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.
The NF-κB/IκB signaling pathway is a critical regulator of cell survival in cancer. Here, we report that combined down-regulation of growth arrest- and DNA-damage-inducible proteins (GADD)45α and γ expression by NF-κB is an essential step for various cancer types to escape programmed cell death. We demonstrate that inhibition of NF-κB in cancer cells results in GADD45α- and γ-dependent induction of apoptosis and inhibition of tumor growth. Inhibition of GADD45α and γ in cancer cells by small interfering RNA abrogates apoptosis induction by the inhibitor of NF-κB and blocks c-Jun N-terminal kinase activation, whereas overexpression of GADD45α and γ activates c-Jun N-terminal kinase and induces apoptosis. These results establish an unambiguous role for the GADD45 family as an essential mediator of cell survival in cancer cells with implications for cancer chemotherapy and novel drug discovery.
Conclusion. ESE-1 is expressed in synovial tissues in RA and, to a variable extent, in OA, and is specifically induced in synovial fibroblasts, chondroDr. Libermann
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