HORMONE REGULATION OF HUMAN PROSTATE IN ORGAN-CULTURE

We have established organ cultures of human prostate for in vitro anal ysis of the hormone responsiveness of prostatic carcinoma. Tissue samp les were obtained from total prostatectomies for localized cancer. Nor mal prostate tissues with age-related hyperplastic changes were obtain ed from cystoprostatectomies of bladder cancer patients representing t he same age group, and they were cultivated as controls. The explants of prostates were cultured for 7 days in basal medium containing 5 % d extran charcoal-treated fetal calf serum, insulin (0.08 IU/ml), and de xamethasone (10(-7) M) with or without dihydrotestosterone (DHT) (10(- 7) M) or estradiol (10(-9) M). Control prostates showed involutive cha nges of morphology when cultured in basal medium. These changes were p revented by DHT, which also maintained a strong epithelial immunostain ing for PSA (prostate specific antigen), which was used as a marker fo r tissue-specific functions. The concentration of PSA in the medium wa s high. The rate of [H-3]thymidine incorporation into DNA was stimulat ed by DHT in some cultures of control prostates, but no increase was s een in the others. Androgen stimulation of [H-3]thymidine incorporatio n was consistently inhibited by the antihormone cyproterone acetate. T he main morphological response of cultured control prostates to estrad iol was induction of squamous metaplasia. This was associated with inc reased incorporation of [H-3]thymidine, which was radioautographically localized to the basal layer of epithelium. Estradiol effects were co unteracted by the antihormone toremifene. The expression of androgen r eceptor mRNA and protein in cultured control prostate was demonstrated by Northern blotting and immunohistochemistry, respectively. Also, th e expression of estrogen receptor was demonstrated by the polymerase c hain reaction analysis of total mRNA from cultured control and cancer prostate. The cultured explants of prostate cancer maintained the over all morphology of the original carcinoma. However, the presence of DHT improved the morphology of cancerous acini in all better differentiat ed carcinomas (3 grade I and 5 grade II), and corresponding responses to DHT were observed in the rate of DNA labeling with [H-3]thymidine. In 2 of 3 grade I carcinomas, DHT increased DNA synthesis, but in grad e II cancers the patterns of hormone responses were more variable. The poorly differentiated grade III prostatic carcinomas did not respond to either hormone as measured by [H-3]thymidine uptake, and no hormone effects could be seen in morphology. Immunostaining for PSA differed from that in control prostates: besides cancerous acini, the surroundi ng stroma was also intensively stained, which suggests unpolarized and impaired secretion of PSA by the cancer cells. In conclusion, our stu dy shows that organ cultures can be used to analyze the hormone respon siveness and/or biology of normal and malignant human prostate in vitr o. The results provide a basis for creating a method for in vitro test ing of the individual hormone and drug responsiveness of a prostate ca ncer.