Prostate-specific Antigen Expression Is Regulated by an Upstream Enhancer

Abstract

Prostate cancer can be detected using assays for blood-borne prostate-specific antigen (PSA), which is the clinically most useful diagnostic marker of malignant disease. This paper characterizes the 5-flanking prostate-specific enhancer which controls expression of the human PSA gene This enhancer, located between ؊5824 and ؊3738, is androgen-responsive and requires a promoter for activity. Inductions of 12-100-fold activity occur at 1 nM concentrations of the testosterone analog R1881. The enhancer demonstrated tissue specificity as judged by transfections of several human cell lines. Electrophoretic mobility shift assays comparing nuclear extracts from breast cancer cells MCF-7, and prostate cancer cells LNCaP, showed three regions of prostatespecific binding. These three regions are ؊4168 to ؊4797 (region I), ؊4710 to 4479 (region II), and ؊4168 to ؊3801 (region III). Region III contained a putative androgen response element at ؊4136 that markedly affected activity if mutated. These data suggest that prostate-specific gene expression may involve interaction of prostatespecific proteins or protein complexes with the enhancer in addition to binding of the androgen receptor to androgen response elements.

Prostate targeting: PSP94 gene promoter/enhancer region directed prostate tissue-specific expression in a transgenic mouse prostate cancer model

“…Prostatic-specific antigen (PSA) was characterized for several prostate tissue-specific elements (TSE) by in Gene Therapy vitro tissue cell culture studies. [13][14][15] A 657 bp promoter of the human PSA gene linked with T24-ras in transgenic mice showed tumor induction in the salivary gland and gastrointestinal tract. 16 Two other PSA transgenes were constructed based on a 6 kb promoter/enhancer region 17 and the whole human PSA gene (12 kb), and were reported to be essentially prostate-specific with LacZ as a reporter gene.…”

Chimeric PSA enhancers exhibit augmented activity in prostate cancer gene therapy vectors

“…16,23 Studies have also pointed to the involvement of both prostatespecific and ubiquitous transcription factors in cellspecific regulation. 5,6,37 We manipulated the known PSA regulatory components, namely the proximal 600-bp promoter, the enhancer core centered at −4.2 kb, and high affinity AREs, to achieve augmented prostate specific expression. The three strategies we utilized (1) insertion of ARE4; (2) duplication of the enhancer core element; and (3) removal of intervening sequences between the enhancer and promoter, all increased transcription activity and androgen inducibility.…”

“…[5][6][7] The PSA regulatory region ( Figure 1a) includes a proximal promoter (600 bp upstream of the transcription initiation site) which contains a TATA box and two functionally important AREs (AREs, binding sites for the transcription factor AR [8][9][10][11][12] ). This promoter alone exhibits tissue-specific expression in vitro in cell-based assays, although it is insufficient to direct prostate specific expression in vivo.…”

“…13,15 Three important studies narrowed down smaller upstream enhancer regions within the 6 kb that conferred prostate-specific PSA gene expression. [5][6][7] An 1.6-kb enhancer (−5322 to −3738) containing putative recognition sites for AR, AP-1, and c-fos 5 and a smaller 822-bp enhancer fragment 7 (−4757 to −3935) were able to achieve maximal activity comparable to the entire 6 kb PSA regulatory region. The importance of this region was highlighted by the identification of an androgen-inducible DNase hypersensitive site (DHS II) centered at −4.2 kb, mapped in chromatin from LNCaP prostate cancer cells.…”

“…The importance of this region was highlighted by the identification of an androgen-inducible DNase hypersensitive site (DHS II) centered at −4.2 kb, mapped in chromatin from LNCaP prostate cancer cells. 6 Functional analyses of the DHS II region revealed a minimal 440-bp core enhancer (−4324 to −3884), which provided strong enhancer activity and contains a high [5][6][7]16,23 and proximal promoter 5,[8][9][10][11] affinity ARE (AREIII 6 ). Subsequent studies demonstrated that the core enhancer contains at least four non-consensus AREs with variable binding affinity for AR, 16 all of which contribute to the synergistic activation of PSA gene expression.…”