OBJECTIVETo study p63 expression at mRNA transcript and protein levels in human lung cancers, including squamous cell lung carcinoma (SCC), adenocarcinoma, large cell lung carcinoma (LCLC) and small cell lung carcinoma (SCLC), or the corresponding metastatic foci. The relationship of p63 expression and alterations in p63 locus at chromosomal 3q27-29 was also determined.

METHODSp63 gene expression in 72 cases of SCC, adenocarcinoma, LCLC and SCLC was analyzed by cDNA microarray technology. Tissue microarray of specimens from 150 cases of primary lung cancer was prepared for immunohistochemical study for p63 protein. Possible chromosomal alterations at the p63 locus in 70 cases of primary lung cancer were studied by comparative genomic hybridization (CGH) technology.

RESULTSp63 mRNA transcript expression was significantly increased by more than 10-fold in SCC, as compared with that in other histologic subtypes including adenocarcinoma, LCLC and SCLC. p63 mRNA expression in metastatic foci was also remarkably higher than that in their primary tumors (P < 0.001). Immunostaining showed that p63 protein expression was observed in 94.64% of SCC, whereas only one lung adenocarcinoma (1.79%) was positive. Immunopositivity was also demonstrated in 2 of the 4 LCLC cases studied. None of the SCLC cases was positive. There was a statistically significant difference in p63 expression between pT1 and pT2 tumors (P < 0.05). The CGH results showed that overrepresentation of p63 locus at chromosomal 3q27-29 was a typical finding in SCC. p63 immunopositivity also correlated significantly with pronounced gains of p63 locus at chromosomal 3q27-q29 (P < 0.000 1), suggesting that strong expression of p63 in lung SCC was associated with increased gene amplification.

CONCLUSIONp63 may play a role in oncogenesis of human lung squamous cell carcinoma and development of metastasis.

Adenocarcinoma ; genetics ; metabolism ; Carcinoma, Large Cell ; genetics ; metabolism ; Carcinoma, Small Cell ; genetics ; metabolism ; Carcinoma, Squamous Cell ; genetics ; metabolism ; Chromosomes, Human, Pair 3 ; DNA-Binding Proteins ; Female ; Gene Expression Regulation, Neoplastic ; Genes, Tumor Suppressor ; Humans ; Immunohistochemistry ; Lung Neoplasms ; genetics ; metabolism ; Male ; Oligonucleotide Array Sequence Analysis ; Phosphoproteins ; biosynthesis ; genetics ; Protein Array Analysis ; RNA, Messenger ; biosynthesis ; genetics ; Trans-Activators ; biosynthesis ; genetics ; Transcription Factors ; Tumor Suppressor Proteins

BACKGROUNDTo investigate the relationship of p63 expression and p63 locus at chromosomal 3q27-q29 in non-small cell lung cancer (NSCLC).

METHODSChromosomal imbalance in 30 cases of squamous cell carcinoma (SCC) and 40 cases of adenocarcinoma of the lung were evaluated by comparative genomic hybridization (CGH) technology. A tissue microarray of specimens from 122 primary NSCLC specimens was employed and used for immunohistochemical detection of p63 protein expression.

RESULTSp63 positivity was found in 54 (44.26%) cases of NSCLC. p63 immunostaining was observed in 51 (86.44%) of 59 SCC, whereas only one adenocarcinoma (1.67%) showed immunoreactivity. Immunopositivity was seen in 2 (66.66%) of 3 large cell lung cancer (LCLC). No correlation existed between p63 protein expression and the age of patient, sex, tumor grading, tumor metastasis, prognosis (P > 0.05). The CGH results revealed that the gain of chromosome 3q27-q29 was identified in 32 (48.57%) of 70 NSCLC samples tested. Overrepresentation was detected in 24 cases of 30 SCC. In 40 adenocarcinoma, only 8 cases showed chromosome gain at chromosomal 3q27-q29. The comparison of p63 immunostaining with chromosomal alteration of 3q27-q29 demonstrated that pronounced gain was detected in 23 (95.83%) cases of 24 SCC with p63 immunopositivity. One case of adenocarcinoma that was p63 positive showed a chromosomal 3q27-q29 normal representation but not pronounced gain.

CONCLUSIONSThe results suggest that p63 immuno-positivity correlates significantly with pronounced gains of the p63 locus at chromosomal 3q27-q29, and p63 gene amplification correlates with development and progression of lung SCC.