title: Induction of the early response protein EGR-1 in human tumour cells after ionizing radiation is correlated with a reduction of repair of lethal lesions and an increase of repair of sublethal lesions.
abstract: The role of EGR-1 in potentially lethal damage repair (PLDR) was studied. Induction of the early response protein EGR-1 and survival after ionizing radiation of two human tumour cell lines after culturing for 48 h in serum-deprived medium was investigated. The glioblastoma cell line (Gli-6) and a lung carcinoma cell line (SW-1573) were selected as these cell lines differ considerably in the degree of PLD repair after radiation. In both cell lines induction of EGR-1 protein was observed between 30-120 min after treatment with 10 Gy in serum-deprived cultures. In cells growing in medium with normal serum no induction of EGR-1 was observed. No difference in EGR-1 expression levels between the two cell lines was detected. Linear-Quadratic analysis of the survival curves showed a much larger difference between the values of alpha after immediate and delayed plated cells of the cultures in normal serum as compared to cells cultured in serum-deprived medium. The cells cultured in serum-deprived medium showed much larger difference between the values of beta. This indicates that induction of EGR-1 is correlated with a reduction of repair of lethal lesions (PLDRalpha) and with an increase of repair of sublethal lesions (PLDRbeta).
authors.affiliation: Department of Radiotherapy, Academic Medical Center, University of Amsterdam, 1100 DE Amsterdam, The Netherlands. n.a.franken@amc.uva.nl
authors.forename: Nicolaas A P
authors.initials: NA
authors.lastname: Franken
authors.forename: Rosemarie
authors.initials: R
authors.lastname: Ten Cate
authors.forename: Chris
authors.initials: C
authors.lastname: Van Bree
authors.forename: Jaap
authors.initials: J
authors.lastname: Haveman
mesh_terms: D002470:Cell Survival / Q000528:radiation effects*; D004260:DNA Repair / Q000528:radiation effects*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D005720:Gamma Rays; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism; D008175:Lung Neoplasms / Q000473:pathology*; D011832:Radiation Injuries / Q000473:pathology*; D011836:Radiation Tolerance; D011839:Radiation, Ionizing; D014157:Transcription Factors / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000528:radiation effects; D014410:Tumor Stem Cell Assay
chemical_list: D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D014157:Transcription Factors