Overexpression Of TPX2 Research Articles

The clinical significance and prognostic value of Xenopus kinesin-like protein 2 expressions in human tumors: A systematic review and meta-analysis.

Targeting protein for Xenopus kinesin-like protein 2 (TPX2) is a microtubule-associated protein that plays a pivotal part in the formation of spindles. There is accumulating evidence that the expression of TPX2 is upregulated in many kinds of human cancers and that this protein is involved in the occurrence and progression of tumors. The purpose of this meta-analysis was to investigate the relationship between the overexpression of TPX2 and poor prognosis in cancer patients. A total of 18 eligible studies encompassing 3115 patients were included by searching relevant databases. Hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were pooled under random-/fixed-effect models. After calculation, the results showed that patients with increased TPX2 expression had a significantly shorter overall survival (HR = 2.21; 95% CI: 1.70-2.86), and disease-free survival (HR = 2.10; 95% CI: 1.67-2.64). In addition, it was found that increased TPX2 expression was significantly associated with TNM stage (OR = 2.17; 95% CI:1.42-3.32), lymph node metastasis (OR = 2.98; 95% CI: 2.28-3.89), distant metastasis (OR = 2.25; 95% CI:1.03-4.92), and vascular invasion (OR = 2.22; 95% CI:1.26-3.91). Nevertheless, there was no significant correlation between increased expression of TPX2 and either gender, tumor differentiation, or tumor size. Thus, we can come to the conclusion that the overexpression of TPX2 is related to poor clinical outcomes and can be used as a biomarker for the prognosis of patients with cancer.

Multi-Omics of Aurora Inhibition Induced Polyploidy Reveals Mechanisms of Disease Relapse in MYC/BCL2-Addicted High Grade B-Cell Lymphoma

Key Points•MYC mediated upregulation of TPX2, KPNA2 and RanGAP1 dysregulate the spindle assembly checkpoint in drug-induced polyploid cells.•Drug-induced polyploid cells re-enter cell cycle via multipolar mitosis, fission or budding, a mechanism of disease relapse.AbstractDouble-hit (DH) or double-expresser (DE) diffuse large B-cell lymphomas (DLBCL) are high-grade B-cell lymphomas that are mostly incurable with standard chemo-immunotherapy due to treatment resistance. The generation of drug-induced aneuploid/polyploid (DIAP) cells is a common effect of anti-DLBCL therapies (e.g. vincristine, doxorubicin). DIAP cells are thought to be responsible for treatment resistance, as they are capable of re-entering the cell cycle during off-therapy periods. Previously (DOI: 10.1158/1535-7163.MCT-17-0089) we demonstrated that combination of alisertib plus ibrutinib plus rituximab can partially abrogate DIAP cells and induce cell death. Here, we provide evidence that DIAP cells can re-enter the cell cycle and escape apoptosis during anti-DLBCL treatment. We also discuss MYC/BCL2 mediated molecular mechanisms that underlie treatment resistance. We isolated aneuploid/polyploid populations (2n-similar, 4n and 8n) of DH/DE-DLBCL cells after treatment with the aurora kinase (AK) inhibitor alisertib. Time-lapse microscopy of single polyploid cells (8n) revealed that following drug removal, these cells divide and proliferate by reductive cell divisions, including multipolar mitosis, meiosis-like nuclear fission and budding. Genomic, proteomic, and kinomic profiling of DIAP cells demonstrated up-regulation DNA damage, DNA replication and immune evasion pathways. In addition, the immune-kinome, AKT/MTorc1/2, and ERK/MAPK pathway are over-represented in 8n cells. Further, MYC-mediates dysregulation of the spindle assembly checkpoints by over-expression of RanGAP1, TPX2 and KPNA2. Multiple mechanisms contribute to DIAP which are amenable to novel therapeutic intervention(s) in MYC/BCL2-addicted high-grade B-cell lymphomas. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

TPX2 level correlates with cholangiocarcinoma cell proliferation, apoptosis, and EMT

PurposeThe molecular signatures of cholangiocarcinoma are not well characterized. Targeting protein for Xenopus kinesin-like protein 2 (TPX2) has been shown to promote oncogenesis in the context of several cancers; however, its’ role in cholangiocarcinoma has not been studied. We evaluated the role of TPX2 in cholangiocarcinoma. MethodsExpression levels of TPX2 in cholangiocarcinoma were assessed by immunohistochemistry. Potential correlations were assessed by Chi-squared test. Impact of TPX2 expression on cell proliferation, cell cycle, apoptosis, cell invasion and migration was investigated by CCK-8, flow cytometric analysis, and transwell assay, respectively. The expressions of cell-cycle, cell-apoptosis and EMT related target proteins were detected by immunoblotting. ResultsTPX2 expression in cholangiocarcinoma tissues was significantly higher than that paracancerous tissue (44.3% vs. 5.7%; P<0.01). Overexpression of TPX2 showed a positive correlation with TNM stage, lymph node metastasis, and prognosis of patients. Knockdown of TPX2 expression induced G2-M arrest, apoptosis and inhibited invasion and migration of cholangiocarcinoma cells. Treatment of cholangiocarcinoma cells with TPX2 siRNA resulted in upregulation of cyclin A1, cyclin B1, p53, Bax, and E-cadherin; while downregulation of cyclin D1, CDK2, Bcl-2, N-cadherin, β-cadherin MMP-2, MMP-9, Slug, and Twist1. ConclusionsCollectively, these results indicate that TPX2 may serve as a potential biomarker of prognostic relevance and a potential therapeutic target for cholangiocarcinoma.

Overexpression of TPX2 is associated with progression and prognosis of prostate cancer.

Targeting protein for Xenopus kinesin-like protein 2 (TPX2) activates Aurora kinase A during mitosis and targets its activity to the mitotic spindle, serving an important role in mitosis. It has been associated with different types of cancer and is considered to promote tumor growth. The aim of the present study was to explore the role of TPX2 in diagnosing prostate cancer (PCa). It was identified that TPX2 expression in PCa tissues was increased compared with benign prostate tissues. Microarray analysis demonstrated that TPX2 was positively associated with the Gleason score, tumor-node-metastasis (TNM) stage, clinicopathological stage, metastasis, overall survival and biochemical relapse-free survival. In vitro studies revealed that the high expression of TPX2 in PCa cells improved proliferative, invasive and migratory abilities, and repressed apoptosis of the PCa cells, without affecting tolerance to docetaxel. The results suggested that TPX2 serves as a tumorigenesis-promoting gene in PCa, and a potential therapeutic target for patients with PCa.

TPX2-p53-GLIPR1 regulatory circuitry in cell proliferation, invasion, and tumor growth of bladder cancer.

The targeting protein for Xenopus kinesin-like protein 2 (TPX2) is associated with the metastasis and prognosis of bladder cancer. p53 is closely related to the progression of bladder cancer. Human glioma pathogenesis-related protein 1 (GLIPR1) is a p53 target gene with antitumor activity. This study aims to explore the interplay between TPX2, p53, and GLIPR1 and its correlation with cell proliferation, invasion, and tumor growth in bladder cancer. Here, Western blot and qRT-PCR analysis revealed that TPX2 at both mRNA and protein levels was up-regulated in bladder carcinoma tissues compared to their paired adjacent normal tissues. Additionally, tissues expressing high TPX2 level exhibited high p53 level and low GLIPR1 level. The expressions of TPX2 and p53 in non-muscle-invasive bladder cancer cells (KK47 and RT4) were lower than those in muscle-invasive bladder cancer cells (T24, 5637, and UM-UC-3), while GLIPR1 showed the converse expression pattern. Further investigation revealed that TPX2 activated the synthesis of p53; and GLIPR1 is up-regulated by wild-type (wt)-p53 but not affected by mutated p53; Additionally, GLIPR1 inhibited TPX2. These data suggested a TPX2-p53-GLIPR1 regulatory circuitry. Meanwhile, TPX2 overexpression promoted while overexpression of GLIPR1 or p53 inhibited bladder cancer growth. Interestingly, in T24 cells with mutated p53, p53 silence suppressed bladder cancer growth. This study identified a novel TPX2-p53-GLIPR1 regulatory circuitry which modulated cell proliferation, migration, invasion, and tumorigenicity of bladder cancer. Our findings provide new insight into underlying mechanisms of tumorigenesis and novel therapeutic options in bladder cancer.

Targeting protein for Xenopus kinesin-like protein 2 knockdown enhances radiation sensitivity of human lung squamous carcinoma cell.

The targeting protein for Xenopus kinesin-like protein 2 (TPX2) has been demonstrated to be associated with the tumourigenesis of many cancers. In the present study, we investigated the role and preliminary mechanism of TPX2 in the resistance of lung squamous carcinoma to radiation therapy. The results showed that SK-MES-1R and NCI-H226R cells were more resistant to X-ray irradiation than the parental cells (SK-MES-1 and NCI-H226). Moreover, TPX2 was upregulated in the radioresistant cells compared with the parental cells. TPX2 knockdown significantly decreased TPX2 expression in SK-MES-1 cells, while TPX2 overexpression increased TPX2 expression in NCI-H226 cells compared with the corresponding control cells. TPX2 knockdown enhanced the radiosensitivity of SK-MES-1 and promoted cell apoptosis following exposure to irradiation, whereas TPX2 overexpression decreased the radiosensitivity of NCI-H226 and inhibited cell apoptosis. In in vivo studies, the combination of TPX2 knockdown and irradiation significantly inhibited tumour growth, decreased tumour weight, downregulated TPX2 expression in tumour tissue and induced cell apoptosis in nude mice, while TPX2 overexpression exerted an opposite effect. Our results indicated that TPX2 was correlated with cell radioresistance and it might be served as a therapeutic target to enhance cell radiosensitivity in the radiation therapy of lung squamous carcinoma.

WDR62 overexpression is associated with a poor prognosis in patients with lung adenocarcinoma.

Human WDR62, which is localized in the cytoplasm including the centrosome, is known to be responsible for primary microcephaly; however, the role of WDR62 abnormality in cancers remains largely unknown. In this study, we aimed to reveal the pathological role of WDR62 abnormality in lung adenocarcinoma (LAC). We first examined the WDR62 mRNA expression level of LAC (n = 64) using a QRT-PCR analysis and found that WDR62 mRNA transcripts were significantly overexpressed in LAC (P = 0.0432, Wilcoxon matched pairs test). An immunohistochemical analysis for LAC (n = 237) showed that WDR62 proteins were also significantly overexpressed in LAC (P < 0.0001, Mann-Whitney U test). A Kaplan-Meier analysis demonstrated that patients with LAC who exhibit WDR62 overexpression have a short overall survival (P = 0.0378, log-rank test), and a multivariate analysis revealed that WDR62 overexpression was an independent predictor of a poor survival outcome among LAC patients (hazard ratio, 2.032; 95% confidence interval, 1.071-3.777; P = 0.0305). Next, we examined the functional effect of WDR62 overexpression on the lung cancer cell line H1299. WDR62-overexpressing lung cancer cells exhibited an increase in cell growth. Moreover, the concurrent overexpression of WDR62 and TPX2, a WDR62-interacting protein that is also overexpressed in LAC, induced centrosome amplification in the lung cells. Finally, we disclosed that the concurrent overexpression of WDR62 and TPX2 is common in diverse human cancers, using data from the Cancer Genome Atlas. These results suggested that WDR62 overexpression is associated with a poor prognosis in patients with LAC and leads to an increase in the malignant potential of lung cells.

TPX2 expression is associated with poor survival in gastric cancer

BackgroundTargeting protein for Xenopus kinesin-like protein 2 (TPX2) is a microtubule-associated protein required for microtubule formation in human cells. Several studies have demonstrated that TPX2 is overexpressed in multiple tumor types and promotes tumor growth and metastasis. However, there have been few reports regarding its role in gastric cancer. In this study, we evaluated TPX2 expression and investigated its correlations with gastric cancer clinicopathological features and prognosis.MethodsTumor samples were obtained from 290 patients with gastric adenocarcinoma who had undergone gastrectomy. The expression of TPX2 protein was examined using immunohistochemical staining. TPX2 messenger RNA (mRNA) levels were evaluated using real-time quantitative reverse transcription PCR in 19 of the gastric cancer tumors and adjacent normal tissues.ResultsThe mRNA levels of TPX2 were significantly higher in gastric cancer tissues than in matched adjacent normal tissues (p = 0.004). In the immunohistochemical analysis, TPX2 overexpression was found in 123 (42.4%) of 290 patients. High TPX2 expression was positively associated with age, type of histology, depth of tumor, lymph node metastasis, stage, and remote metastasis or recurrence. High TPX2 expression was significantly associated with poorer disease-specific survival (p = 0.004) and relapse-free interval (p = 0.013).ConclusionsOur results indicated that high TPX2 expression was associated with tumor progression and poor survival in gastric cancer.

TPX2 promotes glioma cell proliferation and invasion via activation of the AKT signaling pathway.

Glioblastoma multiforme (GBM) is the most common and most malignant type of primary adult brain cancer. The most common phenotype associated with GBM is cellular invasion; however, the molecular mechanisms governing this process are poorly understood. Targeting protein for Xenopus kinesin-like protein 2 (TPX2) is a nuclear protein with roles in cellular proliferation and mitotic spindle assembly. TPX2 is overexpressed in various malignancies, including human malignant astrocytoma. Despite this finding, the exact role of TPX2 in human glioma is not well defined. The present study reports the elevated expression of TPX2 in a number of glioma cell lines. TPX2 overexpression promoted cellular proliferation, decreased the percentage of cells in G0/G1 phase, and increased invasion of both U251 and U87 cells. Overexpression of TPX2 also significantly enhanced the phosphorylation of AKT, decreased the expression of p21, and increased the expression of cyclin D1 and matrix metallopeptidase (MMP)-9. In both U251 and U87 cells, knockdown of TPX2 resulted in phenotypes that are in direct contrast to those observed following TPX2 overexpression. Specifically, TPX2 knockdown inhibited cell proliferation, increased the percentage of cells in G0/G1 phase, inhibited invasion, decreased AKT phosphorylation, decreased the expression of MMP-9 and cyclin D1, and increased p21 expression. The AKT inhibitor IV in large part phenocopied the effect of TPX2 knockdown. The present data suggest that TPX2 promotes glioma cell proliferation and invasion via AKT signaling.

Expression of microtubule-associated protein TPX2 in human gastric carcinoma and its prognostic significance.

BackgroundThe molecular mechanisms underlying the development and progression of gastric carcinoma remain poorly understood. The main objective of this study was to investigate the expression level of targeting protein for Xenopus kinesin-like protein 2 (TPX2) and its clinical significance in human gastric carcinoma.MethodsReal-time quantitative polymerase chain reaction (RT-PCR) and western blotting were used to determine the mRNA and protein levels of TPX2 in 20 paired gastric carcinoma tissues and the adjacent normal tissues, and the expression of TPX2 protein in 106 specimens of a gastric carcinoma tissue microarray was determined by immunohistochemistry. The associations of TPX2 expression with the clinicopathological features were analyzed, and the prognosis of gastric carcinoma patients was evaluated.ResultsThe results showed that the expression of TPX2 mRNA was significantly higher in gastric carcinoma than in the adjacent normal tissues in 20 paired samples. Western blotting analysis revealed that TPX2 protein was differentially increased in 17 of 20 specimens from primary human gastric carcinoma tissues compared with those from adjacent non-tumor tissues. Immunohistochemical staining showed that TPX2 over-expression was significantly associated with advanced age (P = 0.001) and tumor T stage (P = 0.003). In addition, TPX2 was an independent prognostic factor for overall survival (OS) in the multivariate analysis [hazard ratio (HR) 0.001; 95 % confidence interval (CI) 2.626–7.198; P = 0.001].ConclusionsTPX2 is up-regulated in gastric carcinoma and is associated with old age and tumor T stage. TPX2 may serve as a good prognostic indicator in patients with gastric carcinoma.Electronic supplementary materialThe online version of this article (doi:10.1186/s12935-016-0357-7) contains supplementary material, which is available to authorized users.

Abstract 2822: TPX2 overexpression is essential for the survival of MYC-driven triple negative breast cancer

Abstract Triple-negative breast cancer (TNBC) presents the most challenging subtype with the poorest clinical outcome and no targeted therapy. Our lab previously showed that oncogenic MYC pathways are deregulated in human TNBC tumors and predict patients’ poor prognosis. However, clinical development of small molecule inhibitors for MYC has not been successful yet. We identified a synthetic-lethal interaction in which inhibition of cyclin-dependent kinase 1 (CDK1) resulted in the selective killing of MYC overexpressing cancer cells. CDK1 is a mitotic kinase that regulates a large number of substrates and its inhibition causes proliferation arrest in all cells, which may be associated with toxicity. We hypothesize that the MYC-CDK1 synthetic lethality can be attributed to the loss of function of only one or a handful of CDK1 substrates. To identify those substrates, we combined bioinformatics analysis of gene expression data from patient samples and cell based screening approaches. We identified TPX2 depletion to efficiently kill MYC overexpressing cells, while sparing normal cells. Using analog-sensitive CDK1 we confirmed that TPX2 is a direct substrate of CDK1. TPX2 is highly overexpressed in TNBC and predicts patients’ poor prognosis. Its loss of function efficiently kills TNBC cells in a MYC dependent manner. We hypothesize that TPX2 is a novel synthetic lethal interaction partner of MYC. Our studies will help elucidate the biology of MYC-driven cancer such as TNBC, which will eventually lead to the development of less toxic and more efficacious targeted therapies. Citation Format: Julia Rohrberg, Alexandra Corella, Sanjeev Balakrishnan, Andrei Goga. TPX2 overexpression is essential for the survival of MYC-driven triple negative breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2822.

Upregulation of TPX2 by STAT3: identification of a novel STAT3 binding site.

TPX2, a protein involved in mitosis, is considered a good marker for actively proliferating tissues, highly expressed in a number of cancer cells. We show the presence of high-affinity binding site for STAT3 in the 5′-flanking region of the Tpx2 gene, which is in vivo bound by activated STAT3. A specific STAT3 peptide inhibitor represses the expression of the Tpx2 gene and inhibits the binding of STAT3 to its consensus sequence in human cell lines where STAT3 is activated. These results indicate that activated STAT3 contributes to the over-expression of Tpx2 through the binding to an enhancer site.

TPX2 impacts acetylation of histone H4 at lysine 16: implications for DNA damage response.

During interphase, the spindle assembly factor TPX2 is compartmentalized in the nucleus where its roles remain largely uncharacterized. Recently, we found that TPX2 regulates the levels of serine 139-phosphoryated H2AX (γ-H2AX) at chromosomal breaks induced by ionizing radiation. Here, we report that TPX2 readily associates with the chromatin in the absence of ionizing radiation. Overexpression of TPX2 alters the DAPI staining pattern of interphase cells and depletion of TPX2 constitutively decreases the levels of histone H4 acetylated at lysine16 (H4K16ac) during G1-phase. Upon ionizing irradiation, this constitutive TPX2 depletion-dependent decrease in H4K16ac levels correlates with increased levels of γ-H2AX. The inversely correlated levels of H4K16ac and γ-H2AX can also be modified by altering the levels of SIRT1, herein identified as a novel protein complex partner of TPX2. Furthermore, we find that TPX2 depletion also interferes with formation of 53BP1 ionizing radiation-induced foci, known to depend on γ-H2AX and the acetylation status of H4K16. In brief, our study is the first indication of a constitutive control of TPX2 on H4K16ac levels, with potential implications for DNA damage response.

TPX2 as a novel prognostic biomarker for hepatocellular carcinoma.

Targeting protein for Xenopus kinesin-like protein 2 (TPX2) is a microtubule-associated protein that impacts spindle assembly in human cells. Several studies have shown that the overexpression of TPX2 is correlated with multiple tumor types. However, the role of TPX2 in hepatocellular carcinoma (HCC) remains undetermined. TPX2 expression was detected by quantitative reverse transcription polymerase chain reaction and immunoblotting in six cell lines and 130 pairs of HCC and adjacent non-cancerous liver tissues. Matrix metalloproteinase (MMP)2 and MMP9 expression was detected by immunohistochemistry to evaluate their correlations with TXP2. TPX2 siRNA was used to knock down TPX2 expression, and cell migration and invasion were determined. Moreover, clinical significance of TPX2 in HCC was analyzed. TPX2 expression was found to be obviously higher in HCC tissues than that in non-tumor tissues. Elevated TPX2 expression was observed in HCC cell lines as compared with that in a non-transformed hepatic cell line. Clinical analysis indicated that TPX2 expression in the HCC tissues was evidently correlated with the tumor-node-metastasis stage, tumor number and tumor differentiation. TPX2 is a novel prognostic marker for predicting 5-year overall survival and disease-free survival of HCC patients. TPX2 expression was positively correlated with MMP2 and MMP9. In vitro studies found that TPX2 knockdown prominently reduced cell invasion and migration and decreased phosphorylated AKT, MMP2 and MMP9 expression in MHCC-97H cells. Overexpression of TPX2 was associated with clinicopathological characteristics and poor patient outcomes. TPX2 may serve as a novel prognostic marker for HCC.

TPX2: of spindle assembly, DNA damage response, and cancer.

For more than 15 years, TPX2 has been studied as a factor critical for mitosis and spindle assembly. These functions of TPX2 are attributed to its Ran-regulated microtubule-associated protein properties and to its control of the Aurora A kinase. Overexpressed in cancers, TPX2 is being established as marker for the diagnosis and prognosis of malignancies. During interphase, TPX2 resides preferentially in the nucleus where its function had remained elusive until recently. The latest finding that TPX2 plays a role in amplification of the DNA damage response, combined with the characterization of TPX2 knockout mice, open new perspectives to understand the biology of this protein. This review provides an historic overview of the discovery of TPX2 and summarizes its cytoskeletal and signaling roles with relevance to cancer therapies. Finally, the review aims to reconcile discrepancies between the experimental and pathological effects of TPX2 overexpression and advances new roles for compartmentalized TPX2.

TPX2 is a novel prognostic marker for the growth and metastasis of colon cancer

BackgroundWe have previously demonstrated an aberrant overexpression of the microtubule-associated protein TPX2 in colon cancer using a genome-wide gene expression profiling analysis. Here, we aim to investigate its expression pattern, clinical significance, and biological function in colon cancer.MethodsTPX2 expression was analyzed in human colon cancer cell lines and tumor samples. The effect of TPX2 on cell proliferation, tumorigenesis, and metastasis was examined in vitro and in vivo.ResultsTPX2 was overexpressed in 129 of the 203 (60.8%) colon cancer metastatic lesions, with the expression being significantly higher than that in primary cancerous tissue and normal colon mucosa. Overexpression of TPX2 was significantly associated with clinical staging, vessel invasion, and metastasis. In survival analyses, patients with TPX2 overexpression had worse overall survival and metastasis free survival, suggesting that deregulation of TPX2 may contribute to the metastasis of colon cancer. Consistent with this, suppression of TPX2 expression inhibited proliferation and tumorigenicity of colon cancer cells both in vitro and in vivo. Strikingly, we found that TPX2 knockdown significantly attenuated the migration and invasion ability of colon cancer cells, which was further shown to be mechanistically associated with AKT-mediated MMP2 activity.ConclusionsThese findings suggest that TPX2 plays an important role in promoting tumorigenesis and metastasis of human colon cancer, and may represent a novel prognostic biomarker and therapeutic target for the disease.

Validation of TPX2 as a novel prognostic marker for malignant progression and metastasis of colon cancer.

442 Background: We previously identified aberrant overexpression of TPX2 in colon cancer by using a genome-wide gene expression profiling analysis. Here, we aimed to investigate its expression pattern, clinical significance, and biological function in colon cancer. Methods: The expression of TPX2 was analyzed in human colon cancer cell lines and tumor samples. The effect of TPX2 on cell proliferation, tumorigenesis and metastasis was examined in vitro and in vivo. Results: Overexpression of TPX2 was found in metastatic lesion of colon cancer, significantly higher than primary cancererous tissue and normal colon mucosa. Overexpression of TPX2 was significantly associated with the clinical staging, vessel invasion and metastasis. In survival analyses, patients with TPX2 expression had worse overall survival and metastasis free survival, suggesting that deregulation of TPX2 may contribute to the metastasis of colon cancer. Consistently, Silencing TPX2 inhibited proliferation and tumorigenicity of colon cancer cells both in vitro and in vivo. Strikingly, we found that TPX2 knockdown significantly attenuated the migration and invasion ability of colon cancer cells, which was further shown to be mechanistically associated with AKT mediated MMP9 activity. Conclusions: These findings suggest that TPX2 plays an important role in promoting tumorigenesis and metastasis of human colon cancer and may represent a novel prognostic biomarker and therapeutic target for the disease.

Abstract P2-04-05: Prolonged targeted overexpression of Aurora-A in mammary epithelium promotes mammary adenocarcinoma with genomic instability

Abstract Aurora kinase-A (referred to as Aurora-A) identified as a sereine/threonine kinase induces mitotic progression process including centrosome amplification, bipolar spindle formation and chromosome segregation through modulation of activity and localization of its interacting proteins during cell division. Beside its essential roles in mitosis, cancer profiling studies have revealed that Aurora-A function is implicated in tumor relevant signaling pathways and overexpressed in many human tumors. The findings showed highly frequent overexpression of Aurora-A in human breast ductal carcinoma in situ and primary invasive ductal breast carcinoma. Moreover, the Aurora-A overexpression correlates with poor prognosis in breast carcinoma, deregulated overexpression of Aurora-A associates with centrosome anomalies and chromosome instability in rodent models of mammary caricinogenesis. However, published studies in several transgenic mouse models attempting to address the role of Aurora-A in tumorigenesis and genomic instability have raised conflicting results. In this report we targeted expression of Aurora-A transgene in an inducible mouse model in which expression of Aurora-A was restricted to mammary epithelium during multiple pregnancy and lactation cycles under the activity of β-lactoglobulin promotor. The results demonstrate that overexpression of Aurora-A could induce tumorigenesis in mouse mammary epithelium. The tumor incidence was 70% of Aurora-A transgenic mice at 16 months of age. Of note, overexpression of Aurora-A led to genomic instability. Comparative genomic hybridization (CGH) array analyses revealed loss of Trim12a, Trim12c, Trim30b, Trim30d, Trim30e, Cdkn2d, Pten, Cep55 and gain of Adam6. Notably, Aurora-A overexpression caused nuclear accumulation of cyclin D1, activation of AKT, overexpression of TPX2 and PLK1and loss of ERα expression in tumors. Our findings indicated that prolonged Aurora-A expression in mammary epithelium leads to mammary adenocarcinomas with genomic instability. Aurora-A driven adenocarcinoma reveals deregulation of critical tumor relevant genetic pathways involving both oncogenes and tumor suppressor genes. These transgenic mouse model findings indicate that Aurora-A may be an important therapeutic target for mammary cancer. Keywords: Aurora-A, carcinogenesis. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-04-05.

A novel role for TPX2 as a scaffold and co-activator protein of the Chromosomal Passenger Complex

Aurora B kinase forms the enzymatic core of the Chromosomal Passenger Complex (CPC) and is a master regulator of mitosis. Understanding the regulation of Aurora B is critical to illuminate its role in mitosis. INCENP, Survivin and Borealin have all been known to promote Aurora B activation. In this study, we have identified the Aurora A activator protein TPX2 as a novel scaffold and co-activator protein of the CPC. Studies utilizing M-phase Xenopus egg extracts (XEE) revealed that the immunodepletion of endogenous TPX2 from XEE decreases Aurora B–Survivin and Aurora B–INCENP interactions, leading to a consequent reduction in Aurora B activity. Further, residues 138 to 328 of Xenopus TPX2 (TPX2 B) are sufficient to enhance Aurora B–Survivin association and Aurora B kinase activity in vitro. Importantly, experiments with pancreatic cancer cell lines suggest that this mechanism of Aurora B activation by TPX2 is likely to be conserved in human cells. Strikingly, the overexpression of human TPX2 B in HeLa cells causes defects in metaphase chromosome alignment and INCENP localization. Thus, in addition to its already established role as an Aurora A activator, our data support the role of TPX2 as a novel co-activator of Aurora kinase B.

Abstract 731: TPX2 overexpression is associated with tumorigenesis and patient outcome of esophageal squamous cell carcinoma

Abstract Background Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy with dismal prognosis. By microarray data analysis, we aim to identify molecular changes involved in ESCC tumorigenesis and investigate their clinical relevance. Methods Five microarray datasets were obtained from GEO database. Differentially expressed genes (DEGs) were identified using t-test with permutation. Pathway analysis was performed with LS/KS permutation statistics and Efron-Tibshirani's gene set analysis. As for the validation, we studied: (i) mRNA expression of tumor (T) and matched normal (N) tissues in 16 ESCC cases from Taipei and Taichung Veterans General Hospital by the Affymetrix HG U133A array, (ii) protein expression of target genes in 97 ESCC specimens by immunohistochemical stains (IHC), and (iii) impact of TPX2 expression on tumor cell proliferation in ESCC cell line (CE81T). Results A set of 69 DEGs (46 up and 23 down-regulated in T) was found to be overlapped among five datasets. Pathway analysis revealed eight out of 306 gene sets to have altered expression between T and N esophageal epithelium in at least three datasets. The “Role of Ran in mitotic spindle regulation” pathway, which includes AURKA and TPX2 as key regulators, was selected for further investigation. Verification by microarray analysis of 16 ESCC patients identified 12 out of 306 gene sets to have altered expression between T and N specimens. In accordance with previous results, the “Role of Ran in mitotic spindle regulation” pathway remains a significant overexpressed gene set. Both AURKA and TPX2 showed overexpression in tumor tissues (AURKA, T/N ratio = 3.13, p = 2e-07; TPX2, T/N ratio = 3.22, p = 3e-07). IHC verification showed positive AURKA and TPX2 expression in 88.4% and 90.6% of ESCC specimens, respectively. Although the expression of AURKA and TPX2 did not correlate with any clinicopathological factor, univariate survival analysis indicated high TPX2 expression as a significant prognostic factor for overall (OS) and disease-free survival (DFS) (p = 0.036 for OS and 0.038 for DFS). There was also a non-significant trend toward worse outcome in patients with high AURKA expression. In multivariate analysis, high TPX2 expression remained an independent prognostic factor (HR = 2.255, p = 0.005). To further investigate the effect of TPX2 expression, we performed MTT assay to determine cell growth of CE81T cell line after manipulating TPX2 expression level. Growth curves demonstrated that growths of vector-based TPX2 shRNA-mediated knockdown clones were inhibited compared with that of the parental and vector control groups (p &amp;lt; 0.05 on day 4 and 5). Conclusions Using bioinformatics resources, which were validated by microarray analysis/IHC in our clinical cohorts, and manipulation of TPX2 expression in CE81T cell line, we demonstrated that TPX2 overexpression is associated with tumorigenesis and patient outcome of ESCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 731. doi:1538-7445.AM2012-731