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.

Estrogen acting through the estrogen receptor (ER) is able to regulate cell growth and differentiation of a variety of normal tissues and hormone-responsive tumors. Ligand-activated ER binds DNA and transactivates the promoters of estrogen target genes. In addition, ligandactivated ER can interact with other factors to alter the physiology and growth of cells. Using a yeast two-hybrid screen, we have identified an interaction between ER␣ and the proapoptotic forkhead transcription factor FKHR. The ER␣-FKHR interaction depends on ␤-estradiol and is reduced significantly in the absence of hormone or the presence of Tamoxifen. A glutathione S-transferase pull-down assay was used to confirm the interaction and localized two interaction sites, one in the forkhead domain and a second in the carboxyl terminus. The FKHR interaction was specific to ER␣ and was not detected with other ligand-activated steroid receptors. The related family members, FKHRL1 and AFX, also bound to ER␣ in the presence of ␤-estradiol. FKHR augmented ER␣ transactivation through an estrogen response element. Conversely, ER␣ repressed FKHRmediated transactivation through an insulin response sequence, and cell cycle arrest induced by FKHRL1 in MCF7 cells was abrogated by estradiol. These results suggest a novel mechanism of estrogen action that involves regulation of the proapoptotic forkhead transcription factors.Estrogen and related steroid ligands play a critical role in the normal development and function of numerous cell types. Estrogens induce physiologic effects through an interaction with nuclear steroid receptors. Two human estrogen receptors have been identified, ER␣ 1 and ER␤ (1-4). The ERs are members of the steroid-thyroid-retinoic acid superfamily of transcription factors (5). In the classic model of steroid hormone action, ␤-estradiol induces homodimerization of ER, which is able to bind specific regulatory sequences in the promoters of ER target genes called estrogen response elements (EREs) (6). It is through this classic model of steroid hormone action that ERs alter the expression of a set of target genes. Several target genes for ER␣ in hormone-responsive breast tumors have been described including progesterone receptor (PR) (7), pS2 (8), TGF-␣ (9), cathepsin D (10), HSP27 (11), and GREB1 (12). These genes are directly activated by ER␣, and the induction of gene expression depends on the ability for ER␣ to bind to the promoters of each target gene.Increasingly, it has been reported that estrogen acting through ERs can have profound effects on cell physiology through mechanisms independent of DNA binding. One mechanism that has been proposed is through the ability of ER␣ to regulate the activity of other nuclear transcription factors by mechanisms involving direct protein-protein interactions. In many cases the interactions between ER␣ and other nuclear factors have been shown to be ligand-dependent. One example of this alternate mechanism of gene regulation is the effect of ER␣ on the expression of AP1-regulated genes (13). ER␣ ...

Expression of human estrogen receptor-␣ (ER␣) involves the activity from several promoters that give rise to alternate untranslated 5 exons. However, the genomic locations of the alternate 5 exons have not been reported previously. We have developed a contig map of the human ER␣ gene that includes all of the known alternate 5 exons. By using S1 nuclease and 5-rapid amplification of cDNA ends, the cap sites for the alternate ER␣ transcripts E and H were identified. DNase I-hypersensitive sites specific to ER␣-positive cells were associated with each of the cap sites. A DNase I-hypersensitive site, HS1, was localized to binding sites for AP2 in the untranslated region of exon 1 and was invariably present in the chromatin structure of ER␣-positive cells. Overexpression of AP2␥ in human mammary epithelial cells generated the HS1-hypersensitive site. The ER␣ promoter was induced by AP2␥ in mammary epithelial cells, and trans-activation was dependent upon the region of the promoter containing the HS1 site. These results demonstrate that AP2␥ trans-activates the ER␣ gene in hormone-responsive tumors by inducing changes in the chromatin structure of the ER␣ promoter. These data are further evidence for a critical role for AP2 in the oncogenesis of hormone-responsive breast cancers.There are at least two nuclear receptors for estrogen receptor, ER␣ 1 (1, 2) and ER␤ (3). Most breast cancers that occur in post-menopausal women overexpress ER␣ (4). Patients with breast cancers that express ER␣ are more likely to respond to hormonal therapy (4, 5) and have an improved prognosis compared with patients with ER␣-negative tumors (4, 6, 7). Studies of breast cancer cell lines (8) and primary tumors (9, 10) have indicated that transcription of the ER␣ gene plays an important role in regulating the expression of ER␣. Thus, understanding transcriptional regulation of the ER␣ gene will likely provide critical insights into the pathogenesis of hormone-responsive breast cancers.Transcription of the ER␣ gene is complex and involves activity of several distinct promoters (11-14). Functional promoter studies have concluded that ER␣ expression in breast cancer cell lines and various tissues is likely to involve transacting factors that have a specific cell or tissue distribution pattern (15-19). There appear to be a variety of factors that interact with the ER␣ promoter with trans-activating (15-17) or trans-repressing (20) functions. There is also evidence that ER␣ can autoregulate its own transcription (21,22). Other studies suggest that the lack of ER␣ expression in ER␣-negative breast cancer cell lines and tumors may be controlled by methylation of CpG islands in the 5Ј end of the ER␣ gene (23,24).The main ER␣ promoter, P1, initiates transcription at a cap site previously mapped at the start of exon 1 (1). Exon 1 has a 233-base 5Ј-untranslated region preceding the AUG codon that initiates translation of the ER␣ protein. Studies in ER␣-positive breast cancer cell lines have shown that transcription initiated at exon 1 accounts for 50 -9...

Risk stratification of patients with early stage breast cancer may support adjuvant chemotherapy decision‐making. This review details the development and validation of six multi‐gene classifiers, each of which claims to provide useful prognostic and possibly predictive information for early stage breast cancer patients. A careful assessment is presented of each test's analytical validity, clinical validity, and clinical utility, as well as the quality of evidence supporting its use.

Circulating tumor cells (CTCs) were discovered nearly 150 years ago but have only recently been recognized as a feature of most solid tumors due to their extremely low concentration in the peripheral circulation. Several technologies have been developed to isolate and analyze CTCs, which can now be routinely accessed for clinical information. The most mature of these (the CELLSEARCH system) uses immunomagnetic selection of epithelial cell adhesion molecule to isolate CTCs for analysis. Studies using this system have demonstrated that categorization of patients into high and low CTC groups using a validated decision point is prognostic in patients with metastatic breast, colorectal, or prostate cancer. Initial attempts to use CTC counts to guide therapeutic decisions appeared to yield positive results and key concepts in clinical application of CTC information, including the CTC cutoff, predictive value in disease subtypes, and comparison to current evaluation methods, have been demonstrated. Clinical studies of the impact of CTC counts in routine clinical practice are ongoing; however, recent published evidence on the clinical use of CTCs in metastatic breast cancer continues to support these concepts, and experience in the community oncology setting also suggests that CTC enumeration can be useful for therapy management.