Genome-Wide Profile of Pleural Mesothelioma versus Parietal and Visceral Pleura: The Emerging Gene Portrait of the Mesothelioma Phenotype

Malignant pleural mesothelioma is considered an almost incurable tumour with increasing incidence worldwide. It usually develops in the parietal pleura, from mesothelial lining or submesothelial cells, subsequently invading the visceral pleura. Chromosomal and genomic aberrations of mesothelioma are diverse and heterogenous. Genome-wide profiling of mesothelioma versus parietal and visceral normal pleural tissue could thus reveal novel genes and pathways explaining its aggressive phenotype.Well-characterised tissue from five mesothelioma patients and normal parietal and visceral pleural samples from six non-cancer patients were profiled by Affymetrix oligoarray of 38 500 genes. The lists of differentially expressed genes tested for overrepresentation in KEGG PATHWAYS (Kyoto Encyclopedia of Genes and Genomes) and GO (gene ontology) terms revealed large differences of expression between visceral and parietal pleura, and both tissues differed from mesothelioma. Cell growth and intrinsic resistance in tumour versus parietal pleura was reflected in highly overexpressed cell cycle, mitosis, replication, DNA repair and anti-apoptosis genes. Several genes of the “salvage pathway” that recycle nucleobases were overexpressed, among them TYMS, encoding thymidylate synthase, the main target of the antifolate drug pemetrexed that is active in mesothelioma. Circadian rhythm genes were expressed in favour of tumour growth. The local invasive, non-metastatic phenotype of mesothelioma, could partly be due to overexpression of the known metastasis suppressors NME1 and NME2. Down-regulation of several tumour suppressor genes could contribute to mesothelioma progression. Genes involved in cell communication were down-regulated, indicating that mesothelioma may shield itself from the immune system. Similarly, in non-cancer parietal versus visceral pleura signal transduction, soluble transporter and adhesion genes were down-regulated. This could represent a genetical platform of the parietal pleura propensity to develop mesothelioma.Genome-wide microarray approach using complex human tissue samples revealed novel expression patterns, reflecting some important features of mesothelioma biology that should be further explored

Predicting Corrosion Delamination Failure in Active Implantable Medical Devices: Analytical Model and Validation Strategy

The ingress of body fluids or their constituents is one of the main causes of failure of active implantable medical devices (AIMDs). Progressive delamination takes its origin at the junctions where exposed electrodes and conductive pathways enter the implant interior. The description of this interface is considered challenging because electrochemically-diffusively coupled processes are involved. Furthermore, standard tests and specimens, with clearly defined 3-phase boundaries (body fluid-metal-polymer), are lacking. We focus on polymers as substrate and encapsulation and present a simple method to fabricate reliable test specimens with defined boundaries. By using silicone rubber as standard material in active implant encapsulation in combination with a metal surface, a corrosion-triggered delamination process was observed that can be universalised towards typical AIMD electrode materials. Copper was used instead of medical grade platinum since surface energies are comparable but corrosion occurs faster. The finding is that two processes are superimposed there: First, diffusion-limited chemical reactions at interfaces that undermine the layer adhesion. The second process is the influx of ions and body fluid components that leave the aqueous phase and migrate through the rubber to internal interfaces. The latter observation is new for active implants. Our mathematical description with a Stefan-model coupled to volume diffusion reproduces the experimental data in good agreement and lends itself to further generalisation

Cell types fraction of nucleated cells in parietal pleura (PP) and tumour (T).

<p>One of the two samples of case no. 10 is removed as non-representative histologically (see text). ND = not done.</p

Differentially overexpressed genes in tumour (red boxes) depicted in the Cell Cycle map from KEGG PATHWAYS (Kanehisa <i>et al</i>., 2008) (<i>P</i><0.05).

<p>21 of 21 cell cycle genes were overexpressed in mesothelioma versus normal parietal pleura tissue. Potential targets for anti-tumour treatment described in the litterature are marked (see text). Abbreviations: CDK7 = cyclin-dependent kinase 7, CHEK1 = checkpoint homolog, E2F2 = E2F transcription factor 2, ORC6L = origin recognition complex, subunit 6 like, MCM2-3-4-6 = minichromosome maintenance complex component 2-3-4-6, PCNA = proliferating cell nuclear antigen, RB1 = retinoblastoma, BUB1 = budding uninhibited by benzimidazoles 1 homolog, BUB1B = BUB1 beta, CDC7 = cell division cycle 7 homolog, APC/C = CDC23, cell division cycle 23 homolog, anaphase-promoting complex subunit 8, CCNB1 = cyclin B1, CCNB2 = cyclin B2, ESPL1 = extra spindle pole bodies homolog 1, CDC2/CDK1 = cell division cycle 2, G1 to S and G2 to M, CDC6 = cell division cycle 6 homolog, CDC20 = cell division cycle 20 homolog, CDC25A = cell division cycle 25 homolog A.</p

Circadian rhythm genes differentially expressed in tumour shown with KEGG PATHWAYS (modified from Kanehisa <i>et al</i>., 2008) (<i>P</i><0.05).

<p>CRY2, PER1, PER3 and NR1D1/Rev-Erb alpha that function as negative regulators of transcription are down-regulated (green) whereas both genes encoding the active transcriptional heterodimeric complex Bmal1(ARNTL):Npas2 (NPAS2) are overexpressed in mesothelioma versus normal parietal pleura. Damaged circadian rhythms may be a key to the continuous replicative force in tumour cells, and thus possible treatment targets.</p

Venn diagram of significantly up- and down-regulated genes (n) in mesothelioma (T) versus normal parietal pleura (pp) and normal visceral pleura (pv) (<i>P</i><0.05).

<p>828 genes are overexpressed (red) and 1004 genes are down-regulated (green) in T versus pp. 341 genes are overexpressed (blue) and 52 genes downregulated (brown) in pv versus pp.</p

Protein expression of selected genes, AGGF1, TYMS and MSLN by immunohistochemistry.

<p>A–C–E: normal parietal pleura. B–D–F: Biphasic mesothelioma with epithelial and sarcomarous components. A–B (x20): AGGF1(VG5Q) mRNA was overexpressed in mesothelioma, and clearly protein was expressed (brown) in both tumour components (arrows). Strong expression in normal mesothelium was seen (arrow) but the majority of endothelial and other pleural cells were negative. C–D (x40): TYMS (Thymidylate synthase) mRNA was overexpressed, also on the protein level (brown), mostly in the epithelial component (arrow) of tumour. Normal pleura was negative. E–F (x20): MSLN (Mesothelin) mRNA was not differentially expressed, that could be explained by the intense protein expression not only in epithelial tumour cells, but also in normal mesothelial and stromal cells.</p

A selection of down-regulated gene ontology (GO) entities and genes (Down Genes) in normal parietal pleura versus visceral pleural tissue.

<p>Genes on Chip = the number of genes from each entity represented on the gene chip.</p