Overexpression Of Aurora Kinase Research Articles

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

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. 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. 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. 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.

Evaluation of the Aurora Kinase Inhibitor, ZM447439, in Canine Malignant Lymphoid Cells &amp;lt;i&amp;gt;in Vitro&amp;lt;/i&amp;gt;

Aurora kinases play an important role in the cell cycle. These enzymes help establish mitotic spindles by directing centrosome duplication and separation and by regulating the spindle assembly checkpoint thereby helping control cytokinesis. An over-expression of aurora kinases has been reported in a variety of human tumors. In this study, we identified the expression of aurora-A and aurora-B kinases in canine malignant lymphoid cells. We also evaluated the effects of the aurora kinase inhibitor (ZM447439), and found that this inhibitor decreases cell viability, increases DNA content change, and leads to apoptosis in canine B- and T-cell lymphoid cell lines. The lymphotoxicity induced by ZM447439 in these canine lymphoid cell lines suggests that further in vivo evaluation of aurora kinase inhibitors as a potential treatment for canine malignant lymphoid tumors is warranted.

The potential role of Aurora kinase inhibitors in haematological malignancies

Aurora kinases play an important role in the control of the cell cycle and have been implicated in tumourigenesis in a number of cancers. Among the haematological malignancies, overexpression of Aurora kinases has been reported in acute myeloid leukaemia, chronic myeloid leukaemia, acute lymphoblastic leukaemia, multiple myeloma, aggressive non-Hodgkin lymphoma and Hodgkin lymphoma. A large number of Aurora kinase inhibitors are currently in different stages of clinical development. In addition to varying in their selectivity for the different Aurora kinases, some also have activity directed at other cellular kinases involved in important molecular pathways in cancer cells. This review summarizes the biology of Aurora kinases and discusses why they may be good therapeutic targets in different haematological cancers. We describe preclinical data that has served as the rationale for investigating Aurora kinase inhibitors in different haematological malignancies, and summarize published results from early phase clinical trials. While the anti-tumour effects of Aurora kinase inhibitors appear promising, we highlight important issues for future clinical research and suggest that the optimal use of these inhibitors is likely to be in combination with cytotoxic agents already in use for the treatment of various haematological cancers.

Effects of stable knockdown of Aurora kinase A on proliferation, migration, chromosomal instability, and expression of focal adhesion kinase and matrix metalloproteinase-2 in HEp-2 cells

Overexpression of Aurora kinase A (AURKA) is frequently observed in various cancers, including laryngeal squamous cell carcinoma (LSCC). We investigated the effects of knockdown of AURKA on laryngeal cancer HEp-2 cells both in vitro and in vivo. A plasmid containing short hairpin (sh)RNA against AURKA was constructed and transfected into HEp-2. Measurements included the CCK-8 assay for viability and proliferation, flow cytometry for apoptosis and effects on the mitotic checkpoint, a trans-well assay for migration, immunofluorescence for assessment of genomic instability, and western blotting for protein expression. AURKA knockdown inhibited proliferation, migration, and colony formation in vitro and tumorigenicity in vivo. The knockdown induced the accumulation of cells in G2-M phase and eventual apoptosis. Knockdown of AURKA caused delayed entry into mitosis after treatment with nocodazole, reduced chromosomal instability, and decreased expression of focal adhesion kinase (FAK), phosphorylated FAK, and matrix metalloproteinase-2 (MMP-2), key regulators in cell adhesion and invasion. Knockdown of AURKA inhibits the growth and invasiveness of this LSCC cell line both in vitro and in vivo. These effects may partially result from the reduced expression of FAK and MMP-2. Knockdown of AURKA expression may represent a promising therapeutic strategy for the treatment of LSCC.

Abstract 3554: CCT137690, a dual inhibitor of Aurora and FLT3 kinases, sensitizes FLT3-ITD positive acute myeloid leukemia and overcomes resistance to selective FLT3-inhibition

Abstract The Aurora kinases are a family of serine-threonine kinases that play key roles in different stages of mitosis. Over-expression of Aurora kinases has been demonstrated in a range of malignancies including leukemia. Aurora kinase inhibitors are emerging as promising agents in the treatment of acute myeloid leukemia (AML) with a number of compounds currently being assessed in clinical trials (Moore AS et al, Leukemia 2010). CCT137690, an imidazo[4,5-b]pyridine derivative discovered at our Institute, is an orally bioavailable, potent, pan-Aurora and FLT3 inhibitor. CCT137690 showed in vitro and in vivo activity in human colon cancer cell lines and xenograft models (Bavetsias V et al, J Med Chem 2010). Here we report the in vitro and in vivo activity of CCT137690 in FLT3-ITD positive AML and demonstrate that CCT137690 overcomes resistance to the selective FLT3 inhibitor MLN518. In cellular assays using FLT3-ITD positive MOLM-13 cells, CCT137690 inhibits autophosphorylation of Aurora A and Aurora B kinases and phosphorylation of histone H3, a direct target of Aurora B kinase. CCT137690 also inhibits autophosphorylation of FLT3 and its downstream targets phospho-STAT5 and phospho-p44/42 MAPK. Dual inhibition of Aurora and FLT3 kinases in FLT3-ITD positive AML with CCT137690 induces apoptosis and results in a unique cell cycle profile with cells accumulating in G2/M. When given orally to athymic mice, CCT137690 achieved target modulation and potently inhibited the growth of subcutaneous MOLM-13 xenografts, with no obvious toxicity or loss of body weight. Inhibition of MOLM-13 xenograft growth was more pronounced with CCT137690 compared to the selective FLT3 inhibitor MLN518, suggesting that dual inhibition of Aurora and FLT3 kinases may have advantages compared to selective FLT3 inhibition alone. To assess whether dual Aurora-FLT3 inhibition with CCT137690 could overcome FLT3-inhibitor resistance, we successfully cultured MOLM-13 cells in the presence of increasing concentrations of MLN518. Although resistant to MLN518, these cells maintained sensitivity to dual Aurora-FLT3 inhibition with CCT137690. The potent preclinical activity of CCT137690 in FLT3-ITD positive AML models supports the growing body of evidence that dual pan-Aurora and FLT3 kinase inhibitors may be of benefit in the high-risk group of patients with FLT3-ITD positive AML, including those with FLT3-inhibitor resistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3554. doi:10.1158/1538-7445.AM2011-3554

Dual Inhibition of Aurora and FLT3 Kinases by CCT137690: A Novel Treatment Strategy Against FLT3-ITD Positive AML In Vitro and In Vivo

AbstractAbstract 3289The Aurora kinases are a family of serine-threonine kinases that play key roles in different stages of mitosis. Over-expression of Aurora kinases has been demonstrated in a range of malignancies including leukemia. Aurora kinase inhibitors are emerging as promising agents in the treatment of acute myeloid leukemia (AML) with a number of compounds currently being assessed in clinical trials (Moore AS et al, Leukemia 2010). CCT137690, an imidazo[4,5-b]pyridine derivative discovered at our Institute, is an orally bioavailable, potent, pan-Aurora and FLT3 inhibitor with low nanomolar IC50 values against Aurora A (15 nM), Aurora B (25 nM), Aurora C (19 nM), and FLT3 (<0.5 nM) kinases. CCT137690 showed in vitro and in vivo activity in human colon cancer cell lines and xenograft models (Bavetsias V et al, J Med Chem 2010). Here we report the in vitro and in vivo activity of CCT137690 in FLT3-ITD positive AML. In vitro, the FLT3-ITD positive cell lines MV-4-11 and MOLM-13 are particularly sensitive with GI50 values less than 50 nM. Cellular assays demonstrate that CCT137690 inhibits autophosphorylation of Aurora A, Aurora B and Aurora C kinases and phosphorylation of histone H3, a direct target of Aurora B kinase. CCT137690 also inhibits autophosphorylation of FLT3 and phosphorylation of its downstream targets STAT5 and p44/42 MAPK (Erk1/2). Dual inhibition of Aurora and FLT3 kinases in FLT3-ITD positive AML with CCT137690 induces apoptosis and results in a unique cell cycle profile with cells accumulating in G2/M, whilst selective FLT3 inhibition with MLN518 resulted in G1/S arrest. When given orally to athymic mice, CCT137690 achieved target modulation and potently inhibited the growth of subcutaneous MOLM-13 xenografts, with no obvious toxicity or loss of body weight. Inhibition of MOLM-13 xenograft growth was more pronounced with CCT137690 compared to the selective FLT3 inhibitor MLN518, suggesting that dual inhibition of Aurora and FLT3 kinases may have advantages compared to selective FLT3 inhibition alone. The potent preclinical activity of CCT137690 in FLT3-ITD positive AML models supports the growing body of evidence that dual pan-Aurora and FLT3 kinase inhibitors may be of benefit in the high-risk group of patients with FLT3-ITD positive AML. Disclosures:Moore:The Institute of Cancer Research: Employment, The Institute of Cancer Research (ICR) has a commercial interest in drug development programs. Authors employed by ICR are subject to a Rewards to Inventors Scheme, which may reward contributors to a program that is subsequently licensed. Faisal:The Institute of Cancer Research: Employment. Bavetsias:The Institute of Cancer Research: Employment. Sun:The Institute of Cancer Research: Employment. Atrash:The Institute of Cancer Research: Employment. Valenti:The Institute of Cancer Research: Employment. de Haven Brandon:The Institute of Cancer Research: Employment. Avery:The Institute of Cancer Research: Employment. Raynaud:The Institute of Cancer Research: Employment. Workman:The Institute of Cancer Research: Employment. Pearson:The Institute of Cancer Research: Employment. Blagg:The Institute of Cancer Research: Employment. Eccles:The Institute of Cancer Research: Employment. Linardopoulos:The Institute of Cancer Research: Employment.

Segmental amplification of MLL gene associated with high expression of AURKA and AURKB genes in a case of acute monoblastic leukemia with complex karyotype

We report a case of acute monoblastic leukemia showing a jumping translocation with the MLL gene in a 17-year-old male. Classic cytogenetic and spectral karyotyping revealed a complex karyotype, and fluorescence in situ hybridization (FISH) demonstrated amplification of the MLL gene followed by translocation to chromosomes 15q, 17q, and 19q. In addition, molecular analyses showed a high expression of AURKA and AURKB genes. It is already known that overexpression of Aurora kinases is associated with chromosomal instability and poor prognosis. The formation of jumping translocations is a rare cytogenetic event and there is evidence pointing toward preferential involvement of the heterochromatin region of donor chromosomes and the telomere ends of recipient chromosomes. Jumping translocation with the MLL gene rearrangement is an uncommon phenomenon reported in leukemia cytogenetics.

Aurora kinase inhibitors: novel small molecules with promising activity in acute myeloid and Philadelphia-positive leukemias

Aurora kinases are a family of protein kinases that have a key role in multiple stages of mitosis. Over-expression of Aurora kinases, particularly Aurora A, has been demonstrated in a number of solid tumors and hematological malignancies. Not surprisingly, these serine/threonine kinases have become attractive small molecule targets for cancer therapeutics, with several inhibitors currently in early-phase clinical trials. A small number of compounds developed to date are highly selective for either Aurora A or Aurora B, while the majority inhibit both Aurora A and Aurora B; many of these compounds exhibit 'off-target' inhibition of kinases such as ABL, JAK2 and FLT3. It is currently unclear whether the therapeutic activity of these compounds in leukemia is primarily due to selective Aurora or multi-kinase inhibition. The most promising application for Aurora kinase inhibitors to date appears to be in FLT3-mutated acute myeloid leukemia (AML) and imatinib-resistant chronic myeloid leukemia/Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia, particularly when caused by the T315I mutation. Here we review the growing body of evidence supporting the use of Aurora kinase inhibitors as effective agents for AML and Ph+ leukemias.

Aurora Kinase Inhibitors - Rising Stars in Cancer Therapeutics?

Standard therapeutic approaches of cytotoxics and radiation in cancer are not only highly toxic, but also of limited efficacy in treatment of a significant number of cancer patients. The molecular analysis of the cancer genomes have shown a remarkable complexity and pointed to key genomic and epigenomic alterations in cancer. These discoveries are paving the way for targeted therapy approaches. However, although there are a large number of potential targets, only a few can regulate key cellular functions and intersect multiple signaling networks. The Aurora kinase family members (A, B, and C) are a collection of highly related and conserved serine-threonine kinases that fulfill these criteria, being key regulators of mitosis and multiple signaling pathways. Alterations in Aurora kinase signaling are associated with mitotic errors and have been closely linked to chromosomal aneuploidy in cancer cells. Several studies have shown amplification and/or overexpression of Aurora kinase A and B in hematologic malignancies and solid tumors. Over the past several years, Aurora kinases have become attractive targets. Several ongoing clinical trials and bench-based research are assessing the unique therapeutic potential of Aurora-based targeted therapy.

Abstract C77: In vivo anticancer activity of an aurora kinase inhibitor, VX-680, in gastric cancer

Abstract Background: Aurora kinases (AK) constitute one family of seine/threonine kinases, whose activity is essential for mitotic progression. Expression of aurora kinase is greatest in G2-M phase, and their function includes spindle formation, centrosome maturation, chromosomal segregation, and cytokinesis. Over-expression of AK is related to aneuploidy and carcinogenesis. Herein, we investigated the in vitro and in vivo anticancer acvitivity of a novel AK inhibitor, VX-680 in gastric cancer. Methods: AK protein expression and kinase activity were screened in gastric cancer cell lines using immunoblot and in vitro kinase assay, respectively. The anti-proliferative activity of VX-680 was measured using MTT assay. The changes of cell cycle by the treatment of VX-680 were analyzed by flow cytometry. YCC-16 cell line selected for tumor xenograft models. In vivo activity validation using mouse xenograft models and extract protein or tissue slide from each tumors. Results: AK protein expression and its kinase activity were variable among cell lines. VX-680 showed anti-proliferative effect in vitro on a wide range of gastric cancer cell lines, and calculating the IC50 value, it was distributed from 0.04uM to 19.87uM. It was correlated with kinase activity, not with protein expression of AK. VX-680 induced the reduction of phosphor-histone H3 and the cell cycle defects that accumulated &amp;gt;4N DNA. In vivo experiment, confirmed that AKI had an effect on tumor inhibition. Solid tumor formed with YCC-16 cell lines and VX-680 was injected twice a day for 5 days with a dose of 50mg/kg. Estimating the tumor volume for 21 days after VX-680 injection, the difference in tumor volume between the control and the treated mice were statistically significant. Kinase activity and phospho-histone H3 in VX-680 treated tumor was reduced in drug treatment samples compared to the control samples. Conclusion: We demonstrated that VX-680 has anti-cancer activity in gastric cancer. Kinase activity of AK might be a predictor for sensitivity of VX-680. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C77.

Targeting Aurora Kinase in Aggressive B-Cell Non-Hodgkin's Lymphomas.

Abstract 284Aurora kinases (A and B) are oncogenic serine/threonine (S/T) kinases that play central roles in the mitotic phase of the eukaryotic cell cycle. Over-expression of Aurora kinases during the cell cycle over-rides mitotic and spindle check points leading to aneuploidy in many human cancers; Aurora kinases are therefore attractive therapeutic targets. Gene expression profiling in aggressive B- and T-cell non-Hodgkin's lymphoma (NHL) has shown the Aurora kinases to be over-expressed and they may be key component genes of the ‘proliferative' signature. We hypothesized (1) Aurora kinases are over-expressed in human aggressive B-cell NHL (mantle cell lymphoma (MCL), diffuse large B-cell lymphoma (DLBCL) and transformed follicular lymphoma (TFL)), (2) Aurora ATP-binding site small molecule inhibitor (SMI) is effective in promoting apoptosis in cell culture and tumor growth inhibition (TGI) in mouse xenograft model(s) of NHL, and (3) Aurora SMI will be safe and effective in treating patients with relapsed aggressive B-cell NHL in early phase clinical trials.To analyze Aurora expression, tissue microarrays (TMA) were constructed from 43 patients with DLBCL and 40 with MCL, and Aurora A and B expression optimized with commercially available antibodies by immunohistochemistry (IHC). The IHC was rated as a staining intensity on a scale of 0 to 3+. The NHL TMAs demonstrated intense staining (2+ to 3+) for Aurora A (nucleus) and Aurora B (nucleus) in >60% compared to normal lymph nodes. We also analyzed the Lymphoma/Leukemia Molecular Profiling Project (LLMPP) publicly available database for Aurora A and B expression in MCL and found a worse survival in those with A > B over-expression (p<0.01). Since both Auroras are transforming genes, the LLMPP data support the conclusion that these S/T kinases are associated with a poor prognosis and are potential targets for therapy.Western blotting analysis of 13 B-cell NHL cell lines (DLBCL, MCL and TFL) for Aurora A and B expression showed significant over-expression compared to B-cells isolated from normal lymph nodes. Aurora A knockdown by shRNA in the B-NHL cell lines showed inhibition of mitosis with a polyploid phenotype (4n, 8n) that ends in apoptosis as shown by PARP-cleavage. The Aurora A specific inhibitor (MLN8237) evaluated in the 13 NHL cell lines phenocopies shRNA knockdown with associated inhibition of proliferation (IC50=0.05 mM) and promotes apoptosis (flow cytometry, PARP-cleavage) in a dose-dependent manner. Combination of MLN8237 with a microtubule targeting agent (docetaxel) to abrogate the spindle checkpoint is synergistic in a sequence specific manner. Moreover, MLN8237 effectively inhibits Aurora A auto-phosphorylation and eliminates phospho-histone H3 (Ser10) phosphorylation. Currently, 2 mouse MCL (Granta 519) xenograft models are underway evaluating tumor growth inhibition (TGI), safety and survival of MLN8237 alone and in combination with docetaxel or rituximab respectively. Preliminary data show that MLN8237 is synergistic with docetaxel in TGI in the MCL xenograft model. Together the data suggest inhibition of Aurora kinases may offer a promising treatment strategy for patients with aggressive B-cell NHL [Funded by the Lymphoma SPORE, P50 CA130805501A1, PI: Richard Fisher, MD.]. Disclosures:Rimsza:High Throughput Genomics:.

Preclinical characterization of Aurora kinase inhibitor R763/AS703569 identified through an image-based phenotypic screen

Aurora kinases play a key role in mitotic progression. Over-expression of Aurora kinases is found in several human cancers and correlated with histological malignancy and clinical outcomes. Therefore, Aurora kinase inhibitors should be useful in the treatment of cancers. Cell-based screening methods have an advantage over biochemical approaches because hits can be optimized to inhibit targets in the proper intracellular context. We developed a novel Aurora kinase inhibitor R763/AS703569 using an image-based phenotypic screen. The anti-proliferative effect was examined in a panel of tumor cell lines and primary cells. The efficacy was determined in a broad panel of xenograft models. R763/AS703569 inhibits Aurora kinases, along with a limited number of other kinases including FMS-related tyrosine kinase 3 (FLT3), and has potent anti-proliferative activity against many cell types accompanying unique phenotypic changes such as enlarged cell size, endoreduplication and apoptosis. The endoreduplication cycle induced by R763/AS703569 was irreversible even after the compound was withdrawn from the culture. Oral administration of R763/AS703569 demonstrated marked inhibition of tumor growth in xenograft models of pancreatic, breast, colon, ovarian, and lung tumors and leukemia. An acute myeloid leukemia cell line MV4-11, which carries a FLT3 internal tandem duplication mutation, is particularly sensitive to R763/AS703569 in vivo. R763/AS703569 is a potent inhibitor of Aurora kinases and exhibited significant anti-proliferative activity against a wide range of tumor cells both in vitro and in vivo. Inhibition of Aurora kinases has the potential to be a new addition to the treatment of cancers.

Aurora Kinase Family: A New Target for Anticancer Drug

Aurora kinases (AK) are the name given to a family of Serine/threonine (Ser/Thr) protein kinases. These proteins represent a novel family of kinases crucial for cell cycle control. The cell division process is one of the hallmarks of every living organism. Within the complete cell-cycle process, mitosis constitutes one of the most critical steps. The main purpose of mitosis is to segregate sister chromatics into two daughters cells. It is a complex biologic process, and errors in this mechanism can lead to genomic instability, a condition associated with tumorigenesis. This process is tightly regulated by several proteins, some of them acting as check-points that ultimately ensure the correct temporal and spatial coordination of this critical biologic process. Among this network of mitotic regulators, AK play a critical role in cellular division by controlling chromatid segregation. Three AK family members have been identified in mammalian cells: A, B, and C. These proteins are implicated in several vital events in mitosis. In experimental models, overexpression of AK can induce spindle defects, chromosome mis-segregation, and malignant transformation. Conversely, downregulation of AK expression cause mitotic arrest and apoptosis in tumor cell lines. The expression levels of human AK are increased in certain types of cancer including breast, colon, pancreatic, ovarian, and gastric tumors. This observation has lent an interest to this family of kinases as potential drug targets for development of new anticancer therapies. This review focuses in recent progress in the role of AK in tumorogenesis and the development of new anticancer drug against AK proteins. This manuscript also includes some relevant patents as well.

ZM 447439 inhibition of aurora kinase induces Hep2 cancer cell apoptosis in three-dimensional culture

Mitotic Aurora kinases are essential for accurate chromosome segregation during cell division. Forced over-expression of Aurora kinase results in centrosome amplification and multipolar spindles, causing aneuploidy, a hallmark of cancer. ZM447439 (ZM), an Aurora selective ATP-competitive inhibitor, interferes with the spindle integrity checkpoint and chromosome segregation. Here, we showed that inhibition of Aurora kinase by ZM reduced histone H3 phosphorylation at Ser10 in Hep2 carcinoma cells. Multipolar spindles were induced in these ZM-treated G2/M-arrested cells with accumulation of 4N/8N DNA, similar to cells with genetically suppressed Aur-B. Cells subsequently underwent apoptosis, as assessed by cleavage of critical apoptotic associated protein PARP. Hep2 cells formed a tumor-like cell mass in 3-dimensional matrix culture; inhibition of Aurora kinase by ZM either destructed the preformed cell mass or prevented its formation, by inducing apoptotic cell death as stained for cleaved caspase-3. Lastly, ZM inhibition of Aurora kinase was potently in association with decrease of Akt phosphorylation at Ser473 and its substrates GSK3α/beta; phosphorylation at Ser21 and Ser9. Together, we demonstrated that Aurora kinase served as a potential molecular target of ZM for more selective therapeutic cancer treatment.

Mechanism of action of the Aurora kinase inhibitor CCT129202 and in vivo quantification of biological activity

The Aurora family of serine/threonine kinases is important for the regulation of centrosome maturation, chromosome segregation, and cytokinesis during mitosis. Overexpression of Aurora kinases in mammalian cells leads to genetic instability and transformation. Increased levels of Aurora kinases have also been linked to a broad range of human tumors. Here, we describe the properties of CCT129202, a representative of a structurally novel series of imidazopyridine small-molecule inhibitors of Aurora kinase activity. This compound showed high selectivity for the Aurora kinases over a panel of other kinases tested and inhibits proliferation in multiple cultured human tumor cell lines. CCT129202 causes the accumulation of human tumor cells with >or=4N DNA content, leading to apoptosis. CCT120202-treated human tumor cells showed a delay in mitosis, abrogation of nocodazole-induced mitotic arrest, and spindle defects. Growth of HCT116 xenografts in nude mice was inhibited after i.p. administration of CCT129202. We show that p21, the cyclin-dependent kinase inhibitor, is induced by CCT129202. Up-regulation of p21 by CCT129202 in HCT116 cells led to Rb hypophosphorylation and E2F inhibition, contributing to a decrease in thymidine kinase 1 transcription. This has facilitated the use of 3'-deoxy-3'[(18)F]fluorothymidine-positron emission tomography to measure noninvasively the biological activity of the Aurora kinase inhibitor CCT129202 in vivo.

Overexpression of aurora kinase A in mouse mammary epithelium induces genetic instability preceding mammary tumor formation

Aurora-A/STK15/BTAK, which encodes a centrosome-associated kinase, is amplified and overexpressed in multiple types of human tumors, including breast cancer. However, the causal relationship between overexpression of Aurora-A and tumorigenesis has not been fully established due to contradictory data obtained from different experimental systems. To investigate this, we generated a mouse strain that carries an MMTV-Aurora-A transgene. We showed that all the MMTV-Aurora-A mice displayed enhanced branch morphogenesis in the mammary gland and about 40% developed mammary tumors at 20 months of age. The tumor incidence was significantly increased in a p53(+/-) mutation background with about 70% MMTV-Aurora-A;p53(+/-) animals developed tumors at 18 months of age. Of note, overexpression of Aurora-A led to genetic instability, characterized by centrosome amplification, chromosome tetraploidization and premature sister chromatid segregation, at stages prior to tumor formation. Most notably, the severe chromosomal abnormality did not cause cell death owing to the activation of AKT pathway, including elevated levels of phosphorylated AKT and mammalian target of rapamycin, and nuclear accumulation of cyclin D1, which enabled continuous proliferation of the tetraploid cells. These data establish Aurora-A as an oncogene that causes malignant transformation through inducing genetic instability and activating oncogenic pathways such as AKT and its downstream signaling.

Global Gene Expression Profiling of Pleural Mesotheliomas: Overexpression of Aurora Kinases and P16/CDKN2A Deletion as Prognostic Factors and Critical Evaluation of Microarray-Based Prognostic Prediction

Most gene expression profiling studies of mesothelioma have been based on relatively small sample numbers, limiting their statistical power. We did Affymetrix U133A microarray analysis on 99 pleural mesotheliomas, in which multivariate analysis showed advanced-stage, sarcomatous histology and P16/CDKN2A homozygous deletion to be significant independent adverse prognostic factors. Comparison of the expression profiles of epithelioid versus sarcomatous mesotheliomas identified many genes significantly overexpressed among the former, including previously unrecognized ones, such as uroplakins and kallikrein 11, both confirmed by immunohistochemistry. Examination of the gene expression correlates of survival showed that more aggressive mesotheliomas expressed higher levels of Aurora kinases A and B and functionally related genes involved in mitosis and cell cycle control. Independent confirmation of the negative effect of Aurora kinase B was obtained by immunohistochemistry in a separate patient cohort. A role for Aurora kinases in the aggressive behavior of mesotheliomas is of potential clinical interest because of the recent development of small-molecule inhibitors. We then used our data to develop microarray-based predictors of 1 year survival; these achieved a maximal accuracy of 68% in cross-validation. However, this was inferior to prognostic prediction based on standard clinicopathologic variables and P16/CDNK2A status (accuracy, 73%), and adding the microarray model to the latter did not improve overall accuracy. Finally, we evaluated three recently published microarray-based outcome prediction models, but their accuracies ranged from 63% to 67%, consistently lower than reported. Gene expression profiling of mesotheliomas is an important discovery tool, but its power in clinical prognostication has been overestimated.

Amplification and overexpression of Aurora kinase A (AURKA) in immortalized human ovarian epithelial (HOSE) cells

Immortalization is an early and essential step of human carcinogenesis. Amplification of chromosome 20q has been shown to be a common event in immortalized cells and cancers. We have previously reported that gain and amplification of chromosome 20q is a non-random and common event in immortalized human ovarian surface epithelial (HOSE) cells. The chromosome 20q harbors genes including TGIF2 (20q11.2-q12), AIB1 (20q12), PTPN1 (20q13.1), ZNF217 (20q13.2), and AURKA (20q13.2-q13.3), which were previously reported to be amplified and overexpressed in ovarian cancers. Some of these genes may be involved in immortalization of HOSE cells and represent crucial premalignant changes in ovarian surface epithelium. Investigation of the involvement of these genes was examined in four pairs of pre-crisis (preimmortalized) and post-crisis (immortalized) HOSE cells. Overexpression of AURKA (Aurora kinase A), also known as BTAK and STK15, by both real time-quantitative polymerase chain reaction (RT-QPCR) and Western blotting was detected in all the four immortalized HOSE cells examined while overexpression of AIB1 and ZNF217 was observed in two of four immortalized HOSE cells examined. Overexpression of TGIF2 and PTPN1 was not significant in our immortalized HOSE cell systems. The degree of overexpression of AURKA was shown to be closely associated with the amplification of chromosome 20q in immortalized HOSE cells. Fluorescence in situ hybridization (FISH) with labeled P1 artificial clone (PAC) confirmed the amplification of the chromosomal region (20q13.2-13.3) where AURKA resides. DNA amplification of AURKA was also confirmed using semi-quantitative PCR. Our study showed that amplification and overexpression of AURKA is a common and significant event during immortalization of HOSE cells and may represent an important premalignant change in ovarian carcinogenesis.