Chromogenic in situ hybridization analysis of Epidermal Growth Factor Receptor gene/chromosome 7 numerical aberrations in hepatocellular carcinoma based on tissue microarrays

Although Epidermal Growth Factor Receptor (EGFR) overexpression is observed frequently in hepatocellular carcinomas (HCC), specific gene deregulation mechanisms remain unknown. Our aim was to investigate the prognostic significance of the combined protein and gene/chromosome 7 numerical alterations. Using tissue microarray technology, thirty-five (n = 35) paraffin embedded histologically confirmed HCCs were cored and re-embedded in a paraffin block. Immunohistochemistry was performed for the determination of EGFR protein levels and evaluated by the performance of digital image analysis. Chromogenic in situ hybridization was also performed based on the use of EGFR gene and chromosome 7 centromeric probes, respectively. EGFR overexpression was observed in 26/35 (74.2%) cases and was correlated to the grade of the tumors and also to the history of the patients (p = 0.013, p = 0.036, respectively). Numerical alterations regarding gene and chromosome 7 were identified in 4/35 (11.4%) and 12/35 (43.2%) cases associated to the grade of the tumors (p = 0.019, p = 0.001, respectively) and to the survival rate of the patients (p = 0.037, p = 0.001, respectively). EGFR overall expression was also correlated to the gene copies (p = 0.020). EGFR gene numerical alterations -although rare- and also chromosome 7 aneuploidy maybe affect prognosis in HCC patients. To our knowledge this is the first chromogenic in situ hybridization analysis based on tissue microarrays in hepatocellular carcinoma.