N-Myc Induces an EZH2-Mediated Transcriptional Program Driving Neuroendocrine Prostate Cancer

The transition from castration-resistant prostate adenocarcinoma (CRPC) to neuroendocrine prostate cancer (NEPC) has emerged as an important mechanism of treatment resistance. NEPC is associated with overexpression and gene amplification of MYCN (encoding N-Myc). N-Myc is an established oncogene in several rare pediatric tumors, but its role in prostate cancer progression is not well established. Integrating a genetically engineered mouse model and human prostate cancer transcriptome data, we show that N-Myc overexpression leads to the development of poorly differentiated, invasive prostate cancer that is molecularly similar to human NEPC. This includes an abrogation of androgen receptor signaling and induction of Polycomb Repressive Complex 2 signaling. Altogether, our data establishes N-Myc as an oncogenic driver of NEPC.

Aurora kinase A promotes inflammation and tumorigenesis in mice and human gastric neoplasia

BACKGROUND & AIMS

Chronic inflammation contributes to the pathogenesis of gastric tumorigenesis. The aurora kinase A (AURKA) gene is frequently amplified and overexpressed in gastrointestinal cancers. We investigated the roles of AURKA in inflammation and gastric tumorigenesis.

METHODS

We used quantitative real-time reverse transcription polymerase chain reaction, immunofluorescence, immunohistochemistry, luciferase reporter, immunoblot, co-immunoprecipitation, and in vitro kinase assays to analyze AGS and MKN28 gastric cancer cells. We also analyzed Tff1(-/-) mice, growth of tumor xenografts, and human tissues.

RESULTS

We correlated increased expression of AURKA with increased levels of tumor necrosis factor-α and inflammation in the gastric mucosa of Tff1(-/-) mice (r = 0.62; P = .0001). MLN8237, an investigational small-molecule selective inhibitor of AURKA, reduced nuclear staining of nuclear factor-κB (NF-κB) p65 in human gastric cancer samples and mouse epithelial cells, suppressed NF-κB reporter activity, and reduced expression of NF-κB target genes that regulate inflammation and cell survival. Inhibition of AURKA also reduced growth of xenograft tumors from human gastric cancer cells in mice and reversed the development of gastric tumors in Tff1(-/-) mice. AURKA was found to regulate NF-κB activity by binding directly and phosphorylating IκBα in cells. Premalignant and malignant lesions from the gastric mucosa of patients had increased levels of AURKA protein and nuclear NF-κB, compared with healthy gastric tissue.

CONCLUSIONS

In analyses of gastric cancer cell lines, human tissue samples, and mouse models, we found AURKA to be up-regulated during chronic inflammation to promote activation of NF-κB and tumorigenesis. AURKA inhibitors might be developed as therapeutic agents for gastric cancer.

Alisertib is active as single agent in recurrent atypical teratoid rhabdoid tumors in 4 children

BACKGROUND

Aurora Kinase A (AURKA) encodes a protein that regulates the formation and stability of the mitotic spindle and is highly active in atypical teratoid rhabdoid tumors (ATRT) through loss of the INI1 tumor suppressor gene. Alisertib (MLN8237) inhibits AURKA in vitro and in vivo. Given the strong preclinical data supporting the use of alisertib for ATRT patients, we sought and obtained permission to use alisertib in single patient treatment plans for 4 recurrent pediatric ATRT patients.

METHODS

Patients with recurrent or progressive ATRT received alisertib 80 mg/m(2) by mouth once daily for 7 days of a 21-day treatment cycle. Disease evaluation (MRI of brain and spine and lumbar puncture) was done after 2 cycles of alisertib and every 2-3 cycles thereafter for as long as the patients remained free from tumor progression.

RESULTS

Four patients with median age of 2.5 years (range, 1.39-4.87 y) at diagnosis received alisertib 80 mg/m(2) by mouth once daily for 7 days of a 21-day treatment cycle, and all 4 patients had disease stabilization and/or regression after 3 cycles of alisertib therapy. Two patients continued to have stable disease regression for 1 and 2 years, respectively, on therapy.

CONCLUSIONS

Single-agent alisertib produced marked and durable regression in disease burden, as detected by brain and spine MRI and by evaluation of spinal fluid cytology. Alisertib has moderate but manageable toxicities, and its chronic administration appears feasible in this pediatric population. These novel data support the incorporation of alisertib in future therapeutic trials for children with ATRT.

Aurora kinase A stabilizes FOXM1 to enhance paclitaxel resistance in triple-negative breast cancer

Triple-negative breast cancer (TNBC) has a relatively poor outcome. Acquired chemoresistance is a major clinical challenge for TNBC patients. Previously, we reported that kinase-dead Aurora kinase A (Aurora-A) could effectively transactivate the FOXM1 promoter. Here, we demonstrate an additional pathway through which Aurora-A stabilizes FOXM1 by attenuating its ubiquitin in TNBC. Specifically, Aurora-A stabilizes FOXM1 in late M phase and early G1 phase of the cell cycle, which promotes proliferation of TNBC cells. Knock-down of Aurora-A significantly suppresses cell proliferation in TNBC cell lines and can be rescued by FOXM1 overexpression. We observe that paclitaxel-resistant TNBC cells exhibit high expression of Aurora-A and FOXM1. Overexpression of Aurora-A offers TNBC cells an additional growth advantage and protection against paclitaxel. Moreover, Aurora-A and FOXM1 could be simultaneously targeted by thiostrepton. Combination of thiostrepton and paclitaxel treatment reverses paclitaxel resistance and significantly inhibits cell proliferation. In conclusion, our study reveals additional mechanism through which Aurora-A regulates FOXM1 and provides a new therapeutic strategy to treat paclitaxel-resistant triple-negative breast cancer.

Alisertib, an Aurora kinase A inhibitor, induces apoptosis and autophagy but inhibits epithelial to mesenchymal transition in human epithelial ovarian cancer cells

Ovarian cancer is a leading killer of women, and no cure for advanced ovarian cancer is available. Alisertib (ALS), a selective Aurora kinase A (AURKA) inhibitor, has shown potent anticancer effects, and is under clinical investigation for the treatment of advanced solid tumor and hematologic malignancies. However, the role of ALS in the treatment of ovarian cancer remains unclear. This study investigated the effects of ALS on cell growth, apoptosis, autophagy, and epithelial to mesenchymal transition (EMT), and the underlying mechanisms in human epithelial ovarian cancer SKOV3 and OVCAR4 cells. Our docking study showed that ALS, MLN8054, and VX-680 preferentially bound to AURKA over AURKB via hydrogen bond formation, charge interaction, and π-π stacking. ALS had potent growth-inhibitory, proapoptotic, proautophagic, and EMT-inhibitory effects on SKOV3 and OVCAR4 cells. ALS arrested SKOV3 and OVCAR4 cells in G₂/M phase and induced mitochondria-mediated apoptosis and autophagy in both SKOV3 and OVCAR4 cell lines in a concentration-dependent manner. ALS suppressed phosphatidylinositol 3-kinase/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and p38 mitogen-activated protein kinase pathways but activated 5′-AMP-dependent kinase, as indicated by their altered phosphorylation, contributing to the proautophagic activity of ALS. Modulation of autophagy altered basal and ALS-induced apoptosis in SKOV3 and OVCAR4 cells. Further, ALS suppressed the EMT-like phenotype in both cell lines by restoring the balance between E-cadherin and N-cadherin. ALS downregulated sirtuin 1 and pre-B cell colony enhancing factor (PBEF/visfatin) expression levels and inhibited phosphorylation of AURKA in both cell lines. These findings indicate that ALS blocks the cell cycle by G₂/M phase arrest and promotes cellular apoptosis and autophagy, but inhibits EMT via phosphatidylinositol 3-kinase/Akt/mTOR-mediated and sirtuin 1-mediated pathways in human epithelial ovarian cancer cells. Further studies are warranted to validate the efficacy and safety of ALS in the treatment of ovarian cancer.

Phosphorylation-dependent regulation of ALDH1A1 by Aurora kinase A: insights on their synergistic relationship in pancreatic cancer

Background

Epithelial-to-mesenchymal transition (EMT) and cancer stem cell (CSC) formation are key underlying causes that promote extensive metastasis, drug resistance, and tumor recurrence in highly lethal pancreatic cancer. The mechanisms leading to EMT and CSC phenotypes are not fully understood, which has hindered the development of effective targeted therapies capable of improving treatment outcomes in patients with pancreatic cancer.

Results

We show a central role of Aurora kinase A (AURKA) in promoting EMT and CSC phenotypes via ALDH1A1, which was discovered as its direct substrate using an innovative chemical genetic screen. AURKA phosphorylates ALDH1A1 at three critical residues which exert a multifaceted regulation over its level, enzymatic activity, and quaternary structure. While all three phosphorylation sites contribute to its increased stability, T267 phosphorylation primarily regulates ALDH1A1 activity. AURKA-mediated phosphorylation rapidly dissociates tetrameric ALDH1A1 into a highly active monomeric species. ALDH1A1 also reciprocates and prevents AURKA degradation, thereby triggering a positive feedback activation loop which drives highly aggressive phenotypes in cancer. Phospho-resistant ALDH1A1 fully reverses EMT and CSC phenotypes, thus serving as dominant negative, which underscores the clinical significance of the AURKA-ALDH1A1 signaling axis in pancreatic cancer.

Conclusions

While increased levels and activity of ALDH1A1 are hallmarks of CSCs, the underlying molecular mechanism remains unclear. We show the first phosphorylation-dependent regulation of ALDH1A1, which increases its levels and activity via AURKA. Recent global phospho-proteomic screens have revealed increased phosphorylation of ALDH1A1 at the T267 site in human cancers and healthy liver tissues where ALDH1A1 is highly expressed and active, indicating that this regulation is likely crucial both in normal and diseased states. This is also the first study to demonstrate oligomer-dependent activity of ALDH1A1, signifying that targeting its oligomerization state may be an effective therapeutic approach for counteracting its protective functions in cancer. Finally, while AURKA inhibition provides a potent tool to reduce ALDH1A1 levels and activity, the reciprocal loop between them ensures that their concurrent inhibition will be highly synergistic when inhibiting tumorigenesis, chemoresistance, and metastasis in highly aggressive pancreatic cancer and beyond.

Electronic supplementary material

The online version of this article (doi:10.1186/s12915-016-0335-5) contains supplementary material, which is available to authorized users.

Characterization of ovarian clear cell carcinoma using target drug-based molecular biomarkers: implications for personalized cancer therapy

BACKGROUND

It has long been appreciated that different subtypes (serous, clear cell, endometrioid and mucinous) of epithelial ovarian carcinoma (EOC) have distinct pathogenetic pathways. However, clinical management, especially chemotherapeutic regimens, for EOC patients is not subtype specific. Ovarian clear cell carcinoma (CCC) is a rare histological subtype of EOC, which exhibits high rates of recurrence and low chemosensitivity. We assessed potential therapeutic targets for ovarian CCC patients through analyzing the variation of drug-based molecular biomarkers expression between ovarian CCC and high-grade serous carcinoma (HGSC).

METHODS

Seven candidate drug-based molecular biomarkers, human epidermal growth factor receptor (EGFR), human epidermal growth factor receptor-2 (HER2), phosphatase and tensin homolog deleted on chromosome ten (PTEN), aurora kinase A (AURKA), breast cancer susceptibility gene 1 (BRCA1), breast cancer susceptibility gene 2 (BRCA2) and programmed death-ligand 1 (PD-L1) were measured in 96 ovarian CCC and 113 HGSC by immunohistochemistry in paraffin embedded tissues. The relationship between these biomarkers and clinicopathological factors were explored.

RESULTS

The expression level of four of the seven drug-based molecular biomarkers was markedly different between HGSC and CCC. High expression levels of HER2 and PD-L1 were more commonly observed in CCC patients (12.6% vs 2.7%, 21.1% vs 11.6%, P = 0.006, 0.064, respectively), while loss of BRCA1 and BRCA2 expression were more frequently occurred in HGSC patients (72.6% vs 54.3%, 89.4% vs 79.8%, P = 0.007, 0.054, respectively). Survival analysis showed that five of seven biomarkers had prognostic values but varied between subtypes. Furthermore, EGFR expressed frequently in CCC patients with endometriosis than in HGSC patients (44.4% vs 8.3%, P = 0.049). AURKA and PD-L1 correlated with the resistance to platinum-based chemotherapy in CCC patients (P = 0.043, 0.028, respectively) while no similar results were observed in HGSC patients.

CONCLUSION

Ovarian CCC showed a markedly different expression map of drug-based molecular biomarkers from HGSC, which suggested a new personalized target therapy in this rare subtype.

Spatial regulation of Aurora A activity during mitotic spindle assembly requires RHAMM to correctly localize TPX2

Construction of a mitotic spindle requires biochemical pathways to assemble spindle microtubules and structural proteins to organize these microtubules into a bipolar array. Through a complex with dynein, the receptor for hyaluronan-mediated motility (RHAMM) cross-links mitotic microtubules to provide structural support, maintain spindle integrity, and correctly orient the mitotic spindle. Here, we locate RHAMM to sites of microtubule assembly at centrosomes and non-centrosome sites near kinetochores and demonstrate that RHAMM is required for the activation of Aurora kinase A. Silencing of RHAMM delays the kinetics of spindle assembly, mislocalizes targeting protein for XKlp2 (TPX2), and attenuates the localized activation of Aurora kinase A with a consequent reduction in mitotic spindle length. The RHAMM-TPX2 complex requires a C-terminal basic leucine zipper in RHAMM and a domain that includes the nuclear localization signal in TPX2. Together, our findings identify RHAMM as a critical regulator for Aurora kinase A signaling and suggest that RHAMM ensures bipolar spindle assembly and mitotic progression through the integration of biochemical and structural pathways.

Silencing of AURKA augments the antitumor efficacy of the AURKA inhibitor MLN8237 on neuroblastoma cells

Background

Aurora kinase A (AURKA) has been implicated in the regulation of cell cycle progression, mitosis and a key number of oncogenic signaling pathways in various malignancies including neuroblastoma. Small molecule inhibitors of AURKA have shown potential, but still not as good as expected effects in clinical trials. Little is known about this underlying mechanism. Here, we evaluated the inhibitory effects of AURKA inhibitor MLN8237 on neuroblastoma cells to understand the potential mechanisms responsible for tumor therapy.

Methods

MLN8237 treatment on neuroblastoma cell line IMR32 was done and in vivo inhibitory effects were investigated using tumor xenograft model. Cellular senescence was evaluated by senescence-associated β-gal Staining assay. Flow cytometry was used to tested cell cycle arrest and cell apoptosis. Senescence-associated signal pathways were detected by western blot. CD133 microbeads and microsphere formation were used to separate and enrich CD133⁺ cells. AURKA small interfering RNA transfection was carried to downregulate AURKA level. Finally, the combination of MLN8237 treatment with AURKA small interfering RNA transfection were adopted to evaluate the inhibitory effect on neuroblastoma cells.

Results

We demonstrate that MLN8237, an inhibitor of AURKA, induces the neuroblastoma cell line IMR32 into cellular senescence and G2/M cell phase arrest. Inactivation of AURKA results in MYCN destabilization and inhibits cell growth in vitro and in a mouse model. Although MLN8237 inhibits AURKA kinase activity, it has almost no inhibitory effect on the AURKA protein level. By contrast, MLN8237 treatment leads to abnormal high expression of AURKA in vitro and in vivo. Knockdown of AURKA reduces cell survival. The combination of MLN8237 with AURKA small interfering RNA results in more profound inhibitory effects on neuroblastoma cell growth. Moreover, MLN8237 treatment followed by AURKA siRNA forces senescent cells into apoptosis via suppression of the Akt/Stat3 pathway.

Conclusions

The effect of AURKA-targeted inhibition of tumor growth plays roles in both the inactivation of AURKA activity and the decrease in the AURKA protein expression level.

The Aurora kinase A inhibitor TC-A2317 disrupts mitotic progression and inhibits cancer cell proliferation

Mitotic progression is crucial for the maintenance of chromosomal stability. A proper progression is ensured by the activities of multiple kinases. One of these enzymes, the serine/threonine kinase Aurora A, is required for proper mitosis through the regulation of centrosome and spindle assembly. In this study, we functionally characterized a newly developed Aurora kinase A inhibitor, TC-A2317. In human lung cancer cells, TC-A2317 slowed proliferation by causing aberrant formation of centrosome and microtubule spindles and prolonging the duration of mitosis. Abnormal mitotic progression led to accumulation of cells containing micronuclei or multinuclei. Furthermore, TC-A2317–treated cells underwent apoptosis, autophagy or senescence depending on cell type. In addition, TC-A2317 inactivated the spindle assembly checkpoint triggered by paclitaxel, thereby exacerbating mitotic catastrophe. Consistent with this, the expression level of Aurora A in tumors was inversely correlated with survival in lung cancer patients. Collectively, these data suggest that inhibition of Aurora kinase A using TC-A2317 is a promising target for anti-cancer therapeutics.

Up-regulated HIF-2α contributes to the Osteoarthritis development through mediating the primary cilia loss

BACKGROUNDS

Up-regulated HIF-2α (hypoxia induced factor 2) had been demonstrated to contribute to Osteoarthritis (OA) development via inducing the expression of matrix-degrading enzymes. However, the HIF-2α also could promote primary cilia loss through HIF-2α/AURKA (Aurora kinase A)/NEDD9 pathway. And the primary cilia dysfunction is another characteristic of the OA. Thus, we investigated here whether the HIF-2α also contributes the OA development through mediating the primary cilia loss.

METHODS

The primary chondrocytes were isolated from the experimental OA mice induced by destabilization of the medial meniscus (DMM). Chondrocytes were cultured under normoxia (21% O₂) or hypoxia (2% O₂) conditions. The HIF-1α and HIF-2α expressions were assessed by western blot. The cilia formation was counted by immuno-staining the acetylated tubulin. The contribution of HIF-1α or HIF-2α to the primary cilia loss was assessed by knocking-down the HIF-1α or HIF-2α individually. The HIF-2α/AURKA/NEDD9 pathway was validated through over-expressing or knocking-down specific components of the pathway and then counting the primary cilia number. Finally, the pathway was further confirmed in the OA mice.

RESULTS

Hypoxia could induce the expression of both HIF-1α and HIF-2α, and also reduce the number of primary cilia on the chondrocytes isolated from the experimental OA mice. Knocking-down or over-expressing HIF-1α or HIF-2α individually showed that the HIF-2α could induce the primary cilia reduction rather than the HIF-1α. Manipulating the HIF-2α expression could positively affect the AURKA and NEDD9 expression. Manipulating the AURKA and NEDD9 expressions could reverse the function of HIF-2α on primary cilia. In the mice, knocking-down both AURKA and NEDD9 could alleviate the OA development significantly.

CONCLUSION

Up-regulated HIF-2α contributes to the Osteoarthritis development through mediating the primary cilia loss, which might be developed as therapeutic targets for OA treatment.

Aurora kinase inhibitors: Potential molecular-targeted drugs for gynecologic malignant tumors

Chemotherapy and surgery are important treatment strategies for gynecologic malignant tumors such as ovarian, cervical and endometrial cancer. However, many anticancer drugs currently available are cytotoxic and cause strong adverse reactions in patients. Aurora kinases have attracted increasing attention in recent years as serine/threonine kinases with various roles in cell division, including chromosomal agglutination and segregation, functions of centromeres, centrosomal maturation, spindle formation and cytokinesis. Aurora kinases are overexpressed in a number of cancers and recent studies have shown that they are involved in onco genesis and cause an aberrant increase in centrosome number, emergence of polykaryocytes and failure of cancer inhibition mechanisms. Thus, drugs that inhibit Aurora kinases are likely to exert anticancer effects in various fields, including the gynecologic field. Aurora kinase inhibitors exert antitumor effects in monotherapy and synergistic effects in combination therapy with taxane-based anticancer agents for gynecologic tumors and are likely to increase the efficacy of existing anticancer drugs. Current Aurora kinase inhibitors include ZM447439, Hesperadin, VX-680/MK-0457, AT9283 and Barasertib, and clinical trials are ongoing to verify the effects of these inhibitors.

AURKA promotes cell migration and invasion of head and neck squamous cell carcinoma through regulation of the AURKA/Akt/FAK signaling pathway

The present study aimed to investigate the mechanism by which Aurora kinase A (AURKA) promotes cell migration and invasion in head and neck squamous cell carcinoma (HNSCC). Transwell assays were performed to investigate the cell migration and invasion abilities of AURKA, whilst western blotting was used to analyze the protein expression in FaDu and Hep2 cells, each treated with pharmacological inhibitors. Following the inhibition of AURKA, Akt and focal adhesion kinase (FAK), the migration and invasion of the FaDu and Hep2 cells decreased. The expression of phosphorylated (p)-AURKA and p-FAK (Y397) was observed to decrease following FaDu and Hep2 cell treatment with VX-680, a small molecular inhibitor of AURKA. The expression of p-Akt and p-FAK (Y397) ceased following treatment with the Akt inhibitor triciribine. The expression of p-FAK (Y397) decreased, however, p-Akt expression did not change following treatment with the FAK inhibitor TAE226. In conclusion, AURKA activates FAK through the AURKA/Akt/FAK signaling pathway, promoting the migration and invasion of HNSCC cells, which may subsequently provide a novel approach for the treatment of HNSCC.

Aurora Kinase A Is a Prognostic Marker in Colorectal Adenocarcinoma

BACKGROUND

Aurora kinase A (AURKA), or STK15/BTAK, is a member of the serine/threonine kinase family and plays important roles in mitosis and chromosome stability. This study investigated the clinical significance of AURKA expression in colorectal cancer patients in Korea.

METHODS

AURKA protein expression was evaluated by immunohistochemistry in 151 patients with colorectal adenocarcinoma using tissue microarray blocks. We analyzed the relationship between clinicopathological characteristics and AURKA expression. In addition, the prognostic significance of various clinicopathological data for progression-free survival (PFS) was assessed. Also we evaluated copy number variations by array comparative genomic hybridization and AURKA gene amplification using fluorescence in situ hybridization in colorectal carcinoma tissues.

RESULTS

AURKA gene amplification was found more frequently in the 20q13.2-13.33 gain-positive group than the group with no significant gain on the AURKA-containing locus. AURKA protein expression was detected in 45% of the cases (68/151). Positive staining for AURKA was observed more often in male patients (p = .035) and distally located tumors (p = .021). PFS was shorter in patients with AURKA expression compared to those with low-level AURKA expression (p < .001). Univariate analysis revealed that AURKA expression (p = .001), age (p = .034), lymphatic invasion (p = .001), perineural invasion (p = .002), and TNM stage (p = .013) significantly affected PFS. In a multivariate analysis of PFS, a Cox proportional hazard model confirmed that AURKA expression was an independent and significant prognostic factor in colorectal adenocarcinoma (hazard ratio, 3.944; p < .001).

CONCLUSIONS

AURKA could serve as an independent factor to predict a poor prognosis in Korean colorectal adenocarcinoma patients.

Aurora kinases are a novel therapeutic target for HPV-positive head and neck cancers

OBJECTIVES

Human papilloma virus (HPV) is the main culprit in cancers of the cervix, penis, anus, skin, eye and head and neck. Current treatments for HPV cancers have not altered survival outcomes for 30 years and there is a significant lack of targeted therapeutic agents in the management of advanced HPV-related HNSCC. Here we show that survival and maintenance of HPV-positive HNC cells relies on the continuous expression of the major HPV oncogene, E7, and that Aurora kinases are critical for survival of high-risk HPV-positive HNC cells.

MATERIALS AND METHODS

To assess the role of HPV E7 on HNC cell survival, RNA interference (RNAi) of the E7 gene was initially performed. Using an Aurora kinase inhibitor, Alisertib, the role of Aurora kinases in the carcinogenesis of HPV E7 positive HNC tumour lines was then investigated. An in vivo HNC xenograft model was also utilised to assess loss of tumour volume in response to RNAi E7 gene silencing and Alisertib treatment.

RESULTS

RNAi silencing of the HPV E7 gene inhibited the growth of HPV-positive HNC cells and in vivo tumour load. We show that HPV E7 oncogene expression confers sensitivity to Alisertib on HNC cells where Alisertib-mediated loss in in vitro cell viability and in vivo tumour load is dependent on E7 expression. Moreover, Aurora kinase inhibition induced degradation of MCL-1 in HPV E7-expressing HNC cells.

CONCLUSION

Overall, we show that Aurora kinases are a novel therapeutic target for HPV-positive HNCs. It might be feasible to combine Aurora kinase and MCL-1 inhibitors for future HNC therapies.

Nuclear Aurora kinase A triggers programmed death-ligand 1-mediated immune suppression by activating MYC transcription in triple-negative breast cancer

Background

Increasing studies have reported that oncogenes regulate components of the immune system, suggesting that this is a mechanism for tumorigenesis. Aurora kinase A (AURKA), a serine/threonine kinase, is involved in cell mitosis and is essential for tumor cell proliferation, metastasis, and drug resistance. However, the mechanism by which AURKA is involved in immune response regulation is unclear. Therefore, this study aimed to investigate the role of AURKA in immune regulation in triple‐negative breast cancer (TNBC).

Methods

Peripheral blood mononuclear cells (PBMCs) were co‐cultured with TNBC cells. The xCELLigence Real‐Time Cell Analyzer‐MP system was used to detect the killing efficiency of immune cells on TNBC cells. The expression of immune effector molecules was tested by quantitative real‐time polymerase chain reaction (qRT‐PCR) to evaluate immune function. Furthermore, to validate AURKA‐regulated immune response in vivo, 4T1 murine breast cancer cell line with AURKA overexpression or downregulation was engrafted into BALB/c mice. The distribution and proportion of immune cells in tumors were further evaluated by immunohistochemistry and flow cytometry.

Results

Downregulation of AURKA in TNBC cells increased immune response by activating CD8⁺ T cell proliferation and activity. Nuclear rather than cytoplasmic AURKA‐derived programmed death‐ligand 1 (PD‐L1) expression was independent of its kinase activity. Mechanistic investigations showed that nuclear AURKA increased PD‐L1 expression via an MYC‐dependent pathway. PD‐L1 overexpression mostly reversed AURKA silencing‐induced expression of immune effector molecules, including interleukin‐ (IL‐2), interferon‐γ (IFN‐γ), and perforin. Moreover, AURKA expression was negatively correlated with the enrichment and activity of tumor‐infiltrating CD8⁺ T cells in 4T1 engrafted BALB/c mouse model.

Conclusions

Nuclear AURKA elevated PD‐L1 expression via an MYC‐dependent pathway and contributed to immune evasion in TNBC. Therapies targeting nuclear AURKA may restore immune responses against tumors.

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 affects radiosenstivity in cervical squamous cell carcinoma and predicts poor prognosis

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Phase 1 study of alisertib (MLN8237) and weekly irinotecan in adults with advanced solid tumors

PURPOSE

Aurora kinases are overexpressed or amplified in numerous malignancies. This study was designed to determine the safety and tolerability of the Aurora A kinase inhibitor alisertib (MLN8237) when combined with weekly irinotecan.

METHODS

In this single-center phase 1 study, adult patients with refractory advanced solid tumors received 100 mg/m² irinotecan intravenously on day 1 and 8 of a 21-day cycle. Alisertib at planned escalating dose levels of 20-60 mg was administered orally twice per day on days 1-3 and 8-10. Patients homozygous for UGT1A1*28 were excluded. The primary objective was the safety of alisertib when combined with irinotecan to determine the maximum tolerated dose (MTD). Secondary objectives included overall response rate by RECIST and pharmacokinetics in a planned expansion cohort of patients with colorectal cancer treated at the MTD.

RESULTS

A total of 17 patients enrolled at three dose levels. Dose-limiting toxicities included diarrhea, dehydration, and neutropenia. The MTD of alisertib combined with weekly irinotecan was 20 mg twice per day on days 1-3 and 8-10. One fatal cardiac arrest at the highest dose level tested was deemed possibly related to drug treatment. One partial response in 11 efficacy evaluable patients (9%) occurred in a patient with small cell lung cancer. The study was terminated prior to the planned expansion in patients with colorectal cancer.

CONCLUSION

In contrast to prior results in a pediatric population, adult patients did not tolerate alisertib combined with irinotecan at clinically meaningful doses due to hematologic and gastrointestinal toxicities. The study was registered with ClinicalTrials.gov under study number NCT01923337 on Aug 15, 2013.

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.

CIP2A acts as a scaffold for CEP192-mediated microtubule organizing center assembly by recruiting Plk1 and aurora A during meiotic maturation

In somatic cells spindle microtubules are nucleated from centrosomes that act as major microtubule organizing centers (MTOCs), whereas oocytes form meiotic spindles by assembling multiple acentriolar MTOCs without canonical centrosomes. Aurora A and Plk1 are required for these events, but the underlying mechanisms remain largely unknown. Here we show that CIP2A regulates MTOC organization by recruiting aurora A and Plk1 at spindle poles during meiotic maturation. CIP2A colocalized with pericentrin at spindle poles with a few distinct cytoplasmic foci. Although CIP2A has been identified as an endogenous inhibitor of protein phosphatase 2A (PP2A), overexpression of CIP2A had no effect on meiotic maturation. Depletion of CIP2A perturbed normal spindle organization and chromosome alignment by impairing MTOC organization. Importantly, CIP2A was reciprocally associated with CEP192, promoting recruitment of aurora A and Plk1 at MTOCs. CIP2A was phosphorylated by Plk1 at S904, which targets CIP2A to MTOCs and facilitates MTOC organization with CEP192. Our results suggest that CIP2A acts as a scaffold for CEP192-mediated MTOC assembly by recruiting Plk1 and aurora A during meiotic maturation in mouse oocytes.

Impacts of AURKA Genetic Polymorphism on Urothelial Cell Carcinoma Development

Urothelial cell carcinoma (UCC) is the most common primary malignancy of the urinary system and the second-most common type of renal cell carcinoma. Aurora kinase A (AURKA), a serine/threonine kinase, has a critical role in centrosome duplication, spindle assembly checkpoint, and cytokinesis. Here, we determined the correlation between UCC susceptibility and AURKA polymorphisms. We used real-time polymerase chain reaction to compare the genotype distributions and allelic frequencies of four single-nucleotide polymorphisms (SNPs) of AURKA, namely rs1047972, rs2273535, rs2064863, and rs6024836, between 431 UCC cases and 862 healthy controls. Logistic regression models demonstrated that the G allele of rs2064863, a genetic polymorphism of AURKA, exhibited a significant protective effect against UCC among the 862 nonsmokers. Moreover, patients with rs2064863 G allele exhibited a slightly lower risk of lymph node metastasis and those with rs6024836 G allele exhibited a lower risk of distant metastases. Our study suggested that several variants of AURKA SNPs rs2064863 and rs6024836 may serve as critical predictors for the clinical status of UCC.

[Clinical significance of targeting drug-based molecular biomarkers expression in ovarian clear cell carcinoma]

Objective: To assess the expression level of targeting drug-based molecular biomarkers in ovarian clear cell carcinoma (OCCC) tissues and its clinical significance. Methods: A total of 63 OCCC patients included 40 primary OCCC and 23 recurrent OCCC for secondary cytoreductive surgery (SCS), who had received primary surgeries at Fudan University Shanghai Cancer Center between January, 2008 and December, 2015 were enrolled, and immunohistochemistry SP method was used to test human epidermal growth factor receptor (EGFR), human epidermal growth factor receptor-2 (HER2), aurora kinase A (AURKA), breast cancer susceptibility gene 1 (BRCA1), BRCA2 and programmed death-ligand 1 (PD-L1)protein expression in paraffin-embedded tissues. Results: The positive rates of EGFR, HER2, AURKA,BRCA1, BRCA2 and PD-L1 in primary and recurrent tumor tissues were respectively 20% (8/40) vs 30% (7/23) , 22% (9/40) vs 35% (8/23) , 38% (15/40) vs 35% (8/23) , 42% (17/40) vs 39% (9/23) , 20% (8/40) vs 22% (5/23) , 25% (10/40) vs 17% (4/23) , and there were no significant differences between primary and recurrent OCCC (all P>0.05). χ(2)-test or Fisher exact analysis revealed that HER2 expression in recurrent tumor tissues had a relationship with chemoresistance (P<0.05), while the expression of other biomarkers showed no significant relationship with chemoresistance (all P>0.05). Further, Kaplan-Meier survival analysis showed that patients with HER2 and AURKA-positive expression had a significantly shorter progression-free survival time in primary OCCC (4 months vs 10 months, log-rank test, P<0.05 for HER2; and 4 months vs 10 months, P<0.05 for AURKA); and a shorter overall survival time after SCS in recurrent OCCC (10 months vs 44 months, P<0.05 for HER2; and 13 months vs 43 months, P<0.05 for AURKA). However, multivariate Cox proportional hazards regression analysis indicated that none of these 6 biomarkers was independent risk factor of progression-free survival time of primary OCCC or overall survival time after SCS for recurrent OCCC (P>0.05). Conclusion: HER2 and AURKA could serve as prognostic factors in ovarian clear cell carcinoma.

Acetyltanshinone IIA reduces the synthesis of cell cycle-related proteins by degrading p70S6K and subsequently inhibits drug-resistant lung cancer cell growth

Targeted therapies using tyrosine kinase inhibitors (TKIs) against epidermal growth factor receptor (EGFR) have improved the outcomes of patients with non-small cell lung cancer (NSCLC). However, due to genetic mutations of EGFR or activation of other oncogenic pathways, cancer cells can develop resistance to TKIs, resulting in usually temporary and reversible therapeutic effects. Therefore, new anticancer agents are urgently needed to treat drug-resistant NSCLC. In this study, we found that acetyltanshinone IIA (ATA) displayed much stronger potency than erlotinib in inhibiting the growth of drug-resistant NSCLC cells and their-derived xenograft tumors. Our analyses revealed that ATA achieved this effect by the following mechanisms. First, ATA could bind p70S6K at its ATP-binding pocket to prevent phosphorylation, and second by increasing the ubiquitination of p70S6K to cause its degradation. Since phosphorylation of S6 ribosome protein (S6RP) by p70S6K can induce protein synthesis at the ribosome, the dramatic reduction of p70S6K after ATA treatment led to great reductions of new protein synthesis on several cell cycle-related proteins including cyclin D3, aurora kinase A, polo-like kinase, cyclin B1, survivin; and reduced the levels of EGFR and MET. In addition, ATA treatment increased the levels of p53 and p21 proteins, which blocked cell cycle progression in the G1/S phase. Taken together, as ATA can effectively block multiple signaling pathways essential for protein synthesis and cell proliferation, ATA can potentially be developed into a multi-target anti-cancer agent to treat TKI-resistant NSCLC.

Natural anthraquinone compound emodin as a novel inhibitor of aurora A kinase: A pilot study

Aurora kinase A (AURKA) carries out an essential role in proliferation and involves in cisplatin resistance in various cancer cells. Overexpression of AURKA is associated with the poor prognosis of cancer patients. Thus, AURKA has been considered as a target for cancer therapy. Developing AURKA inhibitors became an important issue in cancer therapy. A natural compound emodin mainly extracted from rhubarbs possesses anti-cancer properties. However, the effect of emodin on AURKA has never been investigated. In the present study, molecular docking analysis indicated that emodin interacts with AURKA protein active site. We also found nine emodin analogues from Key Organic database by using ChemBioFinder software. Among that, one analogue 8L-902 showed a similar anti-cancer effect as emodin. The bindings of emodin and 8L-902 on AURKA protein were confirmed by cellular thermal shift assay. Furthermore, emodin inhibited the AURKA kinase activity in vitro and enhanced the cisplatin-DNA adduct level in a resistant ovarian cancer cell line. It seems that emodin may have the potential to inhibit cancer cell growth and enhance cisplatin therapy in cancer with resistance. Collectively, our finding reveals a novel AURKA inhibitor, emodin, which may be vulnerable to ovarian cancer therapy in the future.