Novel CaMKII-δ Inhibitor Hesperadin Exerts Dual Functions to Ameliorate Cardiac Ischemia/Reperfusion Injury and Inhibit Tumor Growth.

BACKGROUND: Cardiac ischemia/reperfusion (I/R) injury has emerged as an important therapeutic target for ischemic heart disease, the leading cause of morbidity and mortality worldwide. At present, there is no effective therapy for reducing cardiac I/R injury. CaMKII (Ca2+/calmodulin-dependent kinase II) plays a pivotal role in the pathogenesis of severe heart conditions, including I/R injury. Pharmacological inhibition of CaMKII is an important strategy in the protection against myocardial damage and cardiac diseases. To date, there is no drug targeting CaMKII for the clinical therapy of heart disease. Furthermore, at present, there is no selective inhibitor of CaMKII-δ, the major CaMKII isoform in the heart. METHODS: A small-molecule kinase inhibitor library and a high-throughput screening system for the kinase activity assay of CaMKII-δ9 (the most abundant CaMKII-δ splice variant in human heart) were used to screen for CaMKII-δ inhibitors. Using cultured neonatal rat ventricular myocytes, human embryonic stem cell-derived cardiomyocytes, and in vivo mouse models, in conjunction with myocardial injury induced by I/R (or hypoxia/reoxygenation) and CaMKII-δ9 overexpression, we sought to investigate the protection of hesperadin against cardiomyocyte death and cardiac diseases. BALB/c nude mice with xenografted tumors of human cancer cells were used to evaluate the in vivo antitumor effect of hesperadin. RESULTS: Based on the small-molecule kinase inhibitor library and screening system, we found that hesperadin, an Aurora B kinase inhibitor with antitumor activity in vitro, directly bound to CaMKII-δ and specifically blocked its activation in an ATP-competitive manner. Hesperadin functionally ameliorated both I/R- and overexpressed CaMKII-δ9-induced cardiomyocyte death, myocardial damage, and heart failure in both rodents and human embryonic stem cell-derived cardiomyocytes. In addition, in an in vivo BALB/c nude mouse model with xenografted tumors of human cancer cells, hesperadin delayed tumor growth without inducing cardiomyocyte death or cardiac injury. CONCLUSIONS: Here, we identified hesperadin as a specific small-molecule inhibitor of CaMKII-δ with dual functions of cardioprotective and antitumor effects. These findings not only suggest that hesperadin is a promising leading compound for clinical therapy of cardiac I/R injury and heart failure, but also provide a strategy for the joint therapy of cancer and cardiovascular disease caused by anticancer treatment.

Leishmania donovani Aurora kinase: A promising therapeutic target against visceral leishmaniasis.

BACKGROUND: Aurora kinases are key mitotic kinases executing multiple aspects of eukaryotic cell-division. The apicomplexan homologs being essential for survival, suggest that the Leishmania homolog, annotated LdAIRK, may be equally important. METHODS: Bioinformatics, stage-specific immunofluorescence microscopy, immunoblotting, RT-PCR, molecular docking, in-vitro kinase assay, anti-leishmanial activity assays, flow cytometry, fluorescence microscopy. RESULTS: Ldairk expression is seen to vary as the cell-cycle progresses from G1 through S and finally G2M and cytokinesis. Kinetic studies demonstrate their enzymatic activity exhibiting a Km and Vmax of 6.12µM and 82.9pmoles·min(-1)mg(-1) respectively against ATP using recombinant Leishmania donovani H3, its physiological substrate. Due to the failure of LdAIRK-/+ knock-out parasites to survive, we adopted a chemical knock-down approach. Based on the conservation of key active site residues, three mammalian Aurora kinase inhibitors were investigated to evaluate their potential as inhibitors of LdAIRK activity. Interestingly, the cell-cycle progressed unhindered, despite treatment with GSK-1070916 or Barasertib, inhibitors with greater potencies for the ATP-binding pocket compared to Hesperadin, which at nanomolar concentrations, severely compromised viability at IC50s 105.9 and 36.4nM for promastigotes and amastigotes, respectively. Cell-cycle and morphological studies implicated their role in both mitosis and cytokinesis. CONCLUSION: We identified an Aurora kinase homolog in L. donovani implicated in cell-cycle progression, whose inhibition led to aberrant changes in cell-cycle progression and reduced viability. GENERAL SIGNIFICANCE: Human homologs being actively pursued drug targets and the observations with LdAIRK in both promastigotes and amastigotes suggest their potential as therapeutic-targets. Importantly, our results encourage the exploration of other proteins identified herein as potential novel drug targets.

Chemical Genomics Approach Leads to the Identification of Hesperadin, an Aurora B Kinase Inhibitor, as a Broad-Spectrum Influenza Antiviral.

Influenza viruses are respiratory pathogens that are responsible for annual influenza epidemics and sporadic influenza pandemics. Oseltamivir (Tamiflu®) is currently the only FDA-approved oral drug that is available for the prevention and treatment of influenza virus infection. However, its narrow therapeutic window, coupled with the increasing incidence of drug resistance, calls for the next generation of influenza antivirals. In this study, we discovered hesperadin, an aurora B kinase inhibitor, as a broad-spectrum influenza antiviral through forward chemical genomics screening. Hesperadin inhibits multiple human clinical isolates of influenza A and B viruses with single to submicromolar efficacy, including oseltamivir-resistant strains. Mechanistic studies revealed that hesperadin inhibits the early stage of viral replication by delaying the nuclear entry of viral ribonucleoprotein complex, thereby inhibiting viral RNA transcription and translation as well as viral protein synthesis. Moreover, a combination of hesperadin with oseltamivir shows synergistic antiviral activity, therefore hesperadin can be used either alone to treat infections by oseltamivir-resistant influenza viruses or used in combination with oseltamivir to delay resistance evolution among oseltamivir-sensitive strains. In summary, the discovery of hesperadin as a broad-spectrum influenza antiviral offers an alternative to combat future influenza epidemics and pandemics.

Cell Death in Leishmania donovani promastigotes in response to Mammalian Aurora Kinase B Inhibitor- Hesperadin.

Deciphering how hesperadin, a repurposed mammalian aurora kinase B inhibitor, affects the cellular pathways in Leishmania donovani might be beneficial. This investigation sought to assess the physiological effects of hesperadin on promastigotes of L. donovani, by altering the duration of treatment following exposure to hesperadin. Groups pre-treated with inhibitors such as EGTA, NAC, and z-VAD-fmk before hesperadin exposure were also included. Morphological changes by microscopy, ATP and ROS changes by luminometry; DNA degradation using agarose gel electrophoresis and metacaspase levels through RT-PCR were assessed. Flow cytometry was used to study mitochondrial depolarization using JC-1 and MitoTracker Red; mitochondrial-superoxide accumulation using MitoSOX; plasma membrane modifications using Annexin-V and propidium iodide, and lastly, caspase activation using ApoStat. Significant alterations in promastigote morphology were noted. Caspase activity and mitochondrial-superoxide rose early after exposure whereas mitochondrial membrane potential demonstrated uncharacteristic variations, with significant functional disturbances such as leakage of superoxide radicals after prolonged treatments. ATP depletion and ROS accumulation demonstrated inverse patterns, genomic DNA showed fragmentation and plasma membrane showed Annexin-V binding, soon followed by propidium iodide uptake. Multilobed macronuclei and micronuclei accumulated in hesperadin exposed cells before they disintegrated into necrotic debris. The pathologic alterations were unlike the intrinsic or extrinsic pathways of classical apoptosis and suggest a caspase-mediated cell death most akin to mitotic-catastrophe. Most likely, a G2/M transition block caused accumulation of death signals, disorganized spindles and mechanical stresses, causing changes in morphology, organellar functions and ultimately promastigote death. Thus, death was a consequence of mitotic-arrest followed by ablation of kinetoplast functions, often implicated in L. donovani killing.

[Effect and molecular mechanism of hesperadin-induced ferroptosis in chronic myeloid leukemia K562 cells].

Objective: To investigate the effect and molecular mechanism of hesperadin in inducing ferroptosis in chronic myeloid leukemia cell line K562 cells. Methods: The effects of hesperadin on the viability, proliferation, and migration of K562 cells were detected though CCK8, EDU-594, and Transwell assays, and the apoptotic rate of K562 cells was detected by flow cytometry. In addition, C11-BODIPY and FerroOrange were utilized to detect intracellular lipid peroxidation and Fe(2+) levels. Meanwhile, the expression levels of ferroptosis-associated protein solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) in cells were detected through Western blot. Lipid peroxidation and Fe(2+) levels were also detected after transfection of cells with SLC7A11 overexpression plasmid. Results: Hesperadin decreased cell viability in a dose-dependent manner with IC(50) of 0.544 µmol/L. Hesperadin concentrations of 0.4 and 0.8 µmol/L were selected for follow-up experiments. EDU-594, Transwell, and flow cytometry showed significantly decreased proliferation and migration rate of K562 cells after 0.4 and 0.8 µmol/L hesperadin treatment for 24 h, and the apoptosis rate was significantly increased compared with the control group (P<0.05). Western blot indicated a downregulated expression of the antiapoptotic protein Bcl-2 and an elevated expression of proapoptotic proteins Bax and Caspase-3. Moreover, hesperadin increased intracellular lipid peroxidation and Fe(2+) levels compared with the control treatment (P<0.05). The combination of ferroptosis inhibitor (Fer-1) and hesperadin could reverse the effect of hesperadin on K562 cells. The mRNA and protein levels of ferroptosis-related genes SLC7A11 and GPX4 were significantly decreased in the 0.8 µmol/L hesperadin-treated group (P<0.05). SLC7A11 overexpression can inhibit hesperadin effect and alleviate ferroptosis. Conclusion: Hesperadin can promote ferroptosis in K562 cells by regulating the SLC7A11/GPX4 axis.

An essential Trypanosoma brucei protein kinase: a functional analysis of regulation and the identification of inhibitors.

Introduction: The protein serine/threonine kinase AEK1 is essential in the pathogenic stage of Trypanosoma brucei, the causative agent of African trypanosomiasis. AEK1 is a member of the AGC protein kinase family, although it is not closely related to a specific human AGC kinase. Our previous chemical genetic studies showed that targeted inhibition of AEK1 in parasites expressing analog-sensitive AEK1 blocked parasite growth and enhanced survival of infected mice. Methods: To further validate AEK1 as a drug target, we used the chemical genetic system to determine the effect of a 24 hour loss of AEK1 activity on cell viability at the clonal level. A panel of 429 protein kinase inhibitors were screened against the wild-type protein for binding, using time-resolved fluorescence energy transfer (TR-FRET). The role of phosphorylation sites and motifs was probed by determining whether expression of proteins harboring mutations in these sequences could rescue AEK1 conditional knockout parasites. To determine the effect that mutations in the phosphosites have on the kinase activity of cellular AEK1 we compared the in vitro kinase activity of mutant and wild-type proteins immunoprecipitated from parasite lysates using the exogenous substrate MBP. Finally, the tagged AEK1 protein was localized by deconvolution microscopy. Results: After a 24 hour exposure to an AEK1 inhibitory analog in the chemical genetic system, less than five percent of the remaining live cells can clonally expand, further validating AEK1 as a drug target. In the AEK1 inhibitor screening assay, we identified 17 hit compounds. Complementation studies showed that of the two known phosphorylation sites in the activation loop; mutation of one abolished function while mutation of the other had no discernable effect. Mutation of the other two AEK1 phosphosites gave intermediate phenotypes. Mutations in either the hydrophobic motif at the C-terminus of the protein or in the region of AEK1 predicted to bind the hydrophobic motif were also required for function. All parasites with defective AEK1 showed reduced proliferation and defects in cytokinesis, although the tested mutations differed in terms of the extent of cell death. Kinase activity of immunoprecipitated AEK1 phosphosite mutants largely paralleled the effects seen in complementation studies, although the mutation of the phosphosite adjacent to the hydrophobic motif had a greater impact on activity than predicted by the complementation studies. AEK1 was localized to cytoplasmic puncta distinct from glycosomes and acidocalcisomes. Discussion: The rapid loss of viability of cells inhibited for AEK1 supports the idea that a short course of treatment that target AEK1 may be sufficient for treatment of people or animals infected with T. brucei. Key regulatory elements between AEK1 and its closest mammalian homolog appear to be largely conserved despite the vast evolutionary distance between mammals and T. brucei. The presence of AEK1 in cytoplasmic puncta raises the possibility that its localization may also play a role in functional activity.

Targeting Aurora kinase B attenuates chemoresistance in glioblastoma via a synergistic manner with temozolomide.

BACKGROUND: Recent studies have demonstrated that aberrant expression or activation of kinases results in oncogenesis of a wide range of cancers including GBM. Inhibition of kinases expression induces a reduction of therapy resistance. In this study, we investigate the underlying mechanism by which glioblastoma (GBM) cells acquire resistance to Temozolomide (TMZ) through Aurora kinase B (AURKB) thus to identify novel therapeutic targets and prognostic biomarkers for GBM. METHODS: AURKB was identified as a key candidate kinase-encoding gene in chemoresistance regulation by using kinome-wide bioinformatic analysis. Afterwards, the potential biological functions of AURKB in oncogenesis and chemoresistance were investigated by lentivirus-dependent silencing of AURKB combined with qRT-PCR, western blot and in vivo intra-cranial xenograft mice models. Additionally, immunohistochemistry (IHC) assays were performed to explore the clinical significance of AURKB in glioma patients. Lastly, Chou-Talalay method was used to confirm the synergistic effect of TMZ combined with AURKB inhibitor. RESULTS: AURKB was among the most significantly up-regulated kinase-coding genes in TMZ resistant GBM cells according to database GSE68029, moreover, an increased expression of AURKB was closely associated with poor prognosis in glioma and GBM patients. AURKB knock-down resensitized U87 resistant cells to TMZ both in vitro and in vivo. Additionally, the combination of TMZ and Hesperadin, a specific AURKB inhibitor, significantly suppressed the proliferation of TMZ resistant GBM cells thus dramatically prolonged the survival of xenograft mice viaa synergistic effect with TMZ. CONCLUSION: Elevated AURKB expression was strongly correlated to TMZ resistant acquisition and poor prognosis, furthermore, targeting AURKB would be a potential therapeutic target for GBM patients.

A Cell Biologist's Field Guide to Aurora Kinase Inhibitors.

Aurora kinases are essential for cell division and are frequently misregulated in human cancers. Based on their potential as cancer therapeutics, a plethora of small molecule Aurora kinase inhibitors have been developed, with a subset having been adopted as tools in cell biology. Here, we fill a gap in the characterization of Aurora kinase inhibitors by using biochemical and cell-based assays to systematically profile a panel of 10 commercially available compounds with reported selectivity for Aurora A (MLN8054, MLN8237, MK-5108, MK-8745, Genentech Aurora Inhibitor 1), Aurora B (Hesperadin, ZM447439, AZD1152-HQPA, GSK1070916), or Aurora A/B (VX-680). We quantify the in vitro effect of each inhibitor on the activity of Aurora A alone, as well as Aurora A and Aurora B bound to fragments of their activators, TPX2 and INCENP, respectively. We also report kinome profiling results for a subset of these compounds to highlight potential off-target effects. In a cellular context, we demonstrate that immunofluorescence-based detection of LATS2 and histone H3 phospho-epitopes provides a facile and reliable means to assess potency and specificity of Aurora A versus Aurora B inhibition, and that G2 duration measured in a live imaging assay is a specific readout of Aurora A activity. Our analysis also highlights variation between HeLa, U2OS, and hTERT-RPE1 cells that impacts selective Aurora A inhibition. For Aurora B, all four tested compounds exhibit excellent selectivity and do not significantly inhibit Aurora A at effective doses. For Aurora A, MK-5108 and MK-8745 are significantly more selective than the commonly used inhibitors MLN8054 and MLN8237. A crystal structure of an Aurora A/MK-5108 complex that we determined suggests the chemical basis for this higher specificity. Taken together, our quantitative biochemical and cell-based analyses indicate that AZD1152-HQPA and MK-8745 are the best current tools for selectively inhibiting Aurora B and Aurora A, respectively. However, MK-8745 is not nearly as ideal as AZD1152-HQPA in that it requires high concentrations to achieve full inhibition in a cellular context, indicating a need for more potent Aurora A-selective inhibitors. We conclude with a set of "good practice" guidelines for the use of Aurora inhibitors in cell biology experiments.

Synthesis and investigation of new Hesperadin analogues antitumor effects on HeLa cells.

Hesperadin is one of the indolinones that was designed against the ATP-binding site of Aurora kinase. This molecule inhibits Aurora B kinase by phosphorylation of histone H3. In this study, new derivatives of Hesperadin containing an amide group in their structures were synthesized through sequential Ugi/palladium-catalyzed approach and in vitro antitumor activity of new compounds were evaluated by cell proliferation assay. The results show that compounds 6f, 6i, 6l, and 6o were dose-dependently inhibited in different concentrations, and IC50 values were between 35 and 43 nM. It seems that lipophilic substitution on the indolinone core with the ability to form additional hydrogen bond might lead to increased stability of structure and activity of new Hesperadin analogues.

Aurora kinase inhibitors: Potential molecular-targeted drugs for gynecologic malignant tumors.

Chemotherapy and surgery are important treatment strategies for gynecologic malignant tumors such as ovarian, cervical and endometrial cancer. However, many anticancer drugs currently available are cytotoxic and cause strong adverse reactions in patients. Aurora kinases have attracted increasing attention in recent years as serine/threonine kinases with various roles in cell division, including chromosomal agglutination and segregation, functions of centromeres, centrosomal maturation, spindle formation and cytokinesis. Aurora kinases are overexpressed in a number of cancers and recent studies have shown that they are involved in onco genesis and cause an aberrant increase in centrosome number, emergence of polykaryocytes and failure of cancer inhibition mechanisms. Thus, drugs that inhibit Aurora kinases are likely to exert anticancer effects in various fields, including the gynecologic field. Aurora kinase inhibitors exert antitumor effects in monotherapy and synergistic effects in combination therapy with taxane-based anticancer agents for gynecologic tumors and are likely to increase the efficacy of existing anticancer drugs. Current Aurora kinase inhibitors include ZM447439, Hesperadin, VX-680/MK-0457, AT9283 and Barasertib, and clinical trials are ongoing to verify the effects of these inhibitors.