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CDK8 is a transcriptional cyclin-dependent kinase and considered as a potential target in colon cancer therapeutics. Here, a novel selective CDK8 inhibitor was identified against colon cancer

Progression of prostate cancer (PCa) is characterized by metastasis and castration resistance after response to androgen deprivation. Therapeutic options are limited, causing high morbidity and lethality. Recent work reported pro-oncogenic implications of the Mediator subunits cyclin-dependent kinase (CDK) 8 and 19 for the progression of PCa. The current study explored the underlying molecular mechanisms of CDK8/CDK19 and tested effects of novel CDK8/CDK19 inhibitors. PC3, DU145, LNCaP, and androgen-independent LNCaP Abl were used for in vitro experiments. Two inhibitors and CDK19 overexpression were used to modify CDK8/CDK19 activity. MTT assay, propidium iodide staining, wound healing assay, Boyden chamber assay, and adhesion assay were used to investigate cell viability, cell cycle, migration, and adhesion, respectively. Peptide-kinase screen using the PamGene platform was conducted to identify phosphorylated targets. Combining CDK8/CDK19 inhibitors with anti-androgens led to synergistic antiproliferative effects and sensitized androgen-independent cells to bicalutamide. CDK8/CDK19 inhibition resulted in reduced migration and increased collagen I-dependent adhesion. Phosphorylation of multiple peptides linked to cancer progression was identified to be dependent on CDK8/CDK19. In summary, this study substantially supports recent findings on CDK8/CDK19 in PCa progression. These findings contribute to a better understanding of underlying pro-oncogenic effects, which is needed to develop CDK8/CDK19 as a therapeutic target in PCa.

The Mediator complex controls RNA polymerase II (pol II) activity by coordinating the assembly of pol II regulatory factors at transcription start sites, and by mediating interactions between enhancer-bound transcription factors (TFs) and the pol II enzyme. Mediator structure and function is completely altered upon binding the Mediator kinase module, a multi-subunit complex that contains CDK8 or its vertebrate-specific paralog CDK19. Here, we review the mechanisms by which the Mediator kinase module controls pol II transcription, emphasizing its impact on TF activity, pol II elongation, enhancer function, and chromatin architecture. We also highlight how the Mediator kinase module integrates signaling pathways with transcription to enable rapid, stimulus-specific responses, as well as its links to human disease.

The Senexins are potent and selective quinazoline inhibitors of CDK8/19 Mediator kinases. To improve their potency and metabolic stability, quinoline-based derivatives were designed through a structure-guided strategy based on the simulated drug-target docking model of Senexin A and B. A library of quinoline-Senexin derivatives was synthesized to explore the structure-activity relationship. An optimized compound 20a (Senexin C) exhibits potent CDK8/19 inhibitory activity with a high selectivity. Senexin C is more metabolically stable and provides a more sustained inhibition of CDK8/19-dependent cellular gene expression when compared with the prototype inhibitor Senexin B. In vivo pharmacokinetic (PK) and pharmacodynamic (PD) evaluation using a novel tumor-based PD assay showed good oral bioavailability of Senexin C with a strong tumor-enrichment PK profile and tumor-PD marker responses. Senexin C inhibits MV4-11 leukemia growth in a systemic in vivo model with good tolerability.

[Image: see text] CDK8 and its paralog CDK19 are cyclin-dependent kinases that are core components of the so-called Mediator complex that has essential roles as a positive and negative regulator of gene expression. Several efforts to develop inhibitors have yielded natural and synthetic ATP-competitive compounds including cortistatin A, Sel120, BCD-115, CCT251921 (1), and MSC2530818 (2). Here, we used a hybridization approach starting from CCT251921 and MSC2530818 to derive new inhibitors with the aim of developing highly potent and selective inhibitors of CDK8/19. Initial compounds suffered from rapid aldehyde oxidase-mediated metabolism. This liability was overcome by utilizing a pyrazolopyridine hinge binder with a chlorine at the C-3 position. These efforts resulted in JH-XVI-178 (compound 15), a highly potent and selective inhibitor of CDK8/19 that displays low clearance and moderate oral pharmacokinetic properties.

T cells are the major arm of the immune system responsible for controlling and regressing cancers. To identify genes limiting T cell function, we conducted genome-wide CRISPR knockout screens in human chimeric antigen receptor (CAR) T cells. Top hits were MED12 and CCNC , components of the Mediator kinase module. Targeted MED12 deletion enhanced antitumor activity and sustained the effector phenotype in CAR- and T cell receptor–engineered T cells, and inhibition of CDK8/19 kinase activity increased expansion of nonengineered T cells. MED12 -deficient T cells manifested increased core Meditator chromatin occupancy at transcriptionally active enhancers—most notably for STAT and AP-1 transcription factors—and increased IL2RA expression and interleukin-2 sensitivity. These results implicate Mediator in T cell effector programming and identify the kinase module as a target for enhancing potency of antitumor T cell responses.

Acute myeloid leukemia (AML) is the most lethal form of AML due to disease relapse. Cyclin dependent kinase 8 (CDK8) is a serine/threonine kinase that belongs to the family of Cyclin-dependent kinases and is an emerging target for the treatment of AML. MK256, a potent, selective, and orally available CDK8 inhibitor was developed to target AML. We sought to examine the anticancer effect of MK256 on AML. In CD34+/CD38- leukemia stem cells, we found that MK256 induced differentiation and maturation. Treatment of MK256 inhibited proliferation of AML cell lines. Further studies of the inhibitory effect suggested that MK256 not only downregulated phosphorylated STAT1(S727) and STAT5(S726), but also lowered mRNA expressions of MCL-1 and CCL2 in AML cell lines. Efficacy of MK256 was shown in MOLM-14 xenograft models, and the inhibitory effect on phosphorylated STAT1(S727) and STAT5(S726) with treatment of MK256 was observediin vivo/i. Pharmacologic dynamics study of MK256 in MOLM-14 xenograft models showed dose-dependent inhibition of the STAT pathway. Bothiin vitro/iandiin vivo/istudies suggested that MK256 could effectively downregulate the STAT pathway.iIn vitro/iADME, pharmacological kinetics, and toxicity of MK256 were profiled to evaluate the drug properties of MK256. Our results show that MK256 is a novel CDK8 inhibitor with a desirable efficacy and safety profile and has great potential to be a promising drug candidate for AML through regulating the STAT pathway.

We here describe a computational approach (POEM: Pocket Oriented Elaboration of Molecules) to drive the generation of target-focused libraries while taking advantage of all publicly available structural information on protein-ligand complexes. A collection of 31 384 PDB-derived images with key shapes and pharmacophoric properties, describing fragment-bound microenvironments, is first aligned to the query target cavity by a computer vision method. The fragments of the most similar PDB subpockets are then directly positioned in the query cavity using the corresponding image transformation matrices. Lastly, suitable connectable atoms of oriented fragment pairs are linked by a deep generative model to yield fully connected molecules. POEM was applied to generate a library of 1.5 million potential cyclin-dependent kinase 8 inhibitors. By synthesizing and testing as few as 43 compounds, a few nanomolar inhibitors were quickly obtained with limited resources in just two iterative cycles.

Bronchopulmonary dysplasia (BPD) is an inflammation-related respiratory disorder in infants. MiR-382-5p has displayed low expression in developing lungs with BPD, while the effect of miR-382-5p on BPD remains elusive. Here, a hyperoxia (85% oxygen)-induced BPD model in neonatal mice was established. On postnatal days 10 and 15, hyperoxia reduced miR-382-5p expression in lungs of mice. Besides, CDK8, CD68 and CD86 levels were elevated on day 15 after birth, implying the involvement of CDK8 in M1 macrophage polarization. In addition, in vitro injury in RAW264.7 macrophages was induced by IFN-γ and LPS stimulation. Lentivirus-encoding miR-382-5p decreased CDK8 expression, alleviated the production of inflammatory cytokines TNF-α, IL-1β and IL-6, and restricted the levels of CD40 and CD86 in response to IFN-γ and LPS. Moreover, miR-382-5p inhibited the phosphorylation of STAT1. Luciferase reporter assay verified that miR-382-5p might target the 3'UTR of CDK8. Rescue assays revealed that CDK8 reversed the mitigating roles of miR-382-5p in inflammatory response and M1 macrophage polarization, as reflected by increased IL-6 and CD40 levels. Taken together, these findings indicate that miR-382-5p may suppress M1 macrophage activation and inflammatory response via inhibiting CDK8, thereby regulating the development of BPD, which is possibly mediated by STAT1 signaling.

Few targeted drugs were approved for treatment of colorectal cancer (CRC). Cyclin-dependent kinase 8 played a vital role in regulating transcription and was a key colorectal oncogene associated to colorectal cancer. Here, through de novo drug design and in depth structure-activity relationship analysis, title compound

Positional analogue scanning (PAS) is an accepted strategy for multiparameter lead optimization (MPO) in drug discovery. Small structural changes as introduced by PAS can lead to 10-fold changes in binding potency in ∼10-20% of cases, a significant parameter shift irrespective of other MPO objectives. Sometimes performing a complete PAS is challenging due to resource and time constraints, building block availability, or difficulty in synthesis. Calculating relative binding free energies (RBFEs) for all positions can contribute to prioritizing the most promising analogues for synthesis. We tested a well-established RBFE calculation method, Amber GPU-TI, for 20 positional analogue scans in 14 test systems (cyclin-dependent kinase 8 (CDK8), hepatitis C virus nonstructural protein 5B (HCV NS5B), tankyrase, RAC-α serine/threonine-protein kinase (Akt), phosphodiesterase 1B (PDE1B), orexin/hypocretin receptor type 1 (OX1R), orexin/hypocretin receptor type 2 (OX2R), histone acetyltransferase K (lysine) acetyltransferase 6A (KAT6A), peroxisome proliferator-activated receptor γ (PPARγ), extracellular signal-regulated kinases (ERK1/2), coactivator-associated arginine methyltransferase 1 (PRMT4), α

The majority of pituitary adenomas occur in a sporadic context, and in the absence of known genetic predisposition. Three common variants at the

Embryonic stem cells (ESCs) present a characteristic pluripotency heterogeneity correspondent to specific metastates. We recently demonstrated that retinoic acid (RA) induces an increase in a specific 2C-like metastate marked by target genes specific to the two-cell embryo stage in preimplantation. Prame (Preferentially expressed antigen in melanoma) is one of the principal actors of the pluripotency stage with a specific role in RA responsiveness. Additionally, PRAME is overexpressed in a variety of cancers, but its molecular functions are poorly understood. To further investigate Prame's downstream targets, we used a chromatin immunoprecipitation sequencing (ChIP-seq) assay in RA-enriched 2C-like metastates and identified two specific target genes

Breast cancer is the second most common cancer-related cause of death for women throughout the globe. In spite of some effective measures, the main concerns with traditional anti-cancer chemotherapy are its low bioavailability, physical side effects, acquired resistance of cancer cells and non-specific targeting. Now researchers have taken the initiative to establish natural product-based therapy methods and to identify viable hits for future lead optimization in the development of breast cancer medication. Our study aims to identify the potent phytocompounds from five very popular Indian spices (Zingiber officinale Roscoe, Cuminum cyminum L., Piper nigrum L., Curcuma longa L., and Allium sativum L.). From these spices, a total of 200 phytocompounds were identified and screened against three target genes, namely, cyclin-dependent kinase 8 (CDK 8), progesterone receptor (PR) and epidermal growth factor receptor (EGFR), through structure-based virtual screening using iGEMDOCK 2.1 software. Based on the binding affinity score, the top three phytocompounds against each target protein (cynaroside (−149.66 Kcal/mol), apigetrin (−139.527 Kcal/mol) and curcumin (−138.149 Kcal/mol) against CDK8; apigetrin (−123.298 Kcal/mol), cynaroside (−118.635 Kcal/mol) and xyloglucan (−113.788 Kcal/mol) against PR; cynaroside (−119.18 Kcal/mol), apigetrin (−105.185 Kcal/mol) and xyloglucan (−105.106 Kcal/mol) against EGFR) were selected. Apigetrin, cynaroside, curcumin, and xyloglucan were finally identified for further docking analysis with the respective three target proteins. Autodock 4.2 was applied to screen the optimal binding position and to assess the relative intensity of binding interactions. In addition, the ADME/T property checks and bioactivity scores analysis of were performed to understand the suitability of these four phytocompounds to be potential candidates for developing effective and non-toxic anticancer agents. Based on this in silico analysis, we believe this study could contribute to current efforts to develop new drugs for treating breast cancer.

Breast cancers (BrCas) that overexpress oncogenic tyrosine kinase receptor HER2 are treated with HER2-targeting antibodies (such as trastuzumab) or small-molecule kinase inhibitors (such as lapatinib). However, most patients with metastatic HER2+BrCa have intrinsic resistance and nearly all eventually become resistant to HER2-targeting therapy. Resistance to HER2-targeting drugs frequently involves transcriptional reprogramming associated with constitutive activation of different signaling pathways. We have investigated the role of CDK8/19 Mediator kinase, a regulator of transcriptional reprogramming, in the response of HER2+BrCa to HER2-targeting drugs. CDK8 was in the top 1% of all genes ranked by correlation with shorter relapse-free survival among treated HER2+BrCa patients. Selective CDK8/19 inhibitors (senexin B and SNX631) showed synergistic interactions with lapatinib and trastuzumab in a panel of HER2+BrCa cell lines, overcoming and preventing resistance to HER2-targeting drugs. The synergistic effects were mediated in part through the PI3K/AKT/mTOR pathway and reduced by PI3K inhibition. Combination of HER2- and CDK8/19-targeting agents inhibited STAT1 and STAT3 phosphorylation at S727 and up-regulated tumor suppressor BTG2. The growth of xenograft tumors formed by lapatinib-sensitive or -resistant HER2+breast cancer cells was partially inhibited by SNX631 alone and strongly suppressed by the combination of SNX631 and lapatinib, overcoming lapatinib resistance. These effects were associated with decreased tumor cell proliferation and altered recruitment of stromal components to the xenograft tumors. These results suggest potential clinical benefit of combining HER2- and CDK8/19-targeting drugs in the treatment of metastatic HER2+BrCa.

Activated and promoter-bound heat-shock transcription factor 1 (HSF1) induces RNA polymerase II recruitment upon heat shock, and this is facilitated by the core Mediator in Drosophila and yeast. Another Mediator module, CDK8 kinase module (CKM), consisting of four subunits including MED12 and CDK8, plays a negative or positive role in the regulation of transcription; however, its involvement in HSF1-mediated transcription remains unclear. We herein demonstrated that HSF1 interacted with MED12 and recruited MED12 and CDK8 to the HSP70 promoter during heat shock in mammalian cells. The kinase activity of CDK8 (and its paralog CDK19) promoted HSP70 expression partly by phosphorylating HSF1-S326 and maintained proteostasis capacity. These results indicate an important role for CKM in the protection of cells against proteotoxic stress.

Fine-tuning of lipogenic gene expression is important for the maintenance of long-term homeostasis of intracellular lipids. The SREBP family of transcription factors are master regulators that control the transcription of lipogenic and cholesterogenic genes, but the mechanisms modulating SREBP-dependent transcription are still not fully understood. We previously reported that CDK8, a subunit of the transcription co-factor Mediator complex, phosphorylates SREBP at a conserved threonine residue. Here, using Drosophila as a model system, we observed that the phosphodeficient SREBP proteins (SREBP-Thr390Ala) were more stable and more potent in stimulating the expression of lipogenic genes and promoting lipogenesis in vivo than wild-type SREBP. In addition, starvation blocked the effects of wild-type SREBP-induced lipogenic gene transcription, whereas phosphodeficient SREBP was resistant to this effect. Furthermore, our biochemical analyses identified six highly conserved amino acid residues in the N-terminus disordered region of SREBP that are required for its interactions with both Cdk8 and the MED15 subunit of the small Mediator complex. These results support that the concerted actions of Cdk8 and MED15 are essential for the tight regulation of SREBP-dependent transcription. This article has an associated First Person interview with the first author of the paper.

Increasing the anti-inflammatory cytokine interleukin-10 (IL-10) level is a promising strategy to suppress the progression of pathogenic inflammation including inflammatory bowel disease (IBD). Since cyclin-dependent kinase 8 (CDK8) inhibition can upregulate IL-10 abundance in activated myeloid-derived dendritic cells, it is considered to be an effective target for IBD treatment. Here, the complete discovery process of a novel CDK8 inhibitor as an anti-inflammatory agent was described. Starting with wogonin, structure-based optimization and structure-activity relationship (SAR) study were comprehensively carried out, and then lead compound

Glioblastoma (GBM) is the most malignant form of glioma. Glioma stem cells (GSCs) contribute to the initiation, progression, and recurrence of GBM as a result of their self-renewal potential and tumorigenicity. Cyclin-dependent kinase 8 (CDK8) belongs to the transcription-related CDK family. Although CDK8 has been shown to be implicated in the malignancy of several types of cancer, its functional role and mechanism in gliomagenesis remain largely unknown. Here, we demonstrate how CDK8 plays an essential role in maintaining stemness and tumorigenicity in GSCs. The genetic inhibition of CDK8 by shRNA or CRISPR interference resulted in an abrogation of the self-renewal potential and tumorigenicity of patient-derived GSCs, which could be significantly rescued by the ectopic expression of c-MYC, a stem cell transcription factor. Moreover, we demonstrated that the pharmacological inhibition of CDK8 significantly attenuated the self-renewal potential and tumorigenicity of GSCs. CDK8 expression was significantly higher in human GBM tissues than in normal brain tissues, and its expression was positively correlated with stem cell markers including c-MYC and SOX2 in human GBM specimens. Additionally, CDK8 expression is associated with poor survival in GBM patients. Collectively, these findings highlight the importance of the CDK8-c-MYC axis in maintaining stemness and tumorigenicity in GSCs; these findings also identify the CDK8-c-MYC axis as a potential target for GSC-directed therapy.

Uterine cervical cancer (UCC), or carcinoma of the uterine cervix, is a familiar malignancy in gynecology. The expression of multiple microRNAs is abnormal in UCC. Research has demonstrated that the level of microRNA-101 (miR-101) was decreased in UCC, but the mechanism by which miR-101 regulates UCC is still unclear. The TargetScan software predicted that one of the target genes of miR-101 was CDK8. This study aims to explore whether miR-101 affects the migration, invasion, and proliferation of UCC cells through CDK8. First, nanoparticle-assisted PCR was used to determine the levels of miR-101 and CDK8 in UCC tissues, normal adjacent tissues, and two UCC cell lines, C-33A and Siha. Compared to the normal tissues, the level of miR-101 was decreased in UCC tissues, while the level of CDK8 was increased. The dual-luciferase reporter experiments confirmed that miR-101 directly interacted with the binding site in CDK8 3’UTR to regulate luciferase activity. The UCC cells were transfected with the MIR101 mimic construct to overexpress miR-101. It was demonstrated that cell migration, invasion, and proliferation was reduced in C-33A cells overexpressing miR-101. In the cells co-transfected with CDK8 and MIR101, the overexpression of CDK8 reversed the effect of MIR101 overexpression on cell migration, invasion, and proliferation. Therefore, miR-101 can regulate the migration, invasion, and proliferation of UCC cells by targeting CDK8. Therefore, miR-101 has potential applications in the treatment of UCC.

Background Gastric cancer (GC) is a malignant tumor with a significantly high mortality rate, yet, its pathogenesis is not fully understood. Bioinformatics predicted that LINC01224 is highly expressed in stomach adenocarcinoma (STAD), and showed that LINC01224 adsorbed miR‐193a‐5p to target CDK8. Therefore, this study intended to verify the effect of the LINC01224/miR‐193a‐5p/CDK8 axis on the biological behavior of gastric cancer. Methods Expressions of LINC01224, miR‐193a‐5p, CDK8, apoptosis‐, and EMT‐related genes were analyzed using the GEPIA website, RT‐qPCR, in situ hybridization, and Western blot as needed. Bioinformatics and dual luciferase assay were used to evaluate the relationship between LINC01224, miR‐193a‐5p, and CDK8. Functional experiments and rescue experiments (MTT assay, flow cytometry, wound healing assay, and Transwell) were conducted to detect the effects of the above genes on the biological characteristics of GC cells. Tumorigenesis assay was used to verify the results of in vitro experiments. Results LINC01224 adsorbed miR‐193a‐5p to target and upregulate CDK8. The expressions of LINC01224 and CDK8 were increased, while the expression of miR‐193a‐5p was decreased in GC. Overexpressed LINC01224 promoted cell viability, migration and invasion, accelerated tumor formation, attenuated apoptosis, inhibited the expressions of apoptosis‐related proteins, and promoted the expressions of EMT‐related proteins, whereas silenced LINC01224 led to the opposite effect. MiR‐193a‐5p inhibitor partially offset the effect of silenced LINC01224; interestingly, siCDK8 significantly reversed the effect of miR‐193a‐5p inhibitor on GC cells. Conclusion LINC01224 affects the biological behavior of gastric cancer by mediating miR‐193a‐5p to regulate CDK8.

Mediator is a conserved transcriptional co-activator that links transcription factors bound at enhancer elements to RNA Polymerase II. Mediator-RNA Polymerase II interactions can be sterically hindered by the Cyclin Dependent Kinase 8 (CDK8) module, a submodule of Mediator that acts to repress transcription in response to discrete cellular and environmental cues. The CDK8 module is conserved in all eukaryotes and consists of 4 proteins: CDK8, CYCLIN C (CYCC), MED12, and MED13. In this study, we have characterized the CDK8 module of Mediator in maize using genomic, molecular and functional resources. The maize genome contains single copy genes for Cdk8, CycC, and Med13, and two genes for Med12. Analysis of expression data for the CDK8 module demonstrated that all five genes are broadly expressed in maize tissues, and change their expression in response to phosphate and nitrogen limitation. We performed Dissociation (Ds) insertional mutagenesis, recovering two independent insertions in the ZmMed12a gene, one of which produces a truncated transcript. Our molecular identification of the maize CDK8 module, assays of CDK8 module expression under nutrient limitation, and characterization of transposon insertions in ZmMed12a establish the basis for molecular and functional studies of the role of these important transcriptional regulators in development and nutrient homeostasis in Zea mays.

Mediator complex subunit 13 (MED13, previously known as THRAP1 and TRAP240) is a subunit of the cyclin-dependent kinase 8 (CDK8) kinase module in the eukaryotic mediator complex. MED13 has been known to play critical roles in cell cycle, development, and growth. The purpose of this review is to comprehensively discuss its newly identified potential roles in myocardial energy metabolism and non-metabolic cardiovascular diseases. Evidence indicates that cardiac MED13 mainly participates in the regulation of nuclear receptor signaling, which drives the transcription of genes involved in modulating cardiac and systemic energy homeostasis. MED13 is also associated with several pathological conditions, such as metabolic syndrome and thyroid disease-associated heart failure. Therefore, MED13 constitutes a potential therapeutic target for the regulation of metabolic disorders and other cardiovascular diseases.

Alkylating drugs are among the most often used chemotherapeutics. While cancer cells frequently develop resistance to alkylation treatments, detailed understanding of mechanisms that lead to the resistance is limited. Here, by using genome-wide CRISPR–Cas9 based screen, we identify transcriptional Mediator complex subunit 13 (MED13) as a novel modulator of alkylation response. The alkylation exposure causes significant MED13 downregulation, while complete loss of MED13 results in reduced apoptosis and resistance to alkylating agents. Transcriptome analysis identified cyclin D1 (CCND1) as one of the highly overexpressed genes in MED13 knock-out (KO) cells, characterized by shorter G1 phase. MED13 is able to bind to CCND1 regulatory elements thus influencing the expression. The resistance of MED13 KO cells is directly dependent on the cyclin D1 overexpression, and its down-regulation is sufficient to re-sensitize the cells to alkylating agents. We further demonstrate the therapeutic potential of MED13-mediated response, by applying combinatory treatment with CDK8/19 inhibitor Senexin A. Importantly, the treatment with Senexin A stabilizes MED13, and in combination with alkylating agents significantly reduces viability of cancer cells. In summary, our findings identify novel alkylation stress response mechanism dependent on MED13 and cyclin D1 that can serve as basis for development of innovative therapeutic strategies., Graphical Abstract Graphical AbstractModel of MED13 regulated response to alkylation. Created with BioRender.com.

Transcriptional dysregulation is central to many diseases including cancer. Mutation or deregulated expression of proteins involved in transcriptional machinery leads to aberrant gene expression that disturbs intricate cellular processes of division and differentiation. The subunits of the mediator complex are master regulators of stimuli-derived transcription and are essential for transcription by RNA polymerase II. MED12 is a part of the CDK8 kinase module of the mediator complex and is essential for kinase assembly and function. Other than its function in activation of the kinase activity of CDK8 mediator, it also brings about transcription repression or activation, in response to several signalling pathways, a function that is independent of its role as a part of kinase assembly. Accumulating evidence suggests that MED12 controls complex transcription programs that are defining in cell fate determination, differentiation, and carcinogenesis. Mutations or differential expression of MED12 manifest in several human disorders and diseases. For instance, MED12 mutations are the gold standard for the diagnosis of several X-linked intellectual disability syndromes. Further, certain MED12 mutations are categorised as driver mutations in carcinogenesis as well. This is a timely review that provides for the first time a wholesome view on the critical roles and pathways regulated by MED12, its interactions along with the implications of MED12 alterations/mutations in various cancers and nonneoplastic disorders. Based on the preclinical studies, MED12 indeed emerges as an attractive novel therapeutic target for various diseases and intellectual disorders.

Background: Pancreatic cancer (PC) is a leading cause of cancer-related deaths worldwide. Human leukocyte antigen complex P5 (HCP5), a member of long noncoding RNAs (lncRNAs), was reported to be associated with the poor prognosis of PC. However, the mechanism of HCP5 in regulating the progression of PC remains poorly defined. Materials and Methods: Quantitative real-time polymerase chain reaction was performed to detect the expression levels of HCP5, microRNA (miR)-140-5p, and cyclin-dependent kinase 8 (CDK8) in PC tissues and cells. Cell counting kit-8 (CCK-8) assay was utilized to check cell proliferation. Transwell assay was employed to evaluate the abilities of cell migration and invasion. Xenograft tumor model was established to investigate the biological role of HCP5 in PC in vivo. The interaction between miR-140-5p and HCP5 or CDK8 was predicted by starBase or TargetScan, respectively. The dual-luciferase reporter assay was conducted to corroborate the interaction. The protein level of CDK8 was measured by Western blot. Results: HCP5 and CDK8 were significantly upregulated in PC tissues and cells, opposite to the expression of miR-140-5p. High expression of HCP5 contributed to the low survival rate and HCP5 silencing inhibited proliferation, migration, and invasion of PC cells in vitro. Simultaneously, in vivo experiments indicated that downregulation of HCP5 suppressed tumor growth. In addition, miR-140-5p was a target of HCP5 and bound to the 3'-untranslated region (3'UTR) of CDK8. Further studies revealed that overexpression of CDK8 reversed the miR-140-5p-mediated inhibitory effect on PC progression. Moreover, downregulation of miR-140-5p or upregulation of CDK8 inverted the silencing-mediated repressive impact of HCP5 on PC progression. Conclusion: Downregulation of HCP5 impeded PC progression by downregulating CDK8 via sponging miR-140-5p.

Breast cancer displays high morbidity and mortality. Despite exerting certain effects, traditional treatments cannot eliminate every cancer cell and may kill normal cells due to inaccurate targeting. However, as a traditional Chinese medicine, capsaicin, an active compound extracted from chili peppers, has displayed potent anticarcinogenic activities in vitro and in vivo, but the underlying mechanism is not completely understood. The pharmacological effects of capsaicin on tumors was evaluated in MDA MB 231 breast cancer cells. The MTT, cell scratch assay, cell cycle analysis, cell transfection, reverse transcription‑quantitative PCR and western blotting were performed to investigate the potential antitumor mechanisms of capsaicin. In the present study, the potential anticancer mechanism underlying capsaicin in MDA‑MB‑231 cells in vitro was investigated. Capsaicin significantly inhibited MDA‑MB‑231 breast cancer cell viability and migration compared with the control group. The flow cytometry results indicated that capsaicin induced G2/M cell cycle arrest in MDA‑MB‑231 cells. In addition, capsaicin significantly reduced the expression of cyclin‑dependent kinase 8 (CDK8) in breast cancer cells compared with the control group. Moreover, LV‑CDK8 small interfering RNA‑transduced MDA‑MB‑231 cells displayed lower CDK8 mRNA and protein expression levels compared with LV‑negative control‑shRNA‑transduced cells. Furthermore, capsaicin significantly reduced the expression levels of phosphorylated (p)‑PI3K, p‑Akt, Wnt and β‑catenin in vitro compared with the control group. Collectively, the results of the present study suggested that capsaicin inhibited breast cancer cell viability, induced G2/M cell cycle arrest, reduced CDK8 expression levels, decreased the phosphorylation of PI3K and Akt and downregulated Wnt and β‑catenin expression levels in MDA‑MB‑231 cells.

Chronic inflammation is an underlying cause in a number of diseases. Cyclin-dependent kinase 8 (CDK8) has been implicated as an inflammatory mediator, indicating its potential as an anti-inflammatory target. Herein, we performed structure-based virtual screening (SBVS) to identify novel CDK8 inhibitors. The pharmacological interactions for CDK8 were identified and incorporated into a SBVS protocol. Selected compounds were tested in enzymatic assays, and one compound was confirmed to be a CDK8 inhibitor with a 50% inhibitory concentration (IC50) value of 1684.4 nM. Comparing structural analogs identified a compound, F059–1017, with greater potency (IC50 558.1 nM). When tested in cell lines, the compounds displayed low cytotoxicity. Cellular assays revealed that the identified CDK8 inhibitors can reduce phosphorylation and expression of signaling mediators associated with inflammation. In addition, results of kinase profiling showed that compound F059–1017 is selective towards CDK8. These findings suggest that the new inhibitors have great potential as lead compounds for developing novel anti-inflammatory therapeutics.

Cyclin-dependent kinase 8 (CDK8) is associated with the transcriptional mediator complex and regulates several transcription factors implicated in cancer. CDK8 expression is a poor prognostic marker in colon and breast cancer by immunohistochemistry. However, somatic mutations in exon 2 of the RNA polymerase II transcriptional mediator subunit MED12 occur in 7-30% of cases of uterine leiomyosarcoma (ULMS), suggesting that these alterations contribute to tumorigenesis. Public genomic mutation data of 80 patients with ULMS were used for MED12 and CDK8 mutation analysis. The expression of MED12, CDK8 and β-catenin was evaluated by immunohistochemistry in our cohort of 60 patients with ULMS, in addition with MED12 mutation status and survival stage. Univariate analysis was performed using the log-rank test, and Cox regression was used to identify independent prognostic factors. Multivariate Cox regression analysis revealed that advanced stage (p 0.0001) and high CDK8 expression (p = 0.0014) were independent predictors of poor prognosis. MED12 mutation status was not significantly associated with CDK8 expression (p = 0.6873) and DSS (p = 0.8075). In conclusion, our data suggest that CDK8 expression may identify a subset of ULMS patients with a poor prognosis.

Initiation and maintenance of transcriptional states are critical for controlling normal tissue homeostasis and differentiation. The cyclin dependent kinases CDK8 and CDK19 (Mediator kinases) are regulatory components of Mediator, a highly conserved complex that orchestrates enhancer-mediated transcriptional output. While Mediator kinases have been implicated in the transcription of genes necessary for development and growth, its function in mammals has not been well defined. Using genetically defined models and pharmacological inhibitors, we showed that CDK8 and CDK19 function in a redundant manner to regulate intestinal lineage specification in humans and mice. The Mediator kinase module bound and phosphorylated key components of the chromatin remodeling complex switch/sucrose non-fermentable (SWI/SNF) in intestinal epithelial cells. Concomitantly, SWI/SNF and MED12-Mediator colocalized at distinct lineage-specifying enhancers in a CDK8/19-dependent manner. Thus, these studies reveal a transcriptional mechanism of intestinal cell specification, coordinated by the interaction between the chromatin remodeling complex SWI/SNF and Mediator kinase.