THANATOGEN EXPRESSION DURING INVOLUTION OF THE RAT VENTRAL PROSTATE AFTER CASTRATION

After castration the rat ventral prostate undergoes regression. This p rocess occurs due to the induction of apoptosis, or active cell death, in the epithelial cells of the gland. Several genes, including TRPM-2 , (testosterone repressed prostate message), RVP.1, fos, and myc, have been shown to be induced in the prostate during this process. We have investigated the expression of several other genes that may be associ ated with apoptosis, including tissue transglutaminase (TGase), poly(A DP)ribose polymerase (PARP), and heat shock protein 27 (Hsp27). Northe rn hybridization has been used to determine the steady-state mRNA leve ls of these genes in the ventral prostate after castration, and the ti me course of induction has been compared to the changes in the steady- state levels of prostate steroid binding protein (PSBP), alpha-tubulin , and TRPM-2 mRNAs. The results show that the mRNAs for PARP, transglu taminase, and Hsp27, in addition to TRPM-2, are induced by androgen ab lation in the rat ventral prostate and reach maximum levels between da ys 3 and 4 after castration. Using in situ hybridization we have estab lished that these genes are expressed in the epithelial cells of the p rostate that are known to undergo active cell death; this result sugge sts that their gene products may be required in the dying cells to ens ure that the biochemical and morphological processes of apoptosis are completed appropriately.