Androgen‐repressed messages in the rat ventral prostate

Abstract

Poly (A)+ RNA from the prostates of both intact and castrated rats was translated in a message‐dependent reticulocyte lysate, and the translation products were electrophoresed on SDS/polyacrylamide gels. Fluorography of these gels showed the expected disappearance, after castration, of the prostate steroid‐binding proteins as well as a number of other androgen‐dependent proteins. Two major (M r 40,000 and 45,000) and several minor proteins appeared in the translation products of the castrated rat prostate RNA. Criss‐cross liquid hybridization analysis between prostate poly (A+) RNA from intact and castrated rats also showed the disappearance of the abundant prostate steroid‐binding protein sequences after castration and the synthesis of several new low to medium abundance sequences. Northern hybridization experiments demonstrated the presence of at least two, and possibly four androgen‐repressed poly (A)+ RNA sequences. The most prominent of these, an RNA of 2,000 nucleotides, appeared within 2 days of castration, reaching a maximum on day 4 at a level approximately 400 times greater than the normal level. The other major sequence (a sequence of 1,000 nucleotides) appears after 4 days, reaching a peak between days 8 and 11. Sequences similar to these new RNAs could play an important role in the long‐term resistance of prostatic cancer to hormone therapy in humans.