T-oligo treatment decreases constitutive and UVB-induced COX-2 levels through p53- and NFkappaB-dependent repression of the COX-2 promoter.
Chronically irradiated murine skin and UV light-induced squamous cell carcinomas overexpress the inducible isoform of cyclooxygenase (COX-2), and COX-2 inhibition reduces photocarcinogenesis in mice. We have reported previously that DNA oligonucleotides substantially homologous to the telomere 3'-overhang (T-oligos) induce DNA repair capacity and multiple other cancer prevention responses, in part through up-regulation and activation of p53. To determine whether T-oligos affect COX-2 expression, human newborn keratinocytes and fibroblasts were pretreated with T-oligos or diluent alone for 24 h, UV-irradiated, and processed for Western blotting. In both cell types, T-oligos transcriptionally down-regulated base-line and UV light-induced COX-2 expression, coincident with p53 activation. In fibroblasts with wild type versus dominant negative p53 (p53(WT) versus p53(DN)), T-oligos decreased constitutive expression of a COX-2 reporter plasmid by >50%. We then examined NFkappaB, a known positive regulator of COX-2 transcription. In p53(WT) but not in p53(DN) fibroblasts and in human keratinocytes, T-oligos decreased readout of an NFkappaB promoter-driven reporter plasmid and decreased NFkappaB binding to DNA. After T-oligo treatment and subsequent UV irradiation, binding of the transcriptional co-activator protein p300 to NFkappaB was decreased, whereas binding of p300 to p53 was increased. Human skin explants provided with T-oligos had markedly decreased COX-2 immunostaining both at base-line and post-UV light, coincident with increased p53 immunostaining. We conclude that T-oligos transcriptionally down-regulate COX-2 expression in human skin via activation and up-regulation of p53, at least in part by inhibiting NFkappaB transcriptional activation. Decreased COX-2 expression may contribute to the observed ability of T-oligos to reduce photocarcinogenesis.
Marwaha
Vaneeta
V
Department of Dermatology, Boston University School of Medicine, Massachusetts 02118, USA.
Chen
Ya-Hui
YH
Helms
Elizabeth
E
Arad
Simin
S
Inoue
Hiroyasu
H
Bord
Evelyn
E
Kishore
Raj
R
Sarkissian
Raffi Der
RD
Gilchrest
Barbara A
BA
Goukassian
David A
DA
D000123:Acetyltransferases / Q000378:metabolism; D000328:Adult; D000368:Aged; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000378:metabolism; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D004247:DNA / Q000737:chemistry; D004260:DNA Repair; D015536:Down-Regulation; D005347:Fibroblasts / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D051548:Histone Acetyltransferases; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000378:metabolism; D008027:Light; D008565:Membrane Proteins; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism*; D009841:Oligonucleotides / Q000737:chemistry; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics*; D020033:Protein Isoforms; D012867:Skin / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014466:Ultraviolet Rays; D015854:Up-Regulation; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
D000123:Acetyltransferases; D018797:Cell Cycle Proteins; D051546:Cyclooxygenase 2; D004247:DNA; D051548:Histone Acetyltransferases; D008565:Membrane Proteins; D016328:NF-kappa B; D009841:Oligonucleotides; D011451:Prostaglandin-Endoperoxide Synthases; D020033:Protein Isoforms; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C496540:PTGS2 protein, human