S_ay The presence of specific and high affinity epidermal growth factor receptors (EGF-R) has

(Gleason, 1977). The remainder of the tissue was snap frozen in liquid nitrogen and finally pulverised in a micro-dismembrator (Braun AG, Melsungen, Germany). The powdered tissue was then lyophilised to dryness and stored at -70°C until needed. For growth factor studies 70 mg of the lyophilised material was used whereas only 50 mg were required for steroid measurements.Extraction of growth factors Lyophilised samples were resuspended in 1 ml buffer (50 mmol 1 Tris, 5 mol 1' of phenyl-methylsulphonyl fluoride, 2 mmol I 1' of EDTA pH 7.4) containing 1,000 counts of either '251I-EGF or '25I-TGFx to monitor manipulative losses. The samples were homogenised with a glass/glass Dounce Homogeniser and left on ice for 1 h to equilibrate. The homogenates were then centrifuged, the supernatants saved and the resultant pellets were resuspended in 2 ml of enzyme mixture (230 U ml-' of collagenase, 125 U ml-' of hyaluronidase in 150 mmol 1' of NaCI) and incubated overnight at 37C; these conditions were found to be optimal and ensured maximum growth factor recovery. The digested pellets were subsequently sonicated (six cycles of 20s with 1 min cooling interval at an amplitude of 22 ,; MSE soniprep 150) the resultant mixture was centrifuged as before, the supernatant saved and the pellet was resuspended in 2 ml Tris buffer. Homogenisation, centrifugation and resuspension were then repeated twice with the supernatants always being saved. The supernatants were then pooled and the recoveries were assessed. The mean recovery of '251I-EGF added at the beginning of the extraction procedure was 72 ± 6% whilst that of 125I-TGFo was 69 ± 8%. The. supernatants were finally snap frozen, lyophilised to dryness and stored at -700 until required.

The receptor for epidermal growth factor (EGF) was characterized in the particulate fraction from human benign prostatic hyperplasia (BPH) and was present in 85% of tissues analysed. The uptake of 125I-labelled EGF by BPH was dependent on both time and temperature, with maximum specific uptake achieved after incubation for 90 min at 37 degrees C. Binding characteristics revealed two classes of binding sites of higher (mean dissociation constant (Kd) +/- S.D. = 0.8 +/- 0.2 nmol/l) and lower (Kd = 7.6 +/- 2.8 nmol/l) affinities. Competition studies demonstrated the specificity of the receptor assay since the binding of labelled EGF was abolished with excess unlabelled EGF but not with excess unlabelled human GH, human insulin, venom nerve growth factor, human FSH, human LH and human prolactin. There was a complex biphasic relationship between specific binding and protein concentration in the range 0.1-8 mg/ml. Subcellular fractionation of BPH homogenates demonstrated that the bulk of the specific binding was confined to the 800 g (crude heavy pellet) and 15,000 g (mitochondrial pellet) fractions. The 105,000 g (microsomal pellet) and the 105,000 g (cytosol fraction) exhibited low and variable binding capacities for the growth factor. The presence of EGF receptor was also confirmed by immunocytochemical staining of frozen sections from BPH using monoclonal antibody specific for EGF receptors. A positive correlation between 125I-labelled EGF binding and the intensity of staining was found. The presence of a specific EGF-binding receptor protein in human BPH tissues suggests that EGF may play a role in the pathogenesis of human BPH.

Summary Serum-free media conditioned by the androgen insensitive human prostate cancer cell line DU145 showed immunological transforming growth factor-a (TGFa) activity, as well as competing activity in epidermal growth factor (EGF) radioreceptor assays (RRA). Furthermore, there were factors in the conditioned media which inhibited and stimulated DNA synthesis by DU145

This study examines the effects of removing prostate specimens by different surgical techniques on the androgen receptor levels and 5a-reductase activity of the tissue. Comparison of specimen obtained by transurethral resection (TUR) with those from an open operation revealed that the size of the resected chips was critical in maintaining the hormonal activities of the specimens. Provided that the size (length X thickness) of the resected chips was greater than 1.5 X 0.4 cm there was no effect on either the androgen receptor levels or the testosterone-metabolizing activity of the tissue, and TUR specimens can therefore be reliably used to assess the hormonal activity of the gland.