Differential expression of p63 isoforms in normal tissues and neoplastic cells.
The p63 gene encodes at least six different proteins with homology to the tumour suppressor protein p53 and the related p53 family member p73. So far, there have been limited data concerning the expression patterns of individual p63 proteins, due to a lack of reagents that distinguish between the different isoforms. Three antibodies have been produced specifically directed against the two N-terminal isoforms (TAp63 and DeltaNp63) and the C-terminal region of the p63alpha proteins. TAp63 proteins are located suprabasally in stratified epithelia compared with the N-terminal truncated forms, which are more abundantly expressed in the basal cell layer, indicating a switch in expression of p63 isoforms during normal cellular differentiation. Analysis of squamous cell carcinomas shows DeltaNp63alpha to be the most widely expressed isoform, compatible with a role for this protein in promoting neoplastic cell growth in these tissues. DeltaNp63 protein expression is also restricted to basal cells in breast and prostate, whilst TAp63 isoforms are more widely expressed in these tissues as well as in tumours at these sites. TAp63, but not DeltaNp63 or p63alpha, is detected in normal colon and in colon carcinoma. TAp63 proteins are also expressed in the nuclei of a sub-population of lymphoid cells and in most malignant lymphomas, whereas DeltaNp63 proteins are not expressed. Taken together, a hitherto unrecognized regulation of p63 isoform expression in vivo has been uncovered, with different p63 proteins expressed during differentiation and in different cell types. The data indicate roles for specific p63 isoforms not only in maintaining epithelial stem cell populations, but also in cellular differentiation and neoplasia.
Nylander
Karin
K
Department of Medical Biosciences/Pathology, Umeå University, SE-901 87 Umeå, Sweden. karin.nylander@medbio.umu.se
Vojtesek
Borek
B
Nenutil
Rudolf
R
Lindgren
Britta
B
Roos
Göran
G
Zhanxiang
Wang
W
Sjöström
Björn
B
Dahlqvist
Ake
A
Coates
Philip J
PJ
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism; D018929:Cell Culture Techniques; D004268:DNA-Binding Proteins; D004848:Epithelium / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D008223:Lymphoma / Q000235:genetics / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
C081876:CKAP4 protein, human; D004268:DNA-Binding Proteins; D007106:Immune Sera; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D012334:RNA, Neoplasm; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins