Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P23193 (transcription elongation factor)
 739 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Flavopiridol is active against chronic lymphocytic leukemia (CLL) cells in vitro and in the treatment of advanced stage disease, but the mechanisms of these actions remain unclear. Originally developed as a general cyclin-dependent kinase inhibitor, flavopiridol is a potent transcriptional suppressor through the inhibition of positive transcription elongation factor b (P-TEFb; CDK9/cyclin T). P-TEFb phosphorylates the C-terminal domain (CTD) of RNA polymerase II to promote transcriptional elongation. Because most CLL cells are not actively cycling, and their viability is dependent upon the continuous expression of antiapoptotic proteins, we hypothesized that flavopiridol induces apoptosis in CLL cells through the transcriptional down-regulation of such proteins. This study demonstrated that flavopiridol inhibited the phosphorylation of the CTD of RNA polymerase II in primary CLL cells and reduced RNA synthesis. This was associated with a decline of the transcripts and the levels of short-lived antiapoptotic proteins such as myeloid cell leukemia 1 (Mcl-1), and resulted in the induction of apoptosis. The B-cell lymphoma 2 (Bcl-2) protein level remained stable, although its mRNA was consistently reduced, suggesting that the outcome of transcriptional inhibition by flavopiridol is governed by the intrinsic stability of the individual transcripts and proteins. The dependence of CLL-cell survival on short-lived oncoproteins may provide the biochemical basis for the therapeutic index in response to flavopiridol.
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PMID:Transcription inhibition by flavopiridol: mechanism of chronic lymphocytic leukemia cell death. 1597 45

We have previously shown that a frequently downregulated gene, transcription elongation factor A-like 7 (TCEAL7), promoted anchorage-independent growth and modulated Myc activity in ovarian surface epithelial cells immortalized with temperature-sensitive large T antigen and human telomerase reverse transcriptase (OSEtsT/hTERT). Analysis of protein/DNA array showed that TCEAL7 downregulation resulted in an approximately twofold increase in nuclear factor (NF)-kappaB binding to its target DNA sequence. In this study we showed that short hairpin RNA (shRNA)-mediated downregulation of TCEAL7 in two different immortalized OSE cells showed higher NF-kappaB activity, as determined using reporter and gel-shift assays. Transient transfection of TCEAL7 inhibited the activation of NF-kappaB in TCEAL7-downregulated clones, IOSE-523 and in other ovarian cancer cell lines (OVCAR8, SKOV3ip and DOV13), suggesting that TCEAL7 negatively regulates NF-kappaB pathway. Consistent with this observation, TCEAL7-downregulated clones showed higher levels of NF-kappaB targets, such as pro-proliferative (cyclin-D1 and cMyc), pro-angiogenic (interleukin (IL)-6, IL-8 and vascular endothelial growth factor (VEGF)), inflammatory (intercellular adhesion molecule 1 (ICAM-1) and cyclooxygenase-2 (Cox-2)) and anti-apoptotic (B-cell lymphoma-extra large (Bcl-xl)) genes when compared with vector controls. Inhibition of NF-kappaB by IkappaB kinase (IKK) inhibitor (BMS 345541) attenuated cell survival and proliferation of TCEAL-knockdown clones. Although TCEAL7 inhibited p65 transcriptional activity, it did not modulate the cytoplasmic signaling of the NF-kappaB pathway, by itself or by tumor necrosis factor-alpha (TNF-alpha). Chromatin immunoprecipitation (ChIP) assays revealed increased recruitment of p65 and p300 to the promoters of IL-8 and IL-6 in TCEAL7-downregulated clones. Collectively, these results indicate a novel role for TCEAL7 in the negative regulation of NF-kappaB signaling at the basal level by modulating transcriptional activity of NF-kappaB on its target gene promoters, potentially providing a novel mechanism by which NF-kappaB activity may be deregulated in ovarian cancer cells.
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PMID:TCEAL7, a putative tumor suppressor gene, negatively regulates NF-kappaB pathway. 1996 55

ELL-associated factor 2 (EAF2) is an androgen-responsive tumor suppressor frequently deleted in advanced prostate cancer that functions as a transcription elongation factor of RNA Pol II through interaction with the ELL family proteins. EAF2 knockout mice on a 129P2/OLA-C57BL/6J background developed late-onset lung adenocarcinoma, hepatocellular carcinoma, B-cell lymphoma and high-grade prostatic intraepithelial neoplasia. In order to further characterize the role of EAF2 in the development of prostatic defects, the effects of EAF2 loss were compared in different murine strains. In the current study, aged EAF2(-/-) mice on both the C57BL/6J and FVB/NJ backgrounds exhibited mPIN lesions as previously reported on a 129P2/OLA-C57BL/6J background. In contrast to the 129P2/OLA-C57BL/6J mixed genetic background, the mPIN lesions in C57BL/6J and FVB/NJ EAF2(-/-) mice were associated with stromal defects characteristic of a reactive stroma and a statistically significant increase in prostate microvessel density. Stromal inflammation and increased microvessel density was evident in EAF2-deficient mice on a pure C57BL/6J background at an early age and preceded the development of the histologic epithelial hyperplasia and neoplasia found in the prostates of older EAF2(-/-) animals. Mice deficient in EAF2 had an increased recovery rate and a decreased overall response to the effects of androgen deprivation. EAF2 expression in human cancer was significantly down-regulated and microvessel density was significantly increased compared to matched normal prostate tissue; furthermore EAF2 expression was negatively correlated with microvessel density. These results suggest that the EAF2 knockout mouse on the C57BL/6J and FVB/NJ genetic backgrounds provides a model of PIN lesions associated with an altered prostate microvasculature and reactive stromal compartment corresponding to that reported in human prostate tumors.
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PMID:Development of a reactive stroma associated with prostatic intraepithelial neoplasia in EAF2 deficient mice. 2426 Feb 46