Localization by in situ hybridization of steroid 5α-reductase isozyme gene expression in the human prostate and preputial skin

Purpose: The synthesis of dihydrotestosterone is catalyzed by steroid 5 alpha-reductase isozymes, designated as types 1 and 2. Controversial results have been reported on the identification of the cell types expressing each isozyme in the human prostate and genital skin. The objective of the present study was to clearly identify at the cellular level the cells containing each type of 5 alpha-reductase isozyme, Materials and Methods: We used for the first time an in situ hybridization technique involving use of [S-35]-labeled oligonucleotide probes to determine the cell type expression patterns of the two 5 alpha-reductase isozymes in human prostate and preputial skin, Results: In the prostate, hybridization with types 1 and 2 5 alpha-reductase antisense probes led to a positive reaction in both epithelial and stromal cells, while the sense probes did not generate any signal. The silver grain counts for both isozymes revealed a higher labeling in the epithelial cells. In fact, the ratio epithelial cells/stroma was around 2 for both 5 alpha-reductase types 1 and 2. In the preputial skin, 5 alpha-reductase type 1 was found to be highly expressed in all the layers of the epidermis with the exception of the stratum corneum while a lower labeling was observed in some fibroblasts as well as in the secretory cells of sebaceous glands and excretory duct cells of sweat glands. Type 2 5 alpha-reductase showed a very similar pattern of distribution. Conclusion: It appears that, in two human tissues, the two 5 alpha-reductase isozymes mRNAs are expressed by the same cell types. This new observation should help clarify the physiological role of each type of 5 alpha-reductase isozyme.