Search Results (81)

Aurora kinase B (AURKB), a serine/threonine protein kinase, is essential for accurate chromosome segregation and cytokinesis during mitosis. Dysregulation of AURKB, often characterized by its overexpression, has been implicated in various malignancies, including breast cancer. However, the mechanisms governing its dysregulation remain incompletely understood. Here, we identify a pivotal role for the MOF/MSL complex—which includes the histone acetyltransferase MOF (KAT8)—in modulating AURKB stability through acetylation at lysine 215 (K215). This post-translational modification inhibits AURKB ubiquitination, thereby stabilizing its protein levels. MOF/MSL-mediated AURKB stabilization promotes the proper assembly of the chromosomal passenger complex (CPC), ensuring mitotic fidelity. Notably, inhibition of MOF reduces AURKB K215 acetylation, leading to decreased AURKB expression and activity. Consequently, this downregulation suppresses expression of the downstream oncogene c-MYC, ultimately attenuating the malignant proliferation of breast cancer cells. Collectively, our findings reveal a novel mechanism by which lysine acetylation regulates AURKB stability, highlight the significance of the MOF-AURKB-c-MYC axis in breast cancer progression, and suggest potential therapeutic strategies targeting this pathway in clinical settings. Full article

Background: The treatment landscape for multiple myeloma (MM) has significantly evolved in recent decades with novel therapies like proteasome inhibitors, immunomodulatory drugs and monoclonal antibodies. However, MM remains incurable, necessitating new pharmacological strategies. Mitotic kinases, such as Aurora proteins, have emerged as potential targets. Selective inhibitors of Aurora A and B,- alisertib (MLN8237) and barasertib (AZD1152), respectively, have shown anti-myeloma activity in preclinical studies, with alisertib demonstrating modest efficacy in early clinical trials. Methods and Results: This study investigated the mechanisms of action of alisertib and barasertib and their combination with antitumor agents in a panel of five MM cells lines. Both drugs induced cell cycle arrest phase and abnormal nuclear morphologies. Alisertib caused prolonged mitotic arrest, whereas barasertib induced transient arrest, both resulting in the activation of mitotic catastrophe. These findings revealed three potential outcomes: cell death, senescence, or polyploidy. High mitochondrial reactive oxygen species (mROS) were identified as possible drivers of cell death. Caspase inhibition reduced caspase-3 activation but did not prevent cell death. Interestingly, alisertib at low doses remained toxic to Bax/Bak^DKO cells, although mitochondrial potential disruption and cytochrome c release were observed. Sequential combinations of high-dose Aurora kinase inhibitors with BH3-mimetics, and in specific cases with panobinostat, showed a synergistic effect. Conversely, the simultaneous combination of alisertib and barasertib showed mostly antagonistic effects. Conclusions: Alisertib and barasertib emerge as potential in vitro candidates against MM, although further studies are needed to validate their efficacy and to find the best combinations with other molecules. Full article

Alveolar rhabdomyosarcoma (ARMS) is a highly aggressive pediatric soft-tissue sarcoma driven by PAX3/7-FOXO1 fusion proteins. Despite intensive multimodal therapy, outcomes remain poor for patients with fusion-positive ARMS. This review integrates recent advances in the molecular pathogenesis of ARMS, highlighting key diagnostic and therapeutic targets. We discuss the central role of fusion proteins in transcriptional reprogramming, impaired myogenic differentiation, and super-enhancer activation. Emerging biomarkers (YAP, TFAP2B, P-cadherin) and oncogenic kinases (Aurora A, CDK4, PLK1) are evaluated alongside receptor tyrosine kinases (FGFR, MET) and transcription factors involved in metabolic rewiring (FOXF1, ETS1). Additionally, we examine immunotherapeutic strategies, epigenetic modifiers, and noncoding RNAs as potential therapeutic avenues. Together, these insights provide a comprehensive framework for developing biomarker-guided, multi-targeted therapies to improve outcomes in ARMS. Full article

Epithelial ovarian cancer (EOC) exhibits a unique mode of metastasis, involving spheroid formation in the peritoneum. Our research on EOC spheroid cell biology has provided valuable insights into the signaling plasticity associated with metastasis. We speculate that EOC cells modify their biology between tumour and spheroid states during cancer dormancy, although the specific mechanisms underlying this transition remain unknown. Here, we present novel findings from direct comparisons between cultured EOC spheroids and organoids. Our results indicated that AMP-activated protein kinase (AMPK) activity was significantly upregulated and protein kinase B (Akt) was downregulated in EOC spheroids compared to organoids, suggesting a clear differential phenotype. Through RNA sequencing analysis, we further supported these phenotypic differences and highlighted the significance of cell cycle regulation in organoids. By inhibiting the G2/M checkpoint via kinase inhibitors, we confirmed that this pathway is essential for organoids. Interestingly, our results suggest that specifically targeting aurora kinase A (AURKA) may represent a promising therapeutic strategy since our cells were equally sensitive to Alisertib treatment as both spheroids and organoids. Our findings emphasize the importance of studying cellular adaptations of EOC cells, as there may be different therapeutic targets depending on the step of EOC disease progression. Full article

Background: Aurora kinase B (AurB) is a pivotal regulator of mitosis, making it a compelling target for cancer therapy. Despite significant advances in protein kinase inhibitor development, there are currently no AurB inhibitors readily available for therapeutic use. Methods: This study introduces a machine learning-assisted drug repurposing framework integrating quantitative structure-activity relationship (QSAR) modeling, molecular fingerprints-based classification, molecular docking, and molecular dynamics (MD) simulations. Using this pipeline, we analyzed 4680 investigational and approved drugs from DrugBank database. Results: The machine learning models trained for drug repurposing showed satisfying performance and yielded the identification of saredutant, montelukast, and canertinib as potential AurB inhibitors. The candidates demonstrated strong binding energies, key molecular interactions with critical residues (e.g., Phe88, Glu161), and stable MD trajectories, particularly saredutant, a neurokinin-2 (NK2) antagonist. Conclusions: Beyond identifying potential AurB inhibitors, this study highlights an integrated methodology that can be applied to other challenging drug targets. Full article

Survivin is known for its dual biological role in apoptosis inhibition and mitotic progression. In addition to its being part of the chromosomal passenger complex (CPC), recent findings suggest additional roles for Survivin in the DNA damage response, further contributing to therapy resistance. In this study, we investigated the role of Survivin and the CPC proteins in the cellular response to irradiation with a focus on DNA replication processes. As is known, ionizing radiation leads to an increased expression of Survivin and its accumulation in nuclear foci, which we now know to be specifically localized to centromeric heterochromatin. The depletion of Survivin and Aurora B increases the DNA damage marker γH2AX, indicative of an impaired repair capacity. The presence of Survivin and the CPC in nuclear foci that we already identified during the S phase co-localize with the proliferating cell nuclear antigen (PCNA), further implying a potential role during replication. Indeed, Survivin knockdown reduced replication fork speed as assessed via DNA fiber assays. Mechanistically, we identified a PIP-box motif in INCENP mediating the interaction with PCNA to assist in managing damage-induced replication stress. Survivin depletion forces cells to undergo unphysiological genome replication via mitotic DNA synthesis (MiDAS), resulting in chromosome breaks. Finally, we revealed that Aurora B kinase liberates Pol η by phosphorylating polymerase delta-interacting protein 2 (POLDIP2) to resume the replication of damaged sites via translesion synthesis. In this study, we assigned a direct function to the CPC in the transition from stalled replication forks to translesion synthesis, further emphasizing the ubiquitous overexpression of Survivin particularly in tumors. This study, for the first time, assigns a direct function to the chromosomal passenger complex, CPC, including Survivin, Aurora B kinase, Borealin, and INCENP, in the transition from stalled replication forks (involving PCNA binding) to translesion synthesis (liberating Pol η by phosphorylating POLDIP2), and thus in maintaining genomic integrity. Full article

The centrosome of the amoebozoan model Dictyostelium discoideum provides the best-established model for an acentriolar centrosome outside the Opisthokonta. Dictyostelium exhibits an unusual centrosome cycle, in which duplication is initiated only at the G2/M transition and occurs entirely during the M phase. Little is known about the role of conserved centrosomal kinases in this process. Therefore, we have generated knock-in strains for Aurora (AurK), CDK1, cyclin B, Nek2, and Plk, replacing the endogenous genes with constructs expressing the respective green fluorescent Neon fusion proteins, driven by the endogenous promoters, and studied their behavior in living cells. Our results show that CDK1 and cyclin B arrive at the centrosome first, already during G2, followed by Plk, Nek2, and AurK. Furthermore, CDK1/cyclin B and AurK were dynamically localized at kinetochores, and AurK in addition at nucleoli. The putative roles of all four kinases in centrosome duplication, mitosis, cytokinesis, and nucleolar dynamics are discussed. Full article

Aurora kinase A (AURKA) is a serine/threonine-protein kinase that regulates microtubule organization during neuron migration and neurite formation. Decreased activity of AURKA was found in Alzheimer’s disease (AD) brain samples, but little is known about the role of AURKA in AD pathogenesis. Here, we demonstrate that AURKA is expressed in primary cultured rat neurons, neurons from adult mouse brains, and neurons in postmortem human AD brains. AURKA phosphorylation, which positively correlates with its activity, is reduced in human AD brains. In SH-SY5Y cells, pharmacological activation of AURKA increased AURKA phosphorylation, acidified endolysosomes, decreased the activity of amyloid beta protein (Aβ) generating enzyme β-site amyloid precursor protein cleaving enzyme (BACE-1), increased the activity of the Aβ degrading enzyme cathepsin D, and decreased the intracellular and secreted levels of Aβ. Conversely, pharmacological inhibition of AURKA decreased AURKA phosphorylation, de-acidified endolysosomes, decreased the activity of cathepsin D, and increased intracellular and secreted levels of Aβ. Thus, reduced AURKA activity in AD may contribute to the development of intraneuronal accumulations of Aβ and extracellular amyloid plaque formation. Full article

Many proteins regulating mitosis have emerged as targets for cancer therapy, including the kinesin spindle protein (KSP) and Aurora kinase B (AurB). KSP is crucial for proper spindle pole separation during mitosis, while AurB plays roles in chromosome segregation and cytokinesis. Agents targeting KSP and AurB selectively affect dividing cells and have shown significant activity in vitro. However, these drugs, despite advancing to clinical trials, often yield unsatisfactory outcomes as monotherapy, likely due to variable responses driven by cyclin B degradation and apoptosis signal accumulation networks. Accumulated data suggest that combining emerging antimitotics with various cytostatic drugs can enhance tumor-killing effects compared to monotherapy. Here, we investigated the impact of inhibiting anti-apoptotic signals with the BH3-mimetic Navitoclax in oral cancer cells treated with the selective KSP inhibitor, Ispinesib, or AurB inhibitor, Barasertib, aiming to potentiate cell death. The combination of BH3-mimetics with both KSP and AurB inhibitors synergistically induced substantial cell death, primarily through apoptosis. A mechanistic analysis underlying this synergistic activity, undertaken by live-cell imaging, is presented. Our data underscore the importance of combining BH3-mimetics with antimitotics in clinical trials to maximize their effectiveness. Full article

Primary antibodies are one of the main tools used in molecular biology research. However, the often-occurring cross-reactivity of primary antibodies complicates accurate data analysis. Our results show that three commercial polyclonal antibodies raised against N-6 adenine-specific DNA methyltransferase 1 (N6AMT1) strongly cross-react with endogenous and recombinant mitosis-associated protein Aurora kinase A (AURKA). The cross-reactivity was verified through immunofluorescence, immunoblot, and immunoprecipitation assays combined with mass spectrometry. N6AMT1 and AURKA are evolutionarily conserved proteins that are vital for cellular processes. Both proteins share the motif ENNPEE, which is unique to only these two proteins. We suggest that N6AMT1 antibodies recognise this motif in N6AMT1 and AURKA proteins and exhibit an example of “specific” non-specificity. This serves as an example of the importance of controls and critical data interpretation in molecular biology research. Full article

Glioblastoma (GBM), the most frequent and lethal brain cancer in adults, is characterized by short survival times and high mortality rates. Due to the resistance of GBM cells to conventional therapeutic treatments, scientific interest is focusing on the search for alternative and efficient adjuvant treatments. S-Adenosylmethionine (AdoMet), the well-studied physiological methyl donor, has emerged as a promising anticancer compound and a modulator of multiple cancer-related signaling pathways. We report here for the first time that AdoMet selectively inhibited the viability and proliferation of U87MG, U343MG, and U251MG GBM cells. In these cell lines, AdoMet induced S and G2/M cell cycle arrest and apoptosis and downregulated the expression and activation of proteins involved in homologous recombination DNA repair, including RAD51, BRCA1, and Chk1. Furthermore, AdoMet was able to maintain DNA in a damaged state, as indicated by the increased γH2AX/H2AX ratio. AdoMet promoted mitotic catastrophe through inhibiting Aurora B kinase expression, phosphorylation, and localization causing GBM cells to undergo mitotic catastrophe-induced death. Finally, AdoMet inhibited DNA repair and induced cell cycle arrest, apoptosis, and mitotic catastrophe in patient-derived GBM cells. In light of these results, AdoMet could be considered a potential adjuvant in GBM therapy. Full article

Androgen receptor signaling regulates the normal and pathological growth of the prostate. In particular, the growth and survival of prostate cancer cells is initially dependent on androgen receptor signaling. Exposure to androgen deprivation therapy leads to the development of castration-resistant prostate cancer. There is a multitude of molecular and cellular changes that occur in prostate tumor cells, including the expression of neuroendocrine features and various biomarkers, which promotes the switch of cancer cells to androgen-independent growth. These biomarkers include transcription factors (TP53, REST, BRN2, INSM1, c-Myc), signaling molecules (PTEN, Aurora kinases, retinoblastoma tumor suppressor, calcium-binding proteins), and receptors (glucocorticoid, androgen receptor-variant 7), among others. It is believed that genetic modifications, therapeutic treatments, and changes in the tumor microenvironment are contributing factors to the progression of prostate cancers with significant heterogeneity in their phenotypic characteristics. However, it is not well understood how these phenotypic characteristics and molecular modifications arise under specific treatment conditions. In this work, we summarize some of the most important molecular changes associated with the progression of prostate cancers and we describe some of the factors involved in these cellular processes. Full article

Silkworm ovary-derived BmN4 cells rely on chromatin-induced spindle assembly to form microtubule-based square mitotic spindles that ensure accurate segregation of holocentric chromosomes during cell division. The chromosome passenger protein Aurora B regulates chromosomal condensation and segregation, spindle assembly checkpoint activation, and cytokinesis; however, its role in holocentric organisms needs further clarification. This study examined the architecture and dynamics of spindle microtubules during prophase and metaphase in BmN4 cells and those with siRNA-mediated BmAurora B knockdown using immunofluorescence labeling. Anti-α-tubulin and anti-γ-tubulin antibodies revealed faint γ-tubulin signals colocalized with α-tubulin in early prophase during nuclear membrane rupture, which intensified as prophase progressed. At this stage, bright regions of α-tubulin around and on the nuclear membrane surrounding the chromatin suggested the start of microtubules assembling in the microtubule-organizing centers (MTOCs). In metaphase, fewer but larger γ-tubulin foci were detected on both sides of the chromosomes. This resulted in a distinctive multipolar square spindle with holocentric chromosomes aligned at the metaphase plate. siRNA-mediated BmAurora B knockdown significantly reduced the γ-tubulin foci during prophase, impacting microtubule nucleation and spindle structure in metaphase. Spatiotemporal BmAurora B expression analysis provided new insights into the regulation of this mitotic kinase in silkworm larval gonads during gametogenesis. Our results suggest that BmAurora B is crucial for the formation of multipolar square spindles in holocentric insects, possibly through the activation of γ-tubulin ring complexes in multiple centrosome-like MTOCs. Full article

Ewing sarcoma (EWS) is an aggressive pediatric malignancy of the bone and soft tissues in need of novel therapeutic options. To identify potential therapeutic targets, we focused on essential biological pathways that are upregulated by EWS-FLI1, the primary oncogenic driver of EWS, including mitotic proteins such as Aurora kinase A (AURKA) and kinesin family member 15 (KIF15) and its binding partner, targeting protein for Xklp2 (TPX2). KIF15/TPX2 cooperates with KIF11, a key mitotic kinesin essential for mitotic spindle orientation. Given the lack of clinical-grade KIF15/TPX2 inhibitors, we chose to target KIF11 (using SB-743921) in combination with AURKA (using VIC-1911) given that phosphorylation of KIF15^S1169 by Aurora A is required for its targeting to the spindle. In vitro, the drug combination demonstrated strong synergy (Bliss score ≥ 10) at nanomolar doses. Colony formation assay revealed significant reduction in plating efficiency (1–3%) and increased percentage accumulation of cells in the G2/M phase with the combination treatment (45–52%) upon cell cycle analysis, indicating mitotic arrest. In vivo studies in EWS xenograft mouse models showed significant tumor reduction and overall effectiveness: drug combination vs. vehicle control (p ≤ 0.01), SB-743921 (p ≤ 0.01) and VIC-1911 (p ≤ 0.05). Kaplan–Meier curves demonstrated superior overall survival with the combination compared to vehicle or monotherapy arms (p ≤ 0.0001). Full article

A wide panel of microtubule-associated proteins and kinases is involved in coordinated regulation of the microtubule cytoskeleton and may thus represent valuable molecular markers contributing to major cellular pathways deregulated in cancer. We previously identified a panel of 17 microtubule-related (MT-Rel) genes that are differentially expressed in breast tumors showing resistance to taxane-based chemotherapy. In the present study, we evaluated the expression, prognostic value and functional impact of these genes in breast cancer. We show that 14 MT-Rel genes (KIF4A, ASPM, KIF20A, KIF14, TPX2, KIF18B, KIFC1, AURKB, KIF2C, GTSE1, KIF15, KIF11, RACGAP1, STMN1) are up-regulated in breast tumors compared with adjacent normal tissue. Six of them (KIF4A, ASPM, KIF20A, KIF14, TPX2, KIF18B) are overexpressed by more than 10-fold in tumor samples and four of them (KIF11, AURKB, TPX2 and KIFC1) are essential for cell survival. Overexpression of all 14 genes, and underexpression of 3 other MT-Rel genes (MAST4, MAPT and MTUS1) are associated with poor breast cancer patient survival. A Systems Biology approach highlighted three major functional networks connecting the 17 MT-Rel genes and their partners, which are centered on spindle assembly, chromosome segregation and cytokinesis. Our studies identified mitotic Aurora kinases and their substrates as major targets for therapeutic approaches against breast cancer. Full article