Different intracellular compartmentalization of TA and DeltaNp73 in non-small cell lung cancer.
The p53 homologue p73 is overexpressed in many tumors, including lung cancer. We have evaluated the differential expression and subcellular localization of the functionally distinct apoptotic (TA) and anti-apoptotic (DeltaN) isoforms of p73 in non-small cell lung cancer (NSCLC), their possible association with p53 expression and determined the methylation status of the two p73 gene promoters (P1 and P2) in this tumor type. Immunohistochemical analysis showed that both isoforms are expressed in the majority of cases. However, the oncogenic DeltaN variant, derived from the transcripts DeltaN'p73 (from P1) and/or DeltaNp73 (from P2), is localized mainly in the nucleus, while the anti-oncogenic TAp73 isoform (derived from a P1 transcript) is sequestered in the cytoplasm in almost all cases analyzed. Significant correlation was found between p53 and DeltaNp73 expression (p=0.041). Methylation analysis conducted on 41 tumor samples showed that the P1 promoter is almost invariably unmethylated (39/41 cases) whereas P2 was found completely methylated in 17 cases and partially or totally unmethylated in 24 samples. No correlation was found between the methylation status of P1 and P2 and p73 expression. Our results demonstrate that both isoforms contribute to p73 overexpression in NSCLC and suggest that their different intracellular localization may reflect an alteration of the functional p53-p73 network that might contribute to lung cancer development.
Di Vinci
Angela
A
Laboratory of Tumor Genetics, Istituto Nazionale per la Ricerca sul Cancro (IST), 16132 Genova, Italy.
Sessa
Fausto
F
Casciano
Ida
I
Banelli
Barbara
B
Franzi
Francesca
F
Brigati
Claudio
C
Allemanni
Giorgio
G
Russo
Patrizia
P
Dominioni
Lorenzo
L
Romani
Massimo
M
D017209:Apoptosis; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D019175:DNA Methylation; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism*
D017931:DNA Primers; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; C000606369:delta Np73 protein, human