6qtj
Crystal structure of human CDK8/CYCC in complex with BI 919811
Structural highlights
FunctionCDK8_HUMAN Component of the Mediator complex, a coactivator involved in regulated gene transcription of nearly all RNA polymerase II-dependent genes. Mediator functions as a bridge to convey information from gene-specific regulatory proteins to the basal RNA polymerase II transcription machinery. Mediator is recruited to promoters by direct interactions with regulatory proteins and serves as a scaffold for the assembly of a functional preinitiation complex with RNA polymerase II and the general transcription factors. Phosphorylates the CTD (C-terminal domain) of the large subunit of RNA polymerase II (RNAp II), which may inhibit the formation of a transcription initiation complex. Phosphorylates CCNH leading to down-regulation of the TFIIH complex and transcriptional repression. Recruited through interaction with MAML1 to hyperphosphorylate the intracellular domain of NOTCH, leading to its degradation.[1] [2] Publication Abstract from PubMedNatural killer (NK) cells play a pivotal role in controlling cancer. Multiple extracellular receptors and internal signaling nodes tightly regulate NK activation. Cyclin-dependent kinases of the mediator complex (CDK8 and CDK19) were described as a signaling intermediates in NK cells. Here, we report for the first time the development and use of CDK8/19 inhibitors to suppress phosphorylation of STAT1(S727) in NK cells and to augment the production of the cytolytic molecules perforin and granzyme B (GZMB). Functionally, this resulted in enhanced NK-cell-mediated lysis of primary leukemia cells. Treatment with the CDK8/19 inhibitor BI-1347 increased the response rate and survival of mice bearing melanoma and breast cancer xenografts. In addition, CDK8/19 inhibition augmented the antitumoral activity of anti-PD-1 antibody and SMAC mimetic therapy, both agents that promote T-cell-mediated antitumor immunity. Treatment with the SMAC mimetic compound BI-8382 resulted in an increased number of NK cells infiltrating EMT6 tumors. Combination of the CDK8/19 inhibitor BI-1347, which augments the amount of degranulation enzymes, with the SMAC mimetic BI-8382 resulted in increased survival of mice carrying the EMT6 breast cancer model. The observed survival benefit was dependent on an intermittent treatment schedule of BI-1347, suggesting the importance of circumventing a hyporesponsive state of NK cells. These results suggest that CDK8/19 inhibitors can be combined with modulators of the adaptive immune system to inhibit the growth of solid tumors, independent of their activity on cancer cells, but rather through promoting NK-cell function. Selective and Potent CDK8/19 Inhibitors Enhance NK-Cell Activity and Promote Tumor Surveillance.,Hofmann MH, Mani R, Engelhardt H, Impagnatiello MA, Carotta S, Kerenyi M, Lorenzo-Herrero S, Bottcher J, Scharn D, Arnhof H, Zoephel A, Schnitzer R, Gerstberger T, Sanderson MP, Rajgolikar G, Goswami S, Vasu S, Ettmayer P, Gonzalez S, Pearson M, McConnell DB, Kraut N, Muthusamy N, Moll J Mol Cancer Ther. 2020 Apr;19(4):1018-1030. doi: 10.1158/1535-7163.MCT-19-0789., Epub 2020 Feb 5. PMID:32024684[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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