Identification of androgen-responsive genes in the rat ventral prostate by complementary deoxyribonucleic acid subtraction and microarray.

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 PCR-based 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 microarray, 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.