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 i ncreased during castration-induced rat prostate apoptosis. Materials and methods Differential display of mRNAs from 3-day castrated an d normal rat ventral prostates was used to identify differentially expresse d clones. Northern blots were hybridized to confirm the positive regulation of the candidates and to follow the change in their expression in the invo luting rat prostate, and in thymocytes of dexamethazone-treated rats. Results Five cDNAs were cloned: one encoding ribosomal protein L7, one codi ng for the insulin-like growth factor binding protein-3 (IGFBP-3), and thre e whose products are unknown. After castration, all five genes had expressi on kinetics that closely paralleled the proportion of prostatic epithelial cells undergoing apoptosis. The gene encoding L7 and two of the unknown gen es were also upregulated in glucocorticoid-induced programmed death in thym ocytes. 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-d eprived rats. Conclusion Five new genes were identified that are upregulated during castr ation-induced rat prostate apoptosis, three of which are potentially involv ed in the common intracellular pathway leading to programmed cell death.