Abstract
A series of 24 paired samples of colorectal carcinoma and the respective normal colorectal mucosa were analysed for Epidermal Growth Factor Receptor (EGFR) content by means of a standardised ligand binding assay. We, for the first time, found that EGFR levels are statistically significantly higher in normal colorectal mucosa biopsy samples than they are in colorectal carcinoma biopsy samples, the median EGFR levels being 77.5 fmol mg-1 of membrane protein (range 35-239), against 46 fmol mg-1 of membrane protein (range 22-81), respectively, P less than 0.001. In addition, we found that there are significant regional differences in EGFR expression in the normal human colon mucosa. The EGFR levels were significantly higher in samples from the proximal part of the colon than they were in samples from the distal part, the median EGFR levels being 124 fmol mg-1 of membrane protein (range 70-239) vs 55 fmol mg-1 membrane protein (range 35-156), P less than 0.05. The EGFR levels of the colorectal carcinoma samples did not show any regional variation.
Highlights
For the normal colorectal mucosa biopsy samples, the Epidermal Growth Factor Receptor (EGFR) levels were significantly higher in samples from the proximal part of the colon than in samples from the distal part of the colon, the median EGFR levels being 124 fmol mg-' of membrane protein and 55 fmol mg-' of membrane protein X2w= 4, d.f. = 1, Pw= 0.02) (Figure la)
For the first time, clearly show that measurable amounts of EGFR are present in cell membrane preparations from colorectal carcinomas as well as in those from the normal colorectal mucosa
Lacking information on the method of isolation of the normal colorectal mucosa by other groups, it is possible that the normal colorectal tissue samples they analysed comprised the mucosa, the tissue layer from which the colorectal carcinomas originate, and the deeper colorectal tissue layers, shown to be devoid of EGFR (Zimmerman et al, 1988)
Summary
Colorectal tissue biopsy samples from 24 patients (14 males and ten females, median age 62 and 72 years, respectively) with, non-familiar, adenomatous, colorectal cancer were. Correspondence: P.G. Koenders, Department of Experimental and Chemical Endocrinology, University Hospital Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands. Received 19 August 1991; and in revised form October 1991. Excised by the pathologist within 1 h after surgical resection (resections performed between October 1989 and October 1990). A specimen from the tumour as well as from the adjacent (approximately 10 cm distant from the tumour), non-malignant colorectal tissue were obtained. Adjacent tissue sections of both, colorectal carcinomas and normal colorectal tissues were histologically verified. Tissue samples were immediately frozen in liquid nitrogen and subsequently stored at -80°C
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