Deregulation of epidermal growth factor receptor (EGFR) gene expression is belived to be a major factor in the development of epithelial cell tumorigenesis, including hepatic carcinomas. To examine EGFR expression within the course of liver cirrhosis, we have identified its hepatic mRNA distribution using a biotinylated antisense oligonucleotide probe.

In this study liver samples from liver transplantation recipients were fixed with 4% formaldehyde in PBS for 24 h and embedded in paraffin. Following treatments aimed to promote probe penetration and eliminate non-specific probe binding, an EGFR antisense biotin-labeled oligonucleotide probe was hybridized to sections at 45°C for 4h. High and low stringency washes were designed to remove the unbound probe. Following the blocking of non-specific tissue binding, sections were incubated with streptavidin-peroxidase. Biotinylated tyramide was then used for signal amplification. After washing, streptavidin-peroxidase was reapplied, followed by colorimetric detection of peroxidase activity using DAB as substrate. The sections were counterstained with hematoxylin and coverslipped.