Demonstration of epidermal growth factor receptor in colorectal adenocarcinoma by enzyme immunoassay

The epidermal growth factor receptor (EGFR) was investigated by an enzyme immunoassay in neoplastic tissue and surrounding mucosa from 43 patients with colorectal cancer. This study found a positivity of 86% in normal samples and a positivity of 93% in neoplastic ones. In normal tissue samples, EGFR levels were 162 +/- 129 ng Ab B/mg protein, while in colorectal neoplastic samples EGFR levels were 228 +/- 135 ng Ab B/mg protein. This difference was statistically significant (p < 0.01). There was a significant correlation between the EGFR levels in neoplastic tissue and those in surrounding mucosa (r = 0.75). In 5 of 43 patients, the EGFR was evaluated also by Western blotting with three different anti-EGFR antibodies, of which one was biotin-conjugated. The presence of a 170-kDa band was detected. Moreover, by using the anti-EGFR mAb biotin conjugate a 90-kDa band was also detected.