Overexpression of Aurora-A kinase promotes tumor cell proliferation and inhibits apoptosis in esophageal squamous cell carcinoma cell line

Dihydromyricetin functions as a tumor suppressor in hepatoblastoma by regulating SOD1/ROS pathway

Background

Hepatoblastoma has an unsatisfactory prognosis, and traditional chemotherapy has strong side effects. Dihydromyricetin is a flavonoid extracted from a woody vine of the genus Serpentine in the family Vitaceae, with effects such as preventing alcoholic liver and reducing the incidence of liver cancer. However, the effect of DHM on hepatoblastoma and its specific pathway are still unclear.

Purpose

The purpose of this study was to investigate the effects of DHM on children's hepatoblastoma and its related mechanisms.

Methods

CCK-8 assays were used to measure proliferation. Apoptosis and reactive oxygen species (ROS) were analyzed by flow cytometry. Apoptotic cells were observed using Hoechst 33342 staining and fluorescence microscopy. Protein expression levels in HuH-6 and HepG2 cells were determined by western blotting.

Results

We found that DHM was able to inhibit the growth and increase cellular mortality in HuH-6 and HepG2 cells. Furthermore, DHM decreased the intracellular ROS level and increased the expression of SOD1. ROS scavenger NAC promoted apoptosis, while the use of SOD1 inhibitor LCS-1 weakened the ROS scavenging effect of DHM , and to some extent reduced the killing effect of DHM on hepatoblastoma cells.

Conclusion

These results suggest that regulating SOD1/ROS pathway to induce apoptosis is one of the potential mechanisms of DHM as a tumor suppressor in hepatoblastoma. Therefore, DHM may be a novel candidate for inhibiting hepatoblastoma growth and deserves further study.

Polyacetylene Isomers Isolated from Bidens pilosa L. Suppress the Metastasis of Gastric Cancer Cells by Inhibiting Wnt/β-Catenin and Hippo/YAP Signaling Pathways

(E)-7-Phenyl-2-hepten-4,6-diyn-1-ol (1) and (Z)-7-Phenyl-2-hepten-4,6-diyn-1-ol (2) are isomeric natural polyacetylenes isolated from the Chinese medicinal plant Bidens pilosa L. This study first revealed the excellent anti-metastasis potential of these two polyacetylenes on human gastric cancer HGC-27 cells and the distinctive molecular mechanisms underlying their activities. Polyacetylenes 1 and 2 significantly inhibited the migration, invasion, and adhesion of HGC-27 cells at their non-toxic concentrations in a dose-dependent manner. The results of a further mechanism investigation showed that polyacetylene 1 inhibited the expressions of Vimentin, Snail, β-catenin, GSK3β, MST1, YAP, YAP/TAZ, and their phosphorylation, and upregulated the expression of E-cadherin and p-LATS1. In addition, the expressions of various downstream metastasis-related proteins, such as MMP2/7/9/14, c-Myc, ICAM-1, VCAM-1, MAPK, p-MAPK, Sox2, Cox2, and Cyr61, were also suppressed in a dose-dependent manner. These findings suggested that polyacetylene 1 exhibited its anti-metastasis activities on HGC-27 cells through the reversal of the EMT process and the suppression of the Wnt/β-catenin and Hippo/YAP signaling pathways.

Integrative ontology and pathway-based approach identifies distinct molecular signatures in transcriptomes of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) remains a serious concern globally due to many factors that including late diagnosis, lack of an ideal biomarker for diagnosis and prognosis, and high rate of mortality. In this study, we aimed to identify the essential dysregulated genes and molecular signatures associated with the progression and development of ESCC. The dataset with 15 ESCCs and the 15 adjacent normal tissue samples from the surrounding histopathologically tumor-free mucosa was selected. We applied bioinformatics pipelines including various topological parameters from MCODE, CytoNCA, and cytoHubba to prioritize the most significantly associated DEGs with ESCC. We performed functional enrichment annotation for the identified DEGs using DAVID and MetaCore™ GeneGo platforms. Furthermore, we validated the essential core genes in TCGA and GTEx datasets between the normal mucosa and ESCC for their expression levels. These DEGs were primarily enriched in positive regulation of transferase activity, negative regulation of organelle organization, cell cycle mitosis/S-phase transition, spindle organization/assembly, development, and regulation of angiogenesis. Subsequently, the DEGs were associated with the pathways such as oocyte meiosis, cell cycle, and DNA replication. Our study identified the eight-core genes (AURKA, AURKB, MCM2, CDC20, TPX2, PLK1, FOXM1, and MCM7) that are highly expressed among the ESCC, and TCGA dataset. The multigene comparison and principal component analysis resulted in elevated signals for the AURKA, MCM2, CDC20, TPX2, PLK1, and FOXM1. Overall, our study reported GO profiles and molecular signatures that might help researchers to grasp the pathological mechanisms underlying ESCC development and eventually provide novel therapeutic and diagnostic strategies.

Potential Role of Silencing Ribonucleic Acid for Esophageal Cancer Treatment

INTRODUCTION

Esophageal cancer is an aggressive malignancy with high mortality. Optimal treatment of esophageal cancer remains an elusive goal. Ribonucleic acid (RNA) interference is a novel potential targeted approach to treat esophageal cancer. Targeting oncogenes that can alter critical cellular functions with silencing RNA molecules is a promising approach. The silencing of specific oncogenes in esophageal cancer cells in the experimental setting has been shown to decrease the expression of oncogenic proteins. This has resulted in cell apoptosis, reduction in cell proliferation, reduced invasion, migration, epithelial-mesenchymal transition, decrease in tumor angiogenesis and metastasis, and overcoming drug resistance. The Hedgehog (Hh) signaling pathway has been shown to be involved in esophageal adenocarcinoma formation in a reflux animal model. In addition to Hh, we will focus on other targets with clinical potential in the treatment of esophageal cancer.

MATERIALS AND METHODS

We searched for articles published from 2005 to August 2020 that studied the siRNA effects on inhibiting esophageal cancer formation in experimental settings. We used combinations of the following terms for searching: "esophageal cancer," "RNA interference," "small interfering RNA," "siRNA," "silencing RNA," "Smoothened (Smo)," "Gli," "Bcl-2," "Bcl-XL," "Bcl-W,″ "Mcl-1," "Bfl-1," "STAT3,"and "Hypoxia inducible factor (HIF)". A total of 21 relevant articles were found.

RESULTS AND CONCLUSIONS

Several proto-oncogenes/oncogenes including Hh pathway mediators, glioma-associated oncogene homolog 1 (Gli-1), Smoothened (Smo), and antiapoptotic Bcl-2 have potential as targets for silencing RNA in the treatment of esophageal cancer.

Oxethazaine inhibits esophageal squamous cell carcinoma proliferation and metastasis by targeting aurora kinase A

Esophageal squamous cell carcinoma (ESCC), a malignant neoplasm with high incidence, is a severe global public health threat. The current modalities used for treating ESCC include surgery, chemotherapy, and radiotherapy. Although ESCC management and treatment strategies have improved over the last decade, the overall 5-year survival rate remains <20%. Therefore, the identification of novel therapeutic strategies that can increase ESCC patient survival rates is urgently needed. Oxethazaine, an amino-amide anesthetic agent, is mainly prescribed in combination with antacids to relieve esophagitis, dyspepsia, and other gastric disorders. In the present study, we found that oxethazaine inhibited the proliferation and migration of esophageal cancer cells. According to the results of in vitro screening and binding assays, oxethazaine binds directly to AURKA, suppresses AURKA activity, and inhibits the downstream effectors of AURKA. Notably, we found that oxethazaine suppressed tumor growth in three patient-derived esophageal xenograft mouse models and tumor metastasis in vivo. Our findings suggest that oxethazaine can inhibit ESCC proliferation and metastasis in vitro and in vivo by targeting AURKA.

Effects of Aurora kinase A on mouse decidualization via Stat3-plk1-cdk1 pathway

BACKGROUND

Decidualization is essential to the successful pregnancy in mice. The molecular mechanisms and effects of Aurora kinase A (Aurora A) remain poorly understood during pregnancy. This study is the first to investigate the expression and role of Aurora A during mouse decidualization.

METHODS

Quantitative real time polymerase chain reaction, western blotting and in situ hybridization were used to determine the expression of Aurora A in mouse uteri. Aurora A activity was inhibited by Aurora A inhibitor to explore the role of Aurora A on decidualization via regulating the Aurora A/Stat3/Plk1/Cdk1 signaling pathway.

RESULTS

Aurora A was strongly expressed at implantation sites compared with inter-implantation sites. Furthermore, Aurora A was also significantly increased in oil-induced deciduoma compared with control. Both Aurora A mRNA and protein were significantly increased under in vitro decidualization. Under in vitro decidualization, Prl8a2, a marker of mouse decidualization, was significantly decreased by TC-S 7010, an Aurora A inhibitor. Additionally, Prl8a2 was reduced by Stat3 inhibitor, Plk1 inhibitor and Cdk1 inhibitor, respectively. Moreover, the protein levels of p-Stat3, p-Plk1 and p-Cdk1 were suppressed by TC-S 7010. The protein levels of p-Stat3, p-Plk1 and p-Cdk1 were also suppressed by S3I-201, a Stat3 inhibitor). SBE 13 HCl (Plk1 inhibitor) could reduce the protein levels of p-Plk1 and p-Cdk1. Collectively, Aurora A could regulate Stat3/Plk1/Cdk1 signaling pathway.

CONCLUSION

Our study shows that Aurora A is expressed in decidual cells and should be important for mouse decidualization. Aurora A/Stat3/Plk1/Cdk1 signaling pathway may be involved in mouse decidualization.

TAS-119, a novel selective Aurora A and TRK inhibitor, exhibits antitumor efficacy in preclinical models with deregulated activation of the Myc, β-Catenin, and TRK pathways

Aurora kinase A, a mitotic kinase that is overexpressed in various cancers, is a promising cancer drug target. Here, we performed preclinical characterization of TAS-119, a novel, orally active, and highly selective inhibitor of Aurora A. TAS-119 showed strong inhibitory effect against Aurora A, with an IC50 value of 1.04 nmol/L. The compound was highly selective for Aurora A compared with 301 other protein kinases, including Aurora kinase B. TAS-119 induced the inhibition of Aurora A and accumulation of mitotic cells in vitro and in vivo. It suppressed the growth of various cancer cell lines harboring MYC family amplification and CTNNB1 mutation in vitro. In a xenograft model of human lung cancer cells harboring MYC amplification and CTNNB1 mutation, TAS-119 showed a strong antitumor activity at well-tolerated doses. TAS-119 induced N-Myc degradation and inhibited downstream transcriptional targets in MYCN-amplified neuroblastoma cell lines. It also demonstrated inhibitory effect against tropomyosin receptor kinase (TRK)A, TRKB, and TRKC, with an IC50 value of 1.46, 1.53, and 1.47 nmol/L, respectively. TAS-119 inhibited TRK-fusion protein activity and exhibited robust growth inhibition of tumor cells via a deregulated TRK pathway in vitro and in vivo. Our study indicates the potential of TAS-119 as an anticancer drug, especially for patients harboring MYC amplification, CTNNB1 mutation, and NTRK fusion.

Aurora-a confers radioresistance in human hepatocellular carcinoma by activating NF-κB signaling pathway

BACKGROUND

Radiotherapy failure is a significant clinical challenge due to the development of resistance in the course of treatment. Therefore, it is necessary to further study the radiation resistance mechanism of HCC. In our early study, we have showed that the expression of Aurora-A mRNA was upregulated in HCC tissue samples or cells, and Aurora-A promoted the malignant phenotype of HCC cells. However, the effect of Aurora-A on the development of HCC radioresistance is not well known.

METHODS

In this study, colony formation assay, MTT assays, flow cytometry assays, RT-PCR assays, Western blot, and tumor xenografts experiments were used to identify Aurora-A promotes the radioresistance of HCC cells by decreasing IR-induced apoptosis in vitro and in vivo. Dual-luciferase reporter assay, MTT assays, flow cytometry assays, and Western blot assay were performed to show the interactions of Aurora-A and NF-κB.

RESULTS

We established radioresistance HCC cell lines (HepG2-R) and found that Aurora-A was significantly upregulated in those radioresistant HCC cells in comparison with their parental HCC cells. Knockdown of Aurora-A increased radiosensitivity of radioresistant HCC cells both in vivo and in vitro by enhancing irradiation-induced apoptosis, while upregulation of Aurora-A decreased radiosensitivity by reducing irradiation-induced apoptosis of parental cells. In addition, we have showed that Aurora-A could promote the expression of nuclear IkappaB-alpha (IκBα) protein while enhancing the activity of NF-kappaB (κB), thereby promoted expression of NF-κB pathway downstream effectors, including proteins (Mcl-1, Bcl-2, PARP, and caspase-3), all of which are associated with apoptosis.

CONCLUSIONS

Aurora-A reduces radiotherapy-induced apoptosis by activating NF-κB signaling, thereby contributing to HCC radioresistance. Our results provided the first evidence that Aurora-A was essential for radioresistance in HCC and targeting this molecular would be a potential strategy for radiosensitization in HCC.

Bioinformatics analysis identifies hub genes and pathways in nasopharyngeal carcinoma

The aim of the present study was to identify genes associated with and the underlying mechanisms in nasopharyngeal carcinoma (NPC) using microarray data. GSE12452 and GSE34573 gene expression profiles were obtained from the Gene Expression Omnibus (GEO) database. GEO2R was utilized to obtain differentially expressed genes (DEGs). In addition, the Database for Annotation, Visualization and Integrated Discovery was used to perform pathway enrichment analyses for DEGs using the Gene Ontology (GO) annotation along with the Kyoto Encyclopedia of Genes and Genomes (KEGG). Furthermore, Cytoscape was used to perform module analysis of the protein-protein interaction (PPI) network and pathways of the hub genes were studied. A total of 298 genes were ascertained as DEGs in the two datasets. To functionally categorize these DEGs, we obtained 82 supplemented GO terms along with 7 KEGG pathways. Subsequently, a PPI network consisting of 10 hub genes with high degrees of interaction was constructed. These hub genes included cyclin-dependent kinase (CDK) 1, structural maintenance of chromosomes (SMC) 4, kinetochore-associated (KNTC) 1, kinesin family member (KIF) 23, aurora kinase A (AURKA), ATAD (ATPase family AAA domain containing) 2, NDC80 kinetochore complex component, enhancer of zeste 2 polycomb repressive complex 2 subunit, BUB1 mitotic checkpoint serine/threonine kinase and protein regulator of cytokinesis 1. CDK1, SMC4, KNTC1, KIF23, AURKA and ATAD2 presented with high areas under the curve in receiver operator curves, suggesting that these genes may be diagnostic markers for nasopharyngeal carcinoma. In conclusion, it was proposed that CDK1, SMC4, KNTC1, KIF23, AURKA and ATAD2 may be involved in the tumorigenesis of NPC. Furthermore, they may be utilized as molecular biomarkers in early diagnosis of NPC.

Prognostic value of osteopontin expression in esophageal squamous cell carcinoma: A meta-analysis

OBJECTIVE

To explore the prognostic role of osteopontin (OPN) overexpression in esophageal squamous cell carcinoma (ESCC).

METHODS

The PubMed, EMBASE, The Cochrane Library, China National Knowledge Infrastructure, Wanfang, Chinese Biomedical Data (CBM) and VIP databases were searched from the establishment dates of the databases to March 31, 2019, for potentially related studies. Stata 12.0 software was used for statistical analyses, and the hazard ratios (HRs) with 95% confidence intervals (CIs) were combined to assess the correlation of OPN overexpression with the overall survival (OS) and progression-free survival (PFS) of ESCC patients.

RESULTS

A total of 8 studies involving 811 patients from China or Japan were included. OPN overexpression was demonstrated to be significantly associated with poor OS (HR = 1.86, 95% CI: 1.22-2.83, P = 0.004), with high heterogeneity (I² = 61.2%, P = 0.012), and poor PFS (HR=1.63, 95% CI: 1.08-2.47, P = 0.020), without heterogeneity (I² = 0.0%, P = 0.839). Subgroup analysis results were similar to the pooled results.

CONCLUSION

OPN overexpression might serve as a promising independent prognostic risk factor in Chinese and Japanese ESCC patients. However, more well-designed studies enrolling more patients are still needed to verify our findings.

Overexpression of PRR11 promotes tumorigenic capability and is associated with progression in esophageal squamous cell carcinoma

INTRODUCTION

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies of gastrointestinal tract in the world, and the long-term prognosis for ESCC patients still remains dismal due to the lack of effective early diagnosis biomarkers.

MATERIALS AND METHODS

Western blot and immunochemistry were used to determine the expression of PRR11 in 201 clinicopathologically characterized ESCC specimens. The effects of PRR11 on stem cell-like traits and tumorigenicity were examined by tumor sphere formation assay and SP assays in vitro and by a tumorigenesis model in vivo. The mechanism by which PRR11 mediated Wnt/β-catenin signaling was explored using luciferase reporter, immuno-chemistry, and real time-PCR (RT-PCR) assays.

RESULTS

We found that PRR11 was markedly upregulated, at the level of both transcription and translation, in ESCC cell lines as compared with normal esophageal epithelial cells (NECCs). Immunohistochemical analysis showed that 69.2% paraffin-embedded archival ESCC specimens exhibited high levels of PRR11 expression, and multivariate analysis revealed that PRR11 upregulation might be an independent prognostic indicator for the survival of patients with ESCC. Furthermore, overexpression of PRR11 dramatically enhanced, whereas inhibition of PRR11 reduced the capability of cancer stem cell (CSC)-like phenotypes and tumorigenicity of ESCC cells both in vitro and in vivo. Mechanically, we demonstrated PRR11-enhanced tumorigenicity of ESCC cells via activating Wnt/β-catenin signaling, and PRR11 expression is found to be significantly correlated with β-catenin nuclear location in ESCC.

CONCLUSION

Our findings suggest that the PRR11 might represent a novel and valuable prognostic marker for ESCC progression and play a role during the development and progression of this malignancy.

Targeting AURKA-CDC25C axis to induce synthetic lethality in ARID1A-deficient colorectal cancer cells

ARID1A, a component of the SWI/SNF chromatin remodeling complex, is a tumor suppressor with a high frequency of inactivating mutations in many cancers. Therefore, ARID1A deficiency has been exploited therapeutically for treating cancer. Here we show that ARID1A has a synthetic lethal interaction with aurora kinase A (AURKA) in colorectal cancer (CRC) cells. Pharmacological and genetic perturbations of AURKA selectively inhibit the growth of ARID1A-deficient CRC cells. Mechanistically, ARID1A occupies the AURKA gene promoter and negatively regulates its transcription. Cells lacking ARID1A show enhanced AURKA transcription, which leads to the persistent activation of CDC25C, a key protein for G2/M transition and mitotic entry. Inhibiting AURKA activity in ARID1A-deficient cells significantly increases G2/M arrest and induces cellular multinucleation and apoptosis. This study shows a novel synthetic lethality interaction between ARID1A and AURKA and indicates that pharmacologically inhibiting the AURKA-CDC25C axis represents a novel strategy for treating CRC with ARID1A loss-of-function mutations.

Osteopontin Expression Is Associated with the Poor Prognosis in Patients with Locally Advanced Esophageal Squamous Cell Carcinoma Receiving Preoperative Chemoradiotherapy

BACKGROUND

The osteopontin has been involved in therapeutic resistance in a variety of cancers. But, the significance of osteopontin expression on the prognosis of patients with locally advanced esophageal squamous cell carcinoma (ESCC) receiving chemoradiotherapy is unclear.

METHODS

In 80 patients with locally advanced ESCC receiving preoperative chemoradiotherapy between 1999 and 2012, osteopontin expression was evaluated by immunohistochemistry and correlated with treatment outcome. The functional role of osteopontin in ESCC cell lines was determined by osteopontin-mediated siRNA.

RESULTS

Osteopontin expression and clinical T4 classification were significantly associated with poor pathological complete response. Univariate analyses demonstrated that osteopontin overexpression and clinical T classification, T4, were significantly associated with worse overall survival and disease-free survival. In multivariate comparison, osteopontin overexpression and clinical T classification, T4, represented the independent adverse prognosticator. In ESCC cell lines, endogenous osteopontin depletion by osteopontin-mediated siRNA increased sensitivity to cisplatin. Osteopontin expression is independently correlated with the response of chemoradiotherapy and prognosis of patients with locally advanced ESCC receiving preoperative chemoradiotherapy.

CONCLUSIONS

Our results suggest that osteopontin may be a potential therapeutic target for patients with ESCC treated with preoperative chemoradiotherapy.

Clinical value of Xenopus kinesin-like protein 2 as a prognostic marker in patients with digestive system cancers: a systematic review and meta-analysis

Xenopus kinesin-like protein 2 (TPX2) is a microtubule-associated protein that plays an important role in spindle assembly and dynamics. However, the clinical and prognostic value of TPX2 in the digestive system cancers remains unclear. The objective of this review was to evaluate the association of TPX2 expression with disease-free survival (DFS), overall survival (OS), and clinicopathological features of digestive system cancers. The software Stata 12.0 was used to analyze the outcomes, including OS, disease-free survival (DFS), and clinicopathological characteristics. A total of 10 eligible studies with 906 patients were included. Elevated TPX2 expression was significantly associated with poor DFS (pooled hazard ratio [HR] =2.48, 95% confidence interval [CI]: 1.96–3.13) and OS (pooled HR =2.66, 95% CI: 2.04–3.48) of digestive system malignancies. Subgroup analyses showed that cancer type, sample size, study quality, and laboratory detection methods did not alter the significant prognostic value of TPX2. Additionally, TPX2 expression was found to be an independent predictive factor for DFS (HR =2.31, 95% CI: 1.78–3.01). TPX2 expression might be associated with TNM stage and pathological grade in digestive system cancer. In conclusion, TPX2 is an independent prognostic factor for survival of patients with digestive system cancer. Furthermore, its overexpression is associated with TNM stage and pathological grade in digestive system cancer.

Investigating cytokinesis failure as a strategy in cancer therapy

Effective therapeutics exploit common characteristics shared amongst cancers. As many cancers present chromosomal instability (CIN), one possible approach to treat these cancers could be to increase their CIN above a threshold that would affect their viability. Here, we investigated whether causing polyploidy by cytokinesis failure could represent a useful approach. We show that cytokinesis failure caused by depletion of Citron kinase (CIT-K) dramatically decreased cell proliferation in breast, cervical and colorectal cancer cells. CIT-K depletion activated the Hippo tumor suppressor pathway in normal, but not in cancer cells, indicating that cancer cells have evolved mechanisms to bypass this control. CIT-K depleted cancer cells died via apoptosis in a caspase 7 dependent manner and, consistent with this, p53-deficient HCT116 colon carcinoma cells failed to induce apoptosis after cytokinesis failure. However, other p53-mutated cancer cells were able to initiate apoptosis, indicating that cytokinesis failure can trigger apoptosis through a p53-independent mechanism. Finally, we found that actively dividing and, in some cases, polyploid cancer cells were more susceptible to CIT-K depletion. In sum, our findings indicate that inducing cytokinesis failure could be a promising anti-cancer therapeutic approach for a wide range of cancers, especially those characterized by fast cell proliferation and polyploidy.

Drug-induced inhibition of phosphorylation of STAT5 overrides drug resistance in neoplastic mast cells

Systemic mastocytosis (SM) is a mast cell (MC) neoplasm with complex pathology and a variable clinical course. In aggressive SM (ASM) and MC leukemia (MCL) responses to conventional drugs are poor and the prognosis is dismal. R763 is a multi-kinase inhibitor that blocks the activity of Aurora-kinase-A/B, ABL1, AKT and FLT3. We examined the effects of R763 on proliferation and survival of neoplastic MC. R763 produced dose-dependent inhibition of proliferation in the human MC lines HMC-1.1 (IC₅₀ 5-50 nM), HMC-1.2 (IC₅₀ 1-10 nM), ROSA^{KIT WT} (IC₅₀ 1-10 nM), ROSA^{KIT D816V} (IC₅₀ 50-500 nM) and MCPV-1.1 (IC₅₀ 100-1000 nM). Moreover, R763 induced growth inhibition in primary neoplastic MC in patients with ASM and MCL. Growth-inhibitory effects of R763 were accompanied by signs of apoptosis and a G2/M cell cycle arrest. R763 also inhibited phosphorylation of KIT, BTK, AKT and STAT5 in neoplastic MC. The most sensitive target appeared to be STAT5. In fact, tyrosine phosphorylation of STAT5 was inhibited by R763 at 10 nM. At this low concentration, R763 produced synergistic growth-inhibitory effects on neoplastic MC when combined with midostaurin or dasatinib. Together, R763 is a novel promising multi-kinase inhibitor that blocks STAT5 activation and thereby overrides drug-resistance in neoplastic MC.

Characterization of the Indirubin Derivative LDD970 as a Small Molecule Aurora Kinase A Inhibitor in Human Colorectal Cancer Cells

Aurora kinase A plays an essential role in mitosis including chromosome separation and cytokinesis. Aberrant expression and activity of Aurora kinase A is associated with numerous malignancies including colorectal cancer followed by poor prognosis. The aim of this study is to determine the inhibitory effects of LDD970, an indirubin derivative, on Aurora kinase A in HT29 colorectal cancer cells. In vitro kinase assay revealed that, LDD970 inhibited levels of activated Aurora kinase A (IC₅₀=0.37 mM). The inhibitory effects of LDD970 on Aurora kinase A, autophosphorylation and phosphorylation of histone H3 (Ser10), were confirmed by immunoblot analysis. Moreover, LDD970 inhibited migration of HT29 cells and upregulated apoptosis-related protein cleaved PARP. In cell viability assay, LDD970 was observed to suppress HT29 cell growth (GI₅₀=4.22 µM). Although further studies are required, results of the present study suggest that LDD970 provide a valuable insight into small molecule indirubin derivative for therapeutic potential in human colorectal cancer.

Characterization of Aurora A and Its Impact on the Effect of Cisplatin-Based Chemotherapy in Patients with Non-Small Cell Lung Cancer

BACKGROUND AND OBJECTIVE: Aurora A, as a member of serine/threonine kinase family and a common characteristic of epithelial cancers, plays a critical role in cell mitosis. However, the clinical significance of Aurora A in non–small cell lung cancer (NSCLC) remains undetermined. METHODS: The expression of Aurora A in NSCLC and paired normal adjacent lung tissues was determined by immunohistochemistry, Western blot, and reverse transcriptase polymerase chain reaction. Receiver operating characteristic (ROC) curve analysis was employed to determine a cutoff score for Aurora A expression in a training set (n = 135). For validation, the ROC-derived cutoff score was subjected to analysis of the association of Aurora A expression with patient outcome and clinicopathological characteristics in a testing set (n = 128) and overall patients (n = 263). The correlation of Aurora A with cisplatin resistance and epithelial-mesenchymal transition (EMT) was examined in vitro in NSCLC cells by overexpression or knockdown of Aurora A. RESULTS: Aurora A expression was significantly upregulated in tumor tissues compared with paired normal tissues (P < .01). The expression of Aurora A was closely associated with clinical stage, lymph node metastasis, and recurrence and was an independent prognostic parameter in multivariate analysis. High level of Aurora A expression predicted poorer overall survival and disease-free survival in NSCLC patients treated with cisplatin-based adjuvant chemotherapy. In vitro data showed that overexpression or knockdown of Aurora A resulted in increased or decreased cellular resistance to cisplatin. Furthermore, inhibition of Aurora A reversed the EMT process. CONCLUSIONS: Aurora A was identified as an inferior prognostic and cisplatin-resistant biomarker in NSCLC patients, which provided potential evidences for therapeutic target and reversing drug resistance.

Aurora-A modulates MMP-2 expression via AKT/NF-κB pathway in esophageal squamous cell carcinoma cells

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies. It is necessary to identify new markers for predicting tumor progression and therapeutic molecular targets. It has been reported that overexpressions of Aurora-A and matrix metalloproteinases 2 (MMP-2) may promote the malignant development of tumor. However, the relationship between Aurora-A and MMP-2 expression in tumor patients has not been investigated. In addition, the underlying mechanisms that Aurora-A regulates MMP-2 expression are still not fully elucidated. In this study, we demonstrated that Aurora-A and MMP-2 were overexpressed in ESCC tissues compared with paired normal adjacent tissues (P < 0.0001). Overexpression of Aurora-A was associated with the lymph node metastasis of ESCC (P = 0.01). Significantly, Aurora-A protein expression was positively correlated with MMP-2 protein expression in ESCC tissues (r = 0.66, P < 0.0001) as well as in ESCC cell lines. The level of Aurora-A expression was also positively correlated with the invasion capability of ESCC cells. Furthermore, Aurora-A overexpression significantly increased ESCC cell invasion by the upregulation of MMP-2 expression. In addition, Aurora-A overexpression promoted nuclear factor-kappaB (NF-κB) activation, and Aurora-A-mediated MMP-2 upregulation was abrogated by NF-κB inhibitor. Further analysis showed that activation of NF-κB was severely attenuated by AKT inhibitor in cells overexpressing Aurora-A. Taken together, these data indicate that Aurora-A overexpression upregulates MMP-2 expression through activating AKT/NF-κB signaling pathway in ESCC cells. These findings reveal that Aurora-A may be used as an important indicator for the judgment of malignant behavior of ESCC, and may be an attractive target for cancer therapy.

CRCT1 regulated by microRNA-520 g inhibits proliferation and induces apoptosis in esophageal squamous cell cancer

Cysteine-rich C-terminal 1 (CRCT1) is encoded by the epidermal differentiation complex (EDC), a gene cluster that was recently linked to esophageal cancer. However, the role of CRCT1 in esophageal squamous cell cancer (ESCC) and the underlying mechanism remain unclear. In the present study, we show that CRCT1 is downregulated in ESCC in association with TNM stage and lymph node metastasis. Restoring CRCT1 in ESCC cells by lentivirus-mediated gene transfer inhibited cell proliferation and xenograft tumor formation. CRCT1 overexpression promoted ESCC cell apoptosis and upregulated the expression of apoptosis-related proteins. CRCT1 expression was inversely correlated with the levels of microRNA-520 g (miR-520 g) in ESCC tissues, and CRCT1 was identified as a direct target gene of miR-520 g in ESCC cells. Consistent with the effects of CRCT1 overexpression, knockdown of miR-520 g inhibited growth and induced apoptosis in ESCC cells. Our results suggest that CRCT1 functions as a tumor suppressor gene in ESCC and is regulated by miR-520 g, providing potential therapeutic targets for the treatment of ESCC.

H3S10 phosphorylation-mediated transcriptional regulation by Aurora kinase A

Histone H3S10 phosphorylation has been known as a cell cycle-specific marker and has a role in transcriptional activation. Various kinases phosphorylate H3S10 in different species, however, the role of the mitotic serine/threonine protein kinase Aurora A (AURKA) is largely unknown. Here we present evidence that AURKA phosphorylates H3S10 and activates target gene transcription. We show that down-regulation of AURKA level during leukemia cell differentiation results in decreased H3S10 phosphorylation level. We further show that AURKA is recruited to target gene promoters and activates transcription via H3S10 phosphorylation. Furthermore, this recruitment can be disrupted by the AURKA inhibitor Alisertib and results in H3K9-me2 recruitment by G9a.

Aurora-A promotes chemoresistance in hepatocelluar carcinoma by targeting NF-kappaB/microRNA-21/PTEN signaling pathway

Hepatocellular carcinoma (HCC) is highly resistant to chemotherapy. Previously, we have shown that Aurora-A mRNA is upregulated in HCC cells or tissues and silencing of Aurora-A using small interfering RNA (siRNA) decreases growth and enhances apoptosis in HCC cells. However, the clinical significance of Aurora-A protein expression in HCC and association between Aurora-A expression and HCC chemoresistance is unclear. Here, we showed that Aurora-A protein is upregulated in HCC tissues and significantly correlated with recurrence-free and overall survival of patients and multivariate analysis indicated that immunostaining of Aurora-A will be an independent prognostic factor for patients. Silencing of Aurora-A significantly increased the chemosensitivity of HCC cells both in vitro and in vivo, while overexpression of Aurora-A induced the opposite effects. Furthermore, overexpression of Aurora-A reduces chemotherapy-induced apoptosis by promoting microRNA-21 expression, which negatively regulates PTEN and then inhibits caspase-3-mediated apoptosis induction. Mechanically, we demonstrated that Aurora-A promotes expression of nuclear Ikappaβ-alpha (Iκβα) protein and enhances NF-kappa B (NF-κB) activity, thus promotes the transcription of miR-21. This study first reported the involvement of Aurora-A/NF-κB/miR-21/PTEN/Akt signaling axis in chemoresistance of HCC cells, suggesting that targeting this signaling pathway would be helpful as a therapeutic strategy for the reversal of chemoresistance in HCC.

Scientific Rationale Supporting the Clinical Development Strategy for the Investigational Aurora A Kinase Inhibitor Alisertib in Cancer

Alisertib (MLN8237) is a selective small molecule inhibitor of Aurora A kinase that is being developed in multiple cancer indications as a single agent and in combination with other therapies. A significant amount of research has elucidated a role for Aurora A in orchestrating numerous activities of cells transiting through mitosis and has begun to shed light on potential non-mitotic roles for Aurora A as well. These biological insights laid the foundation for multiple clinical trials evaluating the antitumor activity of alisertib in both solid cancers and heme-lymphatic malignancies. Several key facets of Aurora A biology as well as empirical data collected in experimental systems and early clinical trials have directed the development of alisertib toward certain cancer types, including neuroblastoma, small cell lung cancer, neuroendocrine prostate cancer, atypical teratoid/rhabdoid tumors, and breast cancer among others. In addition, these scientific insights provided the rationale for combining alisertib with other therapies, including microtubule perturbing agents, such as taxanes, EGFR inhibitors, hormonal therapies, platinums, and HDAC inhibitors among others. Here, we link the key aspects of the current clinical development of alisertib to the originating scientific rationale and provide an overview of the alisertib clinical experience to date.

Phase II Intergroup Trial of Alisertib in Relapsed and Refractory Peripheral T-Cell Lymphoma and Transformed Mycosis Fungoides: SWOG 1108

PURPOSE

Aurora A kinase (AAK) is upregulated in highly proliferative lymphomas, suggesting its potential as a therapeutic target. Alisertib is a novel oral AAK inhibitor without adverse safety signals in early-phase studies that demonstrated preliminary activity in T-cell lymphoma. This phase II study was conducted to further investigate the efficacy of alisertib in relapsed or refractory peripheral T-cell non-Hodgkin lymphoma (PTCL).

PATIENTS AND METHODS

Eligible patients with histologically confirmed relapsed/refractory PTCL or transformed Mycosis fungoides (tMF) received alisertib 50 mg twice a day for 7 days on 21-day cycles.

RESULTS

Of 37 eligible patients, the histologic subtypes enrolled included PTCL not otherwise specified (n = 13), angioimmunoblastic T-cell lymphoma (n = 9), tMF (n = 7), adult T-cell lymphoma/leukemia (n = 4), anaplastic large-cell lymphoma (n = 2), and extranodal natural killer/T-cell lymphoma (n = 2). Grade 3 and 4 adverse events in ≥ 5% of patients included neutropenia (32%), anemia (30%), thrombocytopenia (24%), febrile neutropenia (14%), mucositis (11%), and rash (5%). Treatment was discontinued most commonly for disease progression. Among the PTCL subtypes, the overall response rate was 30%, whereas no responses were observed in tMF. Aurora B kinase was more commonly overexpressed than AAK in tumor specimens. Analysis of AAK, Aurora B kinase, MYC, BCL-2, phosphatidylinositol 3-kinase γ, and Notch1 expression revealed no association with response.

CONCLUSION

Alisertib has antitumor activity in PTCL, including heavily pretreated patients. These promising results are being further investigated in an ongoing international, randomized phase III trial comparing alisertib with investigator's choice in PTCL.

Suppression of Aurora-A-FLJ10540 signaling axis prohibits the malignant state of head and neck cancer

BACKGROUND

Head and neck cancer (HNC) is a highly invasive cancer. Aurora-A has been reported for a number of malignancies. However, the identity of downstream effectors responsible for its aggressive phenotype in HNC remains underinvestigated.

METHODS

The mRNA and protein expression levels of Aurora-A and FLJ10540 were assessed in HNC specimens and cell lines using RT-qPCR, western blot, Oncomine, and microarray database analysis. The downstream molecular mechanisms of Aurora-A were confirmed by RT-qPCR, western blot, luciferase reporter, confocal microscopy analyses, immunoprecipitation, colony formation, cell viability, and xenograft model. Cellular functions in response to Aurora-A-modulated downstream targets such as FLJ10540 and MMPs were examined in vitro and in vivo, including cell growth, motility and chemosensitivity. Aurora-A/FLJ10540/MMPs expression was determined in cancer and adjacent normal tissues from HNC patients by immunohistochemistry approach.

RESULTS

In the current study, Aurora-A exhibited similar gene expression profiles with FLJ10540 by using accessibly public microarray and Oncomine database analysis, raising the possibility that these molecules might coordinately participate in cancer progression and metastasis of HNC. These two molecules connection were also examined in cell lines and tissues of HNC. Aurora-A overexpression could not only bind to the promoter of FLJ10540 to induce FLJ10540 expression, but also increase both mRNA and protein levels of MMP-7 and MMP-10 in HNC cells. Conversely, depletion of Aurora-A expression by using siRNA or Aurora-A kinase inhibitor, MLN8237, suppressed FLJ10540, MMP-7 and MMP-10 mRNA and protein expressions in vitro and in vivo. In addition, the FLJ10540-PI3K complex was destroyed by inhibition the Aurora-A kinase activity. Forced overexpression of FLJ10540 in Aurora-A-depleted or in MLN8237-treated HNC cells attenuated the effect on cytotoxicity to cisplatin. Elevated Aurora-A expression in HNC cells led to the characteristics of more aggressive malignancy, including enhanced chemoresistance and increased the abilities of proliferation, migration and invasion, which was required for FLJ10540/MMP-7 or FLJ10540/MMP-10 expressions. Finally, immunohistochemical analysis of human HNC specimens showed a significant positively correlation among Aurora-A, FLJ10540, MMP-7 and MMP-10 expressions.

CONCLUSION

Together, our findings define a novel mechanism by which Aurora-A promotes cell malignancy, with potential implications for understanding the clinical action of Aurora-A.

Jaridonin-induced G2/M phase arrest in human esophageal cancer cells is caused by reactive oxygen species-dependent Cdc2-tyr15 phosphorylation via ATM-Chk1/2-Cdc25C pathway

Jaridonin, a novel diterpenoid from Isodon rubescens, has been shown previously to inhibit proliferation of esophageal squamous cancer cells (ESCC) through G2/M phase cell cycle arrest. However, the involved mechanism is not fully understood. In this study, we found that the cell cycle arrest by Jaridonin was associated with the increased expression of phosphorylation of ATM at Ser1981 and Cdc2 at Tyr15. Jaridonin also resulted in enhanced phosphorylation of Cdc25C via the activation of checkpoint kinases Chk1 and Chk2, as well as in increased phospho-H2A.X (Ser139), which is known to be phosphorylated by ATM in response to DNA damage. Furthermore, Jaridonin-mediated alterations in cell cycle arrest were significantly attenuated in the presence of NAC, implicating the involvement of ROS in Jaridonin's effects. On the other hand, addition of ATM inhibitors reversed Jaridonin-related activation of ATM and Chk1/2 as well as phosphorylation of Cdc25C, Cdc2 and H2A.X and G2/M phase arrest. In conclusion, these findings identified that Jaridonin-induced cell cycle arrest in human esophageal cancer cells is associated with ROS-mediated activation of ATM-Chk1/2-Cdc25C pathway.

Involvement of chromosome region maintenance 1 (CRM1) in the formation and progression of esophageal squamous cell carcinoma

Chromosome region maintenance 1 (CRM1) has been related to several malignancies. The predictive value of CRM1 in the malignance and prognosis of esophageal squamous cell carcinoma (ESCC), however, is not clear yet. In this study, we displayed that CRM1 expression was up-regulated in ESCC using immunohistochemistry and Western blot. Statistical analysis demonstrated that patients with high CRM1 levels indicated shorter survival period. We further found that silencing CRM1 caused apoptosis in ESCC cell lines. Moreover, knockdown of CRM1 disturbed the expression of tumor suppressor proteins and inhibited NF-κB activity in ESCC cell lines, especially if the cell line was treated with 5-fluorouracil. In consequence, our results for the first time indicated that CRM1 was dysregulated in ESCC, and suppression of CRM1 expression which resulted in inhibiting of NF-κB signaling might be developed into a new strategy in ESCC therapy.

Aurora-A contributes to cisplatin resistance and lymphatic metastasis in non-small cell lung cancer and predicts poor prognosis

Background

Platinum-based chemotherapy improves survival among patients with non-small cell lung cancer (NSCLC), but the efficiency is limited due to resistance. In this study, we aimed to identify the expression of Aurora-A and its correlation with cisplatin resistance and prognosis in NSCLC.

Methods

We used immunohistochemical analysis to determine the expression of Aurora-A protein in 102 NSCLC patients treated by surgery and adjuvant cisplatin-based chemotherapy. The prognostic significances were assessed by Kaplan-Meier survival estimates and Cox models. The potential role of Aurora-A in the regulation of cisplatin resistance in NSCLC cells was examined by transfections using expression vector and small interfering RNA or using small-molecule inhibitors.

Results

Aurora-A expression was significantly associated with clinical stage (p = 0.018), lymph node metastasis (p = 0.038) and recurrence (p = 0.005), and was an independent prognostic parameter in multivariate analysis. High level of Aurora-A expression predicted poorer overall survival (OS) and progression-free survival (PFS). In vitro data showed that Aurora-A expression was elevated in cisplatin-resistant lung cancer cells, and overexpression or knockdown of Aurora-A resulted in increased or decreased cellular resistance to cisplatin. Furthermore, inhibition of Aurora-A reversed the migration ability of cisplatin-resistant cells.

Conclusions

The current findings suggest that high Aurora-A expression is correlated with cisplatin-based chemotherapeutic resistance and predicts poor patient survival in NSCLC. Aurora-A might serve as a predictive biomarker of drug response and therapeutic target to reverse chemotherapy resistance.

The tumor suppressive role of NUMB isoform 1 in esophageal squamous cell carcinoma

Esophageal quamous cell carcinoma (ESCC) is the predominant histological type of esophageal carcinoma in Asian populations. To date, few biomarkers have been identified for ESCC. In present study, we found a tumor suppressor, NUMB isoform 1 (NUMB-1), as a promising prognostic biomarker for patients with ESCC. NUMB-1 mRNA was downregulated in 66.7% of primary ESCC tissues when compared with matched adjacent non-tumor tissues. The low expression of NUMB-1 was significantly associated with high tumor recurrence (p=0.029) and poor post-operative overall survival (p=0.016). To further explore the underlying mechanisms by which NUMB-1 regulates ESCC, we demonstrated that ectopic expression of NUMB-1 inhibited cell proliferation through inducing G2/M phase arrest, which was accompanied by an increase in p21 and cyclin B1-cdc2 levels. However, it had no impact on apoptosis of ESCC cells. In addition, overexpression of NUMB-1 prevented epithelial-mesenchymal transition, inhibited invasion of ESCC cells and NOTCH pathway, suppressed Aurora-A activity by preventing phosphorylation of Aurora-A at T288 which resulted in cell cycle arrest. Taken together, our findings suggested NUMB-1 functions as a tumor-suppressor and serves as a prognositc biomarker for ESCC patients; thus, NUMB-1 may be a potential novel therapeutic target for treatment of ESCC.

Identification of Aurora-A Inhibitors by Ligand and Structure-Based Virtual Screening

Aurora kinase A has been identified as one of the most attractive targets for cancer therapy because of its critical role in the regulation of the cell cycle. In order to identify active compounds with structural diversity we performed virtual screening. 3D-QSAR pharmacophore models were developed and the best model was used as a query for screening the databases. Ligand and structure-based virtual screening protocol was conducted sequentially by applying the common feature pharmacophore and molecular docking to discover potent Aurora-A inhibitors. A total of eighty-eight compounds were selected for the in vitro activities against various human cancer cell lines (DU145 and HT29). Considering the activity data, we have identified seven compounds to be considered for the next step, among which four compounds had high inhibition rate (above 50 %) at 10 µM with GI50 lower than 10 µM. Based on the cell line and enzyme assay (Aurora-A & B) result, these four compounds were used as template/query molecule for similarity search. The best result was obtained for similarity hit SH3. It had IC50 of 0.578 and 11.77 µM for Aurora-A and B respectively, which implies 20-fold selectivity over Aurora-B. The hits obtained from this screening scheme could be potential drug candidates after further optimization.

Jaridonin, a novel ent-kaurene diterpenoid from Isodon rubescens, inducing apoptosis via production of reactive oxygen species in esophageal cancer cells

Isodon rubescens, a Chinese herb, has been used as a folk, botanical medicine in China for inflammatory diseases and cancer treatment for many years. Recently, we isolated a new ent-kaurene diterpenoid, named Jaridonin, from Isodon rubescens. The chemical structure of Jaridonin was verified by infrared (IR), nuclear magnetic resonance (NMR), and mass spectrum (MS) data as well as X-ray spectra. Jaridonin potently reduced viabilities of several esophageal cancer cell lines, including EC109, EC9706 and EC1. Jaridonin treatment resulted in typical apoptotic morphological characteristics, increased the number of annexin V-positive staining cells, as well as caused a G2/M arrest in cell cycle progression. Furthermore, Jaridonin resulted in a significant loss of mitochondrial membrane potential, release of cytochrome c into the cytosol, and then activation of Caspase-9 and -3, leading to activation of the mitochondria mediated apoptosis. Furthermore, these effects of Jaridonin were accompanied by marked reactive oxygen species (ROS) production and increased expression of p53, p21(waf1/Cip1) and Bax, whereas two ROS scavengers, N-acetyl-L-cysteine (LNAC) and Vitamin C, significantly attenuated the effects of Jaridonin on the mitochondrial membrane potential, DNA damage, expression of p53 and p21(waf1/Cip1) and reduction of cell viabilities. Taken together, our results suggest that a natural ent-kaurenoid diterpenoid, Jaridonin, is a novel apoptosis inducer and deserves further investigation as a new chemotherapeutic strategy for patients with esophageal cancer.

Overexpression of OLC1 promotes tumorigenesis of human esophageal squamous cell carcinoma

PURPOSE

OLC1 was recently identified to be a potential oncogene. However, the role of OLC1 in human esophageal cell carcinoma (ESCC) is unknown. The aim of this study was therefore to evaluate the expression of OLC1 in human ESCC from normal, premalignant, and malignant lesions, and to clarify the mechanisms by which OLC1 contributes to the progression of ESCC.

EXPERIMENTAL DESIGN

Two hundred and fourteen paired ESCC specimens, and an independent set from 28 ESCC patients, were used to analyze the correlation between OLC1 expression and the pathological characteristics of tumors using immunohistochemistry. Stable OLC1-overexpressing and OLC1-interfering esophageal cancer cells were established and a series of experimental methods were used to investigate the biological functions and mechanisms of action of OLC1.

RESULTS

We showed that OLC1 was overexpressed in 145 of 214 (67.8%) of human ESCC specimens, compared with in only 59 of 214 (27.57%) paired adjacent normal tissues (P<0.001). OLC1 overexpression occurred at a rate of 35% (10/28) at the stage of mild/moderate dysplasia, but was significantly upregulated to 66% (22/33) at the stages of severe dysplasia and in situ carcinoma, while 71% positive staining (22/28) was observed in invasive carcinoma tissues compared with normal tissues (P<0.05). We also provided evidence that OLC1 abnormalities significantly altered the cell proliferation and apoptosis induced by cytotoxic agents. OLC1 overexpression suppressed apoptosis, and was associated with attenuated caspase-3 activation and increased Bcl-2 stability.

CONCLUSION

Our study provides strong evidence suggesting OLC1 abnormalities may contribute to the development of human ESCC and have some important clinical significance.

VX680 suppresses the growth of HepG2 cells and enhances the chemosensitivity to cisplatin

VX680 is an Aurora A inhibitor. It has been reported to inhibit the growth of the HepG2 cell line in several studies. However, whether it enhances chemosensitivity to cisplatin remains unclear. In this study, the synergistic effect of VX680 and cisplatin on the proliferation of HepG2 cells was determined by MTT assay. The changes in cell apoptosis were detected by flow cytometry. Aurora A, Bcl-2 and p53 protein levels were analyzed by western blotting. This study demonstrated that VX680, cisplatin and a combination of the two inhibit the growth of HepG2 cells in a dose- and time-dependent manner. A synergistic effect was observed with the combined therapy. Moreover, the inhibitory effect of VX680 was positively correlated with the expression of Aurora A. The rate of apoptosis in the combined group was significantly higher compared with that of the VX680 and cisplatin groups. In addition, VX680 and cisplatin increased the expression of the p53 protein. Cisplatin reduced the expression of Bcl-2 protein, while VX680 did not. In the combined group, the expression of Bcl-2 and p53 changed significantly compared with the single drug group and control group. This study suggests that Aurora A may represent a valid target in hepatocellular carcinoma. We also demonstrated that the Aurora A inhibitor VX680 has a synergistic effect with cisplatin.

Aurora-A: a potential DNA repair modulator

It is well-known that overexpression of Aurora-A promotes tumorigenesis, but the role of Aurora-A in the development of cancer has not been fully investigated. Recent studies indicate that Aurora-A may confer cancer cell chemo- and radioresistance through dysregulation of cell cycle progression and DNA damage response. Direct evidences from literatures suggest that Aurora-A inhibits pRb, p53, p21(waf1/cip1), and p27(cip/kip) but enhances Plk1, CDC25, CDK1, and cyclin B1 to repeal cell cycle checkpoints and to promote cell cycle progression. Other studies indicate that Aurora-A suppresses BRCA1, BRCA2, RAD51, poly(ADP ribose) polymerase (PARP), and gamma-H2AX to dysregulate DNA damage response. Aurora-A may also interact with RAS and Myc to control DNA repair indirectly. In this review, we summarized the potential role of Aurora-A in DNA repair from the current literatures and concluded that Aurora-A may function as a DNA repair modulator to control cancer cell radio- and chemosensitivity, and that Aurora-A-associated DNA repair molecules may be considered for targeted cancer therapy.

Upregulation of the TPX2 gene is associated with enhanced tumor malignance of esophageal squamous cell carcinoma

PURPOSE

To explore the expression of TPX2 and its significance in esophageal squamous cell carcinoma (ESCC) tissue and approach relationship between the TPX2 and clinicopathological characteristic of esophageal squamous cell carcinoma.

METHOD

RT-PCR and immunohistochemical staining were used to compare the expression of TPX2 in 62 esophageal squamous cell carcinoma, 31 atypical hyperplasia and 62 normal esophageal mucosa.

RESULTS

In ESCC, atypical hyperplasia and in normal mucous membrane tissues, the positive rate of TPX2 protein expression was 85.5% (53/62), 51.6% (16/31) and 4.8% (3/62); the positive rate of TPX2 mRNA expression was 65.5% (40/62), 35.5 (11/31) and 4.83% (3/62). The expression of TPX2 protein and mRNA were correlated with invasive depth and lymphatic metastasis of ESCC (P<0.01).

CONCLUSIONS

Overexpression of TPX2 may be risk factor of lymph node in esophageal carcinoma, and maybe a potential biomarker for early diagnosis and prognosis of esophageal squamous cell carcinoma.

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

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

Actin polymerization negatively regulates p53 function by impairing its nuclear import in response to DNA damage

Actin, one of the most evolutionarily conservative proteins in eukaryotes, is distributed both in the cytoplasm and the nucleus, and its dynamics plays important roles in numerous cellular processes. Previous evidence has shown that actin interacts with p53 and this interaction increases in the process of p53 responding to DNA damage, but the physiological significance of their interaction remains elusive. Here, we show that DNA damage induces both actin polymerization and p53 accumulation. To further understand the implication of actin polymerization in p53 function, cells were treated with actin aggregation agent. We find that the protein level of p53 decrease. The change in p53 is a consequence of the polymeric actin anchoring p53 in the cytoplasm, thus impairing p53 nuclear import. Analysis of phosphorylation and ubiquitination of p53 reveals that actin polymerization promotes the p53 phosphorylation at Ser315 and reduces the stabilization of p53 by recruiting Aurora kinase A. Taken together, our results suggest that the actin polymerization serves as a negative modulator leading to the impairment of nuclear import and destabilization of p53. On the basis of our results, we propose that actin polymerization might be a factor participating in the process of orchestrating p53 function in response to DNA damage.

Long-term cisplatin exposure promotes methylation of the OCT1 gene in human esophageal cancer cells

BACKGROUND

Cisplatin-based chemotherapy is widely used for treatment of a variety of human malignant solid and metastatic tumors, including esophageal cancer. However, the clinical effect of this drug is limited because of intrinsic and acquired resistance to it. Organic cation transporters (OCTs) are important in the cellular uptake of cisplatin.

AIM

Our objective was to test the hypothesis that cisplatin resistance is associated with alteration of expression of OCTs.

METHODS

Levels of expression of OCTs in paired esophageal cancer and adjacent non-cancerous tissues were examined by use of immunohistochemistry.

RESULTS

We found that OCT1 silencing impaired cisplatin-mediated apoptosis of esophageal cancer cells. The level of OCT1 mRNA in cisplatin-resistant cells was markedly reduced compared with parental cells. Promoter methylation of OCT1 was induced in cisplatin-resistant cells.

CONCLUSION

This study shows that long-term exposure to cisplatin promotes methylation of the OCT1 gene in human esophageal cancer cells, which in turn results in cisplatin resistance.

Expression of aurora kinase A and B in chondrosarcoma and its relationship with the prognosis

Purpose

To investigate the expression of Aurora Kinase A and B in patients with chondrosarcoma and consider it as a prognostic marker and molecular target of therapy.

Methods

To evaluate the relationship of the Aurora Kinase A and B and the clinical pathological parameters and prognosis of chondrosarcoma. 72 case chondrosarcoma and 42 case chondroma were performed immunohistochemistry on the tissue microarray paraffin sections. The survival time of patients was followed-up.

Results

The expression of Aurora Kinase A and B in chondrosarcoma was significantly higher than that in chondroma (p<0.01). There were differences about the expression of Aurora Kinase A and B in chondrosarcoma between the recurrence group and the non-recurrence group, metastatic group and non-metastatic group (p<0.05), but not age and gender (p>0.05). The expression of Aurora Kinase A and B were significantly lower in group low grade conventional chondrosarcoma than that in groups medium and high grade conventional chondrosarcoma (p<0.01). The expression of Aurora Kinase A and B in chondrosarcoma showed a positive correlation (p<0.01). According to the Kaplan Meier analysis and multivariate Cox regression analysis, the survival rate was significantly different between the patients with positive Aurora Kinase A and the patients with negative expression (p<0.05) and Aurora Kinase A expression was an independent risk marker of survival(HR=11.263, 95%CI: 2.317–54.748, P=0.003).

Conclusion

Both the Aurora Kinase A and B might involve in the oncogenic, invasive and metastatic process of chondrosarcoma; however, the mechanism is still unclear. The Aurora Kinase A and B could be used as a new prognostic marker and molecular therapeutic target for chondrosarcoma.

Virtual Slide

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9101494267377096.

Genome-wide screening for genetic alterations in esophageal cancer by aCGH identifies 11q13 amplification oncogenes associated with nodal metastasis

Background

Esophageal squamous cell carcinoma (ESCC) is highly prevalent in China and other Asian countries, as a major cause of cancer-related mortality. ESCC displays complex chromosomal abnormalities, including multiple structural and numerical aberrations. Chromosomal abnormalities, such as recurrent amplifications and homozygous deletions, directly contribute to tumorigenesis through altering the expression of key oncogenes and tumor suppressor genes.

Methodology/Principle Findings

To understand the role of genetic alterations in ESCC pathogenesis and identify critical amplification/deletion targets, we performed genome-wide 1-Mb array comparative genomic hybridization (aCGH) analysis for 10 commonly used ESCC cell lines. Recurrent chromosomal gains were frequently detected on 3q26-27, 5p15-14, 8p12, 8p22-24, 11q13, 13q21-31, 18p11 and 20q11-13, with frequent losses also found on 8p23-22, 11q22, 14q32 and 18q11-23. Gain of 11q13.3-13.4 was the most frequent alteration in ESCC. Within this region, CCND1 oncogene was identified with high level of amplification and overexpression in ESCC, while FGF19 and SHANK2 was also remarkably over-expressed. Moreover, a high concordance (91.5%) of gene amplification and protein overexpression of CCND1 was observed in primary ESCC tumors. CCND1 amplification/overexpression was also significantly correlated with the lymph node metastasis of ESCC.

Conclusion

These findings suggest that genomic gain of 11q13 is the major mechanism contributing to the amplification. Novel oncogenes identified within the 11q13 amplicon including FGF19 and SHANK2 may play important roles in ESCC tumorigenesis.

Trichoplein and Aurora A block aberrant primary cilia assembly in proliferating cells

The trichoplein–AurA pathway must suppress primary cilia assembly in order for cells to exit G1.

The primary cilium is an antenna-like organelle that modulates differentiation, sensory functions, and signal transduction. After cilia are disassembled at the G0/G1 transition, formation of cilia is strictly inhibited in proliferating cells. However, the mechanisms of this inhibition are unknown. In this paper, we show that trichoplein disappeared from the basal body in quiescent cells, whereas it localized to mother and daughter centrioles in proliferating cells. Exogenous expression of trichoplein inhibited primary cilia assembly in serum-starved cells, whereas ribonucleic acid interference–mediated depletion induced primary cilia assembly upon cultivation with serum. Trichoplein controlled Aurora A (AurA) activation at the centrioles predominantly in G1 phase. In vitro analyses confirmed that trichoplein bound and activated AurA directly. Using trichoplein mutants, we demonstrate that the suppression of primary cilia assembly by trichoplein required its ability not only to localize to centrioles but also to bind and activate AurA. Trichoplein or AurA knockdown also induced G0/G1 arrest, but this phenotype was reversed when cilia formation was prevented by simultaneous knockdown of IFT-20. These data suggest that the trichoplein–AurA pathway is required for G1 progression through a key role in the continuous suppression of primary cilia assembly.

IQGAP1 interacts with Aurora-A and enhances its stability and its role in cancer

IQGAP1, a ubiquitously expressed scaffold protein, has been identified in a wide range of organisms. It participates in multiple aspects of cellular events by binding to and regulating numerous interacting proteins. In our present study, we identified a new IQGAP1 binding protein named Aurora-A which is an oncogenic protein and overexpressed in various types of human tumors. In vitro analysis with GST-Aurora-A fusion proteins showed a physical interaction between Aurora-A and IQGAP1. Moreover, the binding also occurred in HeLa cells as endogenous Aurora-A co-immunoprecipitated with IQGAP1 from the cell lysates. Overexpression of IQGAP1 resulted in an elevation of both expression and activity of Aurora-A kinase. Endogenous IQGAP1 knockdown by siRNA promoted Aurora-A degradation whereas IQGAP1 overexpression enhanced the stability of Aurora-A. Additionally, we documented that the IQGAP1-induced cell proliferation was suppressed by knocking down Aurora-A expression. Taken together, our results showed an unidentified relationship between Aurora-A and IQGAP1, and provided a new insight into the molecular mechanism by which IQGAP1 played a regulatory role in cancer.

Aurora A mediates cross-talk between N- and C-terminal post-translational modifications of p53

The serine/threonine protein kinase Aurora A is known to interact with and phosphorylate tumor suppressor p53 at Serine 215 (S215), inhibiting the transcriptional activity of p53. We show that Aurora A positively regulates human p53 protein levels and, using isogenic p53 wild-type and p53-null colorectal carcinoma cells, further show that p53 regulates human Aurora A protein expression. S215 is located in the DNA-binding core of p53 and at the center of the cryptic epitope for PAb240 antibody, which is used to detect mutant and denatured p53. Following denaturing SDS PAGE, the PAb240 epitope was detectable by immunoblotting in only two out of eight cell lines. The efficacy of novel p53-targeted anticancer therapies may be influenced by the conformational state of p53, therefore, the initial determination of p53 status may be relevant. We found no correlation between phosphorylation of p53 at S215 and PAb240 antibody recognition. However, phosphorylation at S37 was positively associated with PAb240 reactivity. More importantly, we provide the first evidence of Aurora A-mediated cross-talk between N- and C-terminal p53 post-translational modifications. As p53 and Aurora A are targets for anticancer therapy the impact of their reciprocal relationship and Aurora A-induced post-translational modification of p53 should be considered.

Prognostic significance of Aurora-A expression in human bladder cancer

Aurora-A is an oncogenic serine/threonine kinase, which plays important roles in tumorigenesis, development and chemoresistance of human cancers. The aim of the study was to detect the expression of Aurora-A gene in bladder cancer tissues and analyze its association with prognosis of bladder cancer patients. RT-PCR was performed to detect the expression of Aurora-A mRNA in 20 cases of bladder cancer and corresponding non-tumor tissue samples. Immunohistochemistry was performed to detect the localization of Aurora-A protein in 96 cases of bladder cancer tissue samples. Associations between Aurora-A protein expression and clinico-pathological factors or survival of bladder cancer patients were statistically analyzed. It was found that the expression levels of Aurora-A mRNA in bladder cancer tissues (1.08±0.24) were significantly higher than those in corresponding non-tumor tissues (0.22±0.07; P<0.01). Moreover, immunohistochemical staining results showed the localization of Aurora-A protein to be mainly located in the cytoplasm of bladder cancer cells. High levels of Aurora-A protein expression were correlated with pathological stage (P=0.007), lymph node metastasis (P=0.014) and venous invasion (P=0.008), but not with other factors including age, gender, tumor grade and recurrence of superficial cancer. Patients with high expression levels of Aurora-A protein showed lower disease-free and overall survival rates than those with low expression levels (P=0.0072 and 0.0009, respectively). Univariate and multivariate analysis of prognostic factors in bladder cancer patients indicated that Aurora-A expression was an independent unfavorable prognostic factor (hazard ratio: 0.673; 95% confidence interval: 0.388-0.912; P<0.001). Our study suggests that overexpression of Aurora-A gene may play an important role in the progression of bladder cancer and that Aurora-A expression is an independent factor for predicting the prognosis of bladder cancer in patients.