title: 5-Fluorouracil-radiation interactions in human colon adenocarcinoma cells.
abstract: OBJECTIVE
  To determine the effect of cellular proliferation and cell cycle stage on the ability of postirradiation 5-fluorouracil (5-FU) to radiosensitize cultured human colon adenocarcinoma Clone A cells.
  
  
  METHODS
  Cell survival curves were generated for irradiated: (a) log- and plateau-phase Clone A cells; and (b) Clone A cells separated by centrifugal elutriation into the various phases of the cell cycle; with and without postirradiation treatment with 100 micrograms/ml 5-FU.
  
  
  RESULTS
  Postirradiation treatment with 5-FU sensitized proliferating cells to a greater degree than it sensitized cells growing in plateau phase. The beta component of cell kill in log-phase cells was increased by a factor of 1.5 with a sensitizer enhancement ratio of 1.21 at the 0.01 survival level. Plateau-phase cells showed less radiosensitization (sensitizer enhancement ratio of 1.13 at the 0.01 survival level); however, there was a mild increase in both alpha and beta kill in plateau-phase cells. Elutriated G1 cells were the most radiosensitive, independent of treatment with 5-FU. The phase of the cell cycle had little effect on the ability of fluorouracil to radiosensitize Clone A cells.
  
  
  CONCLUSIONS
  Proliferating cells are more susceptible to radiosensitization with 5-FU than plateau-phase cells are, but this effect appears to be independent of the phase of the cell cycle.
authors.affiliation: Department of Clinical Radiotherapy, University of Texas, M. D. Anderson Cancer Center, Houston 77030, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Buchholz
authors.forename: K J
authors.initials: KJ
authors.lastname: Lepek
authors.forename: T A
authors.initials: TA
authors.lastname: Rich
authors.forename: D
authors.initials: D
authors.lastname: Murray
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy; D005472:Fluorouracil / Q000494:pharmacology*; D006801:Humans; D011829:Radiation Dosage; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D011838:Radiation-Sensitizing Agents; D005472:Fluorouracil