Prostate cancer, the most frequent solid cancer in older men, is a leading cause of cancer deaths. Although proliferation and differentiation of normal prostate epithelia andtheinitialgrowthofprostatecancercellsareandrogendependent, prostate cancers ultimately become androgen-independent and refractory to hormone therapy. The prostate-specific antigen (PSA) gene has been widely used as a diagnostic indicator for androgen-dependent and -independent prostate cancer. Androgen-induced and prostate epithelium-specific PSA expression is regulated by a proximal promoter and an upstream enhancer via several androgen receptor binding sites. However, little progress has been made in identifying androgen-independent regulatory elements involved in PSA gene regulation. We report the isolation of a novel, prostate epithelium-specific Ets transcription factor, PDEF (prostate-derived Ets factor), that among the Ets family uniquely prefers binding to a GGAT rather than a GGAA core. PDEF acts as an androgen-independent transcriptional activator of the PSA promoter. PDEF also directly interacts with the DNA binding domain of androgen receptor and enhances androgen-mediated activation of the PSA promoter. Our results, as well as the critical roles of other Ets factors in cellular differentiation and tumorigenesis, strongly suggest that PDEF is an important regulator of prostate gland and/or prostate cancer development.
Epithelial cell differentiation is tightly controlled by distinct sets of transcription factors that regulate the expression of stage-specific genes. We recently isolated the first epithelium-specific Ets transcription factor (ESE-1). Here we describe the characterization of ESE-2, a second epithelium-restricted ESE-1-related Ets factor. Like ESE-1, ESE-2 is induced during keratinocyte differentiation. However, whereas ESE-1 is expressed in the majority of epithelial cell types, ESE-2 expression is restricted to differentiated keratinocytes and glandular epithelium such as salivary gland, prostate, mammary gland, and kidney. In contrast to ESE-1, full-length ESE-2 binds poorly to DNA due to the presence of a negative regulatory domain at the amino terminus. Furthermore, although ESE-1 and the amino-terminally deleted ESE-2 bind with similar affinity to the canonical E74 Ets site, ESE-2 and ESE-1 differ strikingly in their relative affinity toward binding sites in the c-MET and PSMA promoters. Similarly, ESE-1 and ESE-2 drastically differ in their ability to transactivate epitheliumspecific promoters. Thus, ESE-2, but not ESE-1, transactivates the parotid gland-specific PSP promoter and the prostate-specific PSA promoter. In contrast, ESE-1 transactivates the keratinocyte-specific SPRR2A promoter Ets site and the prostate-specific PSMA promoter significantly better than ESE-2. Our results demonstrate the existence of a unique class of related epitheliumspecific Ets factors with distinct functions in epithelial cell gene regulation.Normal epithelial cell development, proliferation, and differentiation are induced by mesenchymal-epithelial interactions and involve cell-cell interactions, extracellular matrix, and soluble growth and differentiation factors. These interactions trigger the activation or expression of a distinct set of transcription factors leading to a specific pattern of gene expression along a tightly controlled pathway. Abnormalities in this process due to deregulated gene expression can lead to the development of benign adenomas or malignant carcinomas that make up the majority of solid tumors. In order to understand tumor development, it is therefore critical to understand normal epithelial cell differentiation and proliferation. Whereas rapid progress in understanding immune system development and gene regulation has led to the discovery and characterization of a whole set of genes involved in leukemia and lymphoma development, relatively little is known about epithelial cell differentiation and organ development and the mechanisms involved in solid tumor formation. Most of the genes involved in chromosomal translocations in leukemias and lymphomas encode transcription factors that under normal physiological conditions coordinate the correct spatial and temporal expression of genes (1). We therefore postulate that similar mechanisms of oncogenesis play a role in epithelium-derived tumors as well. It is thus surprising that many aspects of epithelium-specific gene expression have not been explore...
Positive effects were observed with CII at the lowest dosage tested, and the presence of serum antibodies to CII at baseline may predict response to therapy. No side effects were associated with this novel therapeutic agent. Further controlled studies are required to assess the efficacy of this treatment approach.
Most cancers originate as a result of aberrant gene expression in mainly glandular epithelial tissues leading to defects in epithelial cell differentiation. The latter is governed by distinct sets of transcriptional regulators. Here we report the characterization of epitheliumspecific Ets factor, family member 3 (ESE-3), a novel member of the ESE subfamily of Ets transcription factors. ESE-3 shows highest homology to two other epithelium restricted Ets factors, ESE-1 and ESE-2. ESE-3, like ESE-1 and ESE-2, is exclusively expressed in a subset of epithelial cells with highest expression in glandular epithelium such as prostate, pancreas, salivary gland, and trachea. A potential role in branching morphogenesis is suggested, since ESE-3 transactivates the c-MET promoter via three high affinity binding sites. Additionally, ESE-3 binding to DNA sequences in the promoters of several glandular epithelium-specific genes suggests a role for ESE-3 in later stages of glandular epithelium differentiation. Although ESE-3 and ESE-1 bind with similar affinity to various Ets binding sites, ESE-3 and ESE-1 differ significantly in their ability to transactivate the promoters containing these sites. Our results support the notion that ESE-1, ESE-2, and ESE-3 represent a unique epithelium-specific subfamily of Ets factors that have critical but distinct functions in epithelial cell differentiation and proliferation.
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