Aurora kinases as anticancer drug targets

Computational identification and experimental characterization of an aurora kinase inhibitor

The serine/threonine kinases of the aurora family are critical for completing various stages of mitotic cell division. They are frequently overexpressed in various cancers, associated with poor prognosis, and have been validated as an attractive drug target. Despite promising preclinical results, the clinical development of small molecule inhibitors targeting aurora kinases is often hampered by limited efficacy as single agents and severe side effects. Recent discoveries of the synthetic interaction of aurora A with various tumor suppressors and its involvement in the development of resistance to third-generation EGFR inhibitors have renewed interest in finding aurora kinase inhibitors. This study utilized computational approaches to discover an aurora kinase inhibitor. Chemical features of two structurally distinct inhibitors of aurora kinase were exploited to develop a molecular shape and color-based model for the virtual screening of small synthetic molecules in the Enamine database. Six hit compounds validated through docking and Molecular Dynamics (MD) simulation studies were evaluated in a cell-based assay. Only MC-688 inhibited both aurora kinases (A and B) and bound to both kinases in a competition binding assay. Analysis of STD-NMR and 2D NOESY spectra confirmed the computationally predicted binding mode of MC-688 with the ATP binding pocket of aurora A. MC-688 inhibited cell proliferation and long-term treatment of HCT116 colorectal cancer cells with MC-688 induced abrogated mitosis, ultimately leading to apoptotic cell death. In conclusion, MC-688 was computationally identified and experimentally validated as a new pan-aurora inhibitor that induces aurora phenotype in cells and can be used as a lead for further optimization.

Inhibition of Aurora B kinase (AURKB) enhances the effectiveness of 5-fluorouracil chemotherapy against colorectal cancer cells

BACKGROUND

5-Fluorouracil (5-FU) remains a core component of systemic therapy for colorectal cancer (CRC). However, response rates remain low, and development of therapy resistance is a primary issue. Combinatorial strategies employing a second agent to augment the therapeutic effect of chemotherapy is predicted to reduce the incidence of treatment resistance and increase the durability of response to therapy.

METHODS

Here, we employed quantitative proteomics approaches to identify novel druggable proteins and molecular pathways that are deregulated in response to 5-FU, which might serve as targets to improve sensitivity to chemotherapy. Drug combinations were evaluated using 2D and 3D CRC cell line models and an ex vivo culture model of a patient-derived tumour.

RESULTS

Quantitative proteomics identified upregulation of the mitosis-associated protein Aurora B (AURKB), within a network of upregulated proteins, in response to a 24 h 5-FU treatment. In CRC cell lines, AURKB inhibition with the dihydrogen phosphate prodrug AZD1152, markedly improved the potency of 5-FU in 2D and 3D in vitro CRC models. Sequential treatment with 5-FU then AZD1152 also enhanced the response of a patient-derived CRC cells to 5-FU in ex vivo cultures.

CONCLUSIONS

AURKB inhibition may be a rational approach to augment the effectiveness of 5-FU chemotherapy in CRC.

Actionable Driver Events in Small Cell Lung Cancer

Small cell lung cancer (SCLC) stands out as the most aggressive form of lung cancer, characterized by an extremely high proliferation rate and a very poor prognosis, with a 5-year survival rate that falls below 7%. Approximately two-thirds of patients receive their diagnosis when the disease has already reached a metastatic or extensive stage, leaving chemotherapy as the remaining first-line treatment option. Other than the recent advances in immunotherapy, which have shown moderate results, SCLC patients cannot yet benefit from any approved targeted therapy, meaning that this cancer remains treated as a uniform entity, disregarding intra- or inter-tumoral heterogeneity. Continuous efforts and technological improvements have enabled the identification of new potential targets that could be used to implement novel therapeutic strategies. In this review, we provide an overview of the most recent approaches for SCLC treatment, providing an extensive compilation of the targeted therapies that are currently under clinical evaluation and inhibitor molecules with promising results in vitro and in vivo.

Synthetic lethality in human bladder cancer cells by curcumin via concurrent Aurora A inhibition and autophagy induction

Combination therapies to induce mixed-type cell death and synthetic lethality have the potential to overcome drug resistance in cancer. In this study, we demonstrated that the curcumin-enhanced cytotoxicity of cisplatin/carboplatin in combination with gemcitabine was associated with Aurora A suppression-mediated G2/M arrest, and thus apoptosis, as well as MEK/ERK-mediated autophagy in human bladder cancer cells. Animal study data confirmed that curcumin combined with cisplatin/gemcitabine reduced tumorigenesis of xenograft in mice and this phenomenon was associated with elevated expressions of p-ERK and reduced p-Aurora A in tumors. Gene analyses using data repositories further revealed that reduced Aurora A expression alone did not significantly elevate the sensitivity of human bladder carcinoma cells to these anticancer drugs. Unlike other major cancer types, human bladder urothelial carcinoma tissue coexpressed higher AURKA and lower MAP1LC3B than normal tissue, and reduced Aurora A and induction of autophagy have been clinically associated with a better prognosis in patients with early but not advanced stage bladder cancer. Therefore, our results suggest that treatment strategies can utilize the synthetic lethal pair to concurrently suppress oncogenic Aurora A and induce autophagy by coadministrating curcumin with anticancer drugs for early-stage bladder cancer with high expression of Aurora A.

Alisertib exerts KRAS allele‑specific anticancer effects on colorectal cancer cell lines

The aim of the present study was to examine the effects of alisertib (ALS) on RAS signaling pathways against a panel of colorectal cancer (CRC) cell lines and engineered Flp-In stable cell lines expressing different Kirsten rat sarcoma virus (KRAS) mutants. The viability of Caco-2_{KRAS wild-type}, Colo-678_{KRAS G12D}, SK-CO-1_{KRAS G12V}, HCT116_{KRAS G13D}, CCCL-18_{KRAS A146T} and HT29_{BRAF V600E} cells was examined by Cell Titer-Glo assay, and that of stable cell lines was monitored by IncuCyte. The expression levels of phosphorylated (p-)Akt and p-Erk as RAS signal outputs were measured by western blotting. The results suggested that ALS exhibited different inhibitory effects on cell viability and different regulatory effects on guanosine triphosphate (GTP)-bound RAS in CRC cell lines. ALS also exhibited various regulatory effects on the PI3K/Akt and mitogen-activated protein kinase (MAPK) pathways, the two dominant RAS signaling pathways, and induced apoptosis and autophagy in a RAS allele-specific manner. Combined treatment with ALS and selumetinib enhanced the regulatory effects of ALS on apoptosis and autophagy in CRC cell lines in a RAS allele-specific manner. Notably, combined treatment exhibited a synergistic inhibitory effect on cell proliferation in Flp-In stable cell lines. The results of the present study suggested that ALS differentially regulates RAS signaling pathways. The combined approach of ALS and a MEK inhibitor may represent a new therapeutic strategy for precision therapy for CRC in a KRAS allele-specific manner; however, this effect requires further study in vivo.

Safety, tolerability, and pharmacokinetics of Aurora kinase B inhibitor AZD2811: a phase 1 dose-finding study in patients with advanced solid tumours

BACKGROUND

AZD2811 is a potent, selective Aurora kinase B inhibitor. We report the dose-escalation phase of a first-in-human study assessing nanoparticle-encapsulated AZD2811 in advanced solid tumours.

METHODS

AZD2811 was administered in 12 dose-escalation cohorts (2-h intravenous infusion; 15‒600 mg; 21-/28-day cycles) with granulocyte colony-stimulating factor (G-CSF) at higher doses. The primary objective was determining safety and maximum tolerated/recommended phase 2 dose (RP2D).

RESULTS

Fifty-one patients received AZD2811. Drug exposure was sustained for several days post-dose. The most common AZD2811-related adverse events (AEs) were fatigue (27.3%) at ≤200 mg/cycle and neutropenia (37.9%) at ≥400 mg/cycle. Five patients had dose-limiting toxicities: grade (G)4 decreased neutrophil count (n = 1, 200 mg; Days 1, 4; 28-day cycle); G4 decreased neutrophil count and G3 stomatitis (n = 1 each, both 400 mg; Day 1; 21-day cycle); G3 febrile neutropenia and G3 fatigue (n = 1 each, both 600 mg; Day 1; 21-day cycle +G-CSF). RP2D was 500 mg; Day 1; 21-day cycle with G-CSF on Day 8. Neutropenia/neutrophil count decrease were on-target AEs. Best overall responses were partial response (n = 1, 2.0%) and stable disease (n = 23, 45.1%).

CONCLUSIONS

At RP2D, AZD2811 was tolerable with G-CSF support. Neutropenia was a pharmacodynamic biomarker.

CLINICAL TRIAL REGISTRATION

NCT02579226.

When Just One Phosphate Is One Too Many: The Multifaceted Interplay between Myc and Kinases

Myc transcription factors are key regulators of many cellular processes, with Myc target genes crucially implicated in the management of cell proliferation and stem pluripotency, energy metabolism, protein synthesis, angiogenesis, DNA damage response, and apoptosis. Given the wide involvement of Myc in cellular dynamics, it is not surprising that its overexpression is frequently associated with cancer. Noteworthy, in cancer cells where high Myc levels are maintained, the overexpression of Myc-associated kinases is often observed and required to foster tumour cells' proliferation. A mutual interplay exists between Myc and kinases: the latter, which are Myc transcriptional targets, phosphorylate Myc, allowing its transcriptional activity, highlighting a clear regulatory loop. At the protein level, Myc activity and turnover is also tightly regulated by kinases, with a finely tuned balance between translation and rapid protein degradation. In this perspective, we focus on the cross-regulation of Myc and its associated protein kinases underlying similar and redundant mechanisms of regulation at different levels, from transcriptional to post-translational events. Furthermore, a review of the indirect effects of known kinase inhibitors on Myc provides an opportunity to identify alternative and combined therapeutic approaches for cancer treatment.

Tartgeting Non-alcoholic Fatty Liver Disease: Design, X-Ray co-crystal structure and synthesis of 'first-in-kind' inhibitors of Serine/Threonine Kinase25

We describe the synthesis of a series of 3-t-butyl 5-aminopyrazole p-substituted arylamides as inhibitors of serine-threonine25 (STK25), an enzyme implicated in the progression of non-alcoholic fatty liver disease (NAFLD). Appending a p-N-pyrrolidinosulphonamide group to the arylamide group led to a 'first-in kind' inhibitor with IC₅₀=228nM. A co-crystal structure with STK 25 revealed productive interactions which were also reproduced using molecular docking. A new series of triazolo dihydro oxazine carboxamides of 3-t-butyl 5-aminopyrazole was not active against STK25.

Aurora-A/FOXO3A/SKP2 axis promotes tumor progression in clear cell renal cell carcinoma and dual-targeting Aurora-A/SKP2 shows synthetic lethality

Renal cell carcinoma (RCC) is a common malignant tumor in the world. Histologically, most of RCC is classified as clear cell renal cell carcinoma (ccRCC), which is the most prevalent subtype. The overall survival of patients with ccRCC is poor, thus it is urgent to further explore its mechanism and target. S-phase kinase-associated protein 2 (SKP2) is overexpressed in a variety of human cancers and is associated with poor prognosis by enhancing tumor progression. However, it is unclear whether or how SKP2 is involved in ccRCC progression. Here, we reported that overexpression of SKP2 enhanced cell proliferation of ccRCC, while SKP2 depletion exhibited the opposite effect. Bioinformatic analyses found that SKP2 was positively correlated with Aurora-A (Aur-A) in ccRCC. The protein and mRNA levels of SKP2 were elevated or reduced by Aur-A overexpression or silencing, respectively. It was further found that Aur-A caused an increase phosphorylation of FOXO3A, which is a negatively transcription factor for SKP2. Interestingly, SKP2 mediated ubiquitylation and degradation of FOXO3A depend on the kinase activity of Aur-A. The combination of Aur-A inhibitor MLN8237 and SKP2 inhibitor SZL P1-41 showed a synergistic tumor growth inhibition in vivo and in vitro of ccRCC models. Thus, our data reveal that Aurora-A/FOXO3A/SKP2 axis promotes tumor progression in ccRCC, and the double inhibition of SKP2 and Aur-A shows significant synergistic effect, which indicates a potential new therapeutic strategy for ccRCC.

Integrative network analysis of early-stage lung adenocarcinoma identifies aurora kinase inhibition as interceptor of invasion and progression

Here we focus on the molecular characterization of clinically significant histological subtypes of early-stage lung adenocarcinoma (esLUAD), which is the most common histological subtype of lung cancer. Within lung adenocarcinoma, histology is heterogeneous and associated with tumor invasion and diverse clinical outcomes. We present a gene signature distinguishing invasive and non-invasive tumors among esLUAD. Using the gene signatures, we estimate an Invasiveness Score that is strongly associated with survival of esLUAD patients in multiple independent cohorts and with the invasiveness phenotype in lung cancer cell lines. Regulatory network analysis identifies aurora kinase as one of master regulators of the gene signature and the perturbation of aurora kinases in vitro and in a murine model of invasive lung adenocarcinoma reduces tumor invasion. Our study reveals aurora kinases as a therapeutic target for treatment of early-stage invasive lung adenocarcinoma.

High-Risk Neuroblastoma: Poor Outcomes Despite Aggressive Multimodal Therapy

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Neuroblastoma (NBL) is a highly malignant embryonal tumor that originates from the primordial neural crest cells. NBL is the most common tumor in infants and the most common extracranial solid tumor in children. The tumor is more commonly diagnosed in children of 1-4 years of age. NBL is characterized by enigmatic clinical behavior that ranges from spontaneous regression to an aggressive clinical course leading to frequent relapses and death. Based on the likelihood of progression and relapse, the International Neuroblastoma Risk Group classification system categorized NBL into very low risk, low risk, intermediate risk, and high risk (HR) groups. HR NBL is defined based on the patient's age (> 18 months), disease metastasis, tumor histology, and MYCN gene amplification. HR NBL is diagnosed in nearly 40% of patients, mainly those > 18 months of age, and is associated with aggressive clinical behavior. Treatment strategies involve the use of intensive chemotherapy (CTR), surgical resection, high dose CTR with hematopoietic stem cell support, radiotherapy, biotherapy, and immunotherapy with Anti-ganglioside 2 monoclonal antibodies. Although HR NBL is now better characterized and aggressive multimodal therapy is applied, the outcomes of treatment are still poor, with overall survival and event-free survival of approximately 40% and 30% at 3-years, respectively. The short and long-term side effects of therapy are tremendous. HR NBL carries a high mortality rate accounting for nearly 15% of pediatric cancer deaths. However, most mortalities are attributed to the high frequency of disease relapse (50%) and disease reactiveness to therapy (20%). Newer treatment strategies are therefore urgently needed. Recent discoveries in the field of biology and molecular genetics of NBL have led to the identification of several targets that can improve the treatment results. In this review, we discuss the different aspects of the epidemiology, biology, clinical presentations, diagnosis, and treatment of HR NBL, in addition to the recent developments in the management of the disease.

Novel Aurora A and Protein Kinase C (α, β1, β2, and θ) Multitarget Inhibitors: Impact of Selenium Atoms on the Potency and Selectivity

Aurora kinases and protein kinase C (PKC) have been shown to be involved in different aspects of cancer progression. To date, no dual Aurora/PKC inhibitor with clinical efficacy and low toxicity is available. Here, we report the identification of compound 2e as a potent small molecule capable of selectively inhibiting Aurora A kinase and PKC isoforms α, β1, β2 and θ. Compound 2e demonstrated significant inhibition of the colony forming ability of metastatic breast cancer cells in vitro and metastasis development in vivo. In vitro kinase screening and molecular modeling studies revealed the critical role of the selenium-containing side chains within 2e, where selenium atoms were shown to significantly improve its selectivity and potency by forming additional interactions and modulating the protein dynamics. In comparison to other H-bonding heteroatoms such as sulfur, our studies suggested that these selenium atoms also confer more favorable PK properties.

Co-treatment with miR-21-5p inhibitor and Aurora kinase inhibitor reversine suppresses breast cancer progression by targeting sprouty RTK signaling antagonist 2

Numerous studies have reported the regulatory effects of miR-21-5p and reversine in human breast cancer (HBC). However, the mechanism of reversine and miR-21-5p has not been fully investigated in HBC. The aim of the current study was to assess the mechanism of action of reversine, with or without miR-21-5p, in HBC progression. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot results confirmed the upregulation of miR-21-5p and downregulation of sprouty RTK signaling antagonist 2 (SPRY2) in HBC. Bioinformatics analysis and luciferase assay identified the correlation between miR-21-5p and SPRY2. Cell function experiment results indicated a decrease in migration, proliferation, and invasion of HBC cells treated with miR-21-5p inhibitor and reversine; however, an increase in apoptosis was observed in these cells. Apoptotic ability was more enhanced and migration, proliferation, and invasion were more impaired in HBC cells treated with both miR-21-5p inhibitor and reversine than in those treated individually with either inhibitors. SPRY2, downstream of miR-21-5p, participated in HBC progression with reversine. Overall, our study proved that combining the miR-21-5p inhibitor with reversine produced a synergistic effect by regulating SPRY2, thereby limiting HBC progression. This knowledge might offer insights into the clinical therapy of HBC.

Molecular hybrids: A five-year survey on structures of multiple targeted hybrids of protein kinase inhibitors for cancer therapy

Protein kinases have grown over the past few years as a crucial target for different cancer types. With the multifactorial nature of cancer, and the fast development of drug resistance for conventional chemotherapeutics, a strategy for designing multi-target agents was suggested to potentially increase drug efficacy, minimize side effects and retain the proper pharmacokinetic properties. Kinase inhibitors were used extensively in such strategy. Different kinase inhibitor agents which target EGFR, VEGFR, c-Met, CDK, PDK and other targets were merged into hybrids with conventional chemotherapeutics such as tubulin polymerization and topoisomerase inhibitors. Other hybrids were designed gathering kinase inhibitors with targeted cancer therapy such as HDAC, PARP, HSP 90 inhibitors. Nitric oxide donor molecules were also merged with kinase inhibitors for cancer therapy. The current review presents the hybrids designed in the past five years discussing their design principles, results and highlights their future perspectives.

Indolin-2-one derivatives as selective Aurora B kinase inhibitors targeting breast cancer

Aurora B is a pivotal cell cycle regulator where errors in its function results in polyploidy, genetic instability, and tumorigenesis. It is overexpressed in many cancers, consequently, targeting Aurora B with small molecule inhibitors constitutes a promising approach for anticancer therapy. Guided by structure-based design and molecular hybridization approach we developed a series of fifteen indolin-2-one derivatives based on a previously reported indolin-2-one-based multikinase inhibitor (1). Seven derivatives, 5g, 6a, 6c-e, 7, and 8a showed preferential antiproliferative activity in NCI-60 cell line screening and out of these, carbamate 6e and cyclopropylurea 8a derivatives showed optimum activity against Aurora B (IC₅₀ = 16.2 and 10.5 nM respectively) and MDA-MB-468 cells (IC₅₀ = 32.6 ± 9.9 and 29.1 ± 7.3 nM respectively). Furthermore, 6e and 8a impaired the clonogenic potential of MDA-MB-468 cells. Mechanistic investigations indicated that 6e and 8a induced G2/M cell cycle arrest, apoptosis, and necrosis of MDA-MB-468 cells and western blot analysis of 8a effect on MDA-MB-468 cells revealed 8a's ability to reduce Aurora B and its downstream target, Histone H3 phosphorylation. 6e and 8a displayed better safety profiles than multikinase inhibitors such as sunitinib, showing no cytotoxic effects on normal rat cardiomyoblasts and murine hepatocytes. Finally, 8a demonstrated a more selective profile than 1 when screened against ten related kinases. Based on these findings, 8a represents a promising candidate for further development to target breast cancer via Aurora B selective inhibition.

Synthesis, biological evaluation and molecular docking of new sulfonamide-based indolinone derivatives as multitargeted kinase inhibitors against leukemia

Series of novel sulfonamide-based 3-indolinones 3a-m and 4a-f were designed, synthesized and then their cytotoxic activity was evaluated against a panel of sixty cancer cell lines. This screening indicated that 4-(2-(5-fluoro-2-oxoindolin-3-ylidene)acetyl)phenyl benzenesulfonate (4f) possessed promising cytotoxicity against CCRF-CEM and SR leukemia cell lines with IC₅₀ values 6.84 and 2.97 µM, respectively. Further investigation of the leukemic cytotoxicity of compound 4f was carried out by performing PDGFRα, VEGFR2, Aurora A/B and FLT3 enzyme assays and CCRF-CEM and SR cell cycle analysis. These investigations showed that compound 4f exhibited pronounced dual inhibition of both kinases PDGFRα and Aurora A with potency of 24.15 and 11.83 nM, respectively. The in vitro results were supported by molecular docking studies in order to explore its binding affinity and its key amino acids interactions. This work represents compound 4f as a promising anticancer agent against leukemia.

Genetic variations in AURORA cell cycle kinases are associated with glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most frequent type of primary astrocytomas. We examined the association between single nucleotide polymorphisms (SNPs) in Aurora kinase A (AURKA), Aurora kinase B (AURKB), Aurora kinase C (AURKC) and Polo-like kinase 1 (PLK1) mitotic checkpoint genes and GBM risk by qPCR genotyping. In silico analysis was performed to evaluate effects of polymorphic biological sequences on protein binding motifs. Chi-square and Fisher statistics revealed a significant difference in genotypes frequencies between GBM patients and controls for AURKB rs2289590 variant (p = 0.038). Association with decreased GBM risk was demonstrated for AURKB rs2289590 AC genotype (OR = 0.54; 95% CI = 0.33-0.88; p = 0.015). Furthermore, AURKC rs11084490 CG genotype was associated with lower GBM risk (OR = 0.57; 95% CI = 0.34-0.95; p = 0.031). Bioinformatic analysis of rs2289590 polymorphic region identified additional binding site for the Yin-Yang 1 (YY1) transcription factor in the presence of C allele. Our results indicated that rs2289590 in AURKB and rs11084490 in AURKC were associated with a reduced GBM risk. The present study was performed on a less numerous but ethnically homogeneous population. Hence, future investigations in larger and multiethnic groups are needed to strengthen these results.

CCT245718, a dual FLT3/Aurora A inhibitor overcomes D835Y-mediated resistance to FLT3 inhibitors in acute myeloid leukaemia cells

BACKGROUND

Activating mutations in the Fms-like tyrosine kinase 3 (FLT3) are among the most prevalent oncogenic mutations in acute myeloid leukaemia. Inhibitors selectively targeting FLT3 kinase have shown promising clinical activity; their success in the clinic, however, has been limited due to the emergence of acquired resistance.

METHODS

CCT245718 was identified and characterised as a dual Aurora A/FLT3 inhibitor through cell-based and biochemical assays. The ability of CCT245718 to overcome TKD-mediated resistance was evaluated in a cell line-based model of drug resistance to FLT3 inhibitors.

RESULTS

CCT245718 exhibits potent antiproliferative activity towards FLT3-ITD + AML cell lines and strongly binds to FLT3-ITD and TKD (D835Y) mutants in vitro. Activities of both FLT3-ITD and Aurora A are also inhibited in cells. Inhibition of FLT3 results in reduced phosphorylation of STAT5, downregulation of survivin and induction of apoptotic cell death. Moreover, CCT245718 overcomes TKD-mediated resistance in a MOLM-13-derived cell line containing FLT3 with both ITD and D835Y mutations. It also inhibits FLT3 signalling in both parental and resistant cell lines compared to FLT3-specific inhibitor MLN518, which is only active in the parental cell line.

CONCLUSIONS

Our results demonstrate that CCT245718 is a potent dual FLT3/Aurora A inhibitor that can overcome TKD-mediated acquired resistance.

Centriole is the pivot coordinating dynamic signaling for cell proliferation and organization during early development in the vertebrates

Vertebrates have an elaborate and functionally segmented body. It evolves from a single cell by systematic cell proliferation but attains a complex body structure with exquisite precision. This development requires two cellular events: cell cycle and ciliogenesis. For these events, the dynamic molecular signaling is converged at the centriole. The cell cycle helps in cell proliferation and growth of the body and is a highly regulated and integrated process. Its errors cause malignancies and developmental disorders. The cells newly proliferated are organized during organogenesis. For a cellular organization, dedicated signaling hubs are developed in the cells, and most often cilia are utilized. The cilium is generated from one of the centrioles involved in cell proliferation. The developmental signaling pathways hosted in cilia are essential for the elaboration of the body plan. The cilium's compartmental seclusion is ideal for noise-free molecular signaling and is essential for the precision of the body layout. The dysfunctional centrioles and primary cilia distort the development of body layout that manifest as serious developmental disorders. Thus, centriole has a dual role in the growth and cellular organization. It organizes dynamically expressed molecules of cell cycle and ciliogenesis and plays a balancing act to generate new cells and organize them during development. A putative master molecule may regulate and coordinate the dynamic gene expression at the centrioles. The convergence of many critical signaling components at the centriole reiterates the idea that centriole is a major molecular workstation involved in elaborating the structural design and complexity in vertebrates. This article is protected by copyright. All rights reserved.

Investigational Drug Treatments for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer (BC) and accounts for 10-20% of cases. Due to the lack of expression of several receptors, hormone therapy is largely ineffective for treatment purposes. Nevertheless, TNBC often responds very well to chemotherapy, which constitutes the most often recommended treatment. New beneficial targeted therapies are important to be investigated in order to achieve enhanced outcomes in patients with TNBC. This review will focus on recent therapeutic innovations for TNBC, focusing on various inhibitors such as phosphoinositide 3-kinase (PI3K) pathway inhibitors, poly-ADP-ribosyl polymerase (PARP) inhibitors, aurora kinase inhibitors, histone deacetylase inhibitors (HDACIs), and immune checkpoint inhibitors.

Aurora Kinase A proximity map reveals centriolar satellites as regulators of its ciliary function

Aurora kinase A (AURKA) is a conserved kinase that plays crucial roles in numerous cellular processes. Although AURKA overexpression is frequent in human cancers, its pleiotropic functions and multifaceted regulation present challenges in its therapeutic targeting. Key to overcoming these challenges is to identify and characterize the full range of AURKA interactors, which are often weak and transient. Previous proteomic studies were limited in monitoring dynamic and non-mitotic AURKA interactions. Here, we generate the proximity interactome of AURKA in asynchronous cells, which consists of 440 proteins involving multiple biological processes and cellular compartments. Importantly, AURKA has extensive proximate and physical interactions to centriolar satellites, key regulators of the primary cilium. Loss-of-function experiments identify satellites as negative regulators of AURKA activity, abundance, and localization in quiescent cells. Notably, loss of satellites activates AURKA at the basal body, decreases centrosomal IFT88 levels, and causes ciliogenesis defects. Collectively, our results provide a resource for dissecting spatiotemporal regulation of AURKA and uncover its proteostatic regulation by satellites as a new mechanism for its ciliary functions.

Identification of potential markers for differentiating epithelial ovarian cancer from ovarian low malignant potential tumors through integrated bioinformatics analysis

Background

Epithelial ovarian cancer (EOC), as a lethal malignancy in women, is often diagnosed as advanced stages. In contrast, intermediating between benign and malignant tumors, ovarian low malignant potential (LMP) tumors show a good prognosis. However, the differential diagnosis of the two diseases is not ideal, resulting in delays or unnecessary therapies. Therefore, unveiling the molecular differences between LMP and EOC may contribute to differential diagnosis and novel therapeutic and preventive policies development for EOC.

Methods

In this study, three microarray data (GSE9899, GSE57477 and GSE27651) were used to explore the differentially expressed genes (DEGs) between LMP and EOC samples. Then, 5 genes were screened by protein–protein interaction (PPI) network, receiver operating characteristic (ROC), survival and Pearson correlation analysis. Meanwhile, chemical-core gene network construction was performed to identify the potential drugs or risk factors for EOC based on 5 core genes. Finally, we also identified the potential function of the 5 genes for EOC through pathway analysis.

Results

Two hundred thirty-four DEGs were successfully screened, including 81 up-regulated genes and 153 down-regulated genes. Then, 5 core genes (CCNB1, KIF20A, ASPM, AURKA, and KIF23) were identified through PPI network analysis, ROC analysis, survival and Pearson correlation analysis, which show better diagnostic efficiency and higher prognostic value for EOC. Furthermore, NetworkAnalyst was used to identify top 15 chemicals that link with the 5 core genes. Among them, 11 chemicals were potential drugs and 4 chemicals were risk factors for EOC. Finally, we found that all 5 core genes mainly regulate EOC development via the cell cycle pathway by the bioinformatic analysis.

Conclusion

Based on an integrated bioinformatic analysis, we identified potential biomarkers, risk factors and drugs for EOC, which may help to provide new ideas for EOC diagnosis, condition appraisal, prevention and treatment in future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00794-0.

7-(2-Anilinopyrimidin-4-yl)-1-benzazepin-2-ones Designed by a "Cut and Glue" Strategy Are Dual Aurora A/VEGF-R Kinase Inhibitors

Although overexpression and hyperactivity of protein kinases are causative for a wide range of human cancers, protein kinase inhibitors currently approved as cancer drugs address only a limited number of these enzymes. To identify new chemotypes addressing alternative protein kinases, the basic structure of a known PLK1/VEGF-R2 inhibitor class was formally dissected and reassembled. The resulting 7-(2-anilinopyrimidin-4-yl)-1-benzazepin-2-ones were synthesized and proved to be dual inhibitors of Aurora A kinase and VEGF receptor kinases. Crystal structures of two representatives of the new chemotype in complex with Aurora A showed the ligand orientation in the ATP binding pocket and provided the basis for rational structural modifications. Congeners with attached sulfamide substituents retained Aurora A inhibitory activity. In vitro screening of two members of the new kinase inhibitor family against the cancer cell line panel of the National Cancer Institute (NCI) showed antiproliferative activity in the single-digit micromolar concentration range in the majority of the cell lines.

The tyrosine kinase v-Src modifies cytotoxicities of anticancer drugs targeting cell division

v-Src oncogene causes cell transformation through its strong tyrosine kinase activity. We have revealed that v-Src-mediated cell transformation occurs at a low frequency and it is attributed to mitotic abnormalities-mediated chromosome instability. v-Src directly phosphorylates Tyr-15 of cyclin-dependent kinase 1 (CDK1), thereby causing mitotic slippage and reduction in Eg5 inhibitor cytotoxicity. However, it is not clear whether v-Src modifies cytotoxicities of the other anticancer drugs targeting cell division. In this study, we found that v-Src restores cancer cell viability reduced by various microtubule-targeting agents (MTAs), although v-Src does not alter cytotoxicity of DNA-damaging anticancer drugs. v-Src causes mitotic slippage of MTAs-treated cells, consequently generating proliferating tetraploid cells. We further demonstrate that v-Src also restores cell viability reduced by a polo-like kinase 1 (PLK1) inhibitor. Interestingly, treatment with Aurora kinase inhibitor strongly induces cell death when cells express v-Src. These results suggest that the v-Src modifies cytotoxicities of anticancer drugs targeting cell division. Highly activated Src-induced resistance to MTAs through mitotic slippage might have a risk to enhance the malignancy of cancer cells through the increase in chromosome instability upon chemotherapy using MTAs.

The Molecular 'Myc-anisms' Behind Myc-Driven Tumorigenesis and the Relevant Myc-Directed Therapeutics

MYC, a well-studied proto-oncogene that is overexpressed in >20% of tumors across all cancers, is classically known as “undruggable” due to its crucial roles in cell processes and its lack of a drug binding pocket. Four decades of research and creativity led to the discovery of a myriad of indirect (and now some direct!) therapeutic strategies targeting Myc. This review explores the various mechanisms in which Myc promotes cancer and highlights five key therapeutic approaches to disrupt Myc, including transcription, Myc-Max dimerization, protein stability, cell cycle regulation, and metabolism, in order to develop more specific Myc-directed therapies.

Calibrated liposomal release of the anti-mitotic agent BI-2536 increases the targeting of mitotic tumor cells

Cancer drugs which are specifically targeted at mitosis have generally under-delivered as a class. One likely reason is that only a small percentage of cancer cells in a tumor are actually dividing at any moment. If this is the case, then prolonged bioavailability in the tumor should significantly increase the efficacy of antimitotic agents. Here, we show that if the Plk1 inhibitor BI 2536 is co-encapsulated in a liposome with a pair of anions, its release rate is dependent on both the identity and stoichiometry of the anions. We created a library of liposomes with varying release rates using this approach and found that liposomal drug release rates correlated inversely with in vitro cancer cell killing. Xenografted mice treated with a single dose of slow-releasing liposomal BI 2536 experienced tumor volume decreases lasting 12 days and complete responses in 20% of mice. Treatment with two doses a week apart increased the response rate to 75%. This approach, which we termed Paired Anion Calibrated Release (PACeR), has the potential to revive the clinical utility of antimitotic cancer drugs which have failed clinical trials.

Mechanisms of tRNA-derived fragments and tRNA halves in cancer treatment resistance

The tRNA-derived fragments (tRFs) and tRNA halves (tiRNAs) are newly discovered noncoding RNAs in recent years. They are derived from specific cleavage of mature and pre-tRNAs and expressed in various cancers. They enhance cell proliferation and metastasis or inhibit cancer progression. Many studies have investigated their roles in the diagnosis, progression, metastasis, and prognosis of various cancers, but the mechanisms through which they are involved in resistance to cancer treatment are unclear. This review outlines the classification of tRFs and tiRNAs and their mechanisms in cancer drug resistance, thus providing new ideas for cancer treatment.

Aurora kinase B inhibitor barasertib (AZD1152) inhibits glucose metabolism in gastric cancer cells

Barasertib is a highly selective Aurora kinase B (AURKB) inhibitor and has been widely applied in a variety of cancer cells to investigate the regulatory function of AURKB. However, the effect of barasertib on glucose metabolism in gastric cancer (GC) remains illustrated. Here, barasertib was identified to effectively reduce glucose uptake and lactate production in GC cells in a dose-dependent and time-dependent manner. The expression levels of GLUT1, LDHA and HK2 were decreased by barasertib treatment of GC cells. Furthermore, we found that barasertib induced the expression of ribosomal protein S7 (RPS7), as a tumor suppressor, to regulate glucose metabolism. Silencing of RPS7 rescued the effects of barasertib on glucose metabolism in GC cells. Overexpression of RPS7 suppressed the promoter activity of C-Myc, which has been identified as an important regulator of glucose metabolism in cancer cells. The clinical data showed that the expression level of AURKB in GC patients' sera and tissues were positively correlated with those of C-Myc, GLUT1 and LDHA, but negatively with that of RPS7. Therefore, these findings provide new evidence that barasertib regulates GC cell glucose metabolism by inducing the RPS7/C-Myc signal pathway, and have important implications for the development of therapeutic approaches using AURKB as a target protein to prevent tumor recurrence.

Hydra: A mixture modeling framework for subtyping pediatric cancer cohorts using multimodal gene expression signatures

Precision oncology has primarily relied on coding mutations as biomarkers of response to therapies. While transcriptome analysis can provide valuable information, incorporation into workflows has been difficult. For example, the relative rather than absolute gene expression level needs to be considered, requiring differential expression analysis across samples. However, expression programs related to the cell-of-origin and tumor microenvironment effects confound the search for cancer-specific expression changes. To address these challenges, we developed an unsupervised clustering approach for discovering differential pathway expression within cancer cohorts using gene expression measurements. The hydra approach uses a Dirichlet process mixture model to automatically detect multimodally distributed genes and expression signatures without the need for matched normal tissue. We demonstrate that the hydra approach is more sensitive than widely-used gene set enrichment approaches for detecting multimodal expression signatures. Application of the hydra analysis framework to small blue round cell tumors (including rhabdomyosarcoma, synovial sarcoma, neuroblastoma, Ewing sarcoma, and osteosarcoma) identified expression signatures associated with changes in the tumor microenvironment. The hydra approach also identified an association between ATRX deletions and elevated immune marker expression in high-risk neuroblastoma. Notably, hydra analysis of all small blue round cell tumors revealed similar subtypes, characterized by changes to infiltrating immune and stromal expression signatures.

The therapeutic potential of Aurora kinases targeting in glioblastoma: from preclinical research to translational oncology

Glioblastoma is the most common aggressive primary brain tumor. Standard care includes maximal safe surgical resection, radiation, and chemotherapy with temozolomide. However, the impact of this therapeutic approach on patient survival is disappointing and poor outcomes are frequently observed. Therefore, new therapeutic targets are needed to treat this potentially deadly tumor. Aurora kinases are one of today's most sought-after classes of therapeutic targets to glioblastoma therapy. They are a family of proteins composed of three members: Aurora-A, Aurora-B, and Aurora-C that play different roles in the cell division through regulation of chromosome segregation. Deregulation of these genes has been reported in glioblastoma and a progressive number of studies have shown that inhibition of these proteins could be a promising strategy for the treatment of this tumor. This review discusses the preclinical and early clinical findings on the potential use of the Aurora kinases as new targets for the treatment of glioblastoma. KEY MESSAGES: GBM is a very aggressive tumor with limited therapeutic options. Aurora kinases are a family of serine/threonine kinases implicated in GBM pathology. Aurora kinases are critical for glioblastoma cell growth, apoptosis, and chemoresistance. Inhibition of Aurora kinases has a synergistic or sensitizing effect with chemotherapy drugs, radiotherapy, or with other targeted molecules in GBM. Several Aurora kinase inhibitors are currently in clinical trials.

TAp63-Regulated miRNAs Suppress Cutaneous Squamous Cell Carcinoma through Inhibition of a Network of Cell-Cycle Genes

TAp63 is a p53 family member and potent tumor and metastasis suppressor. Here, we show that TAp63^-/- mice exhibit an increased susceptibility to ultraviolet radiation-induced cutaneous squamous cell carcinoma (cuSCC). A human-to-mouse comparison of cuSCC tumors identified miR-30c-2* and miR-497 as underexpressed in TAp63-deficient cuSCC. Reintroduction of these miRNAs significantly inhibited the growth of cuSCC cell lines and tumors. Proteomic profiling of cells expressing either miRNA showed downregulation of cell-cycle progression and mitosis-associated proteins. A mouse to human and cross-platform comparison of RNA-sequencing and proteomics data identified a 7-gene signature, including AURKA, KIF18B, PKMYT1, and ORC1, which were overexpressed in cuSCC. Knockdown of these factors in cuSCC cell lines suppressed tumor cell proliferation and induced apoptosis. In addition, selective inhibition of AURKA suppressed cuSCC cell proliferation, induced apoptosis, and showed antitumor effects in vivo. Finally, treatment with miR-30c-2* or miR-497 miRNA mimics was highly effective in suppressing cuSCC growth in vivo. Our data establish TAp63 as an essential regulator of novel miRNAs that can be therapeutically targeted for potent suppression of cuSCC. SIGNIFICANCE: This study provides preclinical evidence for the use of miR-30c-2*/miR-497 delivery and AURKA inhibition in the treatment of cuSCC, which currently has no FDA-approved targeted therapies.See related commentary by Parrales and Iwakuma, p. 2439.

Higher AURKA and PLK1 expression are associated with inferior overall survival in patients with myelofibrosis

Aurora-kinase-A (AURKA), BORA and Polo-like-kinase-1 (PLK1) are regulating cell-cycle control and promotion of mitosis entry. AURKA contributes to Janus-kinase-2 (JAK2) activation and increased AURKA protein levels were reported in CD34+ and CD41+ cells of myeloproliferative neoplasm patients, leading to aneuploidy and aberrant megakaryopoiesis. We aimed to investigate AURKA, BORA and PLK1 mRNA expression in unfractionated bone-marrow aspirates of 43 patients with myelofibrosis (28 primary-/PMF, 15 secondary-myelofibrosis/SMF) and 12 controls and to assess their clinical correlations. AURKA expression did not significantly differ between myelofibrosis and controls (P = 0.466). Higher AURKA expression was significantly associated with higher absolute monocyte-count (P = 0.024) and shorter overall survival (HR = 3.77; P = 0.012). Patients with both PMF and SMF had lower BORA expression than controls (P = 0.009). Higher BORA expression was significantly associated with absence of constitutional symptoms (P = 0.049), absence of circulatory blasts (P = 0.047), higher monocyte- (P = 0.040) and higher eosinophil-counts (P = 0.016) and had neutral effect on survival (P > 0.05). PLK1 expression did not significantly differ between myelofibrosis and controls (P = 0.103). Higher PLK1 expression was significantly associated with higher white-blood-cell-count (P = 0.042) and inferior overall survival (HR = 5.87; P = 0.003). In conclusion, AURKA, BORA and PLK1 are involved in pathogenesis of myelofibrosis and may affect survival. Future studies investigating these interesting associations are warranted.

Design, synthesis, biological evaluation of 6-(2-amino-1H-benzo[d]imidazole-6-yl)quinazolin-4(3H)-one derivatives as novel anticancer agents with Aurora kinase inhibition

Aurora A kinase, a member of the Aurora kinase family, is frequently overexpressed in various human cancers. In addition, Overexpression of Aurora A kinase is associated with drug resistance and poor prognosis in many cancers including breast cancer. Therefore, Aurora A kinase has been considered as an attractive anticancer target for the treatment of human cancers. Herein, A series of 6-(2-amino-1H-benzo[d]imidazole-6-yl)quinazolin-4(3H)-one derivatives were designed, synthesized, and evaluated as Aurora A kinase inhibitors. The cell-based cytotoxicity assays showed that compound 16h was the most potent cytotoxic agent against all tested cancer cells and had a lower IC₅₀ value than ENMD-2076 against MDA-MB-231 cells. Meanwhile, Aurora A kinase assay and Western blot analysis showed that 16h inhibited Aurora A kinase with an IC₅₀ value of 21.94 nM and suppressed the phosphorylation of Histone H3 on Ser10 and Aurora A kinase on Thr288, which were consistent with the activation of Aurora A kinase. Accordingly, 16h caused aberrant mitotic phenotypes and obvious G2/M phase arrest in MDA-MB-231 cells and induced caspase-dependent apoptosis in MDA-MB-231 cells. These results demonstrated that 16h is a potential candidate for the development of anticancer agents targeting Aurora A kinase.

Bcl2l10 mediates the proliferation, invasion and migration of ovarian cancer cells

Bcl2l10, also known as Diva, Bcl‑b and Boo, is a member of the Bcl2 family of proteins, which are involved in signaling pathways that regulate cell apoptosis and autophagy. Previously, it was demonstrated that Bcl2l10 plays a crucial role in the completion of oocyte meiosis and is a key regulator of Aurora kinase A (Aurka) expression and activity in oocytes. Aurka is overexpressed in several types of solid tumors and has been considered a target of cancer therapy. Based on these previous results, in the present study, the authors aimed to investigate the regulatory role of Bcl2l10 in A2780 and SKOV3 human ovarian cancer cells. The protein expression of Bcl2l10 was examined in human cancer tissues and cell lines, including the ovaries, using a tissue microarray and various human ovarian cancer cell lines. It was found that Bcl2l10 regulated the protein stability and activities of Aurka in ovarian cancer cells. Although apoptosis was not affected, the cell cycle was arrested at the G0/G1 phase by Bcl2l10 knockdown. Of note, cell viability and motility were markedly increased by Bcl2l10 knockdown. On the whole, the findings of this study suggest that Bcl2l10 functions as tumor suppressor gene in ovarian cancer.

Inhibition of Aurora A enhances radiosensitivity in selected lung cancer cell lines

Background

In mammalian cells, Aurora serine/threonine kinases (Aurora A, B, and C) are expressed in a cell cycle-dependent fashion as key mitotic regulators required for the maintenance of chromosomal stability. Aurora-A (AURKA) has been proven to be an oncogene in a variety of cancers; however, whether its expression relates to patient survival and the association with radiotherapy remains unclear in non-small cell lung cancer (NSCLC).

Methods

Here, we first analyzed AURKA expression in 63 NSCLC tumor samples by immunohistochemistry (IHC) and used an MTS assay to compare cell survival by targeting AURKA with MLN8237 (Alisertib) in H460 and HCC2429 (P53-competent), and H1299 (P53-deficient) cell lines. The radiosensitivity of MLN8237 was further evaluated by clonogenic assay. Finally, we examined the effect of combining radiation and AURKA inhibition in vivo with a xenograft model and explored the potential mechanism.

Results

We found that increased AURKA expression correlated with decreased time to progression and overall survival (p = 0.0447 and 0.0096, respectively). AURKA inhibition using 100 nM MLN8237 for 48 h decreases cell growth in a partially P53-dependent manner, and the survival rates of H460, HCC2429, and H1299 cells were 56, 50, and 77%, respectively. In addition, the survival of H1299 cells decreased 27% after ectopic restoration of P53 expression, and the radiotherapy enhancement was also influenced by P53 expression (DER H460 = 1.33; HCC2429 = 1.35; H1299 = 1.02). Furthermore, tumor growth of H460 was delayed significantly in a subcutaneous mouse model exposed to both MLN8237 and radiation.

Conclusions

Taken together, our results confirmed that the expression of AURKA correlated with decreased NSCLC patient survival, and it might be a promising inhibition target when combined with radiotherapy, especially for P53-competent lung cancer cells. Modulation of P53 function could provide a new option for reversing cell resistance to the AURKA inhibitor MLN8237, which deserves further investigation.

Characterization and risk association of polymorphisms in Aurora kinases A, B and C with genetic susceptibility to gastric cancer development

BACKGROUND

Single nucleotide polymorphisms (SNPs) in genes encoding mitotic kinases could influence development and progression of gastric cancer (GC).

METHODS

Case-control study of nine SNPs in mitotic genes was conducted using qPCR. The study included 116 GC patients and 203 controls. In silico analysis was performed to evaluate the effects of polymorphisms on transcription factors binding sites.

RESULTS

The AURKA rs1047972 genotypes (CT vs. CC: OR, 1.96; 95% CI, 1.05-3.65; p = 0.033; CC + TT vs. CT: OR, 1.94; 95% CI, 1.04-3.60; p = 0.036) and rs911160 (CC vs. GG: OR, 5.56; 95% CI, 1.24-24.81; p = 0.025; GG + CG vs. CC: OR, 5.26; 95% CI, 1.19-23.22; p = 0.028), were associated with increased GC risk, whereas certain rs8173 genotypes (CG vs. CC: OR, 0.60; 95% CI, 0.36-0.99; p = 0.049; GG vs. CC: OR, 0.38; 95% CI, 0.18-0.79; p = 0.010; CC + CG vs. GG: OR, 0.49; 95% CI, 0.25-0.98; p = 0.043) were protective. Association with increased GC risk was demonstrated for AURKB rs2241909 (GG + AG vs. AA: OR, 1.61; 95% CI, 1.01-2.56; p = 0.041) and rs2289590 (AC vs. AA: OR, 2.41; 95% CI, 1.47-3.98; p = 0.001; CC vs. AA: OR, 6.77; 95% CI, 2.24-20.47; p = 0.001; AA+AC vs. CC: OR, 4.23; 95% CI, 1.44-12.40; p = 0.009). Furthermore, AURKC rs11084490 (GG + CG vs. CC: OR, 1.71; 95% CI, 1.04-2.81; p = 0.033) was associated with increased GC risk. A combined analysis of five SNPs, associated with an increased GC risk, detected polymorphism profiles where all the combinations contribute to the higher GC risk, with an OR increased 1.51-fold for the rs1047972(CT)/rs11084490(CG + GG) to 2.29-fold for the rs1047972(CT)/rs911160(CC) combinations. In silico analysis for rs911160 and rs2289590 demonstrated that different transcription factors preferentially bind to polymorphic sites, indicating that AURKA and AURKB could be regulated differently depending on the presence of particular allele.

CONCLUSIONS

Our results revealed that AURKA (rs1047972 and rs911160), AURKB (rs2241909 and rs2289590) and AURKC (rs11084490) are associated with a higher risk of GC susceptibility. Our findings also showed that the combined effect of these SNPs may influence GC risk, thus indicating the significance of assessing multiple polymorphisms, jointly. The study was conducted on a less numerous but ethnically homogeneous Bosnian population, therefore further investigations in larger and multiethnic groups and the assessment of functional impact of the results are needed to strengthen the findings.

Emerging protein kinase inhibitors for the treatment of multiple myeloma

Introduction: Significant advances have been made during the last two decades in terms of new therapeutic options but also of innovative approaches to diagnosis and management of multiple myeloma (MM). While patient survival has been significantly prolonged, most patients relapse. Including the milestone approval of the first kinase inhibitor imatinib mesylate for CML in 2001, 48 small molecule protein kinase (PK) inhibitors have entered clinical practice until now. However, no PK inhibitor has been approved for MM therapy yet. Areas covered: This review article summarizes up-to-date knowledge on the pathophysiologic role of PKs in MM. Derived small molecules targeting receptor tyrosine kinases (RTKs), the Ras/Raf/MEK/MAPK- pathway, the PI3K/Akt/mTOR- pathway as well as Bruton tyrosine kinase (BTK), Aurora kinases (AURK), and cyclin-dependent kinases (CDKs) are most promising. Preclinical as well as early clinical data focusing on these molecules will be presented and critically reviewed. Expert opinion: Current MM therapy is directed against general vulnerabilities. Novel therapeutic strategies, inhibition of PKs in particular, are directed to target tumor-specific driver aberrations such as genetic abnormalities and microenvironment-driven deregulations. Results of ongoing Precision Medicine trials with PK inhibitors alone or in combination with other agents are eagerly awaited and hold the promise of once more improving MM patient outcome.

Optimization and biological evaluation of nicotinamide derivatives as Aurora kinase inhibitors

Aurora kinases are known to be overexpressed in various solid tumors and implicated in oncogenesis and tumor progression. A series of nicotinamide derivatives were synthesized and their biological activities were evaluated, including kinase inhibitory activity against Aur A and Aur B and in vitro antitumor activity against SW620, HT-29, NCI-H1975 and Hela cancer cell lines. In addition, the study of antiproliferation, cytotoxicity and apoptosis was performed meanwhile. As the most potent inhibitor of Aur A, 4-((3-bromo-4-fluorophenyl)amino)-6-chloro-N-(4-((6,7-dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)nicotinamide (10l) showed excellent antitumor activity against SW620 and NCI-H1975 with IC₅₀ values were 0.61 and 1.06 μM, while the IC₅₀ values of reference compound were 3.37 and 6.67 μM, respectively. Furthermore, binding mode studies indicated that compound 10l forms better interaction with Aur A.

Relation of AURKB over-expression to low survival rate in BCRA and reversine-modulated aurora B kinase in breast cancer cell lines

Background

New therapeutic drug for breast cancer (BRCA), especially triple negative BRCA (TNBC), is urgently needed. Even though 2-(4-morpholinoanilino)-6-cyclohexylaminopurine (reversine) is an aurora kinase inhibitor, it also inhibits some cancer cells and human BRCA cells. However, the potential roles of reversine as a novel therapeutic agent for the treatment of BRCA remains unknown and must be further investigation. Thus, the relationship of reversine to aurora kinase in BCRA has not been reported. The relationship between AURKB and survival rate in BRCA has never been reported. Herein, we tested the roles of reversine on different BRCA cell line subtypes. We also investigated the relationship between AURKB and survival rate in BRCA as well as reversine to Aurora kinase expression in BCRA cell lines, including TNBC subtype, 4T1, MDA-MB-231, and luminal subtype MCF-7.

Methods

Cell viability and apoptosis were detected using Cell Counting Kit-8 and flow cytometry analysis, respectively. Apoptotic and tumor-related proteins were tested using Western blot analysis. Important microRNAs that regulate BRCA were analyzed using RT-PCR. UALCAN public databases were used to analyze the targeted gene profiles, and the PROGgeneV2 database was used to study the prognostic implications of genes.

Results

Reversine inhibits cell proliferation and induces cell apoptosis by modulating caspase-3 and bax/bcl-2 among the three cell lines. Data from the UALCAN public database show that BRCA tissues expressed high gene levels of AURKB, TIMP1, MMP9, and TGFB1 compared with the normal tissue. Among the over-expressed genes in BRCA, AURKB ranks 9th in TNBC, 49th in luminal subtype, and 48th in HER2 subtype. High AURKB level in BRCA is highly related to the low survival rate in patients displayed in 18 databases searched via PROGgeneV2. The protein levels of aurora B kinase (Aurora B), which is encoded by AURKB gene, are highly suppressed by reversine in the three cell lines. The tumor-related proteins TGF-β1, TIMP1, and MMP9 are partially suppressed by reversine but with different sensitivity in the three cell lines. The reversine-affected microRNAs, such as miR129-5p, miR-199a-3p, and miR-3960, in MDA-MB-231 cell line might be the research targets in TNBC regulation.

Conclusions

In BRCA, the level of AURKB are over-expressed and is related to low survival rate. Reversine contributes to anti-growth effect in BRCA cell lines, especially for TNBC, by modulating the aurora B. However, the invasiveness, metastasis, and anti-tumor effects of reversine in vivo and in vitro must be further investigated.

A Phase II Study of Alisertib in Children with Recurrent/Refractory Solid Tumors or Leukemia: Children's Oncology Group Phase I and Pilot Consortium (ADVL0921)

PURPOSE

Aurora A kinase (AAK) plays an integral role in mitotic entry, DNA damage checkpoint recovery, and centrosome and spindle maturation. Alisertib (MLN8237) is a potent and selective AAK inhibitor. In pediatric preclinical models, antitumor activity was observed in neuroblastoma, acute lymphoblastic leukemia, and sarcoma xenografts. We conducted a phase 2 trial of alisertib in pediatric patients with refractory or recurrent solid tumors or acute leukemias (NCT01154816).

PATIENTS AND METHODS

Alisertib (80 mg/m2/dose) was administered orally, daily for 7 days every 21 days. Pharmacogenomic (PG) evaluation for polymorphisms in the AURK gene and drug metabolizing enzymes (UGT1A1*28), and plasma pharmacokinetic studies (PK) were performed. Using a 2-stage design, patients were enrolled to 12 disease strata (10 solid tumor and 2 acute leukemia). Response was assessed after cycle 1, then every other cycle.

RESULTS

A total of 139 children and adolescents (median age, 10 years) were enrolled, 137 were evaluable for response. Five objective responses were observed (2 complete responses and 3 partial responses). The most frequent toxicity was myelosuppression. The median alisertib trough concentration on day 4 was 1.3 μmol/L, exceeding the 1 μmol/L target trough concentration in 67% of patients. No correlations between PG or PK and toxicity were observed.

CONCLUSIONS

Despite alisertib activity in pediatric xenograft models and cogent pharmacokinetic-pharmacodynamic relationships in preclinical models and adults, the objective response rate in children and adolescents receiving single-agent alisertib was less than 5%.

Future Options of Molecular-Targeted Therapy in Small Cell Lung Cancer

Lung cancer is the leading cause of cancer-related deaths worldwide. With a focus on histology, there are two major subtypes: Non-small cell lung cancer (NSCLC) (the more frequent subtype), and small cell lung cancer (SCLC) (the more aggressive one). Even though SCLC, in general, is a chemosensitive malignancy, relapses following induction therapy are frequent. The standard of care treatment of SCLC consists of platinum-based chemotherapy in combination with etoposide that is subsequently enhanced by PD-L1-inhibiting atezolizumab in the extensive-stage disease, as the addition of immune-checkpoint inhibition yielded improved overall survival. Although there are promising molecular pathways with potential therapeutic impacts, targeted therapies are still not an integral part of routine treatment. Against this background, we evaluated current literature for potential new molecular candidates such as surface markers (e.g., DLL3, TROP-2 or CD56), apoptotic factors (e.g., BCL-2, BET), genetic alterations (e.g., CREBBP, NOTCH or PTEN) or vascular markers (e.g., VEGF, FGFR1 or CD13). Apart from these factors, the application of so-called 'poly-(ADP)-ribose polymerases' (PARP) inhibitors can influence tumor repair mechanisms and thus offer new perspectives for future treatment. Another promising therapeutic concept is the inhibition of 'enhancer of zeste homolog 2' (EZH2) in the loss of function of tumor suppressors or amplification of (proto-) oncogenes. Considering the poor prognosis of SCLC patients, new molecular pathways require further investigation to augment our therapeutic armamentarium in the future.

Allosteric Small-Molecule Serine/Threonine Kinase Inhibitors

Deregulation of protein kinase activity has been linked to many diseases ranging from cancer to AIDS and neurodegenerative diseases. Not surprisingly, drugging the human kinome - the complete set of kinases encoded by the human genome - has been one of the major drug discovery pipelines. Majority of the approved clinical kinase inhibitors target the ATP binding site of kinases. However, the remarkable sequence and structural similarity of ATP binding pockets of kinases make selective inhibition of kinases a daunting task. To circumvent these issues, allosteric inhibitors that target sites other than the orthosteric ATP binding pocket have been developed. The structural diversity of the allosteric sites allows these inhibitors to have higher selectivity, lower toxicity and improved physiochemical properties and overcome drug resistance associated with the use of conventional kinase inhibitors. In this chapter, we will focus on the allosteric inhibitors of selected serine/threonine kinases, outline the benefits of using these inhibitors and discuss the challenges and future opportunities.

Dual Targeting of Aurora Kinases with AMG 900 Exhibits Potent Preclinical Activity Against Acute Myeloid Leukemia with Distinct Post-Mitotic Outcomes

Aurora kinase A and B have essential and non-overlapping roles in mitosis, with elevated expression in a subset of human cancers, including acute myeloid leukemia (AML). In this study, pan-aurora kinase inhibitor (AKI) AMG 900 distinguishes itself as an anti-leukemic agent that is more uniformly potent against a panel of AML cell lines than are isoform-selective AKIs and classic AML drugs. AMG 900 inhibited AML cell growth by inducing polyploidization and/or apoptosis. AMG 900 and aurora-B-selective inhibitor AZD1152-hQPA showed comparable cellular effects on AML lines that do not harbor a FLT3-ITD mutation. AMG 900 was active against P-glycoprotein-expressing AML cells resistant to AZD1152-hQPA and was effective at inducing expression of megakaryocyte-lineage markers (CD41, CD42) on human CHRF-288-11 cells and mouse Jak2 V617F cells. In MOLM-13 cells, inhibition of p-histone H3 by AMG 900 was associated with polyploidy, extra centrosomes, accumulation of p53 protein, apoptosis, and cleavage of Bcl-2 protein. Co-administration of cytarabine (Ara-C) with AMG 900 potentiated cell killing in a subset of AML lines, with evidence of attenuated polyploidization. AMG 900 inhibited the proliferation of primary human bone marrow cells in culture, with a better proliferation recovery profile relative to classic antimitotic drug docetaxel. In vivo, AMG 900 significantly reduced tumor burden in a systemic MOLM-13 xenograft model where we demonstrate the utility of 3'-deoxy-3'-18F-fluorothymidine [18F]FLT positron emission tomographic (PET)-CT imaging to measure the antiproliferative effects of AMG 900 in skeletal tissues in mice.

Tumour treating fields in a combinational therapeutic approach

The standard of care for patients with newly diagnosed Glioblastoma multiforme (GBM) has remained unchanged since 2005, with patients undergoing maximal surgical resection, followed by radiotherapy plus concomitant and maintenance Temozolomide. More recently, Tumour treating fields (TTFields) therapy has become FDA approved for adult recurrent and adult newly-diagnosed GBM following the EF-11 and EF-14 trials, respectively. TTFields is a non-invasive anticancer treatment which utilizes medium frequency alternating electric fields to target actively dividing cancerous cells. TTFields selectively targets cells within mitosis through interacting with key mitotic proteins to cause mitotic arrest and cell death. TTFields therapy presents itself as a candidate for the combinational therapy route due to the lack of overlapping toxicities associated with electric fields. Here we review current literature pertaining to TTFields in combination with alkylating agents, radiation, anti-angiogenics, mitotic inhibitors, immunotherapies, and also with novel agents. This review highlights the observed synergistic and additive effects of combining TTFields with various other therapies, as well highlighting the strategies relating to combinations with electric fields.

A Clinical and Molecular Phase II Trial of Oral ENMD-2076 in Ovarian Clear Cell Carcinoma (OCCC): A Study of the Princess Margaret Phase II Consortium

PURPOSE

Patients with recurrent ovarian clear cell carcinoma (OCCC) have limited effective options due to chemoresistance. A phase II study was designed to assess the activity of ENMD-2076, an oral multitarget kinase selective against Aurora A and VEGFR.

PATIENTS AND METHODS

This multicenter phase II study included patients with recurrent OCCC who received prior platinum-based chemotherapy. Primary endpoints were objective response and 6-month progression-free survival (PFS) rates. Correlative analyses include ARID1A and PTEN expression by IHC and gene sequencing with a targeted custom capture next-generation sequencing panel.

RESULTS

Forty patients were enrolled with a median age of 54, of which 38 patients were evaluable. ENMD-2076 was well tolerated with main related grade 3 toxicities being hypertension (28%), proteinuria (10%), and diarrhea (10%). Best response was partial response for 3 patients (1 unconfirmed) and stable disease for 26 patients. The overall 6-month PFS rate was 22% and differed according to ARID1A expression (ARIDIA^- vs. ARID1A⁺; 33% vs. 12%, P = 0.023). PTEN-positive expression was observed in 20 of 36 patients, and there was no correlation with outcome. Median PFS in patients with PI3KCA wild-type versus PI3KCA-mutated group was 5 versus 3.7 months (P = 0.049). Molecular profiling showed variants in PI3KCA (27%), ARID1A (26%), and TP53 (7%). The patient with the longest treatment duration (22 months) was PTEN wild-type, diploid PTEN with putative biallelic inactivation of ARID1A.

CONCLUSIONS

Single-agent ENMD-2076 did not meet the preset bar for efficacy. Loss of ARID1A correlated with better PFS on ENMD-2076 and warrants further investigation as a potential predictive biomarker.

Dynamics of human protein kinase Aurora A linked to drug selectivity

Protein kinases are major drug targets, but the development of highly-selective inhibitors has been challenging due to the similarity of their active sites. The observation of distinct structural states of the fully-conserved Asp-Phe-Gly (DFG) loop has put the concept of conformational selection for the DFG-state at the center of kinase drug discovery. Recently, it was shown that Gleevec selectivity for the Tyr-kinase Abl was instead rooted in conformational changes after drug binding. Here, we investigate whether protein dynamics after binding is a more general paradigm for drug selectivity by characterizing the binding of several approved drugs to the Ser/Thr-kinase Aurora A. Using a combination of biophysical techniques, we propose a universal drug-binding mechanism, that rationalizes selectivity, affinity and long on-target residence time for kinase inhibitors. These new concepts, where protein dynamics in the drug-bound state plays the crucial role, can be applied to inhibitor design of targets outside the kinome.

Protein kinases are a family of enzymes found in all living organisms. These enzymes help to control many biological processes, including cell division. When particular protein kinases do not work correctly, cells may start to divide uncontrollably, which can lead to cancer. One example is the kinase Aurora A, which is over-active in many common human cancers. As a result, researchers are currently trying to design drugs that reduce the activity of Aurora A in the hope that these could form new anticancer treatments.

In general, drugs are designed to be as specific in their action as possible to reduce the risk of harmful side effects to the patient. Designing a drug that affects a single protein kinase, however, is difficult because there are hundreds of different kinases in the body, all with similar structures. Because drugs often work by binding to specific structural features, a drug that targets one protein kinase can often alter the activity of a large number of others too.

Gleevec is a successful anti-leukemia drug that specifically works on one target kinase, producing minimal side effects. It was recently discovered that the drug works through a phenomenon called ‘induced fit’. This means that after the drug binds it causes a change in the enzyme’s overall shape that alters the activity of the enzyme. The shape change is complex, and so even small structural differences can change the effect of a particular drug.

Do other drugs that target other protein kinases also produce induced fit effects? To find out, Pitsawong, Buosi, Otten, Agafonov et al. studied how three anti-cancer drugs interact with Aurora A: two drugs specifically designed to switch off Aurora A, and Gleevec (which does not target Aurora A).

The two drugs that specifically target Aurora A were thought to work by targeting one structural feature of the enzyme. However, the biochemical and biophysical experiments performed by Pitsawong et al. revealed that these drugs instead work through an induced fit effect. By contrast, Gleevec did not trigger an induced fit on Aurora A and so bound less tightly to it.

In light of these results, Pitsawong et al. suggest that future efforts to design drugs that target protein kinases should focus on exploiting the induced fit process. This will require more research into the structure of particular kinases.

AURKA Suppresses Leukemic THP-1 Cell Differentiation through Inhibition of the KDM6B Pathway

Aberrations in histone modifications are being studied in mixed-lineage leukemia (MLL)-AF9-driven acute myeloid leukemia (AML). In this study, we focused on the regulation of the differentiation of the MLL-AF9 type AML cell line THP-1. We observed that, upon phorbol 12-myristate 13-acetate (PMA) treatment, THP-1 cells differentiated into monocytes by down-regulating Aurora kinase A (AURKA), resulting in a reduction in H3S10 phosphorylation. We revealed that the AURKA inhibitor alisertib accelerates the expression of the H3K27 demethylase KDM6B, thereby dissociating AURKA and YY1 from the KDM6B promoter region. Using Flow cytometry, we found that alisertib induces THP-1 differentiation into monocytes. Furthermore, we found that treatment with the KDM6B inhibitor GSK-J4 perturbed the PMA-mediated differentiation of THP-1 cells. Thus, we discovered the mechanism of AURKA-KDM6B signaling that controls the differentiation of THP-1 cells, which has implications for biotherapy for leukemia.

Targeting hepatocarcinogenesis model in C56BL6 mice with pan-aurora kinase inhibitor Danusertib

Background: To elucidate the expression of Aurora kinases (AURK) and the anticancer effects of pan-aurora kinase inhibitor Danusertib in hepatocarcinogenesis model in C56Bl6 mice.

Methods: Thirty mice C56Bl6 were randomly divided into Group A or control, Group B animals who underwent experimental hepatocarcinogenesis with diethylnitrosamine (DEN), and Group C animals with DEN-induced hepatocarcinogenenesis that treated with pan-aurora kinase inhibitor Danusertib. Primary antibodies for immunochistochemistry (IHC) included rabbit antibodies against Ki-67, DKK1, INCENP, cleaved caspase-3, NF-κB p65, c-Jun, β-catenin. Hepatocyte growth factor receptor (C-MET/HGFR) and Bcl-2 antagonist of cell death (BAD) serum levels were determined using a quantitative sandwich enzyme immunoassay technique.

Results: Inhibition of AURK reduced the number of DEN-induced liver tumours. Apoptosis and proliferation was very low in both DEN-induced and anti- AURK groups respectively. The hepatocellular adenoma cells of DEN-treated mice uniformly had ample nuclear INCENP whereas in anti- AURK markedly decreased. Expression of β-catenin, NF-kB and c-Jun did not differ in liver tumors of both AURK -depleted and non-depleted mice.

Conclusions: Depletion of AURK reduced the number of DEN-induced hepatic tumours. However, their size did not differ significantly between the groups.