A 6-kb Promoter Fragment Mimics in Transgenic Mice the Prostate-Specific and Androgen-Regulated Expression of the Endogenous Prostate-Specific Antigen Gene in Humans

Abstract

Prostate-specific antigen (PSA) is a kallikrein-like serine protease, which is almost exclusively synthesized in the luminal epithelial cells of the human prostate. PSA expression is androgen regulated. Previously, we characterized in vitro the proximal promoter, and a strong enhancer region, approximately 4 kb upstream of the PSA gene. Both regions are needed for high, androgen-regulated activity of the PSA promoter in LNCaP cells. The goal of the present study is the in vivo characterization of the PSA promoter. Three transgenic mouse lines carrying the Escherichia coli LacZ gene, driven by the 632-bp proximal PSA promoter, and three lines with LacZ, driven by the 6-kb PSA promoter, were generated. Expression of the LacZ reporter gene was analyzed in a large series of tissues. Transgene expression could not be demonstrated in any of the transgenic animals carrying the proximal PSA promoter. All three lines carrying the 6-kb PSA promoter showed lateral prostate-specific ␤-galactosidase activity. Transgene expression was undetectable until 8 weeks after birth. Upon castration, ␤-galactosidase activity rapidly declined. It could be restored by subsequent androgen administration. A search for mouse PSA-related kallikrein genes expressed in the prostate led to the identification of mGK22, which was previously demonstrated to be expressed in the submandibular salivary gland. Therefore, the 6-kb PSA-LacZ transgene followed the expression pattern of the PSA gene in humans, which is almost completely prostate-specific, rather than that of mGK22 in mice. In conclusion, the 6-kb promoter fragment appears to contain most, if not all, information for androgen regulation and prostate specificity of the

Androgen-induced recruitment of RNA polymerase II to a nuclear receptor–p160 coactivator complex

“…To further understand the molecular underpinnings of hormone induction of gene expression, we analyzed androgen-induced recruitment of AR and its associated coactivators to the entire 5Ј regulatory region of the prostate-specific antigen (PSA) gene in hormoneresponsive LNCaP cells. High-level androgen induction of PSA expression is conferred by an enhancer centered at ϷϪ4.2 kb on the PSA gene, which contains multiple tandem androgen response elements (18)(19)(20). Here, we show that on androgen stimulation, the p160 and CBP͞p300 coactivators are preferentially recruited to the enhancer.…”

Mouse models of prostate cancer

“…Several of the promoters described above such as rat probasin or mouse C3/PSBP for epithelial cells and cryptdin for neuroendocrine cells will be particularly useful in this regard. In addition, other promoters are emerging for this purpose, including human PSA (Cleutjens et al, 1997;Wei et al, 1997Wei et al, , 1998Willis et al, 1998). Access to candidate genes will be facilitated greatly by human genome mapping, the Cancer Genome Anatomy Project (CGAP), and microarray technology, as well as by gene discovery e orts in chromosomal regions of recurrent prostatetumor associated loss or gain.…”

The impact of bcl-2 expression and bax deficiency on prostate homeostasis in vivo

“…Recently, our ability to assess the impact of individual gene products in the prostate has been greatly facilitated by the characterization of gene promoters that enable targetting to the prostate (Greenberg et al, 1994;Maroulakou et al, 1994;Pang et al, 1997;Cleutjens et al, 1997;Zhang et al, 1997). The most extensively studied transgenic model involves the targeting of transgene expression using the probasin promoter (Greenberg et al, 1995;Gingrich et al, 1996Gingrich et al, , 1997.…”