Tumour-amplified kinase BTAK is amplified and overexpressed in gastric cancers with possible involvement in aneuploid formation

Molecular insights and clinical implications for the tumor suppressor role of SCFFBXW7 E3 ubiquitin ligase

FBXW7 is one of the most well-characterized F-box proteins, serving as substrate receptor subunit of SKP1-CUL1-F-box (SCF) E3 ligase complexes. SCFFBXW7 is responsible for the degradation of various oncogenic proteins such as cyclin E, c-MYC, c-JUN, NOTCH, and MCL1. Therefore, FBXW7 functions largely as a major tumor suppressor. In keeping with this notion, FBXW7 gene mutations or downregulations have been found and reported in many types of malignant tumors, such as endometrial, colorectal, lung, and breast cancers, which facilitate the proliferation, invasion, migration, and drug resistance of cancer cells. Therefore, it is critical to review newly identified FBXW7 regulation and tumor suppressor function under physiological and pathological conditions to develop effective strategies for the treatment of FBXW7-altered cancers. Since a growing body of evidence has revealed the tumor-suppressive activity and role of FBXW7, here, we updated FBXW7 upstream and downstream signaling including FBXW7 ubiquitin substrates, the multi-level FBXW7 regulatory mechanisms, and dysregulation of FBXW7 in cancer, and discussed promising cancer therapies targeting FBXW7 regulators and downstream effectors, to provide a comprehensive picture of FBXW7 and facilitate the study in this field.

Influence of different pH milieu on the structure and function of human Aurora kinase B protein (AURK-B): Amalgamation of both spectroscopic and computational approach

Aurora kinase B (AURK-B) is a serine/threonine kinase protein that plays an essential role in chromosomal separation during the cell cycle event. AURK-B is highly expressed in various types of cancer such as human seminoma, thyroid carcinoma, non-small cell lung carcinoma (NSCLC), oral carcinoma, and gastric cancer. Hence, it is a potential therapeutic target in the treatment of various cancers. The structure of AURK-B in complex with one of its substrate inner centromeric protein (INCENP) is present, but the structural and functional characterization of native AURK-B at different pH environment is still unexplored.This study determines the effect of different pH milieu on the structure and function of AURK-B protein wherein the influence of pH on the protein conformation was probed using Circular dichroism (CD) and fluorescence spectroscopy. The structural studies were further combined with functional activity assay to observe the change in kinase activity at various pH milieu (2.0-11.0). CD and fluorescence spectroscopy experiments dictate that at high acidic conditions (pH 2.0 - 5.0), the secondary and tertiary structures of AURK-B become distorted, leading to diminished activity. The protein, however, was observed to stabilize towards pH 7.0 - 8.0 with minimal structure alteration over the basic pH range (pH 9.0 -11.0). The measured spectroscopic structural features were found to be in-line with obtained experimental kinase activity assays. Further, in-vitro experiments indicate that the enzyme is maximally active at pH 8.0. More ordered conformation and compact structure was observed at this pH (pH 8.0) as compared to other pH values through molecular dynamics simulation studies (MDS). As AURK-B localizes itself in the intracellular compartment, this study may provide a clue about the role of different pH environments in enhancing cancer growth, proliferation, and invasion.

Centrosomes and associated proteins in pathogenesis and treatment of breast cancer

Breast cancer is the most prevalent malignancy among women worldwide. Despite significant advances in treatment, it remains one of the leading causes of female mortality. The inability to effectively treat advanced and/or treatment-resistant breast cancer demonstrates the need to develop novel treatment strategies and targeted therapies. Centrosomes and their associated proteins have been shown to play key roles in the pathogenesis of breast cancer and thus represent promising targets for drug and biomarker development. Centrosomes are fundamental cellular structures in the mammalian cell that are responsible for error-free execution of cell division. Centrosome amplification and aberrant expression of its associated proteins such as Polo-like kinases (PLKs), Aurora kinases (AURKs) and Cyclin-dependent kinases (CDKs) have been observed in various cancers, including breast cancer. These aberrations in breast cancer are thought to cause improper chromosomal segregation during mitosis, leading to chromosomal instability and uncontrolled cell division, allowing cancer cells to acquire new genetic changes that result in evasion of cell death and the promotion of tumor formation. Various chemical compounds developed against PLKs and AURKs have shown meaningful antitumorigenic effects in breast cancer cells in vitro and in vivo. The mechanism of action of these inhibitors is likely related to exacerbation of numerical genomic instability, such as aneuploidy or polyploidy. Furthermore, growing evidence demonstrates enhanced antitumorigenic effects when inhibitors specific to centrosome-associated proteins are used in combination with either radiation or chemotherapy drugs in breast cancer. This review focuses on the current knowledge regarding the roles of centrosome and centrosome-associated proteins in breast cancer pathogenesis and their utility as novel targets for breast cancer treatment.

Chromosomal copy number amplification-driven Linc01711 contributes to gastric cancer progression through histone modification-mediated reprogramming of cholesterol metabolism

BACKGROUND

Chromosome gains or localized amplifications are frequently observed in human gastric cancer (GC) and are major causes of aberrant oncogene activation. However, the significance of long non-coding RNAs (LncRNAs) in the above process is largely unknown.

METHODS

The copy number aberrations (CNAs) data of GC samples were downloaded and analyzed from the TCGA database. qRT-PCR and fluorescence in situ hybridization were used to evaluate the expression of Linc01711 in GC. The effects of Linc01711 on GC progression were investigated through in vitro and in vivo assays. The mechanism of Linc01711 action was explored through transcriptome sequencing, chromatin immunoprecipitation sequencing, RNA immunoprecipitation, RNA pull-down and chromatin isolation by RNA purification (ChIRP) assays.

RESULTS

We report for the first time a novel DNA copy number amplification-driven LncRNA on chromosome 20q13, designated Linc01711 in human GC, which is highly associated with malignant features. Functionally, Linc01711 significantly accelerates the proliferation and metastasis of GC. Mechanistically, Linc01711 acts as a modular scaffold to promote the binding of histone acetyltransferase HBO1 and histone demethylase KDM9. By coordinating the localization of the HBO1/KDM9 complex, Linc01711 specifies the histone modification pattern on the target genes, such as LPCAT1, and consequently facilitates the cholesterol synthesis, thereby contributing to tumor progression.

CONCLUSIONS

Our findings suggest that copy number amplification-driven Linc01711 may serve as a promising prognostic predictor for GC patients and targeting Linc01711-related cholesterol metabolism pathway may be meaningful in anticancer strategies.

Targeting mitotic regulators in cancer as a strategy to enhance immune recognition

Eukaryotic DNA has evolved to be enclosed within the nucleus to protect the cellular genome from autoinflammatory responses driven by the immunogenic nature of cytoplasmic DNA. Cyclic GMP-AMP Synthase (cGAS) is the cytoplasmic dsDNA sensor, which upon activation of Stimulator of Interferon Genes (STING), mediates production of pro-inflammatory interferons (IFNs) and interferon stimulated genes (ISGs). However, although this pathway is crucial in detection of viral and microbial genetic material, cytoplasmic DNA is not always of foreign origin. It is now recognised that specifically in genomic instability, a hallmark of cancer, extranuclear material in the form of micronuclei (MN) can be generated as a result of unresolved DNA lesions during mitosis. Activation of cGAS-STING in cancer has been shown to regulate numerous tumour-immune interactions such as acquisition of 'immunologically hot' phenotype which stimulates immune-mediated elimination of transformed cells. Nonetheless, a significant percentage of poorly prognostic cancers is 'immunologically cold'. As this state has been linked with low proportion of tumour-infiltrating lymphocytes (TILs), improving immunogenicity of cold tumours could be clinically relevant by exhibiting synergy with immunotherapy. This review aims to present how inhibition of vital mitotic regulators could provoke cGAS-STING response in cancer and improve the efficacy of current immunotherapy regimens.

Aurora kinase a inhibitor MLN8237 suppresses pancreatic cancer growth

Pancreatic ductal adenocarcinoma (PDAC) is notorious for high mortality due to limited options of appropriate chemotherapy drugs. Here we report that Aurora kinase-A expression is elevated in both human and mouse PDAC samples. MLN8237, an inhibitor of Aurora kinase-A, efficiently reduced the proliferation and motility of PDAC cells in vitro as well as tumor growth in orthotropic xenograft model and genetic pancreatic cancer animal models (p53/LSL/Pdx-Cre mice) in vivo. MLN8237 exhibited tumor inhibitory effect through inhibiting proliferation and migration, and inducing apoptosis and senescence. These results provide the molecular basis for a novel chemotherapy strategy for PDAC patients.

Identification of polypharmacological anticancerous molecules against Aurora kinase family of proteins

The Human Aurora Kinase (AURK) protein family is the key player of cell cycle events including spindle assembly, kinetochore formation, chromosomal segregation, centrosome separation, microtubule dynamics, and cytokinesis. Their aberrant expression has been extensively linked with chromosomal instability in addition to derangement of multiple tumor suppressors and oncoprotein regulated pathways. Therefore, the AURK family of kinases is a promising target for the treatment of various types of cancer. Over the past few decades, several potential inhibitors of AURK proteins have been identified and have reached various phases of clinical trials. But very few molecules have currently crossed the safety criteria due to their various toxic side effects. In the present study, we have adopted a computational polypharmacological strategy and identified four novel molecules that can target all three AURKs. These molecules were further investigated for their binding stabilities at the ATP binding pocket using molecular dynamics based simulation studies. The molecules selected adopting a multipronged computational approach can be considered as potential AURKs inhibitors for cancer therapeutics.

Aurora Kinases as Therapeutic Targets in Head and Neck Cancer

ABSTRACT

The Aurora kinases (AURKA and AURKB) have attracted attention as therapeutic targets in head and neck squamous cell carcinomas. Aurora kinases were first defined as regulators of mitosis that localization to the centrosome (AURKA) and centromere (AURKB), governing formation of the mitotic spindle, chromatin condensation, activation of the core mitotic kinase CDK1, alignment of chromosomes at metaphase, and other processes. Subsequently, additional roles for Aurora kinases have been defined in other phases of cell cycle, including regulation of ciliary disassembly and DNA replication. In cancer, elevated expression and activity of Aurora kinases result in enhanced or neomorphic locations and functions that promote aggressive disease, including promotion of MYC expression, oncogenic signaling, stem cell identity, epithelial-mesenchymal transition, and drug resistance. Numerous Aurora-targeted inhibitors have been developed and are being assessed in preclinical and clinical trials, with the goal of improving head and neck squamous cell carcinoma treatment.

Identification of novel biomarkers in breast cancer via integrated bioinformatics analysis and experimental validation

Breast cancer (BC), an extremely aggressive malignant tumor, causes a large number of deaths worldwide. In this study, we pooled profile datasets from three cohorts to illuminate the underlying key genes and pathways of BC. Expression profiles GSE42568, GSE45827, and GSE124646, including 244 BC tissues and 28 normal breast tissues, were integrated and analyzed. Differentially expressed genes (DEGs) were screened out based on these three datasets. Functional analysis including Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genome (KEGG) pathway were performed using The Database for Annotation, Visualization and Integrated Discovery (DAVID). Moreover, Cytoscape with Search Tool for the Retrieval of Interacting Genes (STRING) and Molecular Complex Detection (MCODE) plugin were utilized to visualize protein protein interaction (PPI) of these DEGs. The module with the highest connectivity of gene interactions was selected for further analysis. All of these hub genes had a significantly worse prognosis in BC by survival analysis. Additionally, four genes (CDK1, CDC20, AURKA, and MCM4) dramatically were enriched in oocyte meiosis and cell cycle pathways through re-analysis of DAVID. Moreover, the mRNA and protein levels of CDK1, CDC20, AURKA, and MCM4 were significantly increased in BC patients. In addition, knockdown of CDK1 and CDC20 by small interfering RNA remarkably suppressed cell migration and invasion in MCF-7 and MDA-MB-231 cells. In conclusion, our results suggested that CDK1, CDC20, AURKA, and MCM4 were reliable biomarkers of BC via bioinformatics analysis and experimental validation and may act as prospective targets for BC diagnosis and treatment.

Heteroarene-fused anthraquinone derivatives as potential modulators for human aurora kinase B

The quest for effective anticancer therapeutics continues to be extensively pursued. Over the past century, several drugs have been developed, however, a majority of these drugs have a poor therapeutic index and increased toxicity profile. Hence, there still exists ample opportunity to discover safe and effective anticancer drugs. Aurora Kinase B (AurB), a member of the Aurora kinase family and a key regulator of mitotic cell division, is found to be frequently overexpressed in a variety of human cancers and has thus emerged as an attractive target for the design of anticancer therapeutics. In the present study, a structure-based scaffold hopping approach was utilized to modify the heterocyclic moiety of (S)-3-(3-aminopyrrolidine-1-carbonyl)-4,11-dihydroxy-2-methylanthra [2,3-b]furan-5,10-dione (anthrafuran 1) to generate a series of heteroarene-fused anthraquinone derivatives, which were then subjected to virtual screening for the identification of potential AurB inhibitors. The obtained hits were subsequently synthesized and evaluated by using a combination of in silico and biophysical techniques for elucidating their in vitro binding and inhibition activity with recombinantly expressed AurB. Four identified hits presented an improved binding profile as compared to their parent analog anthrafuran 1. One derivative, anthrathiophene 2 demonstrated excellent in vitro inhibition of AurB (7.3 μM).

Precision medicine in gastric cancer

Gastric cancer (GC) is a complex disease linked to a series of environmental factors and unhealthy lifestyle habits, and especially to genetic alterations. GC represents the second leading cause of cancer-related deaths worldwide. Its onset is subtle, and the majority of patients are diagnosed once the cancer is already advanced. In recent years, there have been innovations in the management of advanced GC including the introduction of new classifications based on its molecular characteristics. Thanks to new technologies such as next-generation sequencing and microarray, the Cancer Genome Atlas and Asian Cancer Research Group classifications have also paved the way for precision medicine in GC, making it possible to integrate diagnostic and therapeutic methods. Among the objectives of the subdivision of GC into subtypes is to select patients in whom molecular targeted drugs can achieve the best results; many lines of research have been initiated to this end. After phase III clinical trials, trastuzumab, anti-Erb-B2 receptor tyrosine kinase 2 (commonly known as ERBB2) and ramucirumab, anti-vascular endothelial growth factor receptor 2 (commonly known as VEGFR2) monoclonal antibodies, were approved and introduced into first- and second-line therapies for patients with advanced/metastatic GC. However, the heterogeneity of this neoplasia makes the practical application of such approaches difficult. Unfortunately, scientific progress has not been matched by progress in clinical practice in terms of significant improvements in prognosis. Survival continues to be low in contrast to the reduction in deaths from many common cancers such as colorectal, lung, breast, and prostate cancers. Although several target molecules have been identified on which targeted drugs can act and novel products have been introduced into experimental therapeutic protocols, the overall approach to treating advanced stage GC has not substantially changed. Currently, surgical resection with adjuvant or neoadjuvant radiotherapy and chemotherapy are the most effective treatments for this disease. Future research should not underestimate the heterogeneity of GC when developing diagnostic and therapeutic strategies aimed toward improving patient survival.

Aurora A inhibition limits centrosome clustering and promotes mitotic catastrophe in cells with supernumerary centrosomes

The presence of supernumerary centrosomes is prevalent in cancer, where they promote the formation of transient multipolar mitotic spindles. Active clustering of supernumerary centrosomes enables the formation of a functional bipolar spindle that is competent to complete a bipolar division. Disruption of spindle pole clustering in cancer cells promotes multipolar division and generation of non-proliferative daughter cells with compromised viability. Hence molecular pathways required for spindle pole clustering in cells with supernumerary centrosomes, but dispensable in normal cells, are promising therapeutic targets. Here we demonstrate that Aurora A kinase activity is required for spindle pole clustering in cells with extra centrosomes. While cells with two centrosomes are ultimately able to build a bipolar spindle and proceed through a normal cell division in the presence of Aurora A inhibition, cells with supernumerary centrosomes form multipolar and disorganized spindles that are not competent for chromosome segregation. Instead, following a prolonged mitosis, these cells experience catastrophic divisions that result in grossly aneuploid, and non-proliferative daughter cells. Aurora A inhibition in a panel of Acute Myeloid Leukemia cancer cells has a similarly disparate impact on cells with supernumerary centrosomes, suggesting that centrosome number and spindle polarity may serve as predictive biomarkers for response to therapeutic approaches that target Aurora A kinase function.

Gossypin inhibits gastric cancer growth by direct targeting of AURKA and RSK2

Gossypin is a flavone extracted from Hibiscus vitifolius, which has been reported to exhibit anti-inflammatory, antioxidant, and anticancer activities. However, the anticancer properties of gossypin and its molecular mechanism of action against gastric cancer have not been fully investigated. In the present study, we report that gossypin is an Aurora kinase A (AURKA) and RSK2 inhibitor that suppresses gastric cancer growth. Gossypin attenuated anchorage-dependent and anchorage-independent gastric cancer cell growth as well as cell migration. Based on the results of in vitro screening and cell-based assays, gossypin directly binds to and inhibits AURKA and RSK2 activities and their downstream signaling proteins. Gossypin decreased S phase and increased G2/M phase cell cycle arrest by reducing the expression of cyclin A2 and cyclin B1 and the phosphorylation of the CDC protein. Additionally, gossypin also induced intrinsic apoptosis by activating caspases and PARP and increasing the expression of cytochrome c. Our results demonstrate that gossypin is an AURKA and RSK2 inhibitor that could be useful for treating gastric cancer.

AURKA Suppresses Leukemic THP-1 Cell Differentiation through Inhibition of the KDM6B Pathway

Aberrations in histone modifications are being studied in mixed-lineage leukemia (MLL)-AF9-driven acute myeloid leukemia (AML). In this study, we focused on the regulation of the differentiation of the MLL-AF9 type AML cell line THP-1. We observed that, upon phorbol 12-myristate 13-acetate (PMA) treatment, THP-1 cells differentiated into monocytes by down-regulating Aurora kinase A (AURKA), resulting in a reduction in H3S10 phosphorylation. We revealed that the AURKA inhibitor alisertib accelerates the expression of the H3K27 demethylase KDM6B, thereby dissociating AURKA and YY1 from the KDM6B promoter region. Using Flow cytometry, we found that alisertib induces THP-1 differentiation into monocytes. Furthermore, we found that treatment with the KDM6B inhibitor GSK-J4 perturbed the PMA-mediated differentiation of THP-1 cells. Thus, we discovered the mechanism of AURKA-KDM6B signaling that controls the differentiation of THP-1 cells, which has implications for biotherapy for leukemia.

Co-delivery of Aurora-A inhibitor XY-4 and Bcl-xl siRNA enhances antitumor efficacy for melanoma therapy

Background

The newly synthesized Aurora-A kinase inhibitor XY-4 is a potential anti-cancer agent, but its hydrophobicity and limited efficiency restrict further application. Nanotechnology based combined therapy provides an optimized strategy for solving these issues.

Methods

In this study, the newly synthesized Aurora-A kinase inhibitor XY-4 and Bcl-xl targeted siRNA were co-delivered by cationic liposomes, creating an injectable co-delivery formulation. The anti-cancer ability and mechanisms of XY-4/Bcl-xl siRNA co-loaded cationic liposomes were studied both in vitro and in vivo.

Results

The prepared liposomes had a mean particle size of 91.3±4.5 nm with a zeta potential of 38.5±0.5 mV and were monodispersed (Polydispersity index =0.183) in water solution, with high drug loading capacity and stability. Intriguingly, the positive charges of co-delivery liposomes not only facilitated gene delivery, but also obviously enhanced drug uptake. The XY-4/Bcl-xl siRNA co-loaded cationic liposomes demonstrated enhanced anti-cancer effects on B16 melanoma cells in vitro by activation mitochondrial apoptosis pathway. Moreover, intratumoral injection of this co-delivery formulation efficiently inhibited the growth of a B16 melanoma xenograft model in vivo.

Conclusion

By co-delivering Aurora-A kinase inhibitor XY-4 and Bcl-xl targeting siRNA in a nanoformulation, our study supplied a potential combination strategy for melanoma therapy.

Antitumor effects of calgranulin B internalized in human colon cancer cells

Calgranulin B is a small, calcium-binding protein expressed in neutrophils that is secreted into the tumor microenvironment in cancer cases. We previously showed that calgranulin B levels are increased in the stools of colorectal cancer patients. In patient tumor tissues, calgranulin B protein levels correlated with the presence of stromal inflammatory cells surrounding tumor cells, and calgranulin B promoter methylation was observed in both paired human tissues and colon cancer cell lines. Cell lines did not express calgranulin B, but in vitro studies showed that colon cancer cells internalized extracellular calgranulin B, while other types of cancer cells did not. Calgranulin B internalization led to reduced cell proliferation and increased apoptotic cell death. AKT and ERK signals were also increased after calgranulin B treatment, as were p53, β-catenin, E-cadherin and cleaved caspase-3 levels. Additionally, a human protein microarray identified aurora A kinase as a calgranulin B binding partner, and binding inhibited aurora A kinase activity in a dose-dependent manner. Our findings demonstrate the antitumor effects of calgranulin B in the inflammatory microenvironment and suggest that calgranulin B could be potentially efficacious in the treatment of colon cancer.

MLN-8237: A dual inhibitor of aurora A and B in soft tissue sarcomas

Aurora kinases have become an attractive target in cancer therapy due to their deregulated expression in human tumors. Liposarcoma, a type of soft tissue sarcoma in adults, account for approximately 20% of all adult soft tissue sarcomas. There are no effective chemotherapies for majority of these tumors. Efforts made to define the molecular basis of liposarcomas lead to the finding that besides the amplifications of CDK4 and MDM2, Aurora Kinase A, also was shown to be overexpressed. Based on these as well as mathematic modeling, we have carried out a successful preclinical study using CDK4 and IGF1R inhibitors in liposarcoma. MLN8237 has been shown to be a potent and selective inhibitor of Aurora A. MLN-8237, as per our results, induces a differential inhibition of Aurora A and B in a dose dependent manner. At a low nanomolar dose, cellular effects such as induction of phospho-Histone H3 (Ser10) mimicked as that of the inhibition of Aurora kinase A followed by apoptosis. However, micromolar dose of MLN-8237 induced polyploidy, a hallmark effect of Aurora B inhibition. The dose dependent selectivity of inhibition was further confirmed by using siRNA specific inhibition of Aurora A and B. This was further tested by time lapse microscopy of GFP-H2B labelled cells treated with MLN-8237. LS141 xenograft model at a dose of 30 mg/kg also showed efficient growth suppression by selective inhibition of Aurora Kinase A. Based on our data, a dose that can target only Aurora A will be more beneficial in tumor suppression.

Chromosomal Instability in Gastric Cancer Biology

Gastric cancer (GC) is the fifth most common cancer in the world and accounts for 7% of the total cancer incidence. The prognosis of GC is dismal in Western countries due to late diagnosis: approximately 70% of the patients die within 5 years following initial diagnosis. Recently, integrative genomic analyses led to the proposal of a molecular classification of GC into four subtypes, i.e.,microsatellite-instable, Epstein-Barr virus–positive, chromosomal-instable (CIN), and genomically stable GCs. Molecular classification of GC advances our knowledge of the biology of GC and may have implications for diagnostics and patient treatment. Diagnosis of microsatellite-instable GC and Epstein-Barr virus–positive GC is more or less straightforward. Microsatellite instability can be tested by immunohistochemistry (MLH1, PMS2, MSH2, and MSH6) and/or molecular-biological analysis. Epstein-Barr virus–positive GC can be tested by in situ hybridization (Epstein-Barr virus encoded small RNA). However, with regard to CIN, testing may be more complicated and may require a more in-depth knowledge of the underlying mechanism leading to CIN. In addition, CIN GC may not constitute a distinct subgroup but may rather be a compilation of a more heterogeneous group of tumors. In this review, we aim to clarify the definition of CIN and to point out the molecular mechanisms leading to this molecular phenotype and the challenges faced in characterizing this type of cancer.

Phase I study of the aurora A kinase inhibitor alisertib with induction chemotherapy in patients with acute myeloid leukemia

Aberrant expression of aurora kinase A is implicated in the genesis of various neoplasms, including acute myeloid leukemia. Alisertib, an aurora A kinase inhibitor, has demonstrated efficacy as monotherapy in trials of myeloid malignancy, and this efficacy appears enhanced in combination with conventional chemotherapies. In this phase I, dose-escalation study, newly diagnosed patients received conventional induction with cytarabine and idarubicin, after which alisertib was administered for 7 days. Dose escalation occurred via cohorts. Patients could then receive up to four cycles of consolidation, incorporating alisertib, and thereafter alisertib maintenance for up to 12 months. Twenty-two patients were enrolled. One dose limiting toxicity occurred at dose level 2 (prolonged thrombocytopenia), and the recommended phase 2 dose was established at 30mg twice daily. Common therapy-related toxicities included cytopenias and mucositis. Only three (14%) patients had persistent disease at mid-cycle, requiring “5+2” reinduction. The composite remission rate (complete remission and complete remission with incomplete neutrophil recovery) was 86% (nineteen of twenty-two patients; 90% CI 68–96%). Among those over age 65 and those with high-risk disease (secondary acute leukemia or cytogenetically high-risk disease), the composite remission rate was 88% and 100%, respectively. The median follow up was 13.5 months. Of those treated at the recommended phase 2 dose, the 12-month overall survival and progression-free survival were 62% (90% CI 33–81%) and 42% (90% CI 17–65%), respectively. Alisertib is well tolerated when combined with induction chemotherapy in acute myeloid leukemia, with a promising suggestion of efficacy. (clinicaltrials.gov Identifier:01779843).

Satellite Cells in Muscular Dystrophy - Lost in Polarity

Recent findings employing the mdx mouse model for Duchenne muscular dystrophy (DMD) have revealed that muscle satellite stem cells play a direct role in contributing to disease etiology and progression of DMD, the most common and severe form of muscular dystrophy. Lack of dystrophin expression in DMD has critical consequences in satellite cells including an inability to establish cell polarity, abrogation of asymmetric satellite stem-cell divisions, and failure to enter the myogenic program. Thus, muscle wasting in dystrophic mice is not only caused by myofiber fragility but is exacerbated by intrinsic satellite cell dysfunction leading to impaired regeneration. Despite intense research and clinical efforts, there is still no effective cure for DMD. In this review we highlight recent research advances in DMD and discuss the current state of treatment and, importantly, how we can incorporate satellite cell-targeted therapeutic strategies to correct satellite cell dysfunction in DMD.

AURKA promotes cell migration and invasion of head and neck squamous cell carcinoma through regulation of the AURKA/Akt/FAK signaling pathway

The present study aimed to investigate the mechanism by which Aurora kinase A (AURKA) promotes cell migration and invasion in head and neck squamous cell carcinoma (HNSCC). Transwell assays were performed to investigate the cell migration and invasion abilities of AURKA, whilst western blotting was used to analyze the protein expression in FaDu and Hep2 cells, each treated with pharmacological inhibitors. Following the inhibition of AURKA, Akt and focal adhesion kinase (FAK), the migration and invasion of the FaDu and Hep2 cells decreased. The expression of phosphorylated (p)-AURKA and p-FAK (Y397) was observed to decrease following FaDu and Hep2 cell treatment with VX-680, a small molecular inhibitor of AURKA. The expression of p-Akt and p-FAK (Y397) ceased following treatment with the Akt inhibitor triciribine. The expression of p-FAK (Y397) decreased, however, p-Akt expression did not change following treatment with the FAK inhibitor TAE226. In conclusion, AURKA activates FAK through the AURKA/Akt/FAK signaling pathway, promoting the migration and invasion of HNSCC cells, which may subsequently provide a novel approach for the treatment of HNSCC.

Aurora-A Kinase as a Promising Therapeutic Target in Cancer

Mammalian Aurora family of serine/threonine kinases are master regulators of mitotic progression and are frequently overexpressed in human cancers. Among the three members of the Aurora kinase family (Aurora-A, -B, and -C), Aurora-A and Aurora-B are expressed at detectable levels in somatic cells undergoing mitotic cell division. Aberrant Aurora-A kinase activity has been implicated in oncogenic transformation through the development of chromosomal instability and tumor cell heterogeneity. Recent studies also reveal a novel non-mitotic role of Aurora-A activity in promoting tumor progression through activation of epithelial-mesenchymal transition reprograming resulting in the genesis of tumor-initiating cells. Therefore, Aurora-A kinase represents an attractive target for cancer therapeutics, and the development of small molecule inhibitors of Aurora-A oncogenic activity may improve the clinical outcomes of cancer patients. In the present review, we will discuss mitotic and non-mitotic functions of Aurora-A activity in oncogenic transformation and tumor progression. We will also review the current clinical studies, evaluating small molecule inhibitors of Aurora-A activity and their efficacy in the management of cancer patients.

The Non-Canonical Role of Aurora-A in DNA Replication

Aurora-A is a well-known mitotic kinase that regulates mitotic entry, spindle formation, and chromosome maturation as a canonical role. During mitosis, Aurora-A protein is stabilized by its phosphorylation at Ser51 via blocking anaphase-promoting complex/cyclosome-mediated proteolysis. Importantly, overexpression and/or hyperactivation of Aurora-A is involved in tumorigenesis via aneuploidy and genomic instability. Recently, the novel function of Aurora-A for DNA replication has been revealed. In mammalian cells, DNA replication is strictly regulated for preventing over-replication. Pre-replication complex (pre-RC) formation is required for DNA replication as an initiation step occurring at the origin of replication. The timing of pre-RC formation depends on the protein level of geminin, which is controlled by the ubiquitin–proteasome pathway. Aurora-A phosphorylates geminin to prevent its ubiquitin-mediated proteolysis at the mitotic phase to ensure proper pre-RC formation and ensuing DNA replication. In this review, we introduce the novel non-canonical role of Aurora-A in DNA replication.

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

Aurora kinases (AKs) represent a novel group of serine/threonine kinases. They were originally described in 1995 by David Glover in the course of studies of mutant alleles characterized with unusual spindle pole configuration in Drosophila melanogaster. Thus far, three AKs A, B, and C have been discovered in human healthy and neoplastic cells. Each one locates in different subcellular locations and they are all nuclear proteins. AKs are playing an essential role in mitotic events such as monitoring of the mitotic checkpoint, creation of bipolar mitotic spindle and alignment of centrosomes on it, also regulating centrosome separation, bio-orientation of chromosomes and cytokinesis. Any inactivation of them can have catastrophic consequences on mitotic events of spindle formation, alignment of centrosomes and cytokinesis, resulting in apoptosis. Overexpression of AKs has been detected in diverse solid and hematological cancers and has been linked with a dismal prognosis. After discovery and identification of the first aurora kinase inhibitor (AKI) ZM447439 as a potential drug for targeted therapy in cancer treatment, approximately 30 AKIs have been introduced in cancer treatment.

Aurora kinase A in gastrointestinal cancers: time to target

Gastrointestinal (GI) cancers are a major cause of cancer-related deaths. During the last two decades, several studies have shown amplification and overexpression of Aurora kinase A (AURKA) in several GI malignancies. These studies demonstrated that AURKA not only plays a role in regulating cell cycle and mitosis, but also regulates a number of key oncogenic signaling pathways. Although AURKA inhibitors have moved to phase III clinical trials in lymphomas, there has been slower progress in GI cancers and solid tumors. Ongoing clinical trials testing AURKA inhibitors as a single agent or in combination with conventional chemotherapies are expected to provide important clinical information for targeting AURKA in GI cancers. It is, therefore, imperative to consider investigations of molecular determinants of response and resistance to this class of inhibitors. This will improve evaluation of the efficacy of these drugs and establish biomarker based strategies for enrollment into clinical trials, which hold the future direction for personalized cancer therapy. In this review, we will discuss the available data on AURKA in GI cancers. We will also summarize the major AURKA inhibitors that have been developed and tested in pre-clinical and clinical settings.

Advances in targeted therapies and new promising targets in esophageal cancer

Esophageal cancer, comprising squamous carcinoma and adenocarcinoma, is a leading cause of cancer-related death in the world. Notably, the incidence of esophageal adenocarcinoma has increased at an alarming rate in the Western world. Unfortunately, the standard first-line chemo-radiotherapeutic approaches are toxic and of limited efficacy in the treatment of a significant number of cancer patients. The molecular analysis of cancer cells has uncovered key genetic and epigenetic alterations underlying the development and progression of tumors. These discoveries have paved the way for the emergence of targeted therapy approaches. This review will highlight recent progress in the development of targeted therapies in esophageal cancer. This will include a review of drugs targeting receptor tyrosine kinases and other kinases in esophageal cancer. Additional studies will be required to develop a rational integration of these targeted agents with respect to histologic types of esophageal cancer and the optimal selection of cancer patients who would most likely benefit from targeted therapy. Identification of AURKA and AXL as key molecular players in esophageal tumorigenesis and drug resistance strongly justifies the evaluation of the available drugs against these targets in clinical trials.

Aurora kinase A has a significant role as a therapeutic target and clinical biomarker in endometrial cancer

Aurora kinase A (AURKA) regulates the cell cycle checkpoint and maintains genomic integrity. AURKA is overexpressed in various malignant tumors and its upregulation induces chromosomal instability, which leads to aneuploidy and cell transformation. To investigate the role of AURKA in endometrial cancer, we evaluated the association of immunohistochemical expression of AURKA with clinicopathological factors. Furthermore, we examined the effects of AURKA inhibition by transfected siRNA in HEC-1B cells on colony-forming ability, invasion and migration capacity, and chemosensitivity. Immunohistochemical staining showed that overexpression of AURKA was significantly associated with tumor grade (P<0.05) and poor histologic differentiation (P<0.05). The recurrence rate also tended to be high in cases with overexpression of AURKA (P<0.1) and these cases also had a tendency for shorter disease-free survival (DFS) (P<0.1). AURKA inhibition in endometrial cancer cell lines significantly decreased cell growth, invasion and migration (P<0.05), and increased chemosensitivity to paclitaxel. We also evaluated the efficacy of a combination of AURKA siRNA and paclitaxel against subcutaneous tumors formed in a nude mouse. After treatment, the tumor volume shrank significantly compared to treatment with paclitaxel only (P<0.05). To our knowledge, this is the first study in endometrial carcinoma to show a correlation between overexpression of AURKA and tumor grade, histological type and sensitivity to paclitaxel. AURKA is a promising therapeutic target in endometrial cancer and the combination therapy with AURKA inhibitors and paclitaxel could be effective for endometrial cancer that is resistant to conventional treatment and has a poor prognosis.

Expression of regulators of mitotic fidelity are associated with intercellular heterogeneity and chromosomal instability in primary breast cancer

Regulators of transition through mitosis such as SURVIVIN and Aurora kinase A (AURKA) have been previously implicated in the initiation of chromosomal instability (CIN), a driver of intratumour heterogeneity. We investigate the relationship between protein expression of these genes and directly quantified CIN, and their prognostic utility in breast cancer. The expression of SURVIVIN and AURKA was determined by immunohistochemistry in a cohort of 426 patients with primary breast cancer. The association between protein expression and histopathological characteristics, clinical outcome and CIN status, as determined by centromeric FISH and defined by modal centromere deviation, was analysed. Significantly poorer clinical outcome was observed in patients with high AURKA expression levels. Expression of SURVIVIN was elevated in ER-negative relative to ER-positive breast cancer. Both AURKA and SURVIVIN increased expression were significantly associated with breast cancer grade. There was a significant association between increased CIN and both increased AURKA and SURVIVIN expression. AURKA gene amplification was also associated with increased CIN. To our knowledge this is the largest study assessing CIN status in parallel with the expression of the mitotic regulators AURKA and SURVIVIN. These data suggest that elevated expression of AURKA and SURVIVIN, together with AURKA gene amplification, are associated with increased CIN in breast cancer, and may be used as a proxy for CIN in breast cancer samples in the absence of more advanced molecular measurements.

Aurora-A is a novel predictor of poor prognosis in patients with resected lung adenocarcinoma

BACKGROUND

The Aurora-A (Aur-A) gene, a key regulator of mitosis, has been proved as an oncogene in a variety of cancers. The Aur-A overexpression has been proved correlated with aggressiveness of cancer cells. However, the frequency of Aur-A protein overexpression, as well as its association with clinicopathologic parameters and prognosis remain unclear in lung adenocarcinoma (ADC). This study tried to clarify the clinical significance of Aur-A in patients with resected lung ADC.

PATIENTS AND METHODS

A total of 142 informative patients with surgically resected lung ADC and 20 normal lung tissues were enrolled. Western blot and immunohistochemistry (IHC) were utilized to assess protein expression of Aur-A.

RESULT

The expression of Aur-A was elevated in most of tumor tissues compared with the adjacent tissues by western blot. The IHC results showed that Aur-A protein was over-expressed in 98 of 142 (69.0%) tumor sections, while Aur-A was low-expressed in all normal lung sections. A positive correlation between Aur-A overexpression rate and ascending pathologic stages was observed (P<0.05). Kaplan-Meier analysis demonstrated that patients with Aur-A high expression had significantly inferior survival compared to those with Aur-A low expression. Both overall survival (OS) and disease-free survival (DFS) of positive overexpression patients were shorter than the negative group (P=0.036, P=0.041, respectively). Multivariate analysis confirmed that Aur-A expression, as an independent and significant factor for both DFS and OS, could predict a poor prognosis in patients with resected lung ADC (P=0.022, P=0.049, respectively).

CONCLUSIONS

Aur-A was overexpressed in lung ADC and overexpression of Aur-A might be a novel predictor for poor prognosis and potential therapeutic target in lung ADC.

A comparative study of the aneugenic and polyploidy-inducing effects of fisetin and two model Aurora kinase inhibitors

Fisetin, a plant flavonol commonly found in fruits, nuts and vegetables, is frequently added to nutritional supplements due to its reported cardioprotective, anti-carcinogenic and antioxidant properties. Earlier reports from our laboratory and others have indicated that fisetin has both aneugenic and clastogenic properties in cultured cells. More recently, fisetin has also been reported to target Aurora B kinase, a Ser/Thr kinase involved in ensuring proper microtubule attachment at the spindle assembly checkpoint, and an enzyme that is overexpressed in several types of cancer. Here we have further characterized the chromosome damage caused by fisetin and compared it with that induced by two known Aurora kinase inhibitors, VX-680 and ZM-447439, in cultured TK6 cells using the micronucleus assay with CREST staining as well as a flow cytometry-based assay that measures multiple types of numerical chromosomal aberrations. The three compounds were highly effective in inducing aneuploidy and polyploidy as evidenced by increases in kinetochore-positive micronuclei, hyperdiploidy, and polyploidy. With fisetin, however, the latter two effects were most significantly observed only after cells were allowed to overcome a cell cycle delay, and occurred at higher concentrations than those induced by the other Aurora kinase inhibitors. Modest increases in kinetochore-negative micronuclei were also seen with the model Aurora kinase inhibitors. These results indicate that fisetin induces multiple types of chromosome abnormalities in human cells, and indicate a need for a thorough investigation of fisetin-augmented dietary supplements.

The aurora kinases in cell cycle and leukemia

The Aurora kinases, which include Aurora A (AURKA), Aurora B (AURKB) and Aurora C (AURKC), are serine/threonine kinases required for the control of mitosis (AURKA and AURKB) and meiosis (AURKC). Since their discovery nearly 20 years ago, Aurora kinases have been studied extensively in cell and cancer biology. Several early studies found that Aurora kinases are amplified and overexpressed at the transcript and protein level in various malignancies, including several types of leukemia. These discoveries and others provided a rationale for the development of small-molecule inhibitors of Aurora kinases as leukemia therapies. The first generation of Aurora kinase inhibitors did not fare well in clinical trials, owing to poor efficacy and high toxicity. However, the creation of second-generation, highly selective Aurora kinase inhibitors has increased the enthusiasm for targeting these proteins in leukemia. This review will describe the functions of each Aurora kinase, summarize their involvement in leukemia and discuss inhibitor development and efficacy in leukemia clinical trials.

HDM2 regulation by AURKA promotes cell survival in gastric cancer

PURPOSE

Suppression of P53 (tumor protein 53) transcriptional function mediates poor therapeutic response in patients with cancer. Aurora kinase A (AURKA) and human double minute 2 (HDM2) are negative regulators of P53. Herein, we examined the role of AURKA in regulating HDM2 and its subsequent effects on P53 apoptotic function in gastric cancer.

EXPERIMENTAL DESIGN

Primary tumors and in vitro gastric cancer cell models with overexpression or knockdown of AURKA were used. The role of AURKA in regulating HDM2 and cell survival coupled with P53 expression and activity were investigated.

RESULTS

Overexpression of AURKA enhanced the HDM2 protein level; conversely, knockdown of endogenous AURKA decreased expression of HDM2 in AGS and SNU-1 cells. Dual co-immunoprecipitation assay data indicated that AURKA was associated with HDM2 in a protein complex. The in vitro kinase assay using recombinant AURKA and HDM2 proteins followed by co-immunoprecipitation revealed that AURKA directly interacts and phosphorylates HDM2 protein in vitro. The activation of HDM2 by AURKA led to induction of P53 ubiquitination and attenuation of cisplatin-induced activation of P53 in gastric cancer cells. Inhibition of AURKA using an investigational small-molecule specific inhibitor, alisertib, decreased the HDM2 protein level and induced P53 transcriptional activity. These effects markedly decreased cell survival in vitro and xenograft tumor growth in vivo. Notably, analysis of immunohistochemistry on tissue microarrays revealed significant overexpression of AURKA and HDM2 in human gastric cancer samples (P < 0.05).

CONCLUSION

Collectively, our novel findings indicate that AURKA promotes tumor growth and cell survival through regulation of HDM2-induced ubiquitination and inhibition of P53. Clin Cancer Res; 20(1); 76-86. ©2013 AACR.

Proteins related to the spindle and checkpoint mitotic emphasize the different pathogenesis of hypoplastic MDS

Some studies show that alterations in expression of proteins related to mitotic spindle (AURORAS KINASE A and B) and mitotic checkpoint (CDC20 and MAD2L1) are involved in chromosomal instability and tumor progression in various solid and hematologic malignancies. This study aimed to evaluate these genes in MDS patients. The cytogenetics analysis was carried out by G-banding, AURKA and AURKB amplification was performed using FISH, and AURKA, AURKB, CDC20 and MAD2L1 gene expression was performed by qRT-PCR in 61 samples of bone marrow from MDS patients. AURKA gene amplification was observed in 10% of the cases, which also showed higher expression levels than the control group (p=0.038). Patients with normo/hypercellular BM presented significantly higher expression levels than hypocellular BM patients, but normo and hypercellular BM groups did not differ. After logistic regression analysis, our results showed that HIGH expression levels were associated with increased risk of developing normo/hypercellular MDS. It also indicated that age is associated with AURKA, CDC20 and MAD2L1 HIGH expression levels. The distinct expression of hypocellular patients emphasizes the prognostic importance of cellularity to MDS. The amplification/high expression of AURKA suggests that the increased expression of this gene may be related to the pathogenesis of disease.

Response to MLN8237 in pancreatic cancer is not dependent on RalA phosphorylation

The high prevalence of KRAS mutations and importance of the RalGEF-Ral pathway downstream of activated K-ras in pancreatic ductal adenocarcinoma (PDAC) emphasize the importance of identifying novel methods by which to therapeutically target these pathways. It was recently demonstrated that phosphorylation of RalA S194 by Aurora A kinase (AAK) is critical for PDAC tumorigenesis. We sought to evaluate the AAK-selective inhibitor MLN8237 as a potential indirect anti-RalA-targeted therapy for PDAC. We used a site-specific phospho-S194 RalA antibody and determined that RalA S194 phosphorylation levels were elevated in a subset of PDAC cell lines and human tumors relative to unmatched normal controls. Effects of MLN8237 on anchorage-independent growth in PDAC cell lines and growth of patient-derived xenografts (PDX) were variable, with a subset of cell lines and PDX showing sensitivity. Surprisingly, RalA S194 phosphorylation levels in PDAC cell lines or PDX tumors did not correlate with MLN8237 responsiveness. However, we identified Ki67 as a possible early predictive biomarker for response to MLN8237 in PDAC. These results indicate that MLN8237 treatment may be effective for a subset of patients with PDAC independent of RalA S194 phosphorylation. Ki67 may be an effective pharmacodynamic biomarker to identify response early in the course of treatment.

NCIC CTG IND.181: phase I study of AT9283 given as a weekly 24 hour infusion in advanced malignancies

PURPOSE

AT9283 is a potent inhibitor of the mitotic regulators, Aurora-kinases A and B, and has shown anti-tumor activity in patients with solid and haematological malignancies. This phase I study assessed safety, tolerability, pharmacokinetic and pharmacodynamic properties of AT9283.

PATIENTS AND METHODS

Patients with advanced, incurable solid tumors or non-Hodgkin's lymphoma received AT9283 as a continuous 24-hour infusion on days 1, 8 of a 21-day cycle. A 3 + 3 dose escalation design was used with a starting dose of 1.5 mg/m(2)/day. Pharmacokinetic samples were collected from all patients on cycle one, and pharmacodynamic samples were collected from 4 patients at the recommended phase II dose (RP2D).

RESULTS

35 patients were evaluable for toxicity and 32 were evaluable for response. AT9283 was well tolerated, with main toxicities being reversible dose-related fatigue, gastrointestinal disturbance, anemia, lymphocytopenia and neutropenia. The dose limiting toxicities were febrile neutropenia (two patients) and neutropenia with grade 3 infection (1 patient) at 47 mg/m(2)/day (established as the maximum tolerated dose). The RP2D was 40 mg/m(2)/day. Pharmacokinetic analyses showed AT9283 appeared to follow linear kinetics, with a mean elimination half-life of 8.2 h. Pharmacodynamic analyses showed no consistent or significant changes, but trends suggested evidence of AT9283 inhibition and anti-proliferative activity. One patient had partial response and four patients experienced RECIST stable disease (median 2.6 months).

CONCLUSION

In this study, AT9283 was well tolerated. The RP2D is 40 mg/m(2)/day on days 1, 8 of a 21-day cycle. Ongoing AT9283 trials will assess efficacy and safety in solid and haematological cancers.

Depletion of Aurora A leads to upregulation of FoxO1 to induce cell cycle arrest in hepatocellular carcinoma cells

Aurora A kinase has drawn considerable attention as a therapeutic target for cancer therapy. However, the underlying molecular and cellular mechanisms of the anticancer effects of Aurora A kinase inhibition are still not fully understood. Herein, we show that depletion of Aurora A kinase by RNA interference (RNAi) in hepatocellular carcinoma (HCC) cells upregulated FoxO1 in a p53-dependent manner, which induces cell cycle arrest. Introduction of an RNAi-resistant Aurora A kinase into Aurora A-knockdown cells resulted in downregulation of FoxO1 expression and rescued proliferation. In addition, silencing of FoxO1 in Aurora A-knockdown cells allowed the cells to exit cytostatic arrest, which, in turn, led to massive cell death. Our results suggest that FoxO1 is responsible for growth arrest at the G2/M phase that is induced by Aurora A kinase inhibition.

Asymmetric cell division of stem and progenitor cells during homeostasis and cancer

Stem and progenitor cells are characterized by their ability to self-renew and produce differentiated progeny. A fine balance between these processes is achieved through controlled asymmetric divisions and is necessary to generate cellular diversity during development and to maintain adult tissue homeostasis. Disruption of this balance may result in premature depletion of the stem/progenitor cell pool, or abnormal growth. In many tissues, including the brain, dysregulated asymmetric divisions are associated with cancer. Whether there is a causal relationship between asymmetric cell division defects and cancer initiation is as yet not known. Here, we review the cellular and molecular mechanisms that regulate asymmetric cell divisions in the neural lineage and discuss the potential connections between this regulatory machinery and cancer.

Genetics/genomics/proteomics of gastric adenocarcinoma

Hereditary diffuse gastric cancer can be caused by epithelial cadherin mutations for which genetic testing is available. Inherited cancer predisposition syndromes including Lynch, Li-Fraumeni, and Peutz-Jeghers syndromes, can be associated with gastric cancer. Chromosomal and microsatellite instability occur in gastric cancers. Several consistent genetic and molecular alterations including chromosomal instability, microsatellite instability, and epigenetic alterations have been identified in gastric cancers. Biomarkers and molecular profiles are being discovered with potential for diagnostic, prognostic, and treatment guidance implications.

Dysregulating IRES-dependent translation contributes to overexpression of oncogenic Aurora A Kinase

Overexpression of the oncoprotein Aurora A kinase occurs in multiple types of cancer, often early during cell transformation. To identify the mechanism(s) contributing to enhanced Aurora A protein expression, a comparison between normal human lung fibroblast and breast epithelial cells to nontumorigenic breast (MCF10A and MCF12A) and tumorigenic breast (MCF-7) and cervical cell lines (HeLa S3) was performed. A subset of these immortalized lines (MCF10A, MCF12A, and HeLa S3) exhibited increased levels of Aurora A protein, independent of tumorigenicity. The increase in Aurora A protein in these immortalized cells was not due to increased transcription/RNA stability, protein half-life, or cap-dependent translation. Assays utilizing monocistronic and dicistronic RNA constructs revealed that the 5'-leader sequence of Aurora A contains an internal ribosomal entry site (IRES), which is regulated in a cell cycle-dependent manner, peaking in G2/M phase. Moreover, IRES activity was increased in the immortalized cell lines in which Aurora A protein expression was also enhanced. Additional studies indicated that the increased internal initiation is specific to the IRES of Aurora A and may be an early event during cancer progression. These results identify a novel mechanism contributing to Aurora A kinase overexpression.

IMPLICATIONS

The current study indicates that Aurora A kinase contributes to immortalization and tumorigenesis.

Contribution of Aurora-A and -B expression to DNA aneuploidy in gastric cancers

PURPOSE

DNA aneuploidy, which is characterized by cells containing an abnormal number of chromosomes, is closely associated with carcinogenesis and malignant progression. Aneuploidy occurs during cell division when the chromosomes do not separate properly. Aurora kinases (Aurora-A, -B, and -C) contribute to accurate cell division, and are candidate molecular targets for mitosis-specific anticancer drugs.

METHODS

We determined the expression of Aurora-A and -B in 110 gastric cancer specimens by performing an immunohistochemical analysis. We also determined the DNA content, TP53 gene mutations, and microsatellite instability in the same samples.

RESULTS

We found the nuclear expression of Aurora-A and -B to increase in tumor tissue in comparison to that in normal epithelial tissue. A high Aurora-B expression significantly correlated with aneuploidy and TP53 mutations, but not with microsatellite instability. In contrast, the Aurora-A expression did not correlate with either aneuploidy or microsatellite instability. In addition, the expression of Aurora-A or -B was not significantly associated with the clinical outcomes or prognosis.

CONCLUSIONS

Our results suggest that an overexpression of Aurora-B, but not of Aurora-A, might contribute to DNA aneuploidy in gastric cancers by promoting chromosomal instability.

Targeting cell cycle kinases and kinesins in anticancer drug development

The cell cycle is regulated by kinases such as the cyclin-dependent kinases (CDKs) and non-CDKs, which include Aurora and polo-like kinases, as well as checkpoint proteins. Mitotic kinesins are involved in the establishment of the mitotic spindle formation and function, and also play a role in cell cycle control. The disruption of the cell cycle is a hallmark of malignancy. Genetic or epigenetic events result in the upregulation of these kinases and mitotic kinesins in a myriad of tumour types, suggesting that their inhibition could result in preferential targeting of malignant cells. Such findings make the development of these inhibitors a rational and attractive new area for cancer therapeutics. Although challenges of potency and non-specificity have hampered their progress through the clinic, several novel compounds are presently in various phases of clinical trial evaluation.

Prospective assessment of XRCC3, XPD and Aurora kinase A single-nucleotide polymorphisms in advanced lung cancer

PURPOSE

New therapeutic approaches are being developed based on findings that several genetic abnormalities underlying non-small-cell lung cancer (NSCLC) can influence chemosensitivity. The identification of molecular markers, useful for therapeutic decisions in lung cancer, is thus crucial for disease management. The present study evaluated single-nucleotide polymorphisms (SNPs) in XRCC3, XPD and Aurora kinase A in NSCLC patients in order to assess whether these biomarkers were able to predict the outcomes of the patients.

METHODS

The Spanish Lung Cancer Group prospectively assessed this clinical study. Eligible patients had histologically confirmed stage IV or IIIB (with malignant pleural effusion) NSCLC, which had not previously been treated with chemotherapy, and a World Health Organization performance status (PS) of 0-1. Patients received intravenous doses of vinorelbine 25 mg/m(2) on days 1 and 8, and cisplatin 75 mg/m(2) on day 1, every 21 days for a maximum of 6 cycles. Venous blood was collected from each, and genomic DNA was isolated. SNPs in XRCC3 T241M, XPD K751Q, XPD D312N, AURORA 91, AURORA 169 were assessed.

RESULTS

The study included 180 patients. Median age was 62 years; 87 % were male; 34 % had PS 0; and 83 % had stage IV disease. The median number of cycles was 4. Time to progression was 5.1 months (95 % CI, 4.2-5.9). Overall median survival was 8.6 months (95 % CI, 7.1-10.1). There was no significant association between SNPs in XRCC3 T241M, XPD K751Q, XPD D312N, AURORA 91, AURORA 169 in outcome or toxicity.

CONCLUSIONS

Our findings indicate that SNPs in XRCC3, XPD or Aurora kinase A cannot predict outcomes in advanced NSCLC patients treated with platinum-based chemotherapy.

The combination of alisertib, an investigational Aurora kinase A inhibitor, and docetaxel promotes cell death and reduces tumor growth in preclinical cell models of upper gastrointestinal adenocarcinomas

BACKGROUND

Upper gastrointestinal adenocarcinomas (UGCs) respond poorly to current chemotherapeutic regimes. The authors and others have previously reported frequent Aurora kinase A (AURKA) gene amplification and mRNA and protein overexpression in UGCs. The objective of the current study was to determine the therapeutic potential of alisertib (MLN8237) alone and in combination with docetaxel in UGCs.

METHODS

After treatment with alisertib and/or docetaxel, clonogenic cell survival, cell cycle analyses, Western blot analyses, and tumor xenograft growth assays were carried out to measure cell survival, cell cycle progression, apoptotic protein expression, and tumor xenograft volumes, respectively.

RESULTS

By using the AGS, FLO-1, and OE33 UGC cell lines, which have constitutive AURKA overexpression and variable tumor protein 53 (p53) status, significantly enhanced inhibition of cancer cell survival was observed with alisertib and docetaxel treatment in combination (P < .001), compared with single-agent treatments. Cell cycle analyses, after 48 hours of treatment with alisertib, produced a significant increase in the percentage of polyploidy in UGC cells (P < .01) that was further enhanced by docetaxel (P < .001). In addition, an increase in the percentage of cells in sub-G1-phase observed with alisertib (P < .01) was significantly enhanced with the combination treatment (P < .001). Western blot analysis demonstrated higher induction of cleaved caspase 3 protein expression with the combined treatment compared with single-agent treatments. In addition, FLO-1 and OE33 cell xenograft models demonstrated enhanced antitumor activity for the alisertib and docetaxel combination compared with single-agent treatments (P < .001).

CONCLUSIONS

The current study demonstrated that alisertib combined with docetaxel can mediate a better therapeutic outcome in UGC cell lines.

Aurora kinase inhibitor VE 465 synergistically enhances cytotoxicity of carboplatin in ovarian cancer cells through induction of apoptosis and downregulation of histone 3

Aurora kinases are essential for regulation of chromosome segregation and cytokinesis during mitosis and play a role in growth and progression of human tumors, including ovarian cancer. Aurora A and Aurora B are frequently overexpressed in high-grade and low-grade ovarian cancers. Targeting Aurora kinases has great potential for improving the efficacy of chemotherapies of ovarian cancer. In this study, we investigated whether the Aurora kinase inhibitor, VE 465, can enhance the anti-tumor activity of carboplatin in human ovarian cancer cells. The antitumor activity of VE 465 was tested by MTT proliferative assay in multiple established human epithelial ovarian cancer cell lines of varying p53 status. VE 465 and carboplatin had a synergistic effect on cell viability in both platinum-sensitive and -resistant ovarian cancers. The growth-inhibitory effect was accompanied by reduction in expression of histone 3 and an increase in apoptosis. We conclude that VE 465 enhances the efficacy of carboplatin agents in ovarian carcinoma.