Aurora Kinases and Potential Medical Applications of Aurora Kinase Inhibitors: A Review

Aurora kinases are a group of serine/threonine kinases responsible for the regulation of mitosis. In recent years, with the increase in Aurora kinase-related research, the important role of Aurora kinases in tumorigenesis has been gradually recognized. Aurora kinases have been regarded as a new target for cancer therapy, resulting in the development of Aurora kinase inhibitors. The study and application of these small-molecule inhibitors, especially in combination with chemotherapy drugs, represent a new direction in cancer treatment. This paper reviews studies on Aurora kinases from recent years, including studies of their biological function, their relationship with tumor progression, and their inhibitors.

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Targeting Aurora Kinases as Therapy in Multiple Myeloma.

Blood ◽

10.1182/blood.v108.11.3484.3484 ◽

2006 ◽

Vol 108 (11) ◽

pp. 3484-3484

Author(s):

Yijiang Shi ◽

Tony Reiman ◽

Weiqun Li ◽

Christopher Maxwell ◽

Linda Pilarski ◽

...

Keyword(s):

Cell Cycle ◽

Multiple Myeloma ◽

Genetic Instability ◽

Kinase Inhibitors ◽

Aurora Kinase ◽

Cell Cycle Checkpoints ◽

Normal Peripheral Blood ◽

Aurora Kinases ◽

Over Expression ◽

Aurora Kinase Inhibitors

Abstract The aurora kinases A and B are critical for facilitating cell cycle transit from G2 through to cytokinesis. As important regulators of the mitotic event, they are being tested as potential targets in cancer therapy. Multiple myeloma (MM) is a B cell malignancy characterized by progressive genetic instability, suggesting a disruption of cell cycle checkpoints has occurred that normally arrest cells at G2M or within mitosis when injury to the mitotic machinery occurs. Since these deficient checkpoints would prevent cell cycle arrest and potential repair and may render MM cells susceptible to apoptotic death in mitosis, we tested the anti-myeloma effecy of two separate agents that inhibit aurora kinases. Both agents induced cytoreduction of MM cell lines and primary myeloma samples at nM concentrations while normal peripheral blood lymphocytes and CLL cells were not affected. MM cells were not protected by IL-6 or activating mutations of RAS. Anti-myeloma effects were characterized by induction of tetraploidy followed by apoptosis. The myeloma apoptotic effect correlated well with the inhibition of aurora kinase activity as shown by reduction of histone 3B phosphorylation (substrate of auroras). Furthermore, stable ectopic over-expression of aurora kinase A significantly protected MM cells against aurora inhibitors but had no effect on apoptosis induced by velcade. As expression of the centrosomal protein RHAMM in MM cells may contribute to genetic instability, we tested effects of RHAMM over-expression on the sensitivity to aurora inhibitors. Although RHAMM over-expression in transfected MM cells was very modest, it significantly enhanced sensitivity to apoptosis induced by aurora kinase inhibitors. These results suggest the potential for aurora kinase inhibitors in multiple myeloma especially in patients where RHAMM is over-expressed.

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Vincristine Potentiates the Anti-Leukemia Effect of the Aurora Kinase Inhibitor VE-465 by Enhancing Apoptosis in Myeloid Leukemia Cells.

Blood ◽

10.1182/blood.v114.22.2762.2762 ◽

2009 ◽

Vol 114 (22) ◽

pp. 2762-2762

Author(s):

Ken Ohmine ◽

Tadashi Nagai ◽

Kozue Yoshida ◽

Shin-ichiro Fujiwara ◽

Mitsuyo Uesawa ◽

...

Keyword(s):

Cell Lines ◽

Myeloid Leukemia ◽

Kinase Inhibitors ◽

Kinase Inhibitor ◽

Aurora Kinase ◽

Leukemia Cells ◽

Aurora Kinases ◽

Aurora Kinase Inhibitors ◽

M Phase ◽

G1 Cells

Abstract Abstract 2762 Poster Board II-738 Introduction: Aurora kinases (Aurora-A, Aurora-B, Aurora-C) play an essential role in the regulation of mitosis. It has been shown that deregulation of aurora kinases is involved in tumorgenesis and that these kinases are overexpressed in a variety of tumor cells. Aurora kinase inhibitors are potential small-molecule agents for treatment of various kinds of tumors including leukemia, and clinical trials of several aurora kinase inhibitors against certain types of tumors are currently being carried out. However, mono-therapy with other small-molecule agents sometimes shows only limited clinical efficacy for treatment of leukemia, and the establishment of efficacious combination therapies therefore appears to be an attractive approach for making good use of aurora kinase inhibitors. Methods: We examined the cytotoxic effects of VE-465, a specific aurora kinase inhibitor, in combination with various conventional anti-leukemia agents, including doxorubicin, daunorubicin, idarubicin, mitoxantron, cytocine arabinoside, vincristine and etoposide, on AML cell lines (HL60, U937, THP-1, KY821), CML cell lines (KCL22, K562, KU812) and primary leukemia cells from a patient with AML in order to try to determine an effective therapeutic combination. Results: Steel and Peckham isobologram analyses demonstrated that a combination of VE-465 and vincristine had a synergistic/additive inhibitory effect on the growth of all leukemia cell lines as well as primary leukemia cells examined in this study. Flow cytometric analysis showed that the percentage of G2/M-phase cells was significantly increased at 12 h when VE-465 was added to THP-1 cells as a single agent. At 48 h, however, the percentage of sub-G1 cells was increased, with a decrease in the percentage of G2/M-phase cells, suggesting that VE-465 initially induced the cells into blockage of the cell cycle at M-phase, which may be caused by VE-465-mediated inhibition of aurora kinase activity, and that cells at G2/M arrest were subsequently induced to apoptosis. Importantly, vincristine enhanced VE-465-mediated induction of sub-G1 cells. Consistent with these results, vincristine enhanced VE-465-induced increase in the levels of cleaved caspase 3, cleaved caspase 7, cleaved caspase 9 and cleaved PARP. The level of Phospho-Chk2 was markedly increased by the combination, suggesting that Chk2-mediated activation of the G2/M checkpoint is involved in the induction of apoptosis. Interestingly, VE-465 alone and VE-465 in combination with vincristine markedly increased the level of phospho-ERK1/2, suggesting that the combination alters a network of cellular signaling pathways. Taken together, the results suggest that vincristine potentiated the effect of VE-465 by enhancement of apoptosis, resulting in effective inhibition of the growth of leukemia cells. In contrast to the combination of VE-465 and vincristine, however, combinations of VE-465 and other anti-leukemia agents showed no synergistic inhibition but rather had antagonistic effects on growth. Conclusion: Co-administration of VE-465 and most of the conventional anti-leukemia agents might have little clinical value. However, the results of this study indicate the utility of the combination of VE-465 and vincristine as a potential therapy for myeloid leukemia. Disclosures: No relevant conflicts of interest to declare.

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Analysis of Protein Biology to Increase Efficacy of Aurora Kinase Inhibitors for Multiple Myeloma Therapy.

Blood ◽

10.1182/blood.v112.11.1699.1699 ◽

2008 ◽

Vol 112 (11) ◽

pp. 1699-1699

Author(s):

Robert P. Evans ◽

Kim Laginha ◽

Linda M. Pilarski ◽

Andrew Belch ◽

Tony Reiman

Keyword(s):

Multiple Myeloma ◽

Cancer Cells ◽

Protein Interactions ◽

Kinase Inhibitors ◽

Aurora Kinase ◽

Protein Protein Interactions ◽

Aurora Kinases ◽

Aurora Kinase Inhibitors ◽

Anti Cancer ◽

Novel Protein

Abstract Despite improvement in therapeutic regimes which have extended survival of patients with multiple myeloma, the search for novel targets to further advance treatment options continues. It is critical to the success of targeted cancer therapy that the rational selection of drugs be derived from the molecular and cellular biology of protein targets. Furthermore, studies have indicated that focused combination drug therapy could produce remarkable improvement in patient outcomes. Aurora kinases A/B/C (AURK), components of the centrosome and important for cell cycle function, are promising new targets in the treatment of numerous types of cancer. We have previously validated AURKs as a therapeutic target in pre-clinical models of multiple myeloma. In this study our aim is to better define the biology of AURKs in both normal and malignant cells, with the goal of identifying rational strategies for improving the therapeutic potential of Aurora kinase inhibitors (AKIs) as anti-cancer agents. We use a systematic two-pronged approach to map post-translational modifications and novel protein-protein interactions that define the interactome of AURKs. We also examine whether Aurora kinase interactions and posttranslational modifications are significantly different in cancer cells compared to normal cells. Increased understanding of Aurora kinase biology will help develop mechanisms to intensify the anti-cancer effects of AKIs. SUMOylation is a recently discovered posttranslational modification of numerous proteins that has been linked to many cancer types. A small ubiquitin-like modifier (SUMO) group is conjugated at the canonical ubiquitin site of a protein to alter its function, stability or sub-cellular localization. We believe that Aurora kinases may be differentially SUMOylated in cancer cells compared to normal cells, and that SUMOylation of Aurora kinases in cancer cells may alter their function and their susceptibility to AKI therapy. Here we have determined putative SUMOylation sites of all three AURKs in silico and also have evidence of AURK SUMOylation using an in vitro assay and also in human HEK293 cells. Furthermore, the gene encoding the central SUMO conjugating enzyme - UBC9 - is expressed at higher levels in CD138+ malignant plasma cells compared to other CD138−bone marrow cells in myeloma patients. As part of our strategy, we have also used Tandem Affinity Purification (TAP) technology to identify novel protein-protein interactions of Aurora kinases. In the initial stage, we have established stable expressing clones in a human cancer cell line and a normal line that express TAP-tagged AURKA/B or C. In pilot experiments we have successfully isolated pure recombinant AURKA along with interacting proteins using the TAP method. Using mass spectrometry (MS/MS) protein ID, we have identified putative protein interaction partners with AURKA which have implications in general cancer biology and centrosomal structure. In the future, these interactions will be validated using conventional biochemical methods before being tested in myeloma cell lines.

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Targeting Aurora Kinases in Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood.v120.21.4907.4907 ◽

2012 ◽

Vol 120 (21) ◽

pp. 4907-4907

Author(s):

Ya-Ping Chen ◽

Hui-Ju Lin ◽

Kung-Chao Chang ◽

Jiann-Shiuh Chen ◽

Ming-Ying Tsai ◽

...

Keyword(s):

Cell Lines ◽

Drug Sensitivity ◽

Kinase Inhibitors ◽

Lymphoblastic Leukemia ◽

Aurora Kinase ◽

Drug Resistant ◽

Rt Pcr ◽

Aurora Kinases ◽

Aurora Kinase Inhibitors ◽

Mdr 1

Abstract Abstract 4907 Introduction: Despite improved treatment outcome in acute lymphoblastic leukemia (ALL), drug resistance and disease recurrence remain major obstacles in specific subgroups. Thus, there is an urgent need to identify new targets for therapy. Several studies showed that Aurora kinases were therapeutic targets in cancer therapy, including solid tumors and hematological malignancies. Here we describe preclinical testing of Aurora kinase inhibitors in ALL and the molecular mechanism of different drug activity. Materials and methods: Quantitative RT-PCR and Western blot were used to assess the expressions of Aurora kinases and their activators in ALL. RT-PCR was used to detect the expression of MDR-1. To test activity against Aurora kinases, different ALL cell lines were treated with various concentrations of Aurora kinase inhibitors “VE-465 and VX-680”. The effects of Aurora kinase inhibitors on the cell cycle were evaluated by flow cytometry. Gene expression profiling was performed to identify the candidate targets which regulate the different drug sensitivity. Transient knockdown and overexpression of candidate genes in ALL cell lines were also employed in this study. Results: Nine ALL cell lines treated with Aurora kinase inhibitors (VE-465 and VX-680) exhibited different drug sensitivity. Five ALL cell lines were sensitive to drug treatment with IC50 around 10–40 nM, including MLL-AF4-positive and BCR-ABL-positive cell lines. However, RPMI-8402 was one of the three cell lines which were resistant to VE-465 and VX-680 with IC50 more than 10 μM. Among these sensitive ALL cell lines, treatment of Aurora kinase inhibitors resulted in an increased G2/M and sub-G1 populations. In contrast, drug-resistant ALL cell lines showed increased polyploidy status after exposure to Aurora kinase inhibitors. The different treatment efficacy was not related to the expression of Aurora kinases, their activators or MDR-1. In order to elucidate the molecular mechanism to regulate the different drug sensitivity, microarray study was performed. It showed that treatment of Aurora kinase inhibitors resulted in differential expressions of genes (75 up-regulated and 90 down-regulated genes) and CDKN1Awas one of the potential molecules which regulated the treatment diversity. RT-PCR and Western blot confirmed the cDNA microarray data: CDKN1A was up-regulated after treatment with Aurora kinase inhibitors in the drug-sensitive cell lines, but no change in the level of CDKN1A in the drug-resistance cell lines. Knockdown of CDKN1A in drug-sensitive cell lines impaired the treatment activity. Over-expression of CDKN1A in drug-resistant cell lines increased the anti-leukemia effect of Aurora kinase inhibitors. Conclusion: These data suggest that treatment with Aurora kinase inhibitors may be a novel and effective therapy in specific subgroups of ALL, including MLL-AF4-positive ALL. These data show that status of Aurora kinases, their activators or MDR-1 does not correlate with the drug susceptibility in ALL cell lines. The susceptibility to Aurora kinase inhibitors in ALL depends on the activation status of CDKN1A. Disclosures: No relevant conflicts of interest to declare.

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Targeting aurora kinases as therapy in multiple myeloma

Blood ◽

10.1182/blood-2006-07-037671 ◽

2007 ◽

Vol 109 (9) ◽

pp. 3915-3921 ◽

Cited By ~ 58

Author(s):

Yijiang Shi ◽

Tony Reiman ◽

Weiqun Li ◽

Christopher A. Maxwell ◽

Subrata Sen ◽

...

Keyword(s):

Multiple Myeloma ◽

Genetic Instability ◽

Kinase Inhibitors ◽

Ectopic Expression ◽

Aurora Kinase ◽

Aurora Kinases ◽

Activating Mutations ◽

Enhanced Sensitivity ◽

Cycle Arrest ◽

Aurora Kinase Inhibitors

Abstract The aurora kinases facilitate transit from G2 through cytokinesis and, thus, are targets in cancer therapy. Multiple myeloma (MM) is a malignancy characterized by genetic instability, suggesting a disruption of checkpoints that arrest cells at G2M when injury to the mitotic machinery occurs. Since deficient checkpoints would prevent cell cycle arrest and may render cells susceptible to apoptosis in mitosis and since aurora kinases are intermediaries in checkpoint pathways, we tested antimyeloma effects of 2 agents that inhibit aurora kinases. Both inhibited growth of MM lines and primary myeloma samples at nanomolar concentrations while having less of an effect on proliferating lymphocytes and hematopoietic cells. MM cells were not protected by IL-6 or activating mutations of Ras. Antimyeloma effects included induction of tetraploidy followed by apoptosis. Apoptosis correlated with inhibition of aurora activity as shown by reduction of histone 3B phosphorylation. Ectopic expression of aurora A protected MM cells against aurora inhibitors but had no effect on apoptosis induced by bortezomib. As expression of RHAMM in MM contributes to genetic instability, we tested effects of RHAMM. RHAMM overexpression enhanced sensitivity to apoptosis and RHAMM silencing decreased sensitivity. These results suggest potential for aurora kinase inhibitors in MM especially in patients in whom RHAMM is overexpressed.

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