Constitutive expression of DeltaN-p63alpha isoform in human thymus and thymic epithelial tumours.
p63, a member of the p53 family, is involved in the survival and differentiation of reserve/stem cells in different epithelia. To unveil the possible role of p63 in thymic physiology and pathology, we investigated the expression of p63 isoforms in normal thymus, thymomas and other mediastinal tumours. All samples were analysed using immunohistochemistry with three different antibodies: 4A4 antibody recognising all p63 isoforms, p40 antibody reacting only with truncated dominant-negative isoforms (DeltaN-p63) and H-129 antibody recognising all alpha-isoforms. Reverse-transcription polymerase chain reaction (RT-PCR), and real-time PCR analyses were performed on RNA extracted from frozen samples of four thymomas and two primary-mediastinal large-B-cell lymphoma (PMLBCL). In normal thymus, DeltaN-p63alpha was expressed in all cortical and medullary epithelial cells, with decreasing intensity in Hassall's corpuscles. This phenotype was conserved in neoplastic transformation since all 54 investigated thymomas (World Health Organization types A, AB, B1, B2, B3, C) expressed DeltaN-p63alpha (virtually 100% cells). The predominance of DeltaN-p63alpha isoform mRNA was confirmed by real-time PCR. Among other mediastinal tumours, DeltaN-p63alpha was only expressed in those displaying either a stratified epithelial component (teratomas) or epidermoid differentiation (lung carcinoma). Among lymphomas, T-cell-precursor lymphomas did not express p63, whereas most PMLBCL expressed TA-p63alpha (7/8).
Chilosi
Marco
M
Department of Pathology, University of Verona, Policlinico G.B.Rossi, 37134 Verona, Italy. marco.chilosi@univr.it
Zamò
Alberto
A
Brighenti
Antonietta
A
Malpeli
Giorgio
G
Montagna
Licia
L
Piccoli
Paola
P
Pedron
Serena
S
Lestani
Maurizio
M
Inghirami
Giorgio
G
Scarpa
Aldo
A
Doglioni
Claudio
C
Menestrina
Fabio
F
D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008479:Mediastinal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020033:Protein Isoforms / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013945:Thymoma / Q000378:metabolism* / Q000473:pathology; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D013953:Thymus Neoplasms / Q000378:metabolism* / Q000473:pathology
D004268:DNA-Binding Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D012334:RNA, Neoplasm; C077214:L1Hs-encoded protein p40, human