Repair of potentially lethal damage does not depend on functional TP53 in human glioblastoma cells.
The functionality of G(1)-phase arrest was investigated in relation to repair of potentially lethal damage (PLD) in human glioblastoma Gli-06 cells. Confluent cultures were irradiated and plated for clonogenic survival either immediately or 24 h after gamma irradiation. Bivariate flow cytometry was performed to assess the distribution over the cell cycle. Levels of TP53 and CDKN1A protein were assessed with Western blotting and levels of CDKN1A mRNA with RT-PCR. Confluence significantly reduced the number of proliferating cells. Marked PLD repair was found in the absence of an intact G(1) arrest. No accumulation of TP53 was observed, and the protein was smaller than the wild-type TP53 of RKO cells. No increased expression of CDKN1A at the mRNA or protein levels was found in Gli-06 cells. The TP53 of Gli-06 cells was unable to transactivate the CDKN1A gene. From this study, it is evident that PLD repair may be present without a functional TP53 or G(1) arrest.
van Bree
C
C
Academic Medical Center, University of Amsterdam, Department of Radiotherapy, 1100 DE Amsterdam, The Netherlands. c.vanbree@amc.uva.nl
Franken
N A P
NA
Rodermond
H M
HM
Stalpers
L J A
LJ
Haveman
J
J
D017209:Apoptosis / Q000528:radiation effects*; D002455:Cell Division / Q000528:radiation effects; D045744:Cell Line, Tumor; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005909:Glioblastoma / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D011829:Radiation Dosage; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D016159:Tumor Suppressor Protein p53; D004247:DNA