Expression of Aurora kinase A and B in normal and malignant cervical tissue: high Aurora A kinase expression in squamous cervical cancer

A comprehensive review on role of Aurora kinase inhibitors (AKIs) in cancer therapeutics

Aurora kinases (AURKs) are a family of serine /threonine protein kinases that have a crucial role in cell cycle process mainly in the event of chromosomal segregation, centrosome maturation and cytokinesis. The family consists of three members including Aurora kinase A (AURK-A), Aurora kinase B (AURK-B) and Aurora kinase C (AURK-C). All AURKs contain a conserved kinase domain for their activity but differ in their cellular localization and functions. AURK-A and AURK-B are expressed mainly in somatic cells while the expression of AURK-C is limited to germ cells. AURK-A promotes G2 to M transition of cell cycle by controlling centrosome maturation and mitotic spindle assembly. AURK-B and AURK-C form the chromosome passenger complex (CPC) that ensures proper chromosomal alignments and segregation. Aberrant expression of AURK-A and AURK-B has been detected in several solid tumours and malignancies. Hence, they have become an attractive therapeutic target against cancer. The first part of this review focuses on AURKs structure, functions, subcellular localization, and their role in tumorigenesis. The review also highlights the functional and clinical impact of selective as well as pan kinase inhibitors. Currently, >60 compounds that target AURKs are in preclinical and clinical studies. The drawbacks of existing inhibitors like selectivity, drug resistance and toxicity have also been addressed. Since, majority of inhibitors are Aurora kinase inhibitor (AKI) type-1 that bind to the active (DFGin and Cin) conformation of the kinase, this information may be utilized to design highly selective kinase inhibitors that can be combined with other therapeutic agents for better clinical outcomes.

Interaction between Human Papillomavirus-Encoded E6 Protein and AurB Induces Cell Immortalization and Proliferation-A Potential Target of Intervention

The human papillomavirus E6 and E7 oncoproteins interact with a different subset of host proteins, leading to dysregulation of the apoptotic, cell cycle, and signaling pathways. In this study, we identified, for the first time, that Aurora kinase B (AurB) is a bona fide interacting partner of E6. We systematically characterized the AurB-E6 complex formation and its consequences in carcinogenesis using a series of in vitro and cell-based assays. We also assessed the efficacy of Aurora kinase inhibitors in halting HPV-mediated carcinogenesis using in vitro and in vivo models. We showed that AurB activity was elevated in HPV-positive cells, and this correlated positively with the E6 protein level. E6 interacted directly with AurB in the nucleus or mitotic cells. A previously unidentified region of E6, located upstream of C-terminal E6-PBM, was important for AurB-E6 complex formation. AurB-E6 complex led to reduced AurB kinase activity. However, the AurB-E6 complex increased the hTERT protein level and its telomerase activity. On the other hand, AurB inhibition led to the inhibition of telomerase activity, cell proliferation, and tumor formation, even though this may occur in an HPV-independent manner. In summary, this study dissected the molecular mechanism of how E6 recruits AurB to induce cell immortalization and proliferation, leading to the eventual cancer development. Our findings revealed that the treatment of AZD1152 exerted a non-specific anti-tumor effect. Hence, a continuous effort to seek a specific and selective inhibitor that can halt HPV-mediated carcinogenesis should be warranted.

Drugging Hijacked Kinase Pathways in Pediatric Oncology: Opportunities and Current Scenario

Childhood cancer is considered rare, corresponding to ~3% of all malignant neoplasms in the human population. The World Health Organization (WHO) reports a universal occurrence of more than 15 cases per 100,000 inhabitants around the globe, and despite improvements in diagnosis, treatment and supportive care, one child dies of cancer every 3 min. Consequently, more efficient, selective and affordable therapeutics are still needed in order to improve outcomes and avoid long-term sequelae. Alterations in kinases' functionality is a trademark of cancer and the concept of exploiting them as drug targets has burgeoned in academia and in the pharmaceutical industry of the 21st century. Consequently, an increasing plethora of inhibitors has emerged. In the present study, the expression patterns of a selected group of kinases (including tyrosine receptors, members of the PI3K/AKT/mTOR and MAPK pathways, coordinators of cell cycle progression, and chromosome segregation) and their correlation with clinical outcomes in pediatric solid tumors were accessed through the R2: Genomics Analysis and Visualization Platform and by a thorough search of published literature. To further illustrate the importance of kinase dysregulation in the pathophysiology of pediatric cancer, we analyzed the vulnerability of different cancer cell lines against their inhibition through the Cancer Dependency Map portal, and performed a search for kinase-targeted compounds with approval and clinical applicability through the CanSAR knowledgebase. Finally, we provide a detailed literature review of a considerable set of small molecules that mitigate kinase activity under experimental testing and clinical trials for the treatment of pediatric tumors, while discuss critical challenges that must be overcome before translation into clinical options, including the absence of compounds designed specifically for childhood tumors which often show differential mutational burdens, intrinsic and acquired resistance, lack of selectivity and adverse effects on a growing organism.

Targeting aurora kinase a (AURKA) in cancer: molecular docking and dynamic simulations of potential AURKA inhibitors

The Aurora family of serine/threonine kinases in mammals are key regulators of mitotic progression and are commonly upregulated in human tumors. Since AURKA's increased expression has been linked to cancer, AURKA inhibitors could reduce AURKA expression and function as potent therapeutic drugs. The study's objective was to find and categorize inhibitors with a stronger affinity for AURKA. This study also aimed to identify AURKA's expression profile and prognostic significance across pan-cancers. We looked into therapeutic compounds that were structurally comparable to MK8745 for their potential to selectively inhibit AURKA. We used drug likeliness analysis, MD simulation studies to evaluate the therapeutic possibility of screened MK8745 analogues. AURKA was found to be strongly upregulated in several cancers and is linked to worse overall and relapse-free survival. The Molecular docking and dynamic analysis revealed two new MK8745 analogues to be potent AURKA inhibitors with higher binding affinities and stabilities than MK8745. Furthermore, MK8745 analogues are potential replacements for MK8745 because they have strong binding affinity, which is consistent with MDS results, and have appropriate ADMET properties. Through basic, clinical, and preclinical research, the identification of novel compounds may open the door for their prospective use in the prevention of cancer.

Comprehensive analysis identifies as a critical prognostic prediction gene in breast cancer

BACKGROUND

Aurora kinases (AURKs) family plays a vital role not only in cell division but also in tumorigenesis. However, there are still rare systematic analyses of the diverse expression patterns and prognostic value of the AURKs family in breast cancer (BC). Systematic bioinformatics analysis was conducted to explore the biological role, prognostic value, and immunologic function of AURKs family in BC.

METHODS

The expression, prognostic value, and clinical functions of AURKs family in BC were evaluated with several bioinformatics web portals: ONCOMINE Gene Expression Profiling Interactive Analysis, Kaplan-Meier plotter, cBioPortal, Metascape, GeneMANIA, and LinkedOmics; and the result was verified using human tissues.

RESULTS

The expression of AURKA and AURKB were upregulated in BC in subgroup analyses based on tumor stage (all P   <  0.05). BC patients with high AURKA and AURKB expression had a worse overall survival, relapse-free survival, and distant metastasis-free survival (all P   <  0.05). Verification experiment revealed that AURKA and AURKB were upregulated in BC ( P  < 0.05). AURKA and AURKB were specifically associated with several tumor-associated kinases (polo-like kinase 1 and cyclin-dependent kinase 1), miRNAs (miR-507 and miR-381), and E2F transcription factor 1. Moreover, AURKA and AURKB were correlated with immune cell infiltration. Functional enrichment analysis revealed that AURKA and AURKB were involved in the cell cycle signaling pathway, platinum drug resistance signaling pathway, ErbB signaling pathway, Hippo signaling pathway, and nucleotide-binding and oligomerization domain-like receptor signaling pathway.

CONCLUSIONS

Aurora kinases AURKA and AURKB could be employed as novel prognostic biomarkers or promising therapeutic targets for BC.

Exploring Potential Biomarkers, Ferroptosis Mechanisms, and Therapeutic Targets Associated with Cutaneous Squamous Cell Carcinoma via Integrated Transcriptomic Analysis

Background

Cutaneous squamous cell carcinoma (cSCC) is the leading cause of death in patients with nonmelanoma skin cancers (NMSC). However, the unclear pathogenesis of cSCC limits the application of molecular targeted therapy.

Methods

Three microarray datasets (GSE2503, GSE45164, and GSE66359) were downloaded from the Gene Expression Omnibus (GEO). After identifying the differentially expressed genes (DEGs) in tumor and nontumor tissues, five kinds of analyses, namely, functional annotation, protein-protein interaction (PPI) network, hub gene selection, TF-miRNA-mRNA regulatory network analysis, and ferroptosis mechanism, were performed.

Results

A total of 146 DEGs were identified with significant differences, including 113 upregulated genes and 33 downregulated genes. The enriched functions and pathways of the DEGs included microtubule-based movement, ATP binding, cell cycle, P53 signaling pathway, oocyte meiosis, and PLK1 signaling events. Nine hub genes were identified (CDK1, AURKA, RRM2, CENPE, CCNB1, KIAA0101, ZWINT, TOP2A, and ASPM). Finally, RRM2, AURKA, and SAT1 were identified as significant ferroptosis-related genes in cSCC. The differential expression of these genes has been verified in two other independent datasets.

Conclusions

By integrated bioinformatic analysis, the hub genes identified in this study elucidated the molecular mechanism of the pathogenesis and progression of cSCC and are expected to become future biomarkers or therapeutic targets.

Integrative Genomic and Transcriptomic Profiling Reveals a Differential Molecular Signature in Uterine Leiomyoma versus Leiomyosarcoma

The absence of standardized molecular profiling to differentiate uterine leiomyosarcomas versus leiomyomas represents a current diagnostic challenge. In this study, we aimed to search for a differential molecular signature for these myometrial tumors based on artificial intelligence. For this purpose, differential exome and transcriptome-wide research was performed on histologically confirmed leiomyomas (n = 52) and leiomyosarcomas (n = 44) to elucidate differences between and within these two entities. We identified a significantly higher tumor mutation burden in leiomyosarcomas vs. leiomyomas in terms of somatic single-nucleotide variants (171,863 vs. 81,152), indels (9491 vs. 4098), and copy number variants (8390 vs. 5376). Further, we discovered alterations in specific copy number variant regions that affect the expression of some tumor suppressor genes. A transcriptomic analysis revealed 489 differentially expressed genes between these two conditions, as well as structural rearrangements targeting ATRX and RAD51B. These results allowed us to develop a machine learning approach based on 19 differentially expressed genes that differentiate both tumor types with high sensitivity and specificity. Our findings provide a novel molecular signature for the diagnosis of leiomyoma and leiomyosarcoma, which could be helpful to complement the current morphological and immunohistochemical diagnosis and may lay the foundation for the future evaluation of malignancy risk.

Modulation of serine/threonine-protein phosphatase 1 (PP1) complexes: A promising approach in cancer treatment

Cancer is the second leading cause of death worldwide. Despite the availability of numerous therapeutic options, tumor heterogeneity and chemoresistance have limited the success of these treatments, and the development of effective anticancer therapies remains a major focus in oncology research. The serine/threonine-protein phosphatase 1 (PP1) and its complexes have been recognized as potential drug targets. Research on the modulation of PP1 complexes is currently at an early stage, but has immense potential. Chemically diverse compounds have been developed to disrupt or stabilize different PP1 complexes in various cancer types, with the objective of inhibiting disease progression. Beneficial results obtained in vitro now require further pre-clinical and clinical validation. In conclusion, the modulation of PP1 complexes seems to be a promising, albeit challenging, therapeutic strategy for cancer.

Aurora kinase inhibitors as potential anticancer agents: Recent advances

Aurora kinases are a family of serine/threonine kinases that play a crucial role in cell proliferation through the regulation of mitotic spindles. These kinases are the regulatory proteins localized in the various phases of the cell cycle and are involved in centrosome maturation, chromosome alignment, chromosomal segregation, and cytokinesis. They have emerged as one of the validated drug targets for anticancer drug discovery as their overexpression has been implicated in the pathogenesis of various carcinomas. Inhibitors of Aurora kinases induce growth inhibition and apoptosis in a variety of tumor cells. Hence, the design and development of Aurora kinase inhibitors have been widely explored in recent years by the scientific community as potential anticancer agents. Various Aurora kinase inhibitors have been under preclinical and clinical investigations as antitumor agents. This review summarizes the recent strategies of various researchers for the design and development of Aurora kinase inhibitors belonging to different structural classes. Their bioactivity, SARs, molecular modelling, and mechanistic studies have also been described. The comprehensive compilation of research work carried out in the field will provide inevitable scope for the design and development of novel drug candidates with better selectivity and efficacy. The review is constructed after the exhaustive research in this discipline and includes the papers from 2011 to 2020.

Splicing Genomics Events in Cervical Cancer: Insights for Phenotypic Stratification and Biomarker Potency

Gynaecological cancers are attributed to the second most diagnosed cancers in women after breast cancer. On a global scale, cervical cancer is the fourth most common cancer and the most common cancer in developing countries with rapidly increasing mortality rates. Human papillomavirus (HPV) infection is a major contributor to the disease. HPV infections cause prominent cellular changes including alternative splicing to drive malignant transformation. A fundamental characteristic attributed to cancer is the dysregulation of cellular transcription. Alternative splicing is regulated by several splicing factors and molecular changes in these factors lead to cancer mechanisms such as tumour development and progression and drug resistance. The serine/arginine-rich (SR) proteins and heterogeneous ribonucleoproteins (hnRNPs) have prominent roles in modulating alternative splicing. Evidence shows molecular alteration and expression levels in these splicing factors in cervical cancer. Furthermore, aberrant splicing events in cancer-related genes lead to chemo- and radioresistance. Identifying clinically relevant modifications in alternative splicing events and splicing variants, in cervical cancer, as potential biomarkers for their role in cancer progression and therapy resistance is scrutinised. This review will focus on the molecular mechanisms underlying the aberrant splicing events in cervical cancer that may serve as potential biomarkers for diagnosis, prognosis, and novel drug targets.

Viral-Mediated AURKB Cleavage Promotes Cell Segregation and Tumorigenesis

Aurora kinase B (AURKB), a central regulator of chromosome segregation and cytokinesis, is aberrantly expressed in various cancer cells. However, the relationship of AURKB and oncogenic viruses in cancer progression remains unclear. Here, we reveal that N-cleaved isoforms of AURKB exist in several oncovirus-associated tumor cells and patient cancer tissues, including Kaposi's sarcoma-associated herpesvirus (KSHV), Epstein-Barr virus (EBV), and human papillomavirus virus (HPV). Mechanistically, in KSHV-infected tumor cells, the latent viral antigen LANA cleaves AURKB at Asp⁷⁶ in a serine protease-dependent manner. The N'-AURKB relocalizes to the spindle pole and promotes the metaphase-to-telophase transition in mitotic cells. Introduction of N'-AURKB but not C'-AURKB promotes colony formation and malignant growth of tumor cells in vitro and in vivo using a murine xenograft model. Altogether, our findings uncover a proteolytic cleavage mechanism by which oncoviruses induce cancer cell segregation and tumorigenesis.

Prediction of a miRNA-mRNA functional synergistic network for cervical squamous cell carcinoma

Cervical squamous cell carcinoma (CSCC) accounts for a significant proportion of cervical cancer; thus, there is a need for novel and noninvasive diagnostic biomarkers for this malignancy. In this study, we performed integrated analysis of a dataset from the Gene Expression Omnibus database to identify differentially expressed genes (DEGs) and differentially expressed miRNAs (DEmiRNAs) between CSCC, cervical intraepithelial neoplasia (CIN) and healthy control subjects. We further established protein-protein interaction and DEmiRNA-target gene interaction networks, and performed functional annotation of the target genes of DEmiRNAs. In total, we identified 1375 DEGs and 19 DEmiRNAs in CIN versus normal control, and 2235 DEGs and 33 DEmiRNAs in CSCC versus CIN by integrated analysis. Our protein-protein interaction network indicates that the common DEGs, Cyclin B/cyclin-dependent kinase 1 (CDK1), CCND1, ESR1 and Aurora kinase A (AURKA), are the top four hub genes. P53 and prostate cancer were identified as significantly enriched signaling pathways of common DEGs and DEmiRNA targets, respectively. We validated that expression levels of three DEGs (TYMS, SASH1 and CDK1) and one DEmiRNA of hsa-miR-99a were altered in blood samples of patients with CSCC. In conclusion, a total of four DEGs (TYMS, SASH1, CDK1 and AURKA) and two DEmiRNAs (hsa-miR-21 and hsa-miR-99a) may be involved in the pathogenesis of CIN and the progression of CIN into CSCC. Of these, TYMS is predicted to be regulated by hsa-miR-99a and SASH1 to be regulated by hsa-miR-21.

Hsa_circ_0075341 is up-regulated and exerts oncogenic properties by sponging miR-149-5p in cervical cancer

Increasing evidence revealed that circular RNAs (circRNAs) play important roles in tumor progression. In the present study, we explored the roles and underlying mechanisms of hsa_circ_0075341 in cervical cancer development. Our data showed that the expression of hsa_circ_0075341 was significantly upregulated and associated with larger tumor size, advanced FIGO stage, and lymph-node metastasis in cervical cancer patients. Hsa_circ_0075341 inhibition reduced cervical cancer cell proliferation and invasion in vitro. In mechanism, hsa_circ_0075341 negatively regulated miR-149-5p in cervical cancer progression. In addition, AURKA was confirmed as a direct target of miR-149-5p in cervical cancer and positively regulated by hsa_circ_0075341. Collectively, our data suggested that hsa_circ_0075341 promoted cervical cancer cell proliferation and invasion through regulating the miR-149-5p/AURKA axis, which provided a novel therapeutic target for cervical cancer treatment.

Potential new biomarkers for squamous carcinoma of the uterine cervix

Aim

An in silico pathway analysis was performed in an attempt to identify new biomarkers for cervical carcinoma.

Methods

Three publicly available Affymetrix gene expression data sets (GSE5787, GSE7803, GSE9750) were retrieved, vouching for a total 9 cervical cancer cell lines, 39 normal cervical samples, 7 CIN3 samples and 111 cervical cancer samples. An Agilent data set (GSE7410; 5 normal cervical samples, 35 samples from invasive cervical cancer) was selected as a validation set. Predication analysis of microarrays was performed in the Affymetrix sets to identify cervical cancer biomarkers. We compared the lists of differentially expressed genes between normal and CIN3 samples on the one hand (n=1923) and between CIN3 and invasive cancer samples on the other hand (n=628).

Results

Seven probe sets were identified that were significantly overexpressed (at least 2 fold increase expression level, and false discovery rate <5%) in both CIN3 samples respective to normal samples and in cancer samples respective to CIN3 samples. From these, five probes sets could be validated in the Agilent data set (P<0.001) comparing the normal with the invasive cancer samples, corresponding to the genes DTL, HMGB3, KIF2C, NEK2 and RFC4. These genes were additionally overexpressed in cervical cancer cell lines respective to the cancer samples. The literature on these markers was reviewed.

Conclusion

Novel biomarkers in combination with primary human papilloma virus (HPV) testing may allow complete cervical screening by objective, non-morphological molecular methods, which may be particularly important in developing countries.

VHL loss predicts response to Aurora kinase A inhibitor in renal cell carcinoma cells

The majority of molecular targets of anticancer agents are limited to a subset of patients, and therefore identification of more specific biomarkers that can be used to improve clinical outcomes is of increasing interest. The present study showed that von Hippel‑Lindau tumor suppressor (VHL) tumor‑suppressor activity may influence the therapeutic response to Aurora kinase A (AURKA) inhibitors in human renal cell carcinoma (RCC). VHL protein (pVHL) expression was evaluated by immunoblotting in the human RCC cell lines CAKI, ACHN, 786‑O, 769‑P and A498. The anti‑tumor activities of alisertib, an AURKA‑specific chemical inhibitor, were detected by Cell Counting Kit‑8 assay in vitro and mouse xenograft model in vivo. Additionally, the VHL‑mediated anti‑tumor activity was assessed in 769‑P and CAKI cells via the loss or gain of VHL. The results revealed that VHL‑deficient 786‑O, 769‑P and A498 cells were sensitive to alisertib. By contrast, alisertib‑resistant CAKI and ACHN cells expressed the wild type VHL gene. In addition, rescue or knockdown of VHL was observed to increase or decrease alisertib anti‑proliferation activity, respectively, in RCC cells. The inverse correlation between the VHL gene expression profile and alisertib sensitivity was further confirmed in human cancer xenografts models. Taken together, these results suggested that VHL loss could potentially serve as a biomarker for predicting the efficacy of AURKA inhibitors.

Aurora-A affects radiosenstivity in cervical squamous cell carcinoma and predicts poor prognosis

BACKGROUND

Definitive radiation therapy (RT) (with or without cisplatin-based chemotherapy) is one of the most effective treatments for cervical squamous cell carcinoma (CSCC), but efficacy is limited due to resistance. In the present study, we investigated the relationship between the expression of Aurora kinase A (Aurora-A, AURKA)and response to RT in patients with CSCC.

METHODS

The expression of Aurora-A in biopsy specimens of untreated primary tumors in 129 Uyghur patients with CSCC was investigated immunohistochemically. Primary treatment in these patients was definitive radical RT, which consisted of pelvic RT plus brachytherapy (total point A dose:70-85 Gy) (with or without cisplatin-based chemotherapy). The prognostic value of tumoral Aurora-A expression and patients' clinical outcomes were evaluated.

RESULTS

Aurora-A expression was significantly associated with lymph node metastasis (P<0.001), large tumor size (P<0.001), low hemoglobin (Hb) level (P=0.011) and recurrence (P<0.001), but not other clinicopathological factors. Definitive RT was unfavorable in patients with high Aurora-A expression (P < 0.001). In 129 enrolled patients, lymph node metastasis, large tumor size, low Hb level, and AURKA overexpression were prognostic factors for both recurrent free survival (RFS) and overall survival (OS) in univariate analysis. However, only high AURKA expression was an adverse independent risk factor for both RFS (hazard ratio, 3.953; 95% CI, 1.473-10.638; P = 0.006) and OS (hazard ratio 9.091; 95%CI 2.597-32.258; P<0.001) in multivariate analyses.

CONCLUSIONS

Aurora-A may serve as a predictive biomarker of radiation response and a therapeutic target to reverse radiation therapy resistance.

G2/M inhibitors as pharmacotherapeutic opportunities for glioblastoma: the old, the new, and the future

Glioblastoma (GBM) is one of the deadliest tumors and has a median survival of 3 months if left untreated. Despite advances in rationally targeted pharmacological approaches, the clinical care of GBM remains palliative in intent. Since the majority of altered signaling cascades involved in cancer establishment and progression eventually affect cell cycle progression, an alternative approach for cancer therapy is to develop innovative compounds that block the activity of crucial molecules needed by tumor cells to complete cell division. In this context, we review promising ongoing and future strategies for GBM therapeutics aimed towards G2/M inhibition such as anti-microtubule agents and targeted therapy against G2/M regulators like cyclin-dependent kinases, Aurora inhibitors, PLK1, BUB, 1, and BUBR1, and survivin. Moreover, we also include investigational agents in the preclinical and early clinical settings. Although several drugs were shown to be gliotoxic, most of them have not yet entered therapeutic trials. The use of either single exposure or a combination with novel compounds may lead to treatment alternatives for GBM patients in the near future.

Network analysis revealed aurora kinase dysregulation in five gynecological types of cancer

Gene markers are crucial for cancer prognosis and treatment. Previous studies have placed greater emphasis on individual diagnostic genes, thereby ignoring systemic-level attributes across diseases. Female-specific cells namely, breast, endometrium, cervical, ovarian and vulvar cells are highly susceptible to cancer. To date, a limited number of molecular studies have been performed that evaluate common biological processes across gynecological types of cancer. Differentially expressed genes in breast, cervical, endometrial, vulvar and ovarian cancer were utilized to construct protein-protein interaction networks, and to identify a common module across the five cancer types. A single common module with 8 nodes and 26 edges was mined among the five cancer systems. In total, four hub genes were present across the five cancer gene sets. Genes in the common module were enriched for the common pathways and associated diseases. The aurora kinase pathway was revealed to be conserved across the five cancer types surveyed. The present study, therefore, revealed that the aurora kinase pathway has a crucial function in the pathogenesis of the five aforementioned gynecological types of cancer through cross-tumor conservation.

Aurora kinases: novel therapy targets in cancers

Aurora kinases, a family of serine/threonine kinases, consisting of Aurora A (AURKA), Aurora B (AURKB) and Aurora C (AURKC), are essential kinases for cell division via regulating mitosis especially the process of chromosomal segregation. Besides regulating mitosis, Aurora kinases have been implicated in regulating meiosis. The deletion of Aurora kinases could lead to failure of cell division and impair the embryonic development. Overexpression or gene amplification of Aurora kinases has been clarified in a number of cancers. And a growing number of studies have demonstrated that inhibition of Aurora kinases could potentiate the effect of chemotherapies. For the past decades, a series of Aurora kinases inhibitors (AKIs) developed effectively repress the progression and growth of many cancers both in vivo and in vitro, suggesting that Aurora kinases could be a novel therapeutic target. In this review, we'll first briefly present the structure, localization and physiological functions of Aurora kinases in mitosis, then describe the oncogenic role of Aurora kinases in tumorigenesis, we shall finally discuss the outcomes of AKIs combination with conventional therapy.

Anti-mitotic agents: Are they emerging molecules for cancer treatment?

Mutations in cancer cells frequently result in cell cycle alterations that lead to unrestricted growth compared to normal cells. Considering this phenomenon, many drugs have been developed to inhibit different cell-cycle phases. Mitotic phase targeting disturbs mitosis in tumor cells, triggers the spindle assembly checkpoint and frequently results in cell death. The first anti-mitotics to enter clinical trials aimed to target tubulin. Although these drugs improved the treatment of certain cancers, and many anti-microtubule compounds are already approved for clinical use, severe adverse events such as neuropathies were observed. Since then, efforts have been focused on the development of drugs that also target kinases, motor proteins and multi-protein complexes involved in mitosis. In this review, we summarize the major proteins involved in the mitotic phase that can also be targeted for cancer treatment. Finally, we address the activity of anti-mitotic drugs tested in clinical trials in recent years.

Aurora-A Kinase: A Potent Oncogene and Target for Cancer Therapy

The Aurora kinase family is comprised of three serine/threonine kinases, Aurora-A, Aurora-B, and Aurora-C. Among these, Aurora-A and Aurora-B play central roles in mitosis, whereas Aurora-C executes unique roles in meiosis. Overexpression or gene amplification of Aurora kinases has been reported in a broad range of human malignancies, pointing to their role as potent oncogenes in tumorigenesis. Aurora kinases therefore represent promising targets for anticancer therapeutics. A number of Aurora kinase inhibitors (AKIs) have been generated; some of which are currently undergoing clinical evaluation. Recent studies have unveiled novel unexpected functions of Aurora kinases during cancer development and the mechanisms underlying the anticancer actions of AKIs. In this review, we discuss the most recent advances in Aurora-A kinase research and targeted cancer therapy, focusing on the oncogenic roles and signaling pathways of Aurora-A kinases in promoting tumorigenesis, the recent preclinical and clinical AKI data, and potential alternative routes for Aurora-A kinase inhibition.

Aurora A kinase is required for activation of the Fanconi anemia/BRCA pathway upon DNA damage

Previous studies have linked the DNA damage response to mitotic progression machinery. Mitotic kinases, such as Aurora A kinase and Polo‐like kinase, are involved in the phosphorylation of cell cycle regulators in response to DNA damage. Here, we investigated the potential involvement of Aurora A kinase in the activation of the Fanconi anemia (FA)/BRCA pathway, which participates in cellular response to DNA interstrand cross‐link lesions (ICL). Initially, we detected interactions between Aurora A kinase and FANCA protein, one of the components of the FA nuclear core complex. Silencing of Aurora A kinase led to inhibition of monoubiquitination of FANCD2 and formation of nuclear foci, the final consequences of FA/BRCA pathway activation upon ICL induction. An in vitro kinase assay revealed that Aurora A kinase phosphorylates S165 of FANCA. Moreover, this phosphorylation event was induced by the treatment with mitomycin C (MMC), an ICL‐inducing agent. In cells overexpressing S165A mutant FANCA, monoubiquitination of FANCD2 and nuclear foci formation was impaired and cellular sensitivity to MMC was enhanced. These results suggest that S165 phosphorylation by Aurora A kinase is required for proper activation of the FA/BRCA pathway in response to DNA damage.

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.

Spindle assembly checkpoint gene expression in childhood adrenocortical tumors (ACT): Overexpression of Aurora kinases A and B is associated with a poor prognosis

BACKGROUND

Pediatric adrenocortical tumors (ACT) are rare malignancies and treatment has a small impact on survival in advanced disease and the discovery of potential target genes could be important in new therapeutic approaches.

METHODS

The mRNA expression levels of spindle checkpoint genes AURKA, AURKB, BUB, and BUBR1 were analyzed in 60 children with ACT by quantitative real time PCR. The anticancer effect of ZM447439, an experimental AURK inhibitor, was analyzed in a primary childhood ACT culture carrying the TP53 p.R337H mutation.

RESULTS

A significant association was observed between malignancy as defined by Weiss score ≥3 and higher AURKA (2.0-fold, P = 0.01), AURKB (7.0-fold, P = 0.007), and BUBR1 (5.8-fold, P = 0.007) gene expression, and between unfavorable event (death or relapse) and higher expression of AURKA (6.0-fold, P = 0.034) and AURKB (17-fold, P = 0.013). Overexpression of AURKA and AURKB was associated with lower event-free survival in uni- (P < 0.001 and P = 0.006, respectively) and multivariate (P = 0.002 and P = 0.03, respectively) analysis. Significant lower Event free survival (EFS) was also observed in patients with moderate/strong immunostaining to AURKA (P = 0.012) and AURKB (P = 0.045). ZM447439 was able to induce inhibition of proliferation and colony formation in a primary childhood ACT culture carrying the TP53 p.R337H mutation.

CONCLUSION

Our results suggest that AURKA and AURKB overexpression in pediatric ACT may be related to more aggressive disease and the inhibition of these proteins could be an interesting approach for the treatment of these tumors.

The role of Aurora B expression in non-tumor liver tissues of patients with hepatocellular carcinoma

BACKGROUND

Aurora B is a serine-threonine kinase and chromosomal passenger protein involved in the control of chromosome assembly and segregation during mitosis. Aberrant expression of Aurora B has been reported in some tumors, including lung and hepatocellular carcinoma (HCC). We investigated the role of Aurora B expression in both HCC and matched adjacent non-tumor tissue.

METHODS

Sixty-three patients with HCC who underwent hepatic resection were enrolled in this study. Aurora B expression in tumor and non-tumor tissue was examined by use of quantitative reverse transcription-polymerase chain reaction. The patients were divided into high and low gene expression groups by median value, and clinicopathological data were compared between the two groups.

RESULTS

Aurora B expression was significantly higher in tumor tissue than in non-cancerous tissue (P < 0.001). Disease-free survival was not significantly different between groups with high and low expression in the tumor tissues. For non-tumor tissues, disease-free survival of the low-expression group was significantly better than that of the high-expression group (P < 0.05). The gene expression level of Aurora B correlated with results from liver function tests, for example prothrombin time.

CONCLUSION

Aurora B expression in non-cancerous tissues may be a prognostic factor for HCC.

Effects of alpha particle radiation on gene expression in human pulmonary epithelial cells

The general public receives approximately half of its exposure to natural radiation through alpha (α)-particles from radon ((222)Rn) gas and its decay progeny. Epidemiological studies have found a positive correlation between exposure to (222)Rn and lung carcinogenesis. An understanding of the transcriptional responses involved in these effects remains limited. In this study, genomic technology was employed to mine for subtle changes in gene expression that may be representative of an altered physiological state. Human lung epithelial cells were exposed to 0, 0.03, 0.3 and 0.9Gy of α-particle radiation. Microarray analysis was employed to determine transcript expression levels 4h and 24h after exposure. A total of 590 genes were shown to be differentially expressed in the α-particle radiated samples (false discovery rate (FDR)≤0.05). Sub-set of these transcripts were time-responsive, dose-responsive and both time- and dose-responsive. Pathway analysis showed functions related to cell cycle arrest, and DNA replication, recombination and repair (FDR≤0.05). The canonical pathways associated with these genes were in relation to pyrimidine metabolism, G2/M damage checkpoint regulation and p53 signaling (FDR≤0.05). Overall, this gene expression profile suggests that α-particle radiation inhibits DNA synthesis and subsequent mitosis, and causes cell cycle arrest.

Mitotic chromosomal instability and cancer: mouse modelling of the human disease

The stepwise progression from an early dysplastic lesion to full-blown metastatic malignancy is associated with increases in genomic instability. Mitotic chromosomal instability - the inability to faithfully segregate equal chromosome complements to two daughter cells during mitosis - is a widespread phenomenon in solid tumours that is thought to serve as the fuel for tumorigenic progression. How chromosome instability (CIN) arises in tumours and what consequences it has are still, however, hotly debated issues. Here we review the recent literature with an emphasis on models that recapitulate observations from human disease.

Overexpression of Aurora B is associated with poor prognosis in epithelial ovarian cancer patients

Recent studies have indicated that Aurora B expression is related to cell proliferation and prognosis in many cancers, but its association with epithelial ovarian carcinoma is not fully understood. Therefore, we examined the Aurora B kinase expression in epithelial ovarian cancer patients. Using immunohistochemistry, the expression levels of Aurora B and phosphohistone H3 (Ser(10)) (mitosis-specific marker) were measured in 156 patients with epithelial ovarian cancer. The expression levels of Aurora B at the protein and messenger RNA levels were examined using Western blotting and reverse transcriptase polymerase chain reaction. In total, 53 tumorous ovarian samples (34.0%) showed Aurora B overexpression, which was significantly higher than that found in the 15 normal ovarian tissue samples (0%, p = 0.006). The overexpression of Aurora B was also significantly higher in cases showing phosphohistone H3 (Ser(10)) overexpression (44.3% vs. 27.4%, p = 0.03). In addition, the expression of Aurora B in poorly and moderately differentiated carcinomas of the ovary was significantly higher than in well-differentiated carcinomas (53.6% vs. 28.2% vs.10.0%, respectively, p = 0.02). The overexpression of Aurora B was significantly higher in cases with lymph node metastasis (p = 0.01) and a positive ascites cytology (p = 0.008). Overall, the Aurora B overexpression group demonstrated a significantly shorter progression-free survival (p = 0.001) and overall survival (p = 0.023) than the Aurora B low expression group using univariate analysis (log-rank statistic). Aurora B is an effective predictor of aggressive epithelial ovarian carcinoma in terms of differentiation, metastasis, and prognosis.