Aurora-B Expression Research Articles

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

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. 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. 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. 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.

Aurora-B overexpression is correlated with aneuploidy and poor prognosis in non-small cell lung cancer

Aurora-B is a key regulator of mitosis, and the overexpression has been detected in a variety of solid tumors. The Aurora-B overexpression has been suggested to correlate with clinical aggressiveness and aneuploidy in vitro, however, the frequency of overexpression of Aurora-B protein, the association with clinicopathologic parameters and aneuploidy remain poorly defined in non-small-cell lung cancer (NSCLC). Using 157 surgical specimens of human NSCLC, we here show that overexpression of Aurora-B proteins are significantly correlated with aneuploidy and poor outcomes in NSCLC. We examined immunohistochemical protein expression of Aurora-B, and DNA ploidy by laser scanning cytometry in 157 NSCLC cases. Aurora-B overexpression was found in 83 cases (53%) of NSCLC, and was significantly correlated with vascular invasion (p=0.012), poor differentiation (p<0.001), larger tumor size (p=0.010) and lymph node metastasis (p=0.05) and poor prognosis (p=0.011). Aneuploidy was found in 87 cases (57%), and was significantly correlated with Aurora-B overexpression (p=0.0065). Logistic multivariate analysis revealed overexpression of Aurora-B protein to be significant risk factors for aneuploidy compared with other factors. These results indicate that Aurora-B overexpression may contribute to malignant potential and increased aneuploidy in NSCLC. Thus, Aurora-B may serve as a new therapeutic target in against patients with NSCLC, although further studies will be necessary.

Cooperative Lethality of Polo-Like Kinases (PLK) and Aurora Kinases (AK) in Refractory Pediatric Leukemia

AbstractAbstract 3573 Introduction:Recent studies have shown that cell cycle events are tightly controlled by complex and shared activities of a select group of kinases. Among these, Polo like kinases (Plk) are regulatory mitotic proteins that are overexpressed in several types of cancer and are associated with poor prognosis. Consequently, inhibitors for these kinases are currently being evaluated as anticancer drugs in Phase I and Phase II clinical trials. However, details of the mechanisms by which the interference of selective regulators of mitosis lead to cell death is currently unavailable. We describe experimental studies to further understand this process and to investigate the activity, drug combinability and target modulation of Plk inhibition in refractory pediatric leukemia cells. Methods:Cell lines derived from relapsed pediatric leukemia patients were used (n=12). These cells carry the spectrum of moleular abnormalites found in patients including MLL gene rearrangemnet with various fusion genes (Bcr-Abl), and biphenotypic features. Leukemia cells were incubated with increasing concentrations of the Plk1 inhibitor volasertib (BI 6727, Boehringer Ingelheim) and after four days in culture, cell growth characteristics including cellular morphology, ploidy status and cell survival were quantified by automated quantitative microscopy. IC50 values and combination indices were calculated according to the method of Chou and Talalay. Activities of intracellular signaling components and regulators of distinct apoptosis and autophagy pathways were identified by Western blot analysis. Results:Volasertib inhibited the growth of all leukemia cell lines tested, as well as primary specimens from leukemia patients, at sub-micromolar concentrations (IC50 from 1 × 10−6 to 1 μM). Microscopic and ultrastructural analyses revealed a corresponding increase in the number of cells displaying abnormal phenotype and mitotic catastrophe, a characteristic of Plk inhibition. Plk inhibition also resulted in an initial upregulation of Aurora-A and Aurora-B expression and the phosphorylation of Aurora-B and Aurora-C. However, sustained Plk inhibition led to time dependent dephosphorylation of Aurora-A. In addition, Plk inhibition resulted in Caspase-9 cleavage and decreased expression of autophagy related proteins (Atg3). Overall, significant synergy was observed when AK inhibitors were combined with Plk inhibition (CI = 0.02 – 0.8). Conclusions:We provide experimental data to show that Plk1 inhibition by volasertib significantly decreases the growth and survival of refractory pediatric leukemia cells in vitro. We also show synergy between AK and Plk inhibition in leukemia cells and that an effective target modulation by Plk inhibition leads to alterations in intracellular AKs in a time dependent manner. Our data provide relevant information regarding the relationship between the two kinases and the intracellular changes that can be used as biological correlates for therapeutic activity in future clinical studies. These findings provide initial pre-clinical evidence for Plk as a potentially effective target in pediatric leukemia therapy. Disclosures:No relevant conflicts of interest to declare.

Reply to "Aurora-B expression may not contribute to disease progression: a reflection of the heterogeneous pathogenesis?" Haematologica 2012;97(10):e37-39

Fabiola Fernandes et al.1 studied 61 myelodysplastic syndrome (MDS) patients, 31 male and 30 female, with a median age of 66 years (range 15-91 years). They evaluated Aurora-B expression in 61 RNA samples prepared from bone marrow cells. However, Fernandes et al.1 did not examine the expression of this gene using isolated CD34+ cells; they used bone marrow mononuclear cells. Therefore, it is difficult to compare their results with ours. We evaluated the expression levels of Aurora-B in CD34+ cells prepared from patients with myelodysplastic syndrome. If we had examined the expression of Aurora-B in un-fractionated bone marrow cells, we might have obtained the same results as Fabiola Fernandes et al.1 It should be noted that Aurora-B is highly expressed in CD34+ cells from MDS.

Aurora-B expression may not contribute to disease progression: a reflection of the heterogeneous pathogenesis?

We read with great interest the paper by Yoshida et al . entitled “Marked upregulation of survivin and Aurora-B kinase are associated with disease progression in the myelodysplastic syndromes”.[1][1] Aurora kinases are key players in ensuring accurate chromosome segregation during the cell

Marked upregulation of Survivin and Aurora-B kinase is associated with disease progression in the myelodysplastic syndromes

Myelodysplastic syndromes are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis. Survivin is a member of the inhibitor of apoptosis family and suppresses apoptosis. Survivin also functions as a subunit of the chromosomal passenger complex for regulating mitosis with Aurora-B. Survivin and Aurora-B play an important role in maintaining genome stability. The aim of this study was to determine the role of Survivin and Aurora-B kinase in disease progression and prognosis of myelodysplastic syndromes. We evaluated the expression levels of these two genes in CD34(+) cells prepared from 64 patients with myelodysplastic syndrome or leukemic blasts from 50 patients with de novo acute myeloid leukemia using quantitative real-time PCR. Survivin and Aurora-B expression levels were highly correlated with the type of myelodysplastic syndrome, were much higher in refractory anemia with excess blasts-1, refractory anemia with excess blasts-2, and secondary acute myeloid leukemia following myelodysplastic syndrome than in normal control, and increased during disease progression. There was a significant correlation between these expression levels and the International Prognostic Scoring System. Interestingly, these levels were remarkably higher in patients with secondary acute myeloid leukemia following myelodysplastic syndromes than in those with de novo acute myeloid leukemia. This is the first report showing that high levels of Survivin and Aurora-B kinase expression in CD34(+) cells are distinctive molecular features of high-risk myelodysplastic syndromes and secondary acute myeloid leukemia following myelodysplastic syndrome. Marked upregulation of Survivin and Aurora-B kinase may contribute to genetic instability and disease progression of myelodysplastic syndromes. Our data may explain why patients with high-risk myelodysplastic syndromes frequently show complex chromosomal abnormality.

P4-09-24: Correlation of Aurora Family Member Expression with Clinical Breast Cancer Prognosis.

Abstract Introduction: Aurora-A, Aurora-B and Aurora-C are a family of protein kinases which have been identified as key regulators of the mitotic cell division process. Members of this group have been linked with pro-tumorigenic effects and have been reported as being up-regulated in certain cancers. Our current study examines the expression profile of the Aurora-A, Aurora-B and Aurora-C members in a breast cancer cohort in relation to a number of predictive factors. Materials and Methods: The expression of Aurora-A, Aurora-B and Aurora-C was examined in a breast cancer cohort using quantitative real time PCR (normal samples n = 34, tumour samples n = 109) and immunhistochemistry (IHC). Expression of the aurora members was related to clinical parameters such as staging and Nottingham prognostic index (NPI). Results: Examination of Aurora-A levels in the breast cancer cohort revealed an association of Aurora-A expression with NPI grouping. High levels of Aurora-A levels were seen in NPI-1 and NPI-2 stages (NPI-1 median = 66.0, NPI-2 median = 64.3), with expression reducing significantly at the higher NPI-3 group (NPI-3 median = 20.3; p = 0.029 vs NPI-2 and p = 0.009 vs NPI-1 respectively). Additionally, Aurora-A levels were found to be significantly lower in grade 3 cancers compared to grade 1 (median grade 1 = 86.5 vs median grade 3 levels = 52.6, p = 0.04). In contrast to this, examination of Aurora-C levels in the cohort identified a relatively low level of Aurora-C in NPI-1 and NPI-2 group (median values NPI-1 = 88, NPI-2 = 34.4) compared to a substantial increase in Aurora-C expression in NPI-3 (median value = 1602, p = 0.05 vs NPI-1 and p = 0.06 vs NPI-2). Aurora-B expression levels did not exhibit any significant differences within the breast cancer cohort. Conclusions: Differential expression of Aurora-A, Aurora-B and Aurora-C were observed within the breast cancer cohort. Higher Aurora-A expression was associated with low NPI groups and grades and potentially with better patient prognosis whereas lower levels were seen in the poorer prognostic NPI-3 group and higher grades. An opposite trend was seen in Aurora-C where lower levels were associated with the NPI-1 and NPI-2 groups and significantly higher levels were seen in the NPI-3 group. Aurora-B levels appeared to have no predictive function. This data suggests that together Aurora-A and Aurora-C levels, within a patient may be useful for predicting patient outcome. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-09-24.

Marked Upregulations of Survivin and Aurora-B Kinase Are Associated with Disease Progression in the Myelodysplastic Syndromes,

Abstract 3823Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffctive hematopoiesis. Survivin belongs to the inhibitors of apoptosis (IAP) family and inhibits apoptosis. Besides its role as IAP, Survivin appears to function as a subunit of the chromosomal passenger complex (CPC) for regulating mitosis with other CPC proteins including Aurora-B. As the CPC, Survivin and Aurora-B play an important role in the maintenance of a stable genome. Until now, there has been no report to examine whether expression of Survivin and Aurora-B kinase may be increased in CD34(+) cells prepared from the patients with MDS during disease progression. To investigate the contribution of Survivin and Aurora-B to the progression and prognosis of MDS, we evaluated the expression levels of these two genes in CD34(+) cells prepared from 57 patients with MDS and 50 patients with de novo AML using real-time quantitative polymerase chain reaction. The degree of Survivin and Aurora-B expression was highly correlated with the type of MDS, was much higher in RAEB-1, RAEB-2 and secondary AML following MDS (s-AML) compared with normal control, and increased during disease progression. Expression levels of both Survivin and Aurora-B were significantly correlated with International Prognostic Scoring System (IPSS). Furthermore, the amount of Aurora-B kinase was significantly correlated with Survivin expression in MDS and s-AML, but not in de novo AML. Interestingly, the levels of Survivin and Aurora-B were remarkably higher in patients with s-AML when compared with de novo AML. We demonstrated for the first time that high levels of Survivin and Aurora-B kinase expression are distinctive molecular feature of high-risk MDS and s-AML. Marked up-regulations of Survivin and Aurora-B Kinase may contribute to genetic instability and disease progression of MDS. Disclosures:No relevant conflicts of interest to declare.

Occurrence of multipolar mitoses and association with Aurora-A/-B kinases and p53 mutations in aneuploid esophageal carcinoma cells

BackgroundAurora kinases and loss of p53 function are implicated in the carcinogenesis of aneuploid esophageal cancers. Their association with occurrence of multipolar mitoses in the two main histotypes of aneuploid esophageal squamous cell carcinoma (ESCC) and Barrett's adenocarcinoma (BAC) remains unclear. Here, we investigated the occurrence of multipolar mitoses, Aurora-A/-B gene copy numbers and expression/activation as well as p53 alterations in aneuploid ESCC and BAC cancer cell lines.ResultsA control esophageal epithelial cell line (EPC-hTERT) had normal Aurora-A and -B gene copy numbers and expression, was p53 wild type and displayed bipolar mitoses. In contrast, both ESCC (OE21, Kyse-410) and BAC (OE33, OE19) cell lines were aneuploid and displayed elevated gene copy numbers of Aurora-A (chromosome 20 polysomy: OE21, OE33, OE19; gene amplification: Kyse-410) and Aurora-B (chromosome 17 polysomy: OE21, Kyse-410). Aurora-B gene copy numbers were not elevated in OE19 and OE33 cells despite chromosome 17 polysomy. Aurora-A expression and activity (Aurora-A/phosphoT288) was not directly linked to gene copy numbers and was highest in Kyse-410 and OE33 cells. Aurora-B expression and activity (Aurora-B/phosphoT232) was higher in OE21 and Kyse-410 than in OE33 and OE19 cells. The mitotic index was highest in OE21, followed by OE33 > OE19 > Kyse-410 and EPC-hTERT cells. Multipolar mitoses occurred with high frequency in OE33 (13.8 ± 4.2%), followed by OE21 (7.7 ± 5.0%) and Kyse-410 (6.3 ± 2.0%) cells. Single multipolar mitoses occurred in OE19 (1.0 ± 1.0%) cells. Distinct p53 mutations and p53 protein expression patterns were found in all esophageal cancer cell lines, but complete functional p53 inactivation occurred in OE21 and OE33 only.ConclusionsHigh Aurora-A expression alone is not associated with overt multipolar mitoses in aneuploid ESCC and BAC cancer cells, as specifically shown here for OE21 and OE33 cells, respectively. Additional p53 loss of function mutations are necessary for this to occur, at least for invasive esophageal cancer cells. Further assessment of Aurora kinases and p53 interactions in cells or tissue specimens derived from non-invasive dysplasia (ESCC) or intestinal metaplasia (BAC) are necessary to disclose a potential causative role of Aurora kinases and p53 for development of aneuploid, invasive esophageal cancers.

ZM447439, the Aurora kinase B inhibitor, suppresses the growth of cervical cancer SiHa cells and enhances the chemosensitivity to cisplatin

To investigate the effects of an Aurora kinase B inhibitor (ZM447439) on the cervical cancer cell line SiHa and chemotherapy of cisplatin (cDDP). Detected Aurora-B protein in different tissues of the cervix by immunohistochemistry and then analyzed the relationship between Aurora B protein and clinical parameters of cervical cancer. The effect and synergistic effect of ZM447439 and cDDP on proliferation of SiHa cells was tested by MTT. The changes of cell cycle and apoptosis were detected by flow cytometry. Aurora-B, histone H3 phosphorylation (H3-P) protein, human papillomavirus16 E6 (HPV16E6) and BCL-2, P53, VEGF protein were detected by Western blot. The positive rate of Aurora-B expression was the highest in cervical cancer and had no significant correlation with clinical stage, lymph node metastasis and age. ZM447439 can reduce the number of SiHa cells, increase the volume of cells and lead to apoptosis. The growth of SiHa cells treated with ZM447439, cDDP and the combination of both was inhibited in dose- and time-dependent manners. The inhibition rate of the combined treatment is significantly higher than that of two other single drug groups (P < 0.05). The synergistic effect is observed in the combined therapy. S-phase arrest and early apoptosis has become more evident in the combined treatment. ZM447439 significantly inhibited the expression of Aurora-B and H3-P protein (P < 0.05). ZM447439, cDDP and the combination of both reduced the expression of HPV16E6 and BCL-2 protein, raised P53 protein expression (P < 0.05), whose effects were more obvious in the combined therapy. cDDP could also reduce VEGF protein expression, but ZM447439 could not. Our results suggest that Aurora-B may represent a valid target in cervical squamous carcinoma and has a synergistic effect with cDDP.

Abstract 4437: Preclinical characterization of AMG 900, an orally available small molecule inhibitor of aurora kinases in phase 1 clinical trials

Abstract Background: The aurora family of serine-threonine kinases (aurora-A, -B, -C) regulate cell-cycle progression in mammalian cells. Aurora-A and aurora-B are essential for proper chromosome congression, segregation, and cytokinesis during mitosis, whereas aurora-C function appears restricted to male meiosis. Aurora-B is responsible for the direct phosphorylation of histone H3 on serine-10. Aurora-A and aurora-B expression is elevated in a variety of human cancers and is associated with advanced clinical staging and poor prognosis. The emergence of aurora kinases as key mitotic regulators and their potential role in tumorigenesis has focused substantial interest in developing selective small molecule inhibitors for the treatment of human cancers. Objective: The aim of this study was to determine the in vitro effects of AMG 900 on a panel of tumor cell lines and profiling its antitumor activity across multiple human xenograft models. Results: AMG 900 is a novel ATP competitive small molecule inhibitor that is potent and highly selective for aurora kinases A, B, and C. In cells, AMG 900 inhibits autophosphorylation of aurora-A and aurora-B as well as the phosphorylation of histone H3. The predominant cellular response of tumor cells to AMG 900 treatment is aborted cell division, which leads to endoreduplication and cell death. The effect of AMG 900 was tested in a panel of 26 cell lines to evaluate its potential to inhibit cell proliferation across multiple tumor types. AMG 900 inhibited the proliferation of tumor cell lines at low nanomolar concentrations (EC50 values 1-6 nM), including a number of multidrug resistant (MDR) cell lines expressing ATP-binding cassette transporters (P-gp and BCRP1). In contrast, paclitaxel and three aurora kinase inhibitors (AZD1152, MK-0457, and PHA-739358) showed a loss of potency in these MDR cell lines compared to matched parental cell lines. In nude mice, oral administration of AMG 900 inhibited phosphorylation of histone H3 in tumors in a concentration- and dose-dependent manner. The effect of AMG 900 was tested in a panel of nine human xenografts representing five tumor types (breast, colon, lung, pancreatic, and uterine). Oral administration of AMG 900 at 15 mg/kg BID for two consecutive days per week or 3 mg/kg BID every day inhibited tumor growth (50-97%, P &amp;lt; 0.005) in all nine of the xenograft models. Importantly, three of these xenograft models are resistant to taxanes. Mice treated with efficacious doses of AMG 900 showed a transient loss of body weight and bone marrow cellularity, consistent with its on-mechanism effects on normal proliferating cells. Conclusion: Based on these preclinical activities, AMG 900 has the potential to treat advanced cancers, including tumors resistant to chemotherapeutic agents such as paclitaxel and docetaxel. AMG 900 is currently undergoing phase 1 clinical evaluation in patients with advanced solid tumors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4437.

Nuclear Survivin expression is correlated with malignant behaviors of head and neck cancer together with Aurora-B

Survivin belongs to the inhibitors of apoptosis (IAP) gene family and inhibits apoptosis. Besides its role as IAP, Survivin recently appears to function as a subunit of the chromosomal passenger complex (CPC) for regulating cell division with other CPC proteins including Aurora-B and INCENP. Nuclear Survivin is suspected to control cell division, whereas cytoplasmic Survivin is considered cytoprotective. Although there are several studies on Survivin expression and its function as inhibition of apoptosis, there is no study on Survivin function as a CPC and its correlation with other CPC proteins in head and neck squamous cell carcinoma (HNSCC). Here, therefore, we examined nuclear Survivin expression and its functional correlation with Aurora-B in HNSCC. High expression of Survivin was well correlated with Aurora-B expression in nuclear fraction of HNSCC cell lines and tissues. Moreover, nuclear Survivin expression was significantly correlated with Ki-67 and Aurora-B expression by immunohistochemistry. Notably, HNSCC cases with nuclear Survivin and Aurora-B expression exhibited marked malignant behaviors. Interestingly, both Survivin and Aurora-B knockdown inhibited cell growth and tumorsphere formation. Overall suggest that nuclear Survivin may be involved in tumor progression together with Aurora-B, and that Survivin and Aurora-B can be useful diagnostic markers and therapeutic targets.

Comparative immunohistochemical analysis of aurora-A and aurora-B expression in human glioblastomas. Associations with proliferative activity and clinicopathological features

In the present study, we carried out a comparative immunohistochemical analysis of aurora-A and aurora-B expression in 40 patients with primary glioblastomas, and attempted to identify any associations with Ki-67 index and the patients’ clinical features. The impact of various treatment modalities and proliferative activity on patient outcome was also assessed. Immunohistochemistry was carried out using formalin-fixed and paraffin-embedded tissue sections. Aurora-A expression was higher in tumors with high Ki-67 expression ( p=0.01) and was positively, though marginally, related to aurora-B expression ( p=0.085). Aurora-B expression was not linked to Ki-67 expression ( p=0.182). Lower aurora-A immunohistochemical expression, chemotherapy administration, and tumor localization in one lobe of the brain implied a greater probability of patient survival in univariate analysis ( p=0.044, p=0.008, p=0.041, respectively). Ki-67 and aurora-B immunoreactivities were not associated with patient survival ( p=0.918 and p=0.539, respectively). To our knowledge, for the first time, the association between aurora-A and aurora-B expression, the correlation of aurora-A with Ki-67 index, and the prognostic impact of aurora-A expression were assessed in glioblastomas. Although we addressed a prognostic connotation of aurora-A, we presume that aurora-A and aurora-B play a complicated role within glioblastomas. Further examinations of larger series are required, so that definite conclusions can be drawn.

Deregulated Aurora‐B induced tetraploidy promotes tumorigenesis

High expression of Aurora-B has been observed in various cancers, and inhibition of this kinase has been shown to halt cellular proliferation. However, the mechanism of effect of Aurora-B on cellular transformation has not been fully explored. Here, we show that overexpression of Aurora-B in murine epithelial cells promotes generation of tetraploids. In search of a related mechanism, spectral karyotyping was carried out, showing premature chromatid separation (PCS). Of interest, PCS is a hallmark of Robert's syndrome, which also involves cellular polyploidy and aneuploidy. Sorted tetraploid Aurora-B-overexpressing cells promoted significant mammary epithelial cancers when injected into nude mice, as compared to injection of nonfractionated cells, suggesting that tetraploidy is an important mediator of Aurora-B-induced tumorigenesis. Comparative chromosome hybridization performed on DNA derived from tetraploid cell-induced tumors indicates amplifications and deletions of regions throughout the genome, which include tumor-promoting or tumor-suppressing genes, respectively. Thus, sustained expression of Aurora-B induces tetraploidy, which, in turn, facilitates genomic instability and tumor development in a xenograft model.

Nuclear Overexpression of Mitotic Regulatory Proteins in Biliary Tract Cancer: Correlation with Clinicopathologic Features and Patient Survival

Mitosis dysregulation is common in cancers. This study explored the nuclear expression patterns and prognostic significance of mitotic regulatory proteins, including Aurora kinases, survivin, and p53, in biliary tract cancer (BTC). Archival tumor samples from 161 BTC patients who underwent surgery were tested for the expression of Aurora-A, Aurora-B, survivin, and p53 by immunohistochemistry. The potential endogeneity among the clinicopathologic variables and survival outcome was assessed by a generalized simultaneous equations model. Nuclear overexpression of Aurora-A, Aurora-B, survivin, and p53 was found in 79 (49.1%), 45 (28.0%), 55 (34.2%), and 55 (34.2%) patients, respectively. Intrahepatic cholangiocarcinoma, compared with the other two subtypes, had significantly higher proportions of nuclear overexpression of Aurora-B and survivin (37.8% and 47.3%, respectively). Simultaneous overexpression of Aurora-A and Aurora-B was correlated with that of p53. Overexpression of Aurora-B was also correlated with that of survivin and tumor grade. Our data indicate that simultaneous overexpression of Aurora-A and Aurora-B, suggesting dysregulated mitosis is associated with worse survival in patients with BTC. Independent prognostic factors for poor overall survival included simultaneous overexpression of Aurora-A and Aurora-B (hazard ratio, 1.997; 95% confidence interval, 1.239-3.219; P = 0.0045) and tumor grade (hazard ratio, 2.117; 95% confidence interval, 1.339-3.348; P = 0.0013) assessed by a multivariate analysis stratified by American Joint Committee on Cancer stage and p53 overexpression. Endogeneity testing suggested that nuclear overexpression of p53 and tumor type may influence patient survival through their interactions with Aurora-A/Aurora-B expression and tumor grade.

Expression of Aurora-B in hepatocarcinoma and its clinical significance

Expression of Aurora-B in hepatocarcinoma and its clinical significance

Directed expression of dominant-negative p73 enables proliferation of cardiomyocytes in mice

Previous studies have shown that p53 plays an important role in maintaining cell cycle arrest of cardiomyocytes, which might account for the inability of human hearts to regenerate adequately after injury. Therefore, inhibition of p53 represents an attractive strategy to restore cell cycle progression in cardiomyocytes although such an approach is hampered by the potential danger of concomitant tumor induction. During normal development, N-terminal truncated isoforms of the p53-related protein p73 are naturally occurring antagonists of p53 and p73, which are not related to tumor induction. We have generated recombinant adenoviruses encoding dominant-interfering p73 (Ad-p73DD) to inhibit p53/p73 in murine hearts at different developmental stages. We found that the expression of p73DD(wt) in newborn mice led to the increase of the relative heart weights after 14 days which is paralleled by a significant increase of proliferating cardiomyocytes as seen by ICC (BrdU-incorporation, phosphorylation of histone3, expression of AuroraB) without induction of apoptosis. Stimulation of cell cycle progression in cardiomyocytes went along with a significant down-regulation of the p53-dependent cdk-inhibitor p21WAF both on mRNA and protein level. Furthermore, mRNA levels and protein expression of D-type cyclins and cyclins A, B2, and E were selectively increased after expression of p73DD. We further show that the cell cycle entry of cardiomyocytes is not restricted to neonatal hearts but is also found in adult mouse hearts 5 days after intramyocardial injection of Ad-p73DD. Taken together we reason that directed expression of dominant-negative p73 might be utilized to stimulate proliferation of cardiomyocytes to improve cardiac regeneration.

Aurora-B expression and its correlation with cell proliferation and metastasis in oral cancer

Aurora-B kinase is a chromosomal passenger protein and is essential for chromosome segregation and cytokinesis. Aurora-B overexpression in various cancer cells induces chromosomal number instability to produce multinuclearity and relates to metastasis. Here, we examined the expression of Aurora-B in oral squamous cell carcinoma (OSCC) to elucidate the relationship between Aurora-B expression and clinico-pathological findings by immunohistochemistry. Aurora-B expression was observed in normal oral squamous epithelia and OSCC cases, but the number of positive cells was significantly higher in OSCC than in normal squamous epithelium (p < 0.01). The labeling index of Aurora-B was significantly correlated with lymph node metastasis (p < 0.01) and histological grades of differentiation (p < 0.01). We also compared Aurora-B expression with Ki-67 expression and a positive correlation was found (p < 0.0001). Moreover, Aurora-B expression is significantly more frequent in multinuclear tumor cells than in total tumor cells. In summary, we found that Aurora-B expression was well correlated with cell proliferation, induction of multinuclear cells, histological differentiation, and metastasis in OSCC. These findings suggest that Aurora-B may be involved in tumor progression and that Aurora-B can be a new diagnostic and therapeutic target for OSCC.

Differential Functions of the Aurora-B and Aurora-C Kinases in Mammalian Spermatogenesis

The Aurora kinases are cell cycle-regulatory serine-threonine kinases that have been implicated in the function of the centrosomes, kinetechores, chromosome dynamics, and cytokinesis. In comparison with other tissues, there are high levels of expression of Aurora-B and -C in testis. What their respective roles in mammalian spermatogenesis are is an open question. Here we describe the expression and distribution patterns of the three kinases in mouse testis using in situ hybridization and immunohistochemistry. Importantly, the localization of Aurora-B is tightly regulated during spermatogenesis, whereas Aurora-C expression appears to be testis specific. To address the function of Aurora-B in spermatogenesis, we have generated transgenic mice using a pachytene-stage-specific promoter driving the expression of either wild-type Aurora-B or an inactive form of the kinase. Expression of the inactive Aurora-B results in abnormal spermatocytes, increased apoptosis, spermatogenic arrest, and subfertility defects. The function of Aurora-C may also be targeted in the Aurora-B transgenic mutants. To address the function of Aurora-C in testis, we generated Aurora-C knockout mice by homologous recombination. Remarkably, Aurora-C null mice were viable, yet the males had compromised fertility. Aurora-C mutant sperm display abnormalities that included heterogenous chromatin condensation, loose acrosomes, and blunted heads. These findings indicate that Aurora-B and Aurora-C serve specialized functions in mammalian spermatogenesis.

Targeting Aurora Kinases for the Treatment of Prostate Cancer

Inappropriate expression of the Aurora kinases can induce aberrant mitosis, centrosome irregularities, and chromosomal instability, which lead to anueploidy and cell transformation. Here, we report that Aurora-A and Aurora-B are highly expressed in primary human and mouse prostate cancers and prostate cancer cell lines. In clinical samples, levels of Aurora-A and Aurora-B were significantly elevated in prostatic intraepithelial neoplasia lesions and prostate tumors when compared with the non-neoplastic samples. Interestingly, expression of Aurora-A in non-neoplastic prostates correlated with seminal vesicle invasion (rho = 0.275, P = 0.0169) and in prostate tumor with positive surgical margins (rho = 0.265, P = 0.0161). In addition, nuclear expression of Aurora-B in prostatic intraepithelial neoplasia lesions correlated with clinical staging of the tumor (rho = -0.4, P = 0.0474) whereas cytoplasmic expression in tumors correlated with seminal vesicle invasion (rho = 0.282, P = 0.0098). Cell lines and primary tumors derived from the TRAMP model were also found to express high levels of Aurora-A and Aurora-B. When human PC3, LNCaP, and mouse C1A cells were treated with the potent Aurora kinase inhibitor VX680, which attenuates phosphorylation of histone H3, cancer cell survival was reduced. VX680 could further reduce cell viability >2-fold when used in combination with the chemotherapy drug doxorubicin. Our findings support a functional relationship between Aurora kinase expression and prostate cancer and the application of small-molecule inhibitors in therapeutic modalities.