Cytoprotection by WR-1065, the active form of amifostine, is independent of p53 status in human malignant glioma cell lines.
OBJECTIVE
This study tests the hypothesis that p53 status, i.e. wild type versus mutant form, is a determinant in radiation protection of human glioma cells by WR-1065, the active thiol form of amifostine (WR-2721).


METHODS
The cytoprotective effectiveness of WR-1065 when present during irradiation was investigated using four well-characterized human glioma cell lines. The p53 positive lines were U87 and D54, and the mutant p53 lines were U251 (mutant at codon 273; CGT/CAT; Arg/His) and A172 (mutant at codon 242; TGC/TTC; Cys/Phe). Treatment conditions included exposure of cells to a range of doses (0-10Gy) alone or in combination with 4mM of WR-1065 added 30min prior to irradiation. Resultant survival curves were obtained using a clonogenic assay and protection factors, the ratio of terminal slopes +/- WR-1065, were determined for each glioma cell line.


RESULTS
The Do values of wild-type U87 and D54 were 1.62 and 1.89Gy while those of p53 mutants U251 and A172 were 1.64 and 1.68 Gy, respectively. Protection factors were determined to be 2.4 and 1.9 for U87 and D54, and 2.6 and 2.8 for U251 and A172, respectively.


CONCLUSIONS
The p53 status of the four human glioma cell lines tested was not a predictor for either their relative sensitivity to ionizing radiation or ability to be protected by WR-1065. It is concluded that cytoprotection exhibited by cells exposed to WR-1065 during irradiation is independent of their p53 status.
Kataoka
Y
Y
Department of Radiation and Cellular Oncology, University of Chicago, IL 60637, USA.
Murley
J S
JS
Patel
R
R
Grdina
D J
DJ
D004999:Amifostine / Q000494:pharmacology; D002470:Cell Survival / Q000528:radiation effects; D019610:Cytoprotection; D004307:Dose-Response Relationship, Radiation; D016158:Genes, p53 / Q000235:genetics; D005910:Glioma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000532:radiotherapy*; D006801:Humans; D008624:Mercaptoethylamines / Q000494:pharmacology*; D009154:Mutation; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*
D008624:Mercaptoethylamines; D011837:Radiation-Protective Agents; D016159:Tumor Suppressor Protein p53; C020174:N-(2-mercaptoethyl)-1,3-diaminopropane; D004999:Amifostine