Ionizing radiation stimulates octamer factor DNA binding activity in human carcinoma cells.
In mammalian cells, the octamer motif (ATGCAAAT) binding proteins, Oct-1 and Oct-2, play an important role in the transcriptional transactivation of several ubiquitously expressed genes as well as cell-specifically expressed genes. To date, a role of the octamer binding proteins in damage-stimulated response is not known. In this report, we demonstrate that DNA-binding activity of Oct-1, as demonstrated by the electrophoretic mobility shift assay, is significantly induced in a dose-dependent manner upon treatment of human head and neck squamous carcinoma cells (PCI-04A) with ionizing radiation (5 Gy: 5-fold; 15 Gy: 11-fold). By comparison, activities of other transcription factors were modestly increased (15 Gy: AP-1, 2.5-fold; NF-kappaB, 2.6-fold; SP-1, 5-fold). Radiation stimulation of Oct-1 activity was also noted in two other human cancer cell lines, albeit to a lesser extent (MDA-MB231 breast carcinoma cells and PC-3 prostate carcinoma cells (5 Gy: approximately 2-fold). These data represent the first report of the activation of an octamer factor DNA binding activity in response to environmental cues and suggest a novel role of Oct-1 in the radiation signaling cascade in these cancer cells.
Meighan-Mantha
R L
RL
Department of Pharmacology, Lombardi Cancer Center, Georgetown University Medical Center, Washington, DC, USA.
Riegel
A T
AT
Suy
S
S
Harris
V
V
Wang
F H
FH
Lozano
C
C
Whiteside
T L
TL
Kasid
U
U
D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000532:radiotherapy*; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000528:radiation effects*; D006258:Head and Neck Neoplasms / Q000378:metabolism* / Q000532:radiotherapy*; D006657:Histones / Q000235:genetics; D051863:Host Cell Factor C1; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism / Q000528:radiation effects; D050811:Octamer Transcription Factor-1; D011839:Radiation, Ionizing; D016329:Sp1 Transcription Factor / Q000378:metabolism / Q000528:radiation effects; D018808:Transcription Factor AP-1 / Q000378:metabolism / Q000528:radiation effects; D014157:Transcription Factors / Q000378:metabolism / Q000528:radiation effects*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D006657:Histones; D051863:Host Cell Factor C1; D016328:NF-kappa B; D050811:Octamer Transcription Factor-1; C494165:POU2F1 protein, human; D016329:Sp1 Transcription Factor; D018808:Transcription Factor AP-1; D014157:Transcription Factors