Epidermal growth factor receptor expression and gene copy number in fibrolamellar hepatocellular carcinoma☆

• DOI: 10.1016/j.humpath.2005.12.009
• Publication Date: 2006-03-28T07:10:13Z
• Authors: A BUCKLEY; L BURGART; S KAKAR
• Keywords: Adult; Male; 0301 basic medicine; Carcinoma, Hepatocellular; Adolescent; Liver Neoplasms; Gene Dosage; Middle Aged; 3. Good health; ErbB Receptors; Gene Expression Regulation, Neoplastic; Immunoenzyme Techniques; 03 medical and health sciences; Hepatocytes; Humans; Female; Chromosomes, Human, Pair 7; In Situ Hybridization, Fluorescence

Increased expression of epidermal growth factor receptor (EGFR), a transmembrane tyrosine kinase, is associated with tumor progression in many carcinomas. Epidermal growth factor receptor inhibitors have shown promise in treating some of these tumors. Fibrolamellar hepatocellular carcinoma (FL-HCC) is an aggressive neoplasm that occurs in young patients with no history of cirrhosis. This study examines the expression and gene copy number of EGFR in FL-HCC. Formalin-fixed, paraffin-embedded FL-HCC (n = 13) sections were stained with a monoclonal antibody against EGFR. Fluorescence in situ hybridization analysis was performed using probes against EGFR gene and centromeric region of chromosome 7 (CEP 7). Epidermal growth factor receptor and CEP 7 signals were counted in 50 tumor nuclei per case as well as 300 normal hepatocyte nuclei. The EGFR to CEP 7 signal ratio was calculated for each case. Most (92%, 12/13) of FL-HCC showed strong and diffuse staining with anti-EGFR antibody. Fluorescence in situ hybridization was informative in 11 cases, 10 of which showed extra EGFR gene copy numbers (mean, 3.69; range, 3.13-5.0). Epidermal growth factor receptor was overexpressed in all these cases. The mean number of EGFR signals per cell in FL-HCC was double that of normal hepatocytes (3.69 versus 1.80); the mean EGFR/CEP 7 ratio in tumor cells was 1.05. In conclusion, EGFR is strongly overexpressed on the cell membrane in nearly all cases of FL-HCC. Similar gains of chromosome 7 are observed, indicating that the extra EGFR gene copies are due to polysomy rather than gene amplification. The strong expression of EGFR in FL-HCC tumors suggests that they may respond to treatment with EGFR antagonists.