L1CAM, INP10, P-cadherin, tPA and ITGB4 over-expression in malignant pleural mesotheliomas revealed by combined use of cDNA and tissue microarray.

Malignant pleural mesothelioma (MM) is a rare tumour with high mortality, which can exhibit various morphologies classified as epithelioid, biphasic and sarcomatoid subtypes. To investigate the molecular changes in these tumours, we studied gene expression patterns by combined use of cDNA arrays and tumour tissue microarrays (TMA). Deregulation of the expression of 588 cancer-related genes was screened in 16 MM comprising all three subtypes and compared with references, i.e. normal mesothelial cell lines and pleural mesothelium. Array data were analysed using three statistical methods; principal component analysis (PCA), permutation test and receiver operating characteristic (ROC) curves. Eleven genes were verified by real-time RT-PCR. Genes encoding two adhesion molecules [COL1A2 and integrin beta4 (ITGB4)] and a chemokine (INP10) were up-regulated in MM compared with both the cell lines and pleural mesothelium. There was a type-specific up-regulation of semaphorin E, ITGB4 and P-cadherin in epithelioid MM, matrix metalloproteinase 9 (MMP9) and tissue-type plasminogen activator (tPA) in sarcomatoid MM and neural cell adhesion molecule L1 (L1CAM) and INP10 in biphasic MM. Immunohistochemistry on TMA containing 47 MM (26 epithelioid, 15 sarcomatoid and six biphasic) was performed for five proteins, ITGB4, P-cadherin, tPA, INP10 and L1CAM. INP10 expression was increased in MM in general compared with normal mesothelium, while increased expression of P-cadherin, L1CAM and ITGB4 was more specific in MMs exhibiting an epithelioid growth pattern. The over-expression of tPA was more frequent in epithelioid MM despite higher mRNA levels in sarcomatoid and biphasic MM. We conclude that several proteins, associated with cell adhesion either directly (ITGB4, L1CAM, P-cadherin) or as a regulatory factor (INP10), are differentially expressed in MM. In particular, INP10, ITGB4 and COL1A2 were up-regulated in MM compared with both reference sample types, suggesting a relationship with development of these tumours.

Expression and localization of CYP3A4 and CYP3A5 in human lung.

Expression in the lung of procarcinogen-metabolizing P450 enzymes in the CYP3A subfamily may contribute to the initiation of pulmonary carcinogenesis by agents that require metabolic activation, such as tobacco-derived polycyclic aromatic hydrocarbons. Expression and localization of CYP3A4 and CYP3A5 proteins in human lung were determined by immunohistochemistry with three antibodies, one specific for members of the CYP3A subfamily and two antipeptide antibodies specific for CYP3A4 and CYP3A5, respectively. Positive immunostaining in one or several cell types of the lung was observed in all patients with anti-CYP3A4 and anti-CYP3A5 antibodies. With the anti-CYP3A4 antibody epithelial staining was observed in five cases and staining of alveolar macrophages in 12 of 27 cases. To determine which CYP3A genes are transcribed in lung tissue, analysis by reverse-transcriptase-polymerase chain reaction with gene-specific primers for CYP3A4, CYP3A5, and CYP3A7 was performed. CYP3A5 mRNA was detected in all eight samples studied, CYP3A4 mRNA in one sample, and CYP3A7 mRNA in none of the samples. CYP3A5 was localized by immunohistochemistry in the ciliated and mucous cells of the bronchial wall, bronchial glands, bronchiolar columnar and terminal cuboidal epithelium, type I and type II alveolar epithelium, vascular and capillary endothelium, and alveolar macrophages, whereas CYP3A4 was found in bronchial glands, bronchiolar columnar and terminal epithelium, type II alveolar epithelium, and alveolar macrophages. These data establish that CYP3A5 is the predominant CYP3A form in human lung, that CYP3A4 is expressed in about 20% of individuals, and considerable variation of pulmonary expression occurs in both CYPs between individuals.