UPTAKE OF [125I]IODODEOXYURIDINE IN CULTURED RAT AND HUMAN PROSTATE: EFFECTS OF INSULIN AND TESTOSTERONE

Abstract

SUMMARY DNA synthetic activity was monitored in rat and human prostate using [125I]iododeoxyuridine ([125I]UdR). Fresh prostate tissue from 6-week-old rats showed higher incorporation of [125I]UdR than that from 12- or 26-week-old rats. During culture for up to 6 days in the absence of hormones, the incorporation of [125I]UdR fell to a low level for all three age groups. Stimulatory effects were seen when rat prostates were cultured in the presence of insulin (3 μg/ml) and testosterone (10−7 mol/l), the incorporation on day 4 of culture being commensurate with that of fresh prostate of the corresponding age. Thus the magnitude of the response was higher for the 6-week-old prostate than that for the other two age groups. A similar age-related pattern of androgen stimulation was observed in experiments in which immature and adult castrated rats were injected daily with testosterone and the freshly removed prostates were incubated with [125I]UdR. Although insulin, by itself, had a stimulatory effect on [125I]UdR incorporation in cultured prostate, the magnitude of the response did not differ in the 6- and 26-week-old prostate tissue. Maximal stimulation was obtained using 25 μg insulin/ml. Tissue from a benign prostatic hyperplasia was also responsive to insulin in culture but it differed from rat prostate in that increased proliferative activity occurred even in the absence of hormone stimulation. This spontaneous surge in activity during culture tended to mask the stimulatory effects of insulin and testosterone at concentrations of 3 μg/ml and 10−7 mol/l respectively.