p63 expression profiles in human normal and tumor tissues.
OBJECTIVE
The p63 gene, located on chromosome 3q27-28, is a member of the p53 gene family. The product encoded by the p63 gene has been reported to be essential for normal development.


METHODS
In this study, we examined the expression pattern of p63 in human normal and tumor tissues by immunohistochemistry using a monoclonal antibody (clone 4A4) that recognizes all p63 splice variants, and by reverse transcription-PCR using isoform-specific primers.


RESULTS
We found that p63 expression was restricted to the nucleus, with a nucleoplasmic pattern. We also observed that the expression was restricted to epithelial cells of stratified epithelia, such as skin, esophagus, exocervix, tonsil, and bladder, and to certain subpopulations of basal cells in glandular structures of prostate and breast, as well as in bronchi. Consistent with the phenotype observed in normal tissues, we found that p63 is expressed predominantly in basal cell and squamous cell carcinomas, as well as transitional cell carcinomas, but not in adenocarcinomas, including those of breast and prostate. Interestingly, thymomas expressed high levels of p63. Moreover, a subset of non-Hodgkin's lymphoma was also found to express p63. Using isoform-specific reverse transcription-PCR, we found that thymomas express all isoforms of p63, whereas the non-Hodgkin's lymphoma tended to express the transactivation-competent isoforms. We did not detect p63 expression in a variety of endocrine tumors, germ cell neoplasms, or melanomas. Additionally, soft tissue sarcomas were also found to have undetectable p63 levels.


CONCLUSIONS
Our data support a role for p63 in squamous and transitional cell carcinomas, as well as certain lymphomas and thymomas.
Di Como
Charles J
CJ
Division of Molecular Pathology, Department of Pathology, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
Urist
Marshall J
MJ
Babayan
Irina
I
Drobnjak
Marija
M
Hedvat
Cyrus V
CV
Teruya-Feldstein
Julie
J
Pohar
Kamal
K
Hoos
Axel
A
Cordon-Cardo
Carlos
C
D017398:Alternative Splicing; D004268:DNA-Binding Proteins; D016147:Genes, Tumor Suppressor; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D008565:Membrane Proteins; D009369:Neoplasms / Q000378:metabolism; D010750:Phosphoproteins / Q000096:biosynthesis*; D020033:Protein Isoforms; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013945:Thymoma / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution; D015534:Trans-Activators / Q000096:biosynthesis*; D014157:Transcription Factors; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
C081876:CKAP4 protein, human; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins