Mirk/dyrk1B Kinase in Ovarian Cancer

Mirk/Dyrk1B Kinase Inhibitors in Targeted Cancer Therapy

During the last years, there has been an increased effort in the discovery of selective and potent kinase inhibitors for targeted cancer therapy. Kinase inhibitors exhibit less toxicity compared to conventional chemotherapy, and several have entered the market. Mirk/Dyrk1B kinase is a promising pharmacological target in cancer since it is overexpressed in many tumors, and its overexpression is correlated with patients' poor prognosis. Mirk/Dyrk1B acts as a negative cell cycle regulator, maintaining the survival of quiescent cancer cells and conferring their resistance to chemotherapies. Many studies have demonstrated the valuable therapeutic effect of Mirk/Dyrk1B inhibitors in cancer cell lines, mouse xenografts, and patient-derived 3D-organoids, providing a perspective for entering clinical trials. Since the majority of Mirk/Dyrk1B inhibitors target the highly conserved ATP-binding site, they exhibit off-target effects with other kinases, especially with the highly similar Dyrk1A. In this review, apart from summarizing the data establishing Dyrk1B as a therapeutic target in cancer, we highlight the most potent Mirk/Dyrk1B inhibitors recently reported. We also discuss the limitations and perspectives for the structure-based design of Mirk/Dyrk1B potent and highly selective inhibitors based on the accumulated structural data of Dyrk1A and the recent crystal structure of Dyrk1B with AZ191 inhibitor.

Mirk/Dyrk1B controls ventral spinal cord development via Shh pathway

Cross-talk between Mirk/Dyrk1B kinase and Sonic hedgehog (Shh)/Gli pathway affects physiology and pathology. Here, we reveal a novel role for Dyrk1B in regulating ventral progenitor and neuron subtypes in the embryonic chick spinal cord (SC) via the Shh pathway. Using in ovo gain-and-loss-of-function approaches at E2, we report that Dyrk1B affects the proliferation and differentiation of neuronal progenitors at E4 and impacts on apoptosis specifically in the motor neuron (MN) domain. Especially, Dyrk1B overexpression decreases the numbers of ventral progenitors, MNs, and V2a interneurons, while the pharmacological inhibition of endogenous Dyrk1B kinase activity by AZ191 administration increases the numbers of ventral progenitors and MNs. Mechanistically, Dyrk1B overexpression suppresses Shh, Gli2 and Gli3 mRNA levels, while conversely, Shh, Gli2 and Gli3 transcription is increased in the presence of Dyrk1B inhibitor AZ191 or Smoothened agonist SAG. Most importantly, in phenotype rescue experiments, SAG restores the Dyrk1B-mediated dysregulation of ventral progenitors. Further at E6, Dyrk1B affects selectively the medial lateral motor neuron column (LMCm), consistent with the expression of Shh in this region. Collectively, these observations reveal a novel regulatory function of Dyrk1B kinase in suppressing the Shh/Gli pathway and thus affecting ventral subtypes in the developing spinal cord. These data render Dyrk1B a possible therapeutic target for motor neuron diseases.

The cardio-oncology continuum: Bridging the gap between cancer and cardiovascular care

Cancer and cardiovascular disease are two of the leading causes of death worldwide. Although cancer has historically been viewed as a condition characterized by abnormal cell growth and proliferation, it is now recognized that cancer can lead to a variety of cardiovascular diseases. This is due to the direct impact of cancer on the heart and blood vessels, which can cause myocarditis, pericarditis, and vasculitis. Additionally, cancer patients frequently experience systemic effects such as oxidative stress, inflammation, and metabolic dysregulation, which can contribute to the development of cardiovascular risk factors such as hypertension, dyslipidemia, and insulin resistance. It is important to closely monitor patients with cancer, especially those undergoing chemotherapy or radiation therapy, for cardiovascular risk factors and promptly address them. This article aims to explore the clinical implications of the underlying mechanisms connecting cancer and cardiovascular diseases. Our analysis highlights the need for improved cooperation between oncologists and cardiologists, and specialized treatment for cancer survivors.

KCa3.1 regulates cell cycle progression by modulating Ca2+ signaling in murine preosteoblasts

Osteoblasts synthesize and deposit essential components of the extracellular bone matrix and collagen scaffolds, leading to mineralized bone formation. Therefore, the proliferation of preosteoblasts (precursors of mature osteoblasts) helps in regulating skeletal homeostasis. This study demonstrated that the functional expression of KCa3.1, an intermediate-conductance Ca2+-activated K+ channel, is markedly upregulated in murine preosteoblastic MC3T3-E1 cells in the G0/G1 phase. The enhancement of KCa3.1 is involved in the establishment of more negative membrane potentials in MC3T3-E1 cells. This hyperpolarization can promote intracellular Ca2+ signaling because store-operated Ca2+ channels are activated. Treatment with TRAM-34, a specific KCa3.1 inhibitor, attenuated the cell cycle progression from the G0/G1 phase to the S/G2/M phases. In MC3T3-E1 cells, KCa3.1 significantly promoted the transition from the G1 phase to the S phase. KCa3.1 inhibition also caused G0 phase cell accumulation. Furthermore, TRAM-34 decreased the expression of alkaline phosphatase, bone sialoprotein, and osteocalcin, osteoblast differentiation markers in MC3T3-E1 cells, and inhibited the endochondral ossification of murine metatarsals. These results reveal novel ways by which KCa3.1 activity can strongly modulate osteoblast maturation during bone formation.

Dual-Specificity Tyrosine Phosphorylation-Regulated Kinase 1B Inhibition Promotes Megakaryocyte Polyploidization and Platelet Production

Platelets are produced from mature megakaryocytes which undergo polyploidization and proplatelet formation. Cell-cycle regulation plays a crucial role in megakaryocyte terminal differentiation especially in polyploidization. Dual-specificity tyrosine phosphorylation-regulated kinase 1B (DYRK1B) controls cell-cycle progression in cancer cells. The objective of this study was to determine DYRK1B function in megakaryocyte maturation and platelet production. A DYRK1B knock-out mouse was generated with increased peripheral platelet count compared with the wild type mouse without affecting megakaryocyte numbers in bone marrow. Polyploidy and proplatelet formations were significantly enhanced when DYRK1B was depleted in vitro. DYRK1B inhibition promoted megakaryocyte maturation by simultaneously upregulating cyclin D1 and downregulating P27. Furthermore, there was platelet restoration in two mice disease models of transient thrombocytopenia. In summary, DYRK1B plays an important role in megakaryocyte maturation and platelet production by interacting with cyclin D1 and P27. DYRK1B inhibition has potential therapeutic value in transient thrombocytopenia treatment. Graphic Abstract.

Discovery of novel benzothiophene derivatives as potent and narrow spectrum inhibitors of DYRK1A and DYRK1B

The discovery of potent and selective inhibitors for understudied kinases can provide relevant pharmacological tools to illuminate their biological functions. DYRK1A and DYRK1B are protein kinases linked to chronic human diseases. Current DYRK1A/DYRK1B inhibitors also antagonize the function of related protein kinases, such as CDC2-like kinases (CLK1, CLK2, CLK4) and DYRK2. Here, we reveal narrow spectrum dual inhibitors of DYRK1A and DYRK1B based on a benzothiophene scaffold. Compound optimization exploited structural differences in the ATP-binding sites of the DYRK1 kinases and resulted in the discovery of 3n, a potent and cell-permeable DYRK1A/DYRK1B inhibitor. This compound has a different scaffold and a narrower off-target profile compared to current DYRK1A/DYRK1B inhibitors. We expect the benzothiophene derivatives described here to aid establishing DYRK1A/DYRK1B cellular functions and their role in human pathologies.

DREAM On: Cell Cycle Control in Development and Disease

Perfectly orchestrated periodic gene expression during cell cycle progression is essential for maintaining genome integrity and ensuring that cell proliferation can be stopped by environmental signals. Genetic and proteomic studies during the past two decades revealed remarkable evolutionary conservation of the key mechanisms that control cell cycle-regulated gene expression, including multisubunit DNA-binding DREAM complexes. DREAM complexes containing a retinoblastoma family member, an E2F transcription factor and its dimerization partner, and five proteins related to products of Caenorhabditis elegans multivulva (Muv) class B genes lin-9, lin-37, lin-52, lin-53, and lin-54 (comprising the MuvB core) have been described in diverse organisms, from worms to humans. This review summarizes the current knowledge of the structure, function, and regulation of DREAM complexes in different organisms, as well as the role of DREAM in human disease. Expected final online publication date for the Annual Review of Genetics, Volume 55 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Synthesis of novel 1H-Pyrazolo[3,4-b]pyridine derivatives as DYRK 1A/1B inhibitors

As DYRK1A and 1B inhibitors, 1H-pyrazolo[3,4-b]pyridine derivatives were synthesized. Mostly, 3-aryl-5-arylamino compounds (6) and 3,5-diaryl compounds (8 and 9) were prepared and especially, 3,5-diaryl compound 8 and 9 showed excellent DYRK1B inhibitory enzymatic activities with IC50 Values of 3-287 nM. Among them, 3-(4-hydroxyphenyl), 5-(3,4-dihydroxyphenyl)-1H-pyrazolo[3,4-b]pyridine (8h) exhibited the highest inhibitory enzymatic activity (IC50 = 3 nM) and cell proliferation inhibitory activity (IC50 = 1.6 µM) towards HCT116 colon cancer cells. Also compound 8h has excellent inhibitory activities in patient-derived colon cancer organoids model as well as in 3D spheroid assay model of SW480 and SW620. The docking study supported that we confirmed that compound 8h binds to DYRK1B through various hydrogen bonding interactions and hydrophobic interactions.

A Crosstalk Between Dual-Specific Phosphatases and Dual-Specific Protein Kinases Can Be A Potential Therapeutic Target for Anti-cancer Therapy

While protein tyrosine kinases (PTKs) play an initiative role in growth factor-mediated cellular processes, protein tyrosine phosphatases (PTPs) negatively regulates these processes, acting as tumor suppressors. Besides selective tyrosine dephosphorylation of PTKs via PTPs may affect oncogenic pathways during carcinogenesis. The PTP family contains a group of dual-specificity phosphatases (DUSPs) that regulate the activity of Mitogen-activated protein kinases (MAPKs), which are key effectors in the control of cell growth, proliferation and survival. Abnormal MAPK signaling is critical for initiation and progression stages of carcinogenesis. Since depletion of DUSP-MAPK phosphatases (MKPs) can reduce tumorigenicity, altering MAPK signaling by DUSP-MKP inhibitors could be a novel strategy in anti-cancer therapy. Moreover, Cdc25A is, a DUSP and a key regulator of the cell cycle, promotes cell cycle progression by dephosphorylating and activating cyclin-dependent kinases (CDK). Cdc25A-CDK pathway is a novel mechanism in carcinogenesis. Besides the mammalian target of rapamycin (mTOR) kinase inhibitors or mammalian target of rapamycin complex 1 (mTORC1) inhibition in combination with the dual phosphatidylinositol 3 kinase (PI3K)/mTOR or AKT kinase inhibitors are more effective in inhibiting the phosphorylation of eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) and cap-dependent translation. Dual targeting of the Akt and mTOR signaling pathways regulates cellular growth, proliferation and survival. Like the Cdc2-like kinases (CLK), dual-specific tyrosine phosphorylation-regulated kinases (DYRKs) are essential for the regulation of cell fate. The crosstalk between dual-specific phosphatases and dual- specific protein kinases is a novel drug target for anti-cancer therapy. Therefore, the focus of this chapter involves protein kinase modules, critical biochemical checkpoints of cancer therapy and the synergistic effects of protein kinases and anti-cancer molecules.

Minibrain-related kinase/dual-specificity tyrosine-regulated kinase 1B implication in stem/cancer stem cells biology

Dual-specificity tyrosine phosphorylation-regulated kinase 1B (DYRK1B), also known as minibrain-related kinase (MIRK) is one of the best functionally studied members of the DYRK kinase family. DYRKs comprise a family of protein kinases that are emerging modulators of signal transduction pathways, cell proliferation and differentiation, survival, and cell motility. DYRKs were found to participate in several signaling pathways critical for development and cell homeostasis. In this review, we focus on the DYRK1B protein kinase from a functional point of view concerning the signaling pathways through which DYRK1B exerts its cell type-dependent function in a positive or negative manner, in development and human diseases. In particular, we focus on the physiological role of DYRK1B in behavior of stem cells in myogenesis, adipogenesis, spermatogenesis and neurogenesis, as well as in its pathological implication in cancer and metabolic syndrome. Thus, understanding of the molecular mechanisms that regulate signaling pathways is of high importance. Recent studies have identified a close regulatory connection between DYRK1B and the hedgehog (HH) signaling pathway. Here, we aim to bring together what is known about the functional integration and cross-talk between DYRK1B and several signaling pathways, such as HH, RAS and PI3K/mTOR/AKT, as well as how this might affect cellular and molecular processes in development, physiology, and pathology. Thus, this review summarizes the major known functions of DYRK1B kinase, as well as the mechanisms by which DYRK1B exerts its functions in development and human diseases focusing on the homeostasis of stem and cancer stem cells.

Screen identifies DYRK1B network as mediator of transcription repression on damaged chromatin

DNA double-strand breaks (DSBs) trigger transient pausing of nearby transcription, an emerging ATM-dependent response that suppresses chromosomal instability. We screened a chemical library designed to target the human kinome for new activities that mediate gene silencing on DSB-flanking chromatin, and have uncovered the DYRK1B kinase as an early respondent to DNA damage. We showed that DYRK1B is swiftly and transiently recruited to laser-microirradiated sites, and that genetic inactivation of DYRK1B or its kinase activity attenuated DSB-induced gene silencing and led to compromised DNA repair. Notably, global transcription shutdown alleviated DNA repair defects associated with DYRK1B loss, suggesting that DYRK1B is strictly required for DSB repair on active chromatin. We also found that DYRK1B mediates transcription silencing in part via phosphorylating and enforcing DSB accumulation of the histone methyltransferase EHMT2. Together, our findings unveil the DYRK1B signaling network as a key branch of mammalian DNA damage response circuitries, and establish the DYRK1B-EHMT2 axis as an effector that coordinates DSB repair on transcribed chromatin.

Common risk factors for heart failure and cancer

Cardiovascular (CV) disease and cancer are the leading causes of death.1,2 Over the last decades, it has been appreciated that both CV disease and cancer are more common in individuals in whom risk factors for disease development accumulate, and preventative measures have been extremely important in driving down the incidence of disease.3-6 In general, the field of epidemiology, risk reduction, and preventative trials is divided into health care professionals who have an interest in either CV disease or cancer. As a result, the medical literature and medical practice has largely focused on the one disease, or the other. However, human individuals do not behave according to this dogma. Emerging data clearly suggest that identical risk factors may lead to CV disease in the one individual, but may cause cancer in another, or even both diseases in the same individual. This overlap exists between risk factors that are historically classified as 'CV risk factors' as these factors do equally strong predict cancer development. Therefore, we propose that a holistic approach might better estimate actual risks for CV disease and cancer. In this review, we summarize current insights in common behavioural risk factors for heart failure, being the most progressed and lethal form of CV disease, and cancer.

DYRK1B regulates Hedgehog-induced microtubule acetylation

The posttranslational modification (PTM) of tubulin subunits is important for the physiological functions of the microtubule (MT) cytoskeleton. Although major advances have been made in the identification of enzymes carrying out MT-PTMs, little knowledge is available on how intercellular signaling molecules and their associated pathways regulate MT-PTM-dependent processes inside signal-receiving cells. Here we show that Hedgehog (Hh) signaling, a paradigmatic intercellular signaling system, affects the MT acetylation state in mammalian cells. Mechanistically, Hh pathway activity increases the levels of the MT-associated DYRK1B kinase, resulting in the inhibition of GSK3β through phosphorylation of Serine 9 and the subsequent suppression of HDAC6 enzyme activity. Since HDAC6 represents a major tubulin deacetylase, its inhibition increases the levels of acetylated MTs. Through the activation of DYRK1B, Hh signaling facilitates MT-dependent processes such as intracellular mitochondrial transport, mesenchymal cell polarization or directed cell migration. Taken together, we provide evidence that intercellular communication through Hh signals can regulate the MT cytoskeleton and contribute to MT-dependent processes by affecting the level of tubulin acetylation.

MuvB: A Key to Cell Cycle Control in Ovarian Cancer

Cancer cells are characterized by uncontrolled proliferation, whereas the ability to enter quiescence or dormancy is important for cancer cell survival and disease recurrence. Therefore, understanding the mechanisms regulating cell cycle progression and exit is essential for improving patient outcomes. The MuvB complex of five proteins (LIN9, LIN37, LIN52, RBBP4, and LIN54), also known as LINC (LIN complex), is important for coordinated cell cycle gene expression. By participating in the formation of three distinct transcriptional regulatory complexes, including DREAM (DP, RB-like, E2F, and MuvB), MMB (Myb-MuvB), and FoxM1–MuvB, MuvB represents a unique regulator mediating either transcriptional activation (during S–G2 phases) or repression (during quiescence). With no known enzymatic activities in any of the MuvB-associated complexes, studies have focused on the therapeutic potential of protein kinases responsible for initiating DREAM assembly or downstream enzymatic targets of MMB. Furthermore, the mechanisms governing the formation and activity of each complex (DREAM, MMB, or FoxM1–MuvB) may have important consequences for therapeutic response. The MMB complex is associated with prognostic markers of aggressiveness in several cancers, whereas the DREAM complex is tied to disease recurrence through its role in maintaining quiescence. Here, we review recent developments in our understanding of MuvB function in the context of cancer. We specifically highlight the rationale for additional investigation of MuvB in high-grade serous ovarian cancer and the need for further translational research.

Discovery and pharmacological characterization of a novel series of highly selective inhibitors of cyclin-dependent kinases 4 and 6 as anticancer agents

BACKGROUND AND PURPOSE

Cyclin D-dependent kinases 4 and 6 (CDK4/6) are crucial regulators of the G1 to S phase transition of the cell cycle and are actively pursued as therapeutic targets in cancer. We sought to discover a novel series of orally bioavailable and highly selective small molecule inhibitors of CDK4/6.

EXPERIMENTAL APPROACH

The discovery of pharmacological inhibitors and optimization for potency, selectivity and drug properties were achieved by iterative chemical synthesis, biochemical screening against a panel of kinases, cell-based assays measuring cellular viability, cell cycle distribution, induction of apoptosis and the level of retinoblastoma tumour suppressor protein (Rb) phosphorylation and E2 factor (E2F)-regulated gene expression and in vitro biopharmaceutical and in vivo pharmacokinetic profiling.

KEY RESULTS

We discovered several lead compounds that displayed >1000-fold selectivity for CDK4/6 over other members of the CDK family. The lead compounds, 82, 91 and 95, potently inhibited the growth of cancer cells by inducing G1 arrest with a concomitant reduction in the phosphorylation of Rb at S780 and in E2F-regulated gene expression. With a remarkable selectivity for CDK4 over 369 human protein kinases, 91 was identified as a highly potent and orally bioavailable drug candidate.

CONCLUSIONS AND IMPLICATIONS

We have identified unique and new inhibitors of CDK4/6 as potential drug candidates. Compound 91 represents an ideal candidate for further development as targeted cancer therapy.

Targeting DYRK1B suppresses the proliferation and migration of liposarcoma cells

Liposarcoma is a common subtype of soft tissue sarcoma and accounts for 20% of all sarcomas. Conventional chemotherapeutic agents have limited efficacy in liposarcoma patients. Expression and activation of serine/threonine-protein kinase dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1B (DYRK1B) is associated with growth and survival of many types of cancer cells. However, the role of DYRK1B in liposarcoma remains unknown. In this study, we investigated the functional and therapeutic relevance of DYRK1B in liposarcoma. Tissue microarray and immunohistochemistry analysis showed that higher expression levels of DYRK1B correlated with a worse prognosis. RNA interference-mediated knockdown of DYRK1B or targeting DYRK1B with the kinase inhibitor AZ191 inhibited liposarcoma cell growth, decreased cell motility, and induced apoptosis. Moreover, combined AZ191 with doxorubicin demonstrated an increased anti-cancer effect on liposarcoma cells. These findings suggest that DYRK1B is critical for the growth of liposarcoma cells. Targeting DYRK1B provides a new rationale for treatment of liposarcoma.

Cardiovascular disease and cancer: Evidence for shared disease pathways and pharmacologic prevention

Cardiovascular disease (CVD) and cancer are leading causes of mortality and morbidity worldwide. Strategies to improve their treatment and prevention are global priorities and major focus of World Health Organization's joint prevention programs. Emerging evidence suggests that modifiable risk factors including diet, sedentary lifestyle, obesity and tobacco use are central to the pathogenesis of both diseases and are reflected in common genetic, cellular, and signaling mechanisms. Understanding this important biological overlap is critical and may help identify novel therapeutic and preventative strategies for both disorders. In this review, we will discuss the shared genetic and molecular factors central to CVD and cancer and how the strategies commonly used for the prevention of atherosclerotic vascular disease can be applied to cancer prevention.

Dyrk1B overexpression is associated with breast cancer growth and a poor prognosis

Dyrk1B, also called minibrain-related kinase (Mirk), is a member of the dual-specificity tyrosine phosphorylation-regulated kinase (Dyrk)/minibrain family of dual-specificity protein kinases. It is a serine/threonine kinase involved in the regulation of tumor progression and cell proliferation. In this study, the role of Dyrk1B in breast cancer development was investigated. The expression of Dyrk1B was detected by Western blot and immunohistochemistry staining, both of which demonstrated that Dyrk1B was overexpressed in breast cancer tissues and cells. Statistical analysis showed that the extent of Dyrk1B expression was associated with multiple clinicopathologic factors, including tumor size, grade, estrogen receptor status, and Ki-67 expression, and that high expression predicted a poor prognosis. The growth of breast cancer cells was inhibited significantly after knockout of DYRK1B by small interfering RNA (siRNA). Moreover, FoxO1 could be phosphorylated by Dyrk1B, and then FoxO1 was shuttled from the cell nucleus into the cytoplasm, which might be the mechanism of Dyrk1B-mediated survival in breast cancer cells. The results suggest that Dyrk1B plays a key role in the progression of breast cancer and provides a new target for breast cancer therapy.

The phosphorylation status of T522 modulates tissue-specific functions of SIRT1 in energy metabolism in mice

SIRT1, the most conserved mammalian NAD+-dependent protein deacetylase, is an important metabolic regulator. However, the mechanisms by which SIRT1 is regulated in vivo remain unclear. Here, we report that phosphorylation modification of T522 on SIRT1 is crucial for tissue-specific regulation of SIRT1 activity in mice. Dephosphorylation of T522 is critical for repression of its activity during adipogenesis. The phospho-T522 level is reduced during adipogenesis. Knocking-in a constitutive T522 phosphorylation mimic activates the β-catenin/GATA3 pathway, repressing PPARγ signaling, impairing differentiation of white adipocytes, and ameliorating high-fat diet-induced dyslipidemia in mice. In contrast, phosphorylation of T522 is crucial for activation of hepatic SIRT1 in response to over-nutrition. Hepatic SIRT1 is hyperphosphorylated at T522 upon high-fat diet feeding. Knocking-in a SIRT1 mutant defective in T522 phosphorylation disrupts hepatic fatty acid oxidation, resulting in hepatic steatosis after high-fat diet feeding. In addition, the T522 dephosphorylation mimic impairs systemic energy metabolism. Our findings unveil an important link between environmental cues, SIRT1 phosphorylation, and energy homeostasis and demonstrate that the phosphorylation of T522 is a critical element in tissue-specific regulation of SIRT1 activity in vivo.

A Systematic Analysis of Negative Growth Control Implicates the DREAM Complex in Cancer Cell Dormancy

Epithelial ovarian cancer (EOC) generates multicellular aggregates called spheroids that detach from the primary tumor and disseminate through ascites. Spheroids possess a number of characteristics of tumor dormancy including withdrawal from the cell cycle and resistance to chemotherapeutics. This report systematically analyzes the effects of RNAi depletion of 21 genes that are known to contribute to negative regulation of the cell cycle in 10 ovarian cancer cell lines. Interestingly, spheroid cell viability was compromised by loss of some cyclin-dependent kinase inhibitors such as p57Kip2, as well as Dyrk1A, Lin52, and E2F5 in most cell lines tested. Many genes essential for EOC spheroid viability are pertinent to the mammalian DREAM repressor complex. Mechanistically, the data demonstrate that DREAM is assembled upon the induction of spheroid formation, which is dependent upon Dyrk1A. Loss of Dyrk1A results in retention of the b-Myb-MuvB complex, elevated expression of DREAM target genes, and increased DNA synthesis that is coincident with cell death. Inhibition of Dyrk1A activity using pharmacologic agents Harmine and INDY compromises viability of spheroids and blocks DREAM assembly. In addition, INDY treatment improves the response to carboplatin, suggesting this is a therapeutic target for EOC treatment.Implications: Loss of negative growth control mechanisms in cancer dormancy lead to cell death and not proliferation, suggesting they are an attractive therapeutic approach. Mol Cancer Res; 15(4); 371-81. ©2016 AACR.

Role of dual specificity tyrosine-phosphorylation-regulated kinase 1B (Dyrk1B) in S-phase entry of HPV E7 expressing cells from quiescence

The high-risk human papillomavirus (HPV) is the causative agent for cervical cancer. The HPV E7 oncogene promotes S-phase entry from quiescent state in the presence of elevated cell cycle inhibitor p27Kip1, a function that may contribute to carcinogenesis. However, the mechanism by which HPV E7 induces quiescent cells to entry into S-phase is not fully understood. Interestingly, we found that Dyrk1B, a dual-specificity kinase and negative regulator of cell proliferation in quiescent cells, was upregulated in E7 expressing cells. Surprisingly and in contrast to what was previously reported, Dyrk1B played a positive role in S-phase entry of quiescent HPV E7 expressing cells. Mechanistically, Dyrk1B contributed to p27 phosphorylation (at serine 10 and threonine 198), which was important for the proliferation of HPV E7 expressing cells. Moreover, Dyrk1B up-regulated HPV E7. Taken together, our studies uncovered a novel function of Dyrk1B in high-risk HPV E7-mediated cell proliferation. Dyrk1B may serve as a target for therapy in HPV-associated cancers.

Design and synthesis of a potent inhibitor of class 1 DYRK kinases as a suppressor of adipogenesis

Dysregulation of dual-specificity tyrosine-phosphorylation-regulated kinase 1A (DYRK1A) has been demonstrated in several pathological conditions, including Alzheimer's disease and cancer progression. It has been recently reported that a gain of function-mutation in the human DYRK1B gene exacerbates metabolic syndrome by enhancing obesity. In the previous study, we developed an inhibitor of DYRK family kinases (INDY) and demonstrated that INDY suppresses the pathological phenotypes induced by overexpression of DYRK1A or DYRK1B in cellular and animal models. In this study, we designed and synthesized a novel inhibitor of DYRK family kinases based on the crystal structure of the DYRK1A/INDY complex by replacing the phenol group of INDY with dibenzofuran to produce a derivative, named BINDY. This compound exhibited potent and selective inhibitory activity toward DYRK family kinases in an in vitro assay. Furthermore, treatment of 3T3-L1 pre-adipocytes with BINDY hampered adipogenesis by suppressing gene expression of the critical transcription factors PPARγ and C/EBPα. This study indicates the possibility of BINDY as a potential drug for metabolic syndrome.

The structure of a dual-specificity tyrosine phosphorylation-regulated kinase 1A-PKC412 complex reveals disulfide-bridge formation with the anomalous catalytic loop HRD(HCD) cysteine

Dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) is a protein kinase associated with neuronal development and brain physiology. The DYRK kinases are very unusual with respect to the sequence of the catalytic loop, in which the otherwise highly conserved arginine of the HRD motif is replaced by a cysteine. This replacement, along with the proximity of a potential disulfide-bridge partner from the activation segment, implies a potential for redox control of DYRK family activities. Here, the crystal structure of DYRK1A bound to PKC412 is reported, showing the formation of the disulfide bridge and associated conformational changes of the activation loop. The DYRK kinases represent emerging drug targets for several neurological diseases as well as cancer. The observation of distinct activation states may impact strategies for drug targeting. In addition, the characterization of PKC412 binding offers new insights for DYRK inhibitor discovery.

DYRK1A: the double-edged kinase as a protagonist in cell growth and tumorigenesis

DYRK1A (dual-specificity tyrosine-regulated kinase 1A) is a kinase with multiple implications for embryonic development, especially in the nervous system where it regulates the balance between proliferation and differentiation of neural progenitors. The DYRK1A gene is located in the Down syndrome critical region and may play a significant role in the developmental brain defects, early neurodegeneration, and cancer susceptibility of individuals with this syndrome. DYRK1A is also expressed in adults, where it might participate in the regulation of cell cycle, survival, and tumorigenesis, thus representing a potential therapeutic target for certain types of cancer. However, the final readout of DYRK1A overexpression or inhibition depends strongly on the cellular context, as it has both tumor suppressor and oncogenic activities. Here, we will discuss the functions and substrates of DYRK1A associated with the control of cell growth and tumorigenesis with a focus on the potential use of DYRK1A inhibitors in cancer therapy.

Design and synthesis of thiazolo[5,4-f]quinazolines as DYRK1A inhibitors, part II

The convenient synthesis of a focused library (forty molecules) of novel 6,6,5-tricyclic thiazolo[5,4-f]quinazolines was realized mainly under microwave irradiation. A novel 6-aminobenzo[d]thiazole-2,7-dicarbonitrile (1) was used as a versatile molecular platform for the synthesis of various derivatives. Kinase inhibition, of the obtained final compounds, was evaluated on a panel of two kinases (DYRK1A/1B) together with some known reference DYRK1A and DYRK1B inhibitors (harmine, TG003, NCGC-00189310 and leucettine L41). Compound IC50 values were obtained and compared. Five of the novel thiazolo[5,4-f]quinazoline derivatives prepared, EHT 5372 (8c), EHT 6840 (8h), EHT 1610 (8i), EHT 9851 (8k) and EHT 3356 (9b) displayed single-digit nanomolar or subnanomolar IC50 values and are among the most potent DYRK1A/1B inhibitors disclosed to date. DYRK1A/1B kinases are known to be involved in the regulation of various molecular pathways associated with oncology, neurodegenerative diseases (such as Alzheimer disease, AD, or other tauopathies), genetic diseases (such as Down Syndrome, DS), as well as diseases involved in abnormal pre-mRNA splicing. The compounds described in this communication constitute a highly potent set of novel molecular probes to evaluate the biology/pharmacology of DYR1A/1B in such diseases.

A form of the metabolic syndrome associated with mutations in DYRK1B

BACKGROUND

Genetic analysis has been successful in identifying causative mutations for individual cardiovascular risk factors. Success has been more limited in mapping susceptibility genes for clusters of cardiovascular risk traits, such as those in the metabolic syndrome.

METHODS

We identified three large families with coinheritance of early-onset coronary artery disease, central obesity, hypertension, and diabetes. We used linkage analysis and whole-exome sequencing to identify the disease-causing gene.

RESULTS

A founder mutation was identified in DYRK1B, substituting cysteine for arginine at position 102 in the highly conserved kinase-like domain. The mutation precisely cosegregated with the clinical syndrome in all the affected family members and was absent in unaffected family members and unrelated controls. Functional characterization of the disease gene revealed that nonmutant protein encoded by DYRK1B inhibits the SHH (sonic hedgehog) and Wnt signaling pathways and consequently enhances adipogenesis. Furthermore, DYRK1B promoted the expression of the key gluconeogenic enzyme glucose-6-phosphatase. The R102C allele showed gain-of-function activities by potentiating these effects. A second mutation, substituting proline for histidine 90, was found to cosegregate with a similar clinical syndrome in an ethnically distinct family.

CONCLUSIONS

These findings indicate a role for DYRK1B in adipogenesis and glucose homeostasis and associate its altered function with an inherited form of the metabolic syndrome. (Funded by the National Institutes of Health.).

Pyrido[2,3-d]pyrimidines: discovery and preliminary SAR of a novel series of DYRK1B and DYRK1A inhibitors

DYRK1B is a kinase over-expressed in certain cancer cells (including colon, ovarian, pancreatic, etc.). Recent publications have demonstrated inhibition of DYRK1B could be an attractive target for cancer therapy. From a data-mining effort, the team has discovered analogues of pyrido[2,3-d]pyrimidines as potent enantio-selective inhibitors of DYRK1B. Cells treated with a tool compound from this series showed the same cellular effects as down regulation of DYRK1B with siRNA. Such effects are consistent with the proposed mechanism of action. Progress of the SAR study is presented.