Genes upregulated during castration-induced rat prostatic apoptosis: cloning and characterization of new cDNAs

Objective To isolate new cDNAs corresponding to genes whose expression is increased during castration-induced rat prostate apoptosis. Materials and methods Differential display of mRNAs from 3-day castrated and normal rat ventral prostates was used to identify differentially expressed clones. Northern blots were hybridized to confirm the positive regulation of the candidates and to follow the change in their expression in the involuting rat prostate, and in thymocytes of dexamethazone-treated rats. Results Five cDNAs were cloned: one encoding ribosomal protein L7, one coding for the insulin-like growth factor binding protein-3 (IGFBP-3), and three whose products are unknown. After castration, all five genes had expression kinetics that closely paralleled the proportion of prostatic epithelial cells undergoing apoptosis. The gene encoding L7 and two of the unknown genes were also upregulated in glucocorticoid-induced programmed death in thymocytes. In addition to the IGFBP-3 gene, those coding for proteins IGFBP-4, -5 and -6 were also overexpressed in the involuting prostate of androgen-deprived rats. Conclusion Five new genes were identified that are up-regulated during castration-induced rat prostate apoptosis, three of which are potentially involved in the common intracellular pathway leading to programmed cell death.