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, a cyclin-dependent kinase (cdk) inhibitor, can cause cell cycle arrest, induce apoptosis in cancer cells, and inhibit tumor cell growth in vivo. The present study investigated the in vitro radiosensitizing effect of flavopiridol and the underlying molecular mechanisms in a murine ovarian cancer cell line, OCA-I. Flavopiridol inhibited cell growth in a dose-dependent manner and enhanced cell radiosensitivity assessed by the clonogenic cell survival assay. A flavopiridol dose of 300 nM, given for 1 day, enhanced radiosensitivity by a factor of 2.1. Clonogenic cell survival after split-dose radiation showed that flavopiridol inhibited repair from radiation damage. In addition, flavopiridol treatment (300 nM, 1 day) resulted in decreased levels of Ku70 and Ku86 proteins that play a role in DNA repair processes, suggesting that DNA repair processes may have been disrupted by this agent. Flow cytometry analysis showed that flavopiridol (300 nM, 1 day) accumulated the cells in G(1) and G(2) phases, with a significant reduction in the S phase component. This cell cycle redistribution is likely another mechanism underlying flavopiridol-induced cell radiosensitivity. Flavopiridol down-regulated cyclin D1 and cyclin E protein levels and also inhibited phosphorylation of retinoblastoma protein, which is inconsistent with the observed cell cycle arrest. Among the cdks tested, cdk-9, the catalytic subunit of positive transcription elongation factor b, was significantly down-regulated by flavopiridol, suggesting that flavopiridol may modulate cellular transcription processes. Furthermore, flavopiridol on its own induced apoptosis in the OCA-I cells, whereas in combination with radiation, exerted no additional increase in apoptosis. Taken together, our data show that flavopiridol strongly augmented the response of ovarian carcinoma cells to radiation and that the underlying mechanisms included inhibition of sublethal DNA damage repair and cell cycle redistribution. At the molecular level, transcriptional regulation by flavopiridol may have been involved.
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PMID:Flavopiridol, a cyclin-dependent kinase inhibitor, enhances radiosensitivity of ovarian carcinoma cells. 1281 Jun 57

Various stresses on the heart, such as myocardial infarction and hemodynamic overload, activate the sympathetic nervous system and the renin-angiotensin system, ultimately reach the nuclei of cardiomyocytes, and change the pattern of gene expression associated with cardiac hypertrophy. Although present pharmacological therapy for heart failure targets such extracellular molecules, mortality due to heart failure is still high. A zinc finger protein, GATA4, is one of the hypertrophy-responsive transcription factors, forms a functional protein complex with an intrinsic histone acetyltransferase, p300, and regulates pathological cardiac hypertrophy. Disruption of this complex results in the inhibition of cardiac hypertrophy and heart failure in vivo. To establish a more effective therapy for heart failure, we have been analyzing a common nuclear pathway within cardiomyocytes. We identified 73 GATA4 binding proteins by tandem-affinity purification and mass spectrometric analysis. Noble GATA4 binding partners, such as cyclin-dependent kinase-9 (Cdk9: the core factor of positive transcription elongation factor b) and retinoblastoma-association protein 48/46 (RbAp48/46: the co-repressor complexes containing HDAC1/2), regulate the p300/GATA4-mediated signaling pathway and hypertrophic responses. Further analysis of p300/GATA4 complex is expected to identify target molecules for heart failure therapy.
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PMID:[Functional Analysis of GATA4 Complex, a Cardiac Hypertrophy-response Transcriptional Factor, Using a Proteomics Approach]. 2683 85

Cyclin-dependent kinases (CDKs) are potential cancer therapeutic targets because of their critical role in promoting cell growth. Dinaciclib is a novel CDK inhibitor currently under clinical evaluation for the treatment of advanced malignancies. In this study, we demonstrated the anti-tumor activity of dinaciclib in triple negative breast cancer (TNBC) patient derived xenograft (PDX) and cell lines in vitro and in vivo. Treatment with dinaciclib induced cell cycle arrest at G2/M phase and marked apoptosis. These changes were accompanied by reduced phosphorylation of CDK1 and retinoblastoma (Rb) protein and decreased protein levels of cyclin B1, cMYC and survivin. We further demonstrated that siRNA knockdown of CDK9, the kinase subunit of positive transcription elongation factor b (P-TEFb), instead of CDK1 or CDK2, reduced the levels of cyclin B1 and MYC in TNBC cell lines. These data support the importance of CDK9, in addition to CDK1, in mediating the growth inhibitory effect of dinaciclib in TNBC. Further investigation of CDK9 as a therapeutic target in TNBC is needed.
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PMID:Inhibition of cyclin dependent kinase 9 by dinaciclib suppresses cyclin B1 expression and tumor growth in triple negative breast cancer. 2748 54