cells.
MedLine Citation:
PMID:  9167189     Owner:  NLM     Status:  MEDLINE    
To explore the determinants of cytotoxicity during prolonged exposure to pharmacologically relevant concentrations of 5-fluorouracil (FUra), we studied the effects of FUra at concentrations ranging from 0.1 to 1 microM in HCT 116 and HT 29 colon cancer cells grown in the presence of physiologic levels of leucovorin. A 5- and 7-day exposure to 1 microM FUra reduced cell growth to 46% and 20% of control in HT 29 cells and to 74% and 38% of control in HCT 116 cells. Concurrent exposure to thymidine (10 or 20 microM) or uridine (1 mM) provided partial protection against FUra toxicity in HT 29 cells, but did not protect HCT 116 cells. After a 24-h exposure to 1 microM [3H]FUra, free 5-fluoro-2'-deoxyuridine-5' -monophosphate (FdUMP) and FUDP. + FUTP levels were 0.7 and 144 pmol/10(6) cells in HT 29 cells, respectively, and 3.9 and 178 pmol/10(6) cells in HCT 116 cells. FdUMP and FUDP + FUTP pools increased by 5.7- and 2.0-fold in HT 29 cells and by 1.7- and 3.3-fold in HCT 116 cells over the next 48 h, but did not accumulate thereafter. After a 24-h exposure to 1 microM [3H]FUra, FUra-RNA levels were 158 and 280 fmol/microgram in HT 29 and HCT 116 cells, respectively; FUra-RNA levels increased over time, and reached 700 and 1156 fmol/microgram at day 5. Concurrent exposure to 1 mM uridine for 72 h did not diminish [3H]FUra-RNA incorporation. Upon removal of [3H]FUra following a 24-h exposure, FUra-RNA levels remained relatively stable with 57-78% retained at 120 h. A low level of [3H]FUra-DNA incorporation was detected in HT 29 cells. Thymidylate synthase (TS) catalytic activity in control cells was 2-fold higher in HCT 116 cells compared to HT 29 cells (47 vs. 23 pmol/min/mg). Total TS content increased 1.5- to 3-fold over control in both cell lines during FUra exposure, and ternary complex formation was evident for up to 96 h-dTTP pools were not depleted in FUra-treated cells, suggesting that residual TS catalytic activity was sufficient to maintain dTTP pools relative to demand. Surprisingly, the partial inhibition of TS was accompanied by a striking accumulation of immunoreactive "dUMP" pools in both lines; dUTP pools also increased 2-to 3-fold. In summary, the gradual and stable accumulation of FUra in RNA noted in both lines may account for the thymidine-insensitive component of FUra toxicity. Because dTTP pools were not appreciably diminished, the interference with nascent DNA chain elongation and induction of single-strand breaks in newly synthesized DNA in both cell lines may be due to misincorporation of deoxyuridine nucleotides.
Q Ren; C J Van Groeningen; A Hardcastle; G W Aherne; F Geoffroy; C J Allegra; P G Johnston; J L Grem
Related Documents :
16574159 - The effect of n-acetylcysteine in combination with vitamin c on the activity of ornithi...
16754849 - Endonuclease g: a role for the enzyme in recombination and cellular proliferation.
16660339 - Rna synthesis in whole cells and protoplasts of centaurea: a comparison.
7656239 - Effect of polyamine analogues and inhibition of polyamine oxidase on spermidine/spermin...
7372569 - S-adenosylmethionine levels and protein methylation during morphogenesis of mucor racem...
2804229 - Separation of b and t lymphocytes by cellular adsorption chromatography with polyamine ...
12925849 - A new genetic method to generate and isolate small, short-lived but highly potent dendr...
11909959 - Nir2, a novel regulator of cell morphogenesis.
22692729 - Differential expression of galectin-1 and its interactions with cells and laminins in t...
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Oncology research     Volume:  9     ISSN:  0965-0407     ISO Abbreviation:  Oncol. Res.     Publication Date:  1997  
Date Detail:
Created Date:  1997-07-10     Completed Date:  1997-07-10     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  9208097     Medline TA:  Oncol Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  77-88     Citation Subset:  IM    
Developmental Therapeutics Department, National Cancer Institute, National Naval Medical Center, Bethesda, MD 20889-5105, USA.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Cell Division / drug effects
Cell Survival / drug effects*
Colonic Neoplasms
DNA Damage*
DNA, Neoplasm / drug effects
Deoxyribonucleotides / metabolism
Deoxyuracil Nucleotides / metabolism
Dose-Response Relationship, Drug
Fluorodeoxyuridylate / metabolism
Fluorouracil / metabolism,  toxicity*
Gene Expression Regulation, Enzymologic / drug effects
Leucovorin / pharmacology*
Thymidylate Synthase / antagonists & inhibitors,  biosynthesis
Tumor Cells, Cultured
Uridine Triphosphate / analogs & derivatives,  metabolism
Reg. No./Substance:
0/5-fluoro-2'-deoxyuridine-5'-diphosphate; 0/DNA, Neoplasm; 0/Deoxyribonucleotides; 0/Deoxyuracil Nucleotides; 134-46-3/Fluorodeoxyuridylate; 3828-96-4/5-fluorouridine 5'-triphosphate; 51-21-8/Fluorouracil; 58-05-9/Leucovorin; 63-39-8/Uridine Triphosphate; EC Synthase

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

Previous Document:  Changes in lymphocyte subsets following administration of interleukin 2 and cyclophosphamide in mice...
Next Document:  Frequent inactivation of the transforming growth factor beta type II receptor in small-cell lung car...