The p53 homologue DeltaNp63alpha interacts with the nuclear factor-kappaB pathway to modulate epithelial cell growth.
The p53 homologue DeltaNp63alpha is overexpressed and inhibits apoptosis in a subset of human squamous cell carcinomas (SCC). Here, we report that in normal keratinocytes overexpressing DeltaNp63alpha and in human squamous carcinoma cells, DeltaNp63alpha physically associates with phosphorylated, transcriptionally active nuclear c-Rel, a nuclear factor-kappaB family member, resulting in increased c-Rel nuclear accumulation. This accumulation and the associated enhanced proliferation driven by elevated DeltaNp63alpha are attenuated by c-Rel small interfering RNA or overexpression of mutant IkappaBalphaM, indicating that c-Rel-containing complex formation is critical to the ability of elevated DeltaNp63alpha to maintain proliferation in the presence of growth arresting signals. Consistent with a role in growth regulation, DeltaNp63alpha-c-Rel complexes bind a promoter motif and repress the cyclin-dependent kinase inhibitor p21WAF1 in both human squamous carcinoma cells and normal keratinocytes overexpressing DeltaNp63alpha. The relationship between DeltaNp63alpha and activated c-Rel is reflected in their strong nuclear staining in the proliferating compartment of primary head and neck SCC. This is the first report indicating that high levels of DeltaNp63alpha interact with activated c-Rel in keratinocytes and SCC, thereby promoting uncontrolled proliferation, a key alteration in the pathogenesis of cancers.
King
Kathryn E
KE
Division of Monoclonal Antibodies, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
Ponnamperuma
Roshini M
RM
Allen
Clint
C
Lu
Hai
H
Duggal
Praveen
P
Chen
Zhong
Z
Van Waes
Carter
C
Weinberg
Wendy C
WC
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000209:etiology / Q000473:pathology; D049109:Cell Proliferation; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology*; D006258:Head and Neck Neoplasms / Q000209:etiology / Q000473:pathology; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism / Q000502:physiology*; D020033:Protein Isoforms / Q000378:metabolism / Q000502:physiology; D020569:Proto-Oncogene Proteins c-rel / Q000378:metabolism / Q000502:physiology; D017385:Sequence Homology; D015398:Signal Transduction / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D014157:Transcription Factors; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*
D016328:NF-kappa B; D020033:Protein Isoforms; D020569:Proto-Oncogene Proteins c-rel; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins