Human prostatic acid phosphatase (hPAP) is intensely expressed in epithelial cells of the prostate gland following puberty. Its regulatory regions were analyzed in transgenic mice and cell line transfections, in order to clarify the mechanisms of tissue-specific gene expression. A construct containing the sequence of hPAP between the nucleotides -734 and +467 in front of the CAT reporter gene was significantly expressed in the prostate of transgenic mice, while the proximal promoter -734/+50 alone achieved low levels of CAT mRNA in all tissues analyzed. Five homologous sequences (A-E) for our previously identified prostatic GAAAATA TGATA DNA-binding site were found in the area. The competitive reactions in electrophoretic mobility shift assays suggested that the same nuclear factor binds to the GAAAATATGATA and the sites C and E. The importance of the intronic area +57/+467 on the androgen-activated expression in prostatic cells was shown by the reporter construct containing heterologous promoter. (C) 2003 Elsevier Inc. All rights reserved.