Correlation between different p53 expression patterns and chromosome 17 imbalances in pancreatic ductal adenocarcinoma based on tissue microarray analysis.

PURPOSE: p53 (gene location: 17p13.1) overexpression is a common event in pancreatic ductal adenocarcinoma (PDAC), a highly aggressive malignant neoplasm. Although specific mechanisms of p53 gene deregulation have been identified, correlation between p53 expression and chromosome 17 gross numerical imbalances (aneuploidy) are under investigation. METHODS: Using tissue microarray technology, 60 paraffin-embedded tissue samples of histologically confirmed primary PDACs were cored and re-embedded to the final recipient block. Immunohistochemistry (IHC) for p53 expression and chromogenic in situ hybridization (CISH) for chromosome 17 numerical alterations were performed. Digital image analysis was applied for p53 expression levels evaluation (Nuclear Labelling Index-NLIs). RESULTS: p53 overexpression was detected in 38/60 (63.3%), whereas chromosome 17 aneuploidy was observed in 21/60 (35%) cases, respectively. Polysomy was identified in 19 cases, whereas monosomy in 2 of them. p53 overall expression was strongly correlated to the stage of the examined tumors (p=0.02). Chromosome aneuploidy was not associated to tumors' stage and grade (p=0.42, p=0.71, respectively). Although overall chromosome 17 centromeric imbalances were not correlated with p53 overexpression (p=0.32), both cases with monosomy demonstrated high expression levels. CONCLUSION: p53 overexpression combined with chromosome 17 numerical imbalances characterizes a significant proportion of PDACs. Because commercially available antip53 antibodies detect mutant and also wild-type protein expression levels, chromosome 17 monosomy maybe is a gross genetic criterion for discriminating them due to point mutation that frequently affects the remaining allele.

Deregulation of EGFR/VEGF/HIF-1a signaling pathway in colon adenocarcinoma based on tissue microarrays analysis.

PURPOSE: Overexpression of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) in colon adenocarcinoma (CA) is a frequent event, whereas specific deregulation mechanisms in the corresponding signaling pathways remain under investigation. Our aim was to co-evaluate their expression correlated to the hypoxia inducible factor 1alpha (HIF-1a), which activates the transcription of VEGF gene. METHODS: 60 paraffin-embedded primary CAs were cored at 1.5 mm diameter and transferred to the microarray block. Immunohistochemistry (IHC) was performed using anti-EGFR, -VEGF, and -HIF 1a monoclonal antibodies. Concerning EGFR, quantitative evaluation was based on a semi-automated analysis system. Chromogenic in situ hybridization (CISH) was performed using EGFR gene and chromosome 7 centromeric probes. RESULTS: Protein overexpression was observed in 13/60 (21.6%), 45/60 (75%) and 7/60 (11.6%) cases regarding EGFR, VEGF, and HIF 1a, respectively. CISH analysis detected 4/60 (6.6%) EGFR gene amplified cases, whereas chromosome 7 aneuploidy was identified in 11/60 (18.3%) cases. Significant associations raised correlating stage to chromosome 7 (p=0.024), HIF 1a expression to tumor anatomical location (p=0.019) and also VEGF to HIF 1a expression (p=0.001), whereas EGFR expression was not associated to EGFR gene copies. CONCLUSION: According to our results, chromosome 7 instability is correlated to advanced disease, whereas a significant subset of CAs demonstrates an alternative, non- HIF 1a depended mechanism of VEGF overexpression. Furthermore, EGFR protein overexpression does not predict a specific gene deregulation mechanism.

Comparative topoisomerase IIa and ki 67 protein expression in papillary thyroid carcinoma based on tissue microarrays and image analysis.

PURPOSE: Topoisomerase II alpha (Topo IIa gene location 17q21) is a nucleic enzyme involved in the DNA replication, transcription and chromosome topological formation. Topo IIa inhibition strategies include specific chemotherapeutic agents such as anthracyclines. Our aim was to investigate potential protein alterations of the enzyme comparing them to ki 67 proliferation marker expression in papillary thyroid carcinoma (PTC). MATERIALS AND METHODS: Using tissue microarray (TMA) technology, 50 specimens consisting of histologically confirmed PTCs (n=20), multi-nodular goiters (n=20) and also normal thyroid epithelia (n=10) were cored and re-embedded in the final paraffin block. Immunohistochemical analysis was performed using monoclonal anti-Topo IIa and anti-ki 67 (MIB-1) antibodies. Digital image analysis assay was also applied for the evaluation of the protein expression results (Nuclear Labeling Index-NLI). RESULTS: Topo IIa and ki 67 proteins were overexpressed in 4/20 (20%) and 14/20 (70%) cases, respectively. Concerning multi-nodular goiters, overexpression was observed in 2/20 and 4/20 specimens, respectively. Statistical association was assessed correlating ki 67 expression to pathology type, capsular invasion and also to vascular infiltration (p=0.001, p=0.008, and p=0.012, respectively). Topo IIa protein expression was strongly correlated only to capsular invasion (p=0.004). Overall expression of the examined markers demonstrated a medium concordance (kappa=0.27), but a strong association (p=0.001). CONCLUSION: Topo IIa and also ki 67 overexpression are correlated to an aggressive phenotype in PTC. Topo IIa overexpression maybe is a reliable marker for a rational application of targeted chemotherapeutic strategies in some subgroups of patients.