Epidermal growth factor receptors in human prostate cancer: correlation with histological differentiation of the tumour.

The presence of specific and high affinity epidermal growth factor receptors (EGF-R) has been demonstrated in human prostate cancer (CaP). Scatchard analysis of the binding data revealed a linear plot consistent with a single class of binding sites with a mean dissociation constant (Kd) +/- s.d. = 1.6 +/- 0.4 nmol 1-1. Additionally the binding was specific for EGF since no other competitor than EGF was able to displace the binding of the labelled ligand from its receptor. Comparison of the concentrations of EGF-R in tissues from 19 patients with CaP with those measured in a group of 18 patients with benign prostatic hyperplasia (BPH) reveal that the expression of EGF-R was significantly higher in BPH (mean +/- s.d. = 125 +/- 7 fmol mg protein-1) than in CaP (52 +/- 11 fmol mg protein-1; P less than 0.01). Furthermore, in CaP the expression of EGF-R varied according to the histological grade of the cancer: well differentiated tumours demonstrated more receptors (84 +/- 13 fmol mg protein-1) than poorly differentiated tumours (22 +/- 5 fmol mg protein-1; P less than 0.01). Clearly the depletion in the expression of EGF receptors in CaP is a function of the histological grade of the cancer and as such EGF receptors could be used as a biochemical marker for tumour differentiation.