Dose/response study of the effects of oestrogens on tumour growth and morphology in the Dunning R3327 prostatic adenocarcinoma.

The present study was undertaken to investigate to what extent the oestrogen-induced effects on growth and morphology of the Dunning R3327 rat prostatic adenocarcinoma are dose-dependent. Castrated and testosterone-supplemented rats were used in order to study effects of increasing doses of oestrogens on the tumour. It was found that the lowest dose of oestradiol-17 beta that reduced the overall growth, the volume density of the epithelium and epithelial cell area in Dunning R3327 prostatic tumours is 10 micrograms given as daily injections. Higher oestrogen doses (50 micrograms, 200 micrograms, and 500 micrograms), in addition to reducing the volume of tumour epithelium, also induced an increase of the volume density of tumour stroma. The area of stroma cell nuclei was increased by 50 micrograms and 200 micrograms oestradiol-17 beta. These observation, may indicate that the lowest effective oestrogen dose is different in the epithelium and stroma of Dunning tumours and that large doses of oestrogen stimulate the stromal compartment. This stimulatory effect did not influence the inhibitory effects seen on the overall growth of the tumour and on the tumor epithelium.