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 (Mr 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.

Clusterin mRNA expression in apoptotic and activated rat thymocytes

“…In this regard, it is evident that induction of apoptosis, neither in vivo nor in vitro, up-regulates clusterin mRNA expression. Although other report show where clusterin is induced upon apoptosis in rat prostate cells [7] and renal tubular epithelium during tissue regression [3], our data suggest that clusterin expression would be not an universal indicator in apoptotic cells.…”

“…Based on this observation, we are ruling out that clusterin expression is directly affected by thymocyte apoptosis. Since most of the previously published studies had determined clusterin mRNA expressions only using RNA from whole thymic tissues and by DEX-administration in vivo [7,14,15,21], the results on the effect of apoptosis induction in isolated thymocyte single cell suspensions in vitro had been not available so far. Regarding the fact that immature thymocytes are the primary targets for inducing apoptosis in DEXtreatment, the current study precisely shows, without involving interfering background signals from thymic stromal cells, that clusterin mRNA expression is not induced in apoptotic cells.…”

“…While its biological role is still under dispute, a variety of putative functions have been suggested. These include a role in serving as a lipid transport molecule [4], a regulator of complement-mediated cytolysis [5] as well as a playing role in the protection of the cell membrane from stress by acting as a secreted heat shock protein [6] or involvement in the cellular response upon apoptosis [7]. Such variant functional roles have lead to reporting the same protein under several different names, which include sulfated glycoprotein-2 (sgp-2) [8], ionizing radiationinduced protein-8 (XIP8), testosterone-repressed prostate message-2 (TRPM-2) as well as clusterin and Apo/J.…”

Induction of the TRPM-2 gene in cells undergoing programmed death.

“…TRPM-2 cDNA was originally cloned from regressing rat ventral prostate tissue. Quantitation of TRPM-2 transcript levels in ventral prostates removed at various times after castration showed that few, if any, transcripts were present in the normal gland; however, after castration, transcript expression increased rapidly, reaching a peak at 5 to 6 days, and then declined to low levels again after 10 days (30). The temporal pattern of TRPM-2 expression corresponds with the peak period of cell death in this gland (34).…”

“…In this study of gene activity during programmed cell death, we examined the pattern of expression and sequence of the testosterone-repressed prostate message-2 gene (TRPM-2) that was originally cloned from regressing rat ventral prostate tissue (28,30 RNA extraction and Northern (RNA) blot analysis. Polyadenylated mRNA was extracted from frozen tissue by the method of Cathala et al (6), as described previously (5).…”