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Cancer Metastasis Reviews Sep 2020Cyclin-dependent kinase 7 (CDK7), along with cyclin H and MAT1, forms the CDK-activating complex (CAK), which directs progression through the cell cycle via T-loop... (Review)
Review
Cyclin-dependent kinase 7 (CDK7), along with cyclin H and MAT1, forms the CDK-activating complex (CAK), which directs progression through the cell cycle via T-loop phosphorylation of cell cycle CDKs. CAK is also a component of the general transcription factor, TFIIH. CDK7-mediated phosphorylation of RNA polymerase II (Pol II) at active gene promoters permits transcription. Cell cycle dysregulation is an established hallmark of cancer, and aberrant control of transcriptional processes, through diverse mechanisms, is also common in many cancers. Furthermore, CDK7 levels are elevated in a number of cancer types and are associated with clinical outcomes, suggestive of greater dependence on CDK7 activity, compared with normal tissues. These findings identify CDK7 as a cancer therapeutic target, and several recent publications report selective CDK7 inhibitors (CDK7i) with activity against diverse cancer types. Preclinical studies have shown that CDK7i cause cell cycle arrest, apoptosis and repression of transcription, particularly of super-enhancer-associated genes in cancer, and have demonstrated their potential for overcoming resistance to cancer treatments. Moreover, combinations of CDK7i with other targeted cancer therapies, including BET inhibitors, BCL2 inhibitors and hormone therapies, have shown efficacy in model systems. Four CDK7i, ICEC0942 (CT7001), SY-1365, SY-5609 and LY3405105, have now progressed to Phase I/II clinical trials. Here we describe the work that has led to the development of selective CDK7i, the current status of the most advanced clinical candidates, and discuss their potential importance as cancer therapeutics, both as monotherapies and in combination settings. ClinicalTrials.gov Identifiers: NCT03363893; NCT03134638; NCT04247126; NCT03770494.
Topics: Animals; Antineoplastic Agents; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Cyclin-Dependent Kinases; Humans; Neoplasms; Protein Kinase Inhibitors; Cyclin-Dependent Kinase-Activating Kinase
PubMed: 32385714
DOI: 10.1007/s10555-020-09885-8 -
Cancer Cell International 2020Cell cycle dysregulation plays a key role in the pathogenesis of malignant tumors. As a part of the CDK-activating kinase (CAK) trimeric complex, cyclin H is necessary...
BACKGROUND
Cell cycle dysregulation plays a key role in the pathogenesis of malignant tumors. As a part of the CDK-activating kinase (CAK) trimeric complex, cyclin H is necessary to regulate the cell cycle and proliferation. This investigation aims to characterize the clinical significance and the biological functions of cyclin H in ovarian cancer.
METHODS
Immunohistochemical staining was performed on 60 ovarian cancer cases, and a correlation between cyclin H expression and the clinical characteristics of ovarian cancer was analyzed. The function of cyclin H in ovarian cancer was further explored using HO8910 cells and a subcutaneous xenograft model of nude mice.
RESULT
Cyclin H was slightly expressed in grade 1 ovarian cancer but highly expressed in grade 2 and grade 3 cancerous tissues. The Spearman's rank correlation analysis showed that the expression of cyclin H is positively correlated with the tumor grade, the FIGO stage, histological grade, and the peritoneal metastasis of ovarian cancer and is also positively correlated with the Ki67 and p-CDK2 in ovarian cancer. Additionally, we found that the five-year survival rate was higher in patients expressing low cyclin H than those expressing high cyclin H. Further, knockdown of cyclin H was achieved using an shRNA in HO8910 ovarian cancer cell line. Silencing cyclin H resulted in a G1/S cell cycle arrest in ovarian cancer cells suppressing its growth. The Ki67 expression was also decreased in cyclin H silenced ovarian cancer.
CONCLUSION
These results suggest that high expression of cyclin H predicts the poor prognosis and promotes the growth of ovarian cancer by regulating the cell cycle.
PubMed: 32694938
DOI: 10.1186/s12935-020-01406-5 -
Proceedings of the National Academy of... Oct 2020Cyclin-dependent kinase 7 (CDK7), Cyclin H, and the RING-finger protein MAT1 form the heterotrimeric CDK-activating kinase (CAK) complex which is vital for transcription...
Cyclin-dependent kinase 7 (CDK7), Cyclin H, and the RING-finger protein MAT1 form the heterotrimeric CDK-activating kinase (CAK) complex which is vital for transcription and cell-cycle control. When associated with the general transcription factor II H (TFIIH) it activates RNA polymerase II by hyperphosphorylation of its C-terminal domain (CTD). In the absence of TFIIH the trimeric complex phosphorylates the T-loop of CDKs that control cell-cycle progression. CAK holds a special position among the CDK branch due to this dual activity and the dependence on two proteins for activation. We solved the structure of the CAK complex from the model organism at 2.6-Å resolution. Our structure reveals an intricate network of interactions between CDK7 and its two binding partners MAT1 and Cyclin H, providing a structural basis for the mechanism of CDK7 activation and CAK activity regulation. In vitro activity measurements and functional mutagenesis show that CDK7 activation can occur independent of T-loop phosphorylation and is thus exclusively MAT1-dependent by positioning the CDK7 T-loop in its active conformation.
Topics: Cell Cycle; Chaetomium; Cyclin H; Cyclin-Dependent Kinases; Fungal Proteins; Phosphorylation; Transcription, Genetic; Cyclin-Dependent Kinase-Activating Kinase
PubMed: 33055219
DOI: 10.1073/pnas.2010885117 -
Virus Research Oct 2023Human cytomegalovirus (HCMV) infection is shaped by a tightly regulated interplay between viral and cellular proteins. Distinct kinase activities, such as the viral...
Human cytomegalovirus (HCMV) infection is shaped by a tightly regulated interplay between viral and cellular proteins. Distinct kinase activities, such as the viral cyclin-dependent kinase ortholog (vCDK) pUL97 and cellular CDK7 are both crucial for efficient viral replication. Previously, we reported that both kinases, vCDK/pUL97 and CDK7, interact with cyclin H, thereby achieving an enhanced level of kinase activity and overall functionality in viral replication. Here we provide a variety of novel results, as generated on a methodologically extended basis, and present a concept for the codetermination of viral replication efficiency through these kinase activities: (i) cyclin H expression, in various human cell types, is substantially upregulated by strains of HCMV including the clinically relevant HCMV Merlin; (ii) vCDK/pUL97 interacts with human cyclin H in both HCMV-infected and plasmid-transfected cell systems; (iii) a doxycycline-inducible shRNA-dependent knock-down (KD) of cyclin H significantly reduces pUL97 activity (qSox in vitro kinase assay); (iv) accordingly, pUL97 in vitro kinase activity is seen significantly increased upon addition of recombinant cyclin H; (v) as a point of specific importance, human CDK7 activity shows an increase by vCDK/pUL97-mediated trans-stimulation (whereas pUL97 is not stimulated by CDK7); (vi) phosphosite-specific antibodies indicate an upregulated CDK7 phosphorylation upon HCMV infection, as mediated through a pUL97-specific modulatory effect (i.e. shown by pUL97 inhibitor treatment or pUL97-deficient viral mutant); (vii) finally, an efficient KD of cyclin H in primary fibroblasts generally results in an impaired HCMV replication efficiency as measured on protein and genomic levels. These results show evidence for the codetermination of viral replication by vCDK/pUL97, cyclin H and CDK7, thus supporting the specific importance of cyclin H as a central regulatory factor, and suggesting novel targeting options for antiviral drugs.
Topics: Humans; Antiviral Agents; Cyclin H; Cyclin-Dependent Kinases; Cytomegalovirus; Phosphorylation
PubMed: 37591314
DOI: 10.1016/j.virusres.2023.199200 -
Computational and Mathematical Methods... 2021Studies have previously shown that Cyclin H (CCNH) is involved in the tumorigenesis and development of many cancers. The increasing research in CCNH is associated with...
INTRODUCTION
Studies have previously shown that Cyclin H (CCNH) is involved in the tumorigenesis and development of many cancers. The increasing research in CCNH is associated with the poor prognosis of most human cancers. Early diagnosis and clinical treatment are still the main challenges for lung cancer treatment. However, the exact role of CCNH in the tumorigenesis of lung cancer remains unclear.
METHODS
The Tumor Genome Atlas (TCGA) database and the Clinical Proteomics Tumor Analysis Association (CPTAC) database were analyzed to detect key genes that might play an important role in lung cancer. The biological functions of CCNH were further revealed through bioinformatics experiments. The Kaplan-Meier method was applied to explore the relationship between CCNH expression and prognosis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to detect the expression levels of CCNH in 6 lung cancer tissues and 3 cancer cell lines. The effect of CCNH expression on lung cancer progression was studied by in vitro functional experiments.
RESULTS
Database analysis screened out candidate oncogenes, and CCNH was of great significance to the tumorigenesis of lung cancer. The higher the expression of CCNH was, the lower the survival rate of lung cancer patients were. The qRT-PCR data illustrated that the CCNH expression level was largely increased in lung cancer tissues and cells. The reduction of CCNH inhibited cell proliferation, invasion, and migration.
CONCLUSION
CCNH was related to poor prognosis, suggesting that CCNH regulated the tumorigenesis and development of lung cancer. Our study suggested that CCNH was a promising biomarker and target in the treatment of lung cancer.
Topics: Adenocarcinoma of Lung; Biomarkers, Tumor; Carcinogenesis; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Movement; Cell Proliferation; Computational Biology; Cyclin H; Databases, Genetic; Disease Progression; Gene Expression Regulation, Neoplastic; Humans; Kaplan-Meier Estimate; Lung Neoplasms; Neoplasm Invasiveness; Prognosis; Protein Interaction Maps; Proteomics
PubMed: 33777168
DOI: 10.1155/2021/6646077 -
International Journal of Molecular... Oct 2022The complex host interaction network of human cytomegalovirus (HCMV) involves the regulatory protein kinase pUL97, which represents a viral cyclin-dependent kinase (CDK)...
Highly Conserved Interaction Profiles between Clinically Relevant Mutants of the Cytomegalovirus CDK-like Kinase pUL97 and Human Cyclins: Functional Significance of Cyclin H.
The complex host interaction network of human cytomegalovirus (HCMV) involves the regulatory protein kinase pUL97, which represents a viral cyclin-dependent kinase (CDK) ortholog. pUL97 interacts with the three human cyclin types T1, H, and B1, whereby the binding region of cyclin T1 and the pUL97 oligomerization region were both assigned to amino acids 231-280. We further addressed the question of whether HCMVs harboring mutations in ORF-UL97, i.e., short deletions or resistance-conferring point mutations, are affected in the interaction with human cyclins and viral replication. To this end, clinically relevant UL97 drug-resistance-conferring mutants were analyzed by whole-genome sequencing and used for genetic marker transfer experiments. The recombinant HCMVs indicated conservation of pUL97-cyclin interaction, since all viral UL97 point mutants continued to interact with the analyzed cyclin types and exerted wild-type-like replication fitness. In comparison, recombinant HCMVs UL97 Δ231-280 and also the smaller deletion Δ236-275, but not Δ241-270, lost interaction with cyclins T1 and H, showed impaired replication efficiency, and also exhibited reduced kinase activity. Moreover, a cellular knock-out of cyclins B1 or T1 did not alter HCMV replication phenotypes or pUL97 kinase activity, possibly indicating alternative, compensatory pUL97-cyclin interactions. In contrast, however, cyclin H knock-out, similar to virus deletion mutants in the pUL97-cyclin H binding region, exhibited strong defective phenotypes of HCMV replication, as supported by reduced pUL97 kinase activity in a cyclin H-dependent coexpression setting. Thus, cyclin H proved to be a very relevant determinant of pUL97 kinase activity and viral replication efficiency. As a conclusion, the results provide evidence for the functional importance of pUL97-cyclin interaction. High selective pressure on the formation of pUL97-cyclin complexes was identified by the use of clinically relevant mutants.
Topics: Amino Acids; Cyclin H; Cyclin T; Cyclin-Dependent Kinases; Cytomegalovirus; Genetic Markers; Humans; Phosphorylation; Phosphotransferases (Alcohol Group Acceptor); Viral Proteins; Virus Replication
PubMed: 36233116
DOI: 10.3390/ijms231911814 -
ACS Omega Jan 2023Natural products have been a great source of leads for cancer drug discovery. The cyclin-dependent kinases (CDKs) play a vital role in the initiation and progression of...
Natural products have been a great source of leads for cancer drug discovery. The cyclin-dependent kinases (CDKs) play a vital role in the initiation and progression of cancer. The CDK-activating kinase, CDK7/cyclin H/MAT1, has recently gained tremendous attention in targeted cancer drug discovery. Herein, we screened a small library of pure natural products in an ADP-Glo CDK7/H kinase assay that yielded a series of furano- and naphthoflavonoids among actives. Pongol (SBN-88), the hydroxy-substituted furanoflavonoid, inhibits CDK7/H as well as CDK9/T1 with IC values of 0.93 and 0.83 μM, respectively, and >20-fold selectivity over CDK2/E1 (IC > 20 μM). The molecular docking and molecular dynamics simulation revealed that the presence of phenolic -OH in pongol is vital for kinase inhibition, as its absence resulted in a significant loss in activity (e.g., lanceolatin B). The prime MM-GBSA calculations revealed the presence of strong lipophilic and H-bonding interactions of pongol with CDKs.
PubMed: 36643464
DOI: 10.1021/acsomega.2c06733 -
Clinical Cancer Research : An Official... Dec 2016CDK-activating kinase (CAK) is required for the regulation of the cell cycle and is a trimeric complex consisting of cyclin-dependent kinase 7 (CDK7), Cyclin H, and the...
PURPOSE
CDK-activating kinase (CAK) is required for the regulation of the cell cycle and is a trimeric complex consisting of cyclin-dependent kinase 7 (CDK7), Cyclin H, and the accessory protein, MAT1. CDK7 also plays a critical role in regulating transcription, primarily by phosphorylating RNA polymerase II, as well as transcription factors such as estrogen receptor-α (ER). Deregulation of cell cycle and transcriptional control are general features of tumor cells, highlighting the potential for the use of CDK7 inhibitors as novel cancer therapeutics.
EXPERIMENTAL DESIGN
mRNA and protein expression of CDK7 and its essential cofactors cyclin H and MAT1 were evaluated in breast cancer samples to determine if their levels are altered in cancer. Immunohistochemical staining of >900 breast cancers was used to determine the association with clinicopathologic features and patient outcome.
RESULTS
We show that expressions of CDK7, cyclin H, and MAT1 are all closely linked at the mRNA and protein level, and their expression is elevated in breast cancer compared with the normal breast tissue. Intriguingly, CDK7 expression was inversely proportional to tumor grade and size, and outcome analysis showed an association between CAK levels and better outcome. Moreover, CDK7 expression was positively associated with ER expression and in particular with phosphorylation of ER at serine 118, a site important for ER transcriptional activity.
CONCLUSIONS
Expressions of components of the CAK complex, CDK7, MAT1, and Cyclin H are elevated in breast cancer and correlate with ER. Like ER, CDK7 expression is inversely proportional to poor prognostic factors and survival. Clin Cancer Res; 22(23); 5929-38. ©2016 AACR.
Topics: Adult; Breast Neoplasms; Carrier Proteins; Cell Cycle Proteins; Cyclin H; Cyclin-Dependent Kinases; Female; Gene Expression; Humans; Middle Aged; Phosphorylation; Prognosis; Receptors, Estrogen; Signal Transduction; Transcription Factors; Transcription, Genetic; Cyclin-Dependent Kinase-Activating Kinase
PubMed: 27301701
DOI: 10.1158/1078-0432.CCR-15-1104 -
International Journal of Molecular... Dec 2023The infection of human cytomegalovirus (HCMV) is strongly determined by the host-cell interaction in a way that the efficiency of HCMV lytic replication is dependent on...
The infection of human cytomegalovirus (HCMV) is strongly determined by the host-cell interaction in a way that the efficiency of HCMV lytic replication is dependent on the regulatory interplay between viral and cellular proteins. In particular, the activities of protein kinases, such as cyclin-dependent kinases (CDKs) and the viral CDK ortholog (vCDK/pUL97), play an important role in both viral reproduction and virus-host interaction. Very recently, we reported on the complexes formed between vCDK/pUL97, human cyclin H, and CDK7. Major hallmarks of this interplay are the interaction between cyclin H and vCDK/pUL97, which is consistently detectable across various conditions and host cell types of infection, the decrease or increase in pUL97 kinase activity resulting from cyclin H knock-down or elevated levels, respectively, and significant trans-stimulation of human CDK7 activity by pUL97 in vitro. Due to the fact that even a ternary complex of vCDK/pUL97-cyclin H-CDK7 can be detected by coimmunoprecipitation and visualized by bioinformatic structural modeling, we postulated a putative impact of the respective kinase activities on the patterns of transcription in HCMV-infected cells. Here, we undertook a first vCDK/pUL97-specific transcriptomic analysis, which combined conditions of fully lytic HCMV replication with those under specific vCDK/pUL97 or CDK7 drug-mediated inhibition or transient cyclin H knockout. The novel results were further strengthened using bioinformatic modeling of the involved multi-protein complexes. Our data underline the importance of these kinase activities for the C-terminal domain (CTD) phosphorylation-driven activation of host RNA polymerase in HCMV-infected cells. The impact of the individual experimental conditions on differentially expressed gene profiles is described in detail and discussed.
Topics: Humans; Cyclins; Cytomegalovirus; Cyclin H; Cyclin-Dependent Kinases; Phosphorylation; Herpesviridae Infections
PubMed: 38139252
DOI: 10.3390/ijms242417421 -
The Journal of Biological Chemistry Aug 2018The avian reovirus p17 protein is a nucleocytoplasmic shuttling protein. Although we have demonstrated that p17 causes cell growth retardation via activation of p53, the...
The avian reovirus p17 protein is a nucleocytoplasmic shuttling protein. Although we have demonstrated that p17 causes cell growth retardation via activation of p53, the precise mechanisms remain unclear. This is the first report that avian reovirus p17 possesses broad inhibitory effects on cell cycle CDKs, cyclins, CDK-cyclin complexes, and CDK-activating kinase activity in various mammalian, avian, and cancer cell lines. Suppression of CDK activity by p17 occurs by direct binding to CDKs, cyclins, and CDK-cyclin complexes; transcriptional down-regulation of CDKs; cytoplasmic retention of CDKs and cyclins; and inhibition of CDK-activating kinase activity by promoting p53-cyclin H interaction. p17 binds to CDK-cyclin except for CDK1-cyclin B1 and CDK7-cyclin H complexes. We have determined that the negatively charged LAVDVDA(E/D)DGADPN motif in cyclin B1 interacts with a positively charged region of CDK1. p17 mimics the cyclin B1 sequence to compete for CDK1 binding. The PSTAIRE motif is not required for interaction of CDK1-cyclin B1, but it is required for other CDK-cyclin complexes. p17 interacts with cyclins by its cyclin-binding motif, RL Sequence and mutagenic analyses of p17 indicated that a WFD motif and residues Asp-113 and Lys-122 in p17 are critical for CDK2 and CDK6 binding, leading to their sequestration in the cytoplasm. Exogenous expression of p17 significantly enhanced virus replication, whereas p17 mutants with low binding ability to cell cycle CDKs had no effect on virus yield, suggesting that p17 inhibits cell growth and the cell cycle, benefiting virus replication. An tumorigenesis assay also showed a significant reduction in tumor size.
Topics: Animals; Cell Cycle; Chick Embryo; Chlorocebus aethiops; Colorectal Neoplasms; Cyclin H; Cyclin-Dependent Kinases; Cyclins; Humans; Orthoreovirus, Avian; Reoviridae Infections; Tumor Cells, Cultured; Tumor Suppressor Protein p53; Vero Cells; Viral Proteins
PubMed: 29907572
DOI: 10.1074/jbc.RA118.002341