We have reported the identification of approximately two dozen androgen-responsive genes, on the basis of their induction by androgens in the castrated rat ventral prostate, using PCRbased subtractive hybridization. The same prostatic cDNA samples were subjected to a modified subtractive hybridization, resulting in the identification of 21 new androgen-responsive genes, of which 14 were known and 7 were novel genes. To complement our subtraction study, we have used an Incyte rat cDNA

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... consisting of 8951 known genes and expressed sequence tags, and found that 162 genes were up-regulated and 143 genes were down-regulated 2.3-fold or more by androgens. As expected, the genes isolated from our subtraction overlap with genes found with microarray. Northern blot was carried out on all of the genes identified by subtraction and a few selected genes from microarray. All of the assayed genes are regulated by androgens, validating our subtraction and microarray studies. The identified genes can be classified into several functional groups, including metabolism, protein chaperoning and trafficking, protein synthesis, secretions, cell cycle and apoptosis, structural and extracellular matrix proteins, and novel proteins. Identification of these androgen-responsive genes will contribute to the understanding of androgen action in the normal and cancerous prostate. (Endocrinology 144: 1257-1265, 2003) Abbreviations: BMP-6, Bone morphogenetic protein-6; CoA, coenzyme A; DAD1, defender against cell death 1; EST, expressed sequence tag; FPPS, farnesyl pyrophosphate synthase; FKBP51, 51-kDa FK506binding protein; GADD45␥, growth arrest and DNA-damage-inducible, ␥; hKLK, human prostate-specific kallikrein; LDL, low-density lipoprotein; LNCaP, lymph node carcinoma of the prostate; Mib, mibolerone; ORP150, oxygen-regulated protein 150 kDa; PCNA, proliferating cell nuclear antigen; SCAP, SREBP cleavage activating protein; SDS, sodium dodecyl sulfate; SREBP, sterol regulatory element-binding protein; SSC, saline sodium citrate; TIMP3, tissue inhibitor of metalloprotease 3.