title: Relationship between p53 status and radiosensitivity in human tumour cell lines.
abstract: We examined the relationship between p53 levels before and after irradiation, radiation-induced cell cycle delays, apoptotic cell death and radiosensitivity in a panel of eight human tumour cell lines. The cell lines differed widely in their clonogenic survival after radiation, (surviving fraction at 2 Gy: SF2=0.18-0.82). Constitutive p53 protein levels varied from 2.2 +/- 0.4 to 6.3 +/- 0.3 optical density units (OD) per 10(6) cells. p53 after irradiation (6 Gy) also varied between the cell lines, ranging from no induction to a 1.6-fold increase in p53 levels 4 h after treatment. p53 function was also assessed by G1 cell cycle arrest after irradiation. The cellular response to radiation, measured as G0/G1 arrest, and the induction of apoptosis were in good agreement. However, a trace amount of DNA ladder formation was found in two cell lines lacking G1 arrest. Overall cellular radiosensitivity correlated well with the level of radiation-induced G1 arrest (correlation coefficient r=0.856; P=0.0067), with p53 constitutive levels (r=0.874, P=0.0046), and with p53 protein fold induction (r=-0.882, P=0.0038). Our data suggest that (1) the constitutive p53 level, (2) G1 arrest after irradiation, or (3) the p53 protein response to radiation may be good predictive tests for radiosensitivity in some cell types.
authors.affiliation: Departamento de Radiologia y Medicina Fisica, Hospital Universitario, Facultad de Medicina, Granada, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Siles
authors.forename: M
authors.initials: M
authors.lastname: Villalobos
authors.forename: M T
authors.initials: MT
authors.lastname: Valenzuela
authors.forename: M I
authors.initials: MI
authors.lastname: Núñez
authors.forename: A
authors.initials: A
authors.lastname: Gordon
authors.forename: T J
authors.initials: TJ
authors.lastname: McMillan
authors.forename: V
authors.initials: V
authors.lastname: Pedraza
authors.forename: J M
authors.initials: JM
authors.lastname: Ruiz de Almodóvar
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D002453:Cell Cycle / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D004249:DNA Damage; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D009369:Neoplasms / Q000737:chemistry / Q000532:radiotherapy*; D011836:Radiation Tolerance; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000032:analysis*
chemical_list: D016159:Tumor Suppressor Protein p53