Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The androgen receptor (AR) is central to the initiation and progression of prostate cancer, even after castration. There has been some success in therapies targeting AR signaling which have been shown to extend survival in men with castration-resistant prostate cancer (CRPC). However, durable responses to these therapies have been limited and there is a need to identify additional therapeutic targets within the AR-signaling network. Recently a group at University of Michigan Medical School outlined the potential for BET bromodomain protein inhibitors as a novel epigenetic approach to treatment of CRPC. In prostate cancer cell lines, BET bromodomain inhibitor, JQ1, was shown to induce apoptosis and down-regulate AR-regulated gene transcription. Bromodomain and the extra-terminal (BET) subfamily of human bromodomain proteins, with a focus on BRD4, were shown to play a major role in AR signaling and interact with AR via bromodomain (BD) 1/2. JQ1 inhibits this BRD4-AR bond, resulting in removal of RNA polymerase II from AR target genes, causing reduced AR gene transcription and subsequent diminished AR signaling. JQ1 lead to a significant reduction in tumor volume and weight in VCaP xenograft mice.
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PMID:BET bromodomain inhibitors--a novel epigenetic approach in castration-resistant prostate cancer. 2553 92

CDK9 is the kinase subunit of positive transcription elongation factor b (P-TEFb) that enables RNA polymerase (Pol) II's transition from promoter-proximal pausing to productive elongation. Although considerable interest exists in CDK9 as a therapeutic target, little progress has been made due to lack of highly selective inhibitors. Here, we describe the development of i-CDK9 as such an inhibitor that potently suppresses CDK9 phosphorylation of substrates and causes genome-wide Pol II pausing. While most genes experience reduced expression, MYC and other primary response genes increase expression upon sustained i-CDK9 treatment. Essential for this increase, the bromodomain protein BRD4 captures P-TEFb from 7SK snRNP to deliver to target genes and also enhances CDK9's activity and resistance to inhibition. Because the i-CDK9-induced MYC expression and binding to P-TEFb compensate for P-TEFb's loss of activity, only simultaneously inhibiting CDK9 and MYC/BRD4 can efficiently induce growth arrest and apoptosis of cancer cells, suggesting the potential of a combinatorial treatment strategy.
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PMID:Compensatory induction of MYC expression by sustained CDK9 inhibition via a BRD4-dependent mechanism. 2618 95


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