Autor(es):
Reis Filho, Jorge S. 
; Torlo, Beatriz ; Albergaria, André ; Schmitt, Fernando C.
Data: 2002
Identificador Persistente: http://hdl.handle.net/1822/1964
Origem: RepositóriUM - Universidade do Minho
Assunto(s): p63; Cutaneous carcinomas
Descrição
Background: p63 is a p53 homologue that is mapped to chromosome 3q27. This gene encodes six different isoforms, which have either transactivating or dominant negative effects on p53-reporter genes. It has been described that in contrast to p53, p63 seems not to be associated with tumor predisposition, as neither p63 knockout mouse models nor germline p63 mutations are related to an increased risk of tumorigenesis. It has been demonstrated that p63 is a reliable keratinocyte stem cell marker and that it is involved in the maintenance of the stem cell population. Scant data on p63 expression in normal skin, basal cell carcinomas (BCCs), keratoacanthomas and squamous cell carcinomas (SCCs) have been reported. We herein evaluated p63 expression in 16 BCCs, one keratoacanthoma and 13 SCCs.
Methods: Immunohistochemistry according to the streptavidinbiotin-peroxidase technique, using the antibody 4A4 raised against all
p63 isoforms, was performed. p63 expression was evaluated in
epidermal cells and skin appendages. Semi-quantitative evaluation
(–, π, ππ, πππ) of p63 expression in BCCs, keratoacanthoma and
SCCs was carried out. Only nuclear expression was considered as
specific.
Results: p63 was expressed in the nuclei of epidermal basal and
suprabasal cells, in the cells of the germinative hair matrix and the
external root sheath of hair follicles, in the basal cells of the sebaceous
gland and in the myoepithelial/basal cells of the sweat glands. All
terminally differentiated cells were negative for p63. All BCCs showed
ππto πππ immunoreactivity. At variance, keratoacanthomas and
grade I and II SCCs showed variable p63 reactivity in a basal layerlike
distribution, whereas undifferentiated cells of grade III SCCs
showed ππto πππ positivity. A grade IV spindle SCC showed π
immunoreactivity. The SCCs in situ showed remarkable expression of
p63 in all cell layers. Terminally differentiated squamous cells were
either negative or showed only focal immunoreactivity in the
carcinomas.
Conclusions: p63 is consistently expressed in the basal cells of
epidermis and cutaneous appendages, including the basal/
myoepithelial cells of sweat glands. Based on our findings, the balance
of probabilities favors that p63 might play a role in the pattern of
differentiation and in the oncogenesis of usual carcinomas of the skin.
