bims-micesi 2025-07-13 papers

bims-micesi

Biomed News

on Mitotic cell signalling

Issue of 2025–07–13
seventeen papers selected by
Valentina Piano, Uniklinik Köln

High-throughput screening identifies a previously undescribed checkpoint controlling mitotic progression in response to DNA damage.
The mitotic chromosome periphery modulates chromosome mechanics.
Time as a danger signal promoting G1 arrest after mitosis.
Dynamic regulation of Sec24C by phosphorylation and O-GlcNAcylation during cell cycle progression.
Confinement in fibrous environments positions and orients mitotic spindles.
CDK-driven phosphorylation of TRAIP is essential for mitotic replisome disassembly and MiDAS.
Centrosome‑, mitotic spindle‑ and cytokinetic bridge‑specific compartmentalization of AGO2 protein in human liver cells undergoing mitosis: Non‑canonical, RNAi‑dependent, control of local homeostasis.
Semiautomatic quantification of 3D Histone H3 phosphorylation signals during cell division in Arabidopsis root meristems.
Nondisruptive inducible labeling of ER-membrane contact sites using the Lamin B receptor.
A mitotic bookmark coordinates transcription and replication.
Structural basis for a nucleoporin exportin complex between RanBP2, SUMO1-RanGAP1, the E2 Ubc9, Crm1 and the Ran GTPase.
Mitosis detection in histopathological images using customized deep learning and hybrid optimization algorithms.
L-2-hydroxyglutarate regulates centromere and heterochromatin conformation in the male germline.
Tankyrase activity is essential for asymmetric division and chromosome segregation in oocyte meiosis.
Rsk2 inhibition induces an aneuploid post-mitotic arrest of cell cycle progression in osteosarcoma cells.
CDKN1B (p27/kip1) enhances drug-tolerant persister CTCs by restricting polyploidy following mitotic inhibitors.
Zwilch kinetochore protein affects the prognosis of cancer patients by participating in cell proliferation, enhancing cell communication, and reshaping the tumor microenvironment.

FEBS J. 2025 Jul 10.

High-throughput screening identifies a previously undescribed checkpoint controlling mitotic progression in response to DNA damage.

Nan Li, Rachel Gatenby, Thomas Walne, Caroline Daye, Steven Watson, Priya Lata, Stephen Brown, Ruth Thompson.

  Following DNA damage, the cell cycle can be slowed or halted to allow for DNA repair. However, the mechanisms underpinning mitotic delay in response to DNA damage are unclear. Through an unbiased high-throughput screen, here, we have identified superoxide dismutase 1 (SOD1) as an essential factor mediating mitotic delay in response to DNA damage. Cells with damaged DNA arrest at metaphase, indicating involvement of the spindle assembly checkpoint (SAC); however, this response is lost following SOD1 depletion. Furthermore, whilst depletion of SAC proteins promotes rapid cell division (often less than 10 min) in all conditions, SOD1 depletion has no impact on mitotic progression either in unperturbed mitosis or in response to spindle poisons and does not decrease the mitotic transit time beyond the normal rate. Cells depleted of SOD1 display damaged centromeres and mitotic defects but no longer exhibit DNA-damage-induced mitotic delay. SOD1 has previously been shown to mediate redox control of phosphatases such as PP2a. In response to DNA damage, we observed elevated phosphorylation of SAC protein BubR1 and the kinetochore protein KNL1. Dephosphorylation of these proteins is required for SAC silencing, and PP2a has previously been implicated in this. Following SOD1 depletion, we observed elevated PP2a activity and decreased phosphorylation of BubR1 and KNL1. We propose that, in response to damage, SOD1 restrains PP2a activity, resulting in elevated BubR1 and KNL1 phosphorylation leading to persistent SAC activation.

Keywords:  DNA damage; SOD1; cell cycle; checkpoint; mitosis

DOI:  https://doi.org/10.1111/febs.70183
Nat Commun. 2025 Jul 10. 16(1): 6399

The mitotic chromosome periphery modulates chromosome mechanics.

Tania Mendonca, Roman Urban, Kellie Lucken, George Coney, Neil M Kad, Manlio Tassieri, Amanda J Wright, Daniel G Booth.

In dividing cells, chromosomes are coated in a sheath of proteins and RNA called the mitotic chromosome periphery. This sheath is thought to confer biophysical properties to chromosomes, critical for successful cell division. However, the details of chromosome mechanics, and specifically, if and how the chromosome periphery contributes to them, remain poorly understood. In this study, we present a comprehensive characterisation of single-chromosome mechanics using optical tweezers and an improved broadband microrheology analysis. We extend this analysis to direct measurements of the chromosome periphery by manipulating levels of Ki-67, its chief organiser, and apply a rheological model to isolate its contribution to chromosome mechanics. We report that the chromosome periphery governs dynamic self-reorganisation of chromosomes and acts as a structural constraint, providing force-damping properties. This work provides significant insight into chromosome mechanics and will inform our understanding of the mitotic chromosome periphery's role in cell division.

DOI: https://doi.org/10.1038/s41467-025-61755-5
Trends Cell Biol. 2025 Jul 07. pii: S0962-8924(25)00126-6. [Epub ahead of print]

Time as a danger signal promoting G1 arrest after mitosis.

Luke J Fulcher, Caleb Batley, Tomoaki Sobajima, Francis A Barr.

  Cell cycle checkpoints preventing the replication and inheritance of damaged DNA are crucial for maintaining genome stability and stopping the growth of damaged cells. Canonical checkpoints do this by preventing passage between cell cycle phases until damage has been repaired, or by promoting cell cycle exit. Herein we review checkpoint integration between cell cycle phases, specifically findings showing that extended spindle assembly checkpoint surveillance in mitosis is a danger signal triggering G1 cell cycle arrest. Evidence linking mitotic delays induced by activation of the spindle assembly checkpoint with positive and negative regulators of the G1 DNA damage checkpoint target p53 is discussed, with a focus on time-dependent changes to a p53-binding deubiquitinating complex USP28-53BP1 and the p53 ubiquitin-ligase mouse double minute homologue 2 (MDM2), respectively.

Keywords:  MDM2; aneuploidy; cell cycle; mitotic timer; p53; spindle assembly checkpoint

DOI:  https://doi.org/10.1016/j.tcb.2025.06.001
J Biol Chem. 2025 Jul 03. pii: S0021-9258(25)02306-3. [Epub ahead of print] 110456

Dynamic regulation of Sec24C by phosphorylation and O-GlcNAcylation during cell cycle progression.

George R Georgiou, Tetsuya Hirata, Erik Soderblom, Rose Homoelle, Jakob Maiwald, Michael Boyce.

  During mitosis, eukaryotic cells cease anterograde trafficking from the endoplasmic reticulum (ER) towards the Golgi. This cessation corresponds with the dispersal of the COPII transport protein, Sec24C, from juxtanuclear ER exit sites (ERES) into a diffusely cytosolic pool. Redistribution of Sec24 paralogs and other core COPII proteins may underlie the mitotic pause in secretion and may be required for the equal inheritance of endomembrane organelles and machinery by both daughter cells. Therefore, it is important to understand the mechanisms governing the mitotic relocalization of COPII components. Here, we explore the role of post-translational modifications (PTMs) of the model COPII protein Sec24C in this phenotypic switch during mitosis. In interphase, Sec24C is modified by O-linked β-N-acetylglucosamine (O-GlcNAc), and we show that this glycan is rapidly removed upon mitotic entry, influencing the timing of Sec24C dispersal. Additionally, we identify novel, cell cycle phase-enriched phosphorylation events on Sec24C, including phosphosites that regulate the stability and localization of the protein, providing the first systematic characterization of dynamic PTMs on any Sec24 protein. Together, our data support the hypothesis that phosphorylation and glycosylation of Sec24C act in concert to induce rapid dispersal upon mitotic entry and may promote equal partitioning of the endomembrane system to daughter cells after division.

Keywords:  COPII; O-GlcNAcylation; cell cycle; intracellular trafficking; mitosis; phosphorylation

DOI:  https://doi.org/10.1016/j.jbc.2025.110456
PNAS Nexus. 2025 Jul;4(7): pgaf201

Confinement in fibrous environments positions and orients mitotic spindles.

Apurba Sarkar, Aniket Jana, Atharva Agashe, Ji Wang, Rakesh Kapania, Nir S Gov, Jennifer G DeLuca, Raja Paul, Amrinder S Nain.

Accurate positioning of the mitotic spindle within the rounded cell body is critical to physiological maintenance. Mitotic cells encounter confinement from neighboring cells or the extracellular matrix (ECM), which can cause rotation of mitotic spindles and tilting of the metaphase plate (MP). To understand the effect of confinement on mitosis by fibers (ECM confinement), we use flexible ECM-mimicking nanofibers that allow natural rounding of the cell body while confining it to differing levels. Rounded mitotic bodies are anchored in place by actin retraction fibers (RFs) originating from adhesions on fibers. We discover that the extent of confinement influences RF organization in 3D, forming triangular and band-like patterns on the cell cortex under low and high confinement, respectively. Our mechanistic analysis reveals that the patterning of RFs on the cell cortex is the primary driver of the MP rotation. A stochastic Monte Carlo simulation of the centrosome, chromosome, membrane interactions, and 3D arrangement of RFs recovers MP tilting trends observed experimentally. Under high ECM confinement, the fibers can mechanically pinch the cortex, causing the MP to have localized deformations at contact sites with fibers. Interestingly, high ECM confinement leads to low and high MP tilts, which we mechanistically show to depend upon the extent of cortical deformation, RF patterning, and MP position. We identify that cortical deformation and RFs work in tandem to limit MP tilt, while asymmetric positioning of MP leads to high tilts. Overall, we provide fundamental insights into how mitosis may proceed in ECM-confining microenvironments in vivo.

DOI: https://doi.org/10.1093/pnasnexus/pgaf201
Nucleic Acids Res. 2025 Jul 08. pii: gkaf530. [Epub ahead of print]53(13):

CDK-driven phosphorylation of TRAIP is essential for mitotic replisome disassembly and MiDAS.

Divyasree Poovathumkadavil, Alicja Reynolds-Winczura, Aggeliki Skagia, Paolo Passaretti, Martina Muste Sadurni, Georgia Kingsley, Alexander Leitner, Marco Saponaro, Agnieszka Gambus.

Disassembly of the replication machinery (replisome) from chromatin is an active process driven by two ubiquitin ligases Cul2LRR1 and TRAIP, which both target the Mcm7 subunit of the replicative helicase for ubiquitylation. Uncontrolled unloading of replisomes during S-phase would be disastrous for genome stability and cell viability. On the other hand, replisomes retained on under-replicated DNA in mitosis require removal to allow access and processing of the DNA before cell division. TRAIP ubiquitylates replisomes in mitosis but can also act in specific situations during S-phase. However, we do not know how TRAIP's activity is regulated to stop uncontrolled replisome unloading. Here we show that TRAIP activity towards replisomes is not regulated at the level of interaction with the substrate: it interacts with terminated replisomes in S-phase without ubiquitylation. However, in mitosis, TRAIP is phosphorylated by cyclin-dependent kinases (CDKs) and this phosphorylation is essential for mitotic replisome unloading. CDK phosphorylation of TRAIP stimulates its autoubiquitylation activity and ubiquitylation of replisomes isolated from mitotic chromatin. The phosphorylation of TRAIP is also important in human cells for TRAIP functions during MiDAS. Although essential during mitosis, the CDK-driven phosphorylation of TRAIP is not sufficient to activate uncontrolled unloading of replisomes in S-phase.

DOI: https://doi.org/10.1093/nar/gkaf530
Mol Med Rep. 2025 Sep;pii: 244. [Epub ahead of print]32(3):

Centrosome‑, mitotic spindle‑ and cytokinetic bridge‑specific compartmentalization of AGO2 protein in human liver cells undergoing mitosis: Non‑canonical, RNAi‑dependent, control of local homeostasis.

Eleni I Theotoki, Panos Kakoulidis, Konstantinos-Stylianos Nikolakopoulos, Eleni N Vlachou, Ourania E Tsitsilonis, Gerassimos E Voutsinas, Ema Anastasiadou, Dimitrios J Stravopodis.

  Argonaute RNA‑induced silencing complex catalytic component 2 (AGO2) is an evolutionary conserved protein involved in microRNA‑dependent gene expression regulation via the RNA interference (RNAi) mechanism. Nevertheless, AGO2 may also be involved in other key processes, such as histone modification, DNA methylation and alternative splicing. Its role in the proper development of organisms is key and no homologue is able to compensate for its loss. Therefore, using advanced immunofluorescence, transient transfection and molecular bioinformatics, the present study aimed to investigate novel, non‑canonical, RNAi‑dependent functions of AGO2 protein in mRNA/protein local homeostasis. The data revealed microtubule network‑dependent, localization of AGO2 in both centrosome and mitotic spindle assemblies during cell division and in the cytokinetic bridge formed during the last stage of mitosis (cytokinesis). Detection of AGO2 protein in these mitosis‑specific compartments, regardless of the presence of malignant phenotypes or multiple centrosomes/mitotic spindles in liver cells, indicates the cardinal role of AGO2 in centrosome biosynthesis, mitotic spindle formation and function, potentially controlling locality‑dependent homeostasis, in a novel non‑canonical, RNAi‑dependent manner. This novel AGO2/centrosome/mitotic spindle/cytokinetic bridge pathway may serve as a versatile molecular 'toolbox' for targeted therapy of human malignancy, including liver cancer.

Keywords:  HepG2; LX‑2; RNA interference; argonaute2; centrosome; cytokinetic bridge; mitotic spindle

DOI:  https://doi.org/10.3892/mmr.2025.13609
New Phytol. 2025 Jul 07.

Semiautomatic quantification of 3D Histone H3 phosphorylation signals during cell division in Arabidopsis root meristems.

Adrienn Kelemen, Magalie Uyttewaal, Csaba Máthé, Philippe Andrey, David Bouchez, Martine Pastuglia.

  Posttranslational modification of histones during the cell cycle is a major process controlling many aspects of cell division. Among the variety of histone modifications, mitotic phosphorylation of histone H3 at serine 10 (H3S10ph) plays a crucial role, particularly in proper chromosome segregation. Here we aimed at precisely quantifying this phosphorylation dynamics during mitosis in plant cells in order to reveal molecular pathways involved in this process. We describe an analysis pipeline based on 3D image analysis that allows to semiautomatically quantify H3S10ph in mitotic Arabidopsis root cells. We also developed a new method for the compensation of signal attenuation in Z, based on measurement of objects of interest themselves. We show that this new attenuation correction method allows significant gains in accuracy and statistical power. Using this pipeline, we were able to reveal small H3S10ph differences between cells treated with hesperadin, an inhibitor of an H3S10ph kinase, or between Arabidopsis mutants affected in PP2A phosphatase activity. This tool opens new avenues to explore such regulatory pathways in plants, using the wealth of genetic materials available in Arabidopsis. It can also be applied to study other histone posttranslational modifications and more generally to any discrete 3D signals.

Keywords:  3D image analysis; PP2A; cell division; histone phosphorylation; signal quantification

DOI:  https://doi.org/10.1111/nph.70365
PLoS Biol. 2025 Jul;23(7): e3003249

Nondisruptive inducible labeling of ER-membrane contact sites using the Lamin B receptor.

Laura Downie, Nuria Ferrandiz, Elizabeth Courthold, Megan Jones, Stephen J Royle.

Membrane contact sites (MCSs) are areas of close proximity between organelles that allow the exchange of material, among other roles. The endoplasmic reticulum (ER) has MCSs with a variety of organelles in the cell. MCSs are dynamic, responding to changes in cell state, and are, therefore, best visualized through inducible labeling methods. However, existing methods typically distort ER-MCSs, by expanding contacts or creating artificial ones. Here, we describe a new method for inducible labeling of ER-MCSs using the Lamin B receptor (LBR) and a generic anchor protein on the partner organelle. Termed LaBeRling, this versatile, one-to-many approach allows labeling of different types of ER-MCSs (mitochondria, plasma membrane, lysosomes, early endosomes, lipid droplets, and Golgi), on-demand, in interphase or mitotic human cells. LaBeRling is nondisruptive and does not change ER-MCSs in terms of the contact number, extent or distance measured; as determined by light microscopy or a deep-learning volume electron microscopy approach. We applied this method to study the changes in ER-MCSs during mitosis and to label novel ER-Golgi contact sites at different mitotic stages in live cells.

DOI: https://doi.org/10.1371/journal.pbio.3003249
bioRxiv. 2025 Jul 02. pii: 2025.06.29.662044. [Epub ahead of print]

A mitotic bookmark coordinates transcription and replication.

Chun-Yi Cho, Patrick H O'Farrell.

Collisions between advancing replication forks and elongating transcripts pose a universal threat. During the rapid nuclear division cycles in early Drosophila embryos, coordinating transcription and replication is critical to reduce the risk of collisions. In each cycle, replication begins immediately after mitosis, while transcription starts 3 minutes later, overlapping with replication for the remainder of interphase. We previously showed that transcription depends on the coactivator Brd4, which forms hubs at active genes. Here, we show that Brd4 persists on mitotic chromosomes as bookmarks of transcriptional activity and, upon anaphase entry, recruits the replication activator Cdc7 to specify early-replicating genomic regions in the following interphase. Additionally, Cdc7 activity removes Brd4 bookmarks such that post-mitotic transcription occurs only after a new round of Brd4 hub assembly. Early initiation of replication while deferring initiation of transcription is proposed to allow unimpeded transcriptional elongation behind advancing replication forks. Supporting this, inhibiting Cdc7 delayed replication, stabilized Brd4 bookmarks, and resulted in premature transcription with elongation defects. We propose that Cdc7 triggers a functional switch in Brd4 that enforces temporal ordering of the initiation of transcription and replication, thereby minimizing collisions. This switching process might underlie the widespread correlation between transcriptional activity and early replication.

DOI: https://doi.org/10.1101/2025.06.29.662044
Nat Commun. 2025 Jul 11. 16(1): 6403

Structural basis for a nucleoporin exportin complex between RanBP2, SUMO1-RanGAP1, the E2 Ubc9, Crm1 and the Ran GTPase.

Vladimir Baytshtok, Michael A DiMattia, Christopher D Lima.

The human nucleoporin RanBP2/Nup358 interacts with SUMO1-modified RanGAP1 and the SUMO E2 Ubc9 at the nuclear pore complex (NPC) to promote export and disassembly of exportin Crm1/Ran(GTP)/cargo complexes. In mitosis, RanBP2/SUMO1-RanGAP1/Ubc9 remains intact after NPC disassembly and is recruited to kinetochores and mitotic spindles by Crm1 where it contributes to mitotic progression. RanBP2 binds SUMO1-RanGAP1/Ubc9 via motifs that also catalyze SUMO E3 ligase activity. Here, we resolve cryo-EM structures of a RanBP2 C-terminal fragment in complex with Crm1, SUMO1-RanGAP1/Ubc9, and two molecules of Ran(GTP). These structures reveal several interactions with Crm1 including a nuclear export signal (NES) for RanGAP1, the deletion of which mislocalizes RanGAP1 and the Ran GTPase in cells. Our structural and biochemical results support models in which RanBP2 E3 ligase activity is dependent on Crm1, the RanGAP1 NES and Ran GTPase cycling.

DOI: https://doi.org/10.1038/s41467-025-61694-1
PLoS One. 2025 ;20(7): e0327567

Mitosis detection in histopathological images using customized deep learning and hybrid optimization algorithms.

Afnan M Alhassan, Nouf I Altmami.

Identifying mitosis is crucial for cancer diagnosis, but accurate detection remains difficult because of class imbalance and complex morphological variations in histopathological images. To overcome this challenge, we propose a Customized Deep Learning (CDL) model, which integrates advanced deep-learning techniques for better mitosis detection. The CDL model utilizes transfer learning to counter the effects of class imbalance and speed up convergence, while skip connections are also employed to improve the localization of mitosis. Furthermore, we have established an innovative selection mechanism by the hybrid of Jellyfish Search Optimizer (JSO) and Walrus Optimization Algorithm (WOA) to maximize the momentum of the model. The proposed approach is rigorously evaluated on multiple publicly available mitosis detection datasets, including Mitosis WSI CCMCT Training Set, Mitosis-AIC, Mitosis Detection, and Mitosis and Non-Mitosis datasets. To tackle these issues, we hereby bring forth a specifically tailored Custom Deep Learning model, that assimilates hybrid CNN architecture into transfer learning and feature selection for improved mitotic detection. The CDL model comprises a Transfer Learning-based Mitosis Detection module under which extracted features from pre-trained deep networks are used to bolster feature extraction and alleviate class imbalance through skip connections to better localize mitosis. The robust assessment on a benchmark dataset displays the outstanding efficacy of the CDL model, reaching an excellent F1 score of 0.994 and accuracy of 98.8% thus proving its strength for the detection of mitotic figures. This proposed methodology can greatly empower pathologists for accurate appraisal of cancer diagnosis and prognosis. Future lines of exploration will include fusion methodologies and time efficiency for real-time applications, as well as extending CDL to various histopathological analyses.

DOI: https://doi.org/10.1371/journal.pone.0327567
PLoS Genet. 2025 Jul 10. 21(7): e1011785

L-2-hydroxyglutarate regulates centromere and heterochromatin conformation in the male germline.

Nina Mayorek, Miriam Schlossberg, Yousef Mansour, Nir Pillar, Ilan Stein, Fatima Mushasha, Guy Baziza Paz, Eleonora Medvedev, Zakhariya Manevitch, Julia Menzel, Elina Aizenshtein, Boris Sarvin, Nikita Sarvin, Erwin Goldberg, Bryan A Niedenberger, Christopher B Geyer, Tomer Shlomi, Michael Klutstein, Eli Pikarsky.

Germ cell differentiation in the male testis involves extensive phenotypic, transcriptional, and epigenetic modifications, which are essential for producing functional spermatozoa. Among all organs, the testis exhibits the highest baseline physiological levels of L-2-hydroxyglutarate (L-2HG), yet its role in male germ cell development remains unknown. Here, we reveal that L-2HG is synthesized during the pachytene and diplotene stages of meiosis by the testis-specific enzyme lactate dehydrogenase C (LDHC). Surprisingly, LDHC translocates into the nucleus, localizing along the synaptonemal complex and at centromeres. L-2HG, produced by LDHC, regulates centromere condensation and heterochromatin organization via multiple mechanisms, including chromocenter clustering, centromere and chromocenter condensation, and modulation of satellite RNA expression. These effects are rapid, specific to L-2HG, and independent of histone methylation changes. Acute depletion of L-2HG in vivo results in centromere dysfunction and activation of the spindle assembly checkpoint (SAC), suggesting the possible role of this metabolite in ensuring proper chromosome segregation.

DOI: https://doi.org/10.1371/journal.pgen.1011785
J Adv Res. 2025 Jul 07. pii: S2090-1232(25)00506-5. [Epub ahead of print]

Tankyrase activity is essential for asymmetric division and chromosome segregation in oocyte meiosis.

Ping-Shuang Lu, Zhen-Nan Pan, Wen-Lin Pan, Yuan-Jing Zou, Rui-Jie Ma, Kun-Huan Zhang, Yue Wang, Shao-Chen Sun.

   INTRODUCTION: Tankyrase (TNKS) is a poly ADP-ribose polymerase which is known to regulate DNA repair, GLUT4-related vesicles transportation, and mitotic sister telomeres resolution.
OBJECTIVES: In the present study, we reported the novel roles of TNKS in oocyte meiosis.
METHODS: Using specific chemical inhibitors, Western blot, immunofluorescence staining, mass spectrometry, co-immunoprecipitation, and siRNA interference, we disturbed TNKS activity or depleted TNKS expression to investigate the underlying mechanisms.
RESULTS: Our results showed that TNKS associated with microtubules, and upon loss of TNKS activity, unique phenotypes were observed in oocytes where symmetric division and improper chromosome segregation occurred simultaneously during meiotic maturation. Mass spectrometry data indicated interactions between TNKS and proteins involved in actin filaments, microtubule movement/organization, and cell cycle. Further analysis revealed that TNKS strikingly regulated actin filaments for chromosome-spindle complex motility and cortical polarity establishment through Formin2 and Ran/N-WASP/ARP2 pathways, which are crucial for meiotic asymmetric division. Additionally, we found that TNKS associated with p-PLK1 and affected K40 acetylation of α-Tubulin, and it also regulated BubR1 transportation to kinetochore and synthesis or activity of MPF/Securin, all of which contributed to the formation of meiotic bipolar spindle and precise chromosome separation associated with the cell cycle.
CONCLUSIONS: Taken together, our results suggested that poly ADP-ribose polymerases TNKS were required for actin dynamics and cell cycle, which contributed to both asymmetric division and proper chromosome segregation in mouse oocytes.

Keywords:  Actin dynamics; Asymmetric division; Meiosis; Oocyte; Tankyrase

DOI:  https://doi.org/10.1016/j.jare.2025.07.008
Cell Death Discov. 2025 Jul 10. 11(1): 318

Rsk2 inhibition induces an aneuploid post-mitotic arrest of cell cycle progression in osteosarcoma cells.

Armelle Carreau, Christina Baldauf, Lena Warlich, Magdalena Weingartner, Laura Brylka, Michael Amling, Thorsten Schinke, Julia Luther.

Osteosarcoma is the most common primary bone tumor, which is associated with a high mortality rate. The c-Fos transgenic mouse model has been described to spontaneously develop osteosarcoma, and the ribosomal S6 kinase 2 (Rsk2) was found to be essential for c-Fos-induced osteosarcoma formation in mice. By isolating and characterizing osteosarcoma cell lines from FosTg and FosTg;Rsk2-/y mice, we observed that Rsk2 deficiency impairs the growth advantage of FosTg cells. This can be explained by the aberrant number of nuclei due to impaired cytokinesis, inducing mitotic catastrophe. We therefore tested a pharmacological Rsk inhibitor (BI-D1870) for its ability to inhibit the proliferation of osteosarcoma cells and found that the effects observed by genetic Rsk2 inactivation were mimicked. BI-D1870 administration to FosTg cell lines led to reduced expression of Aurora kinase B. Therefore, the influence of a pharmacological Aurora kinase B inhibitor (Hesperadin) was tested. Similar to BI-D1870, Hesperadin caused impaired cytokinesis, resulting in the accumulation of polynuclear cells. This effect was also observed for two human osteosarcoma cell lines, U2OS and SaOS-2. Based on our findings, Rsk2 and/or Aurora kinase B can serve as potential targets for the design of new osteosarcoma therapies.

DOI: https://doi.org/10.1038/s41420-025-02596-5
Proc Natl Acad Sci U S A. 2025 Jul 15. 122(28): e2507203122

CDKN1B (p27/kip1) enhances drug-tolerant persister CTCs by restricting polyploidy following mitotic inhibitors.

Elad Horwitz, Taronish D Dubash, Annamaria Szabolcs, Ben S Wittner, Johannes Kreuzer, Robert Morris, Aditya Bardia, Brian Chirn, Devon Wiley, Dante Che, Hunter C Russell, Xcanda Ixchel Herrera Lopez, Douglas B Fox, Ezgi Antmen, Risa Burr, David T Ting, Wilhelm Haas, Moshe Sade-Feldman, Shyamala Maheswaran, Daniel A Haber.

  The mitotic inhibitor docetaxel (DTX) is often used to treat endocrine-refractory metastatic breast cancer, but initial responses are mitigated as patients develop disease progression. Using a cohort of ex vivo cultured circulating tumor cells (CTCs) from patients with heavily pretreated breast cancer (n=18), we find distinct patterns of response to DTX, which are intrinsic and independent of past clinical treatment with taxanes. In some CTC cultures, treatment with a single dose of DTX results in complete cell killing, associated with accumulation of nonviable polyploid (≥8 N) cells arising from endomitosis. In other CTC cultures, a transient viable drug-tolerant persister (DTP) population emerges, ultimately enabling renewed proliferation of CTCs with preserved parental cell ploidy and restored DTX sensitivity identical to that of the pretreated culture. In these CTCs, efficient cell cycle exit generates a ≤4 N drug-tolerant state dependent on CDKN1B (p27/kip1). Exposure to DTX triggers stabilization of CDKN1B through AKT-mediated phosphorylation at serine 10. Suppression of CDKN1B reduces the number of persister CTCs, increases ≥8 N mitotic cells and abrogates regrowth after DTX exposure. Thus, CDKN1B-mediated suppression of endomitosis contributes to the initiation of a reversible drug-tolerant persister state following mitotic inhibitors in advanced patient-derived breast cancer cells.

Keywords:  CDKN1B; breast cancer; circulating tumor cells; drug-tolerant persister cells; taxanes

DOI:  https://doi.org/10.1073/pnas.2507203122
Discov Oncol. 2025 Jul 11. 16(1): 1308

Zwilch kinetochore protein affects the prognosis of cancer patients by participating in cell proliferation, enhancing cell communication, and reshaping the tumor microenvironment.

Long Yao, Lianpo Liu, Jinsong Wu, Yunlong Huang, Renquan Zhang, Haoxue Zhang.

   BACKGROUND: Zwilch Kinetochore Protein(ZWILCH) has been reported to prevent cells from prematurely exiting mitosis. However, the underlying mechanisms or involvement of ZWILCH in the tumor immune microenvironment in various cancers remain largely unknown.
METHODS: Generalized dysregulation of ZWILCH was observed through the whole transcriptome analysis in this study. The spatial transcriptome analysis was utilized to identify expressed regions of ZWILCH. Next, cells that mainly expressed ZWILCH in the tumor microenvironment were determined using the single-cell transcriptome analysis. Also, the "cellchat" R package was applied to estimate the effect of ZWILCH on malignant cell communication. Combining multiple analytic approaches including GSEA, GSVA, KEGG enrichment analysis, and Aucell, with TCPA functional protein data, Genome-wide CRISPR screening, potential functions of ZWILCH and the pathways in which ZWILCH participated were thoroughly exploited. Univariate Cox regression analysis calculated the association between ZWILCH and cancer patients' adverse outcomes.
RESULTS: ZWILCH is universally highly expressed in tumors. The spatial transcriptome analysis showed that ZWILCH overexpression comes from the tumoral region or mixed tumoral region. At the single-cell level, ZWILCH is chiefly expressed by malignant cells and proliferative T cells. The expression of ZWILCH mRNA is positively correlated with cell proliferation, repair of DNA damage, and cell cycle score. Plenty of metabolic pathways are inhibited in patients with high expression of ZWILCH. Moreover, after ZWILCH knockout, a large number of cancer cell lines are stagnated, inhibited, or died. Additionally, the malignant cells with positive expression of ZWILCH have a stronger ability for cell communication. In short, ZWILCH is meant to be a risk factor for clinical outcomes of multiple tumors.
CONCLUSIONS: ZWILCH is a promising therapeutic target that influences patient prognosis by participating in cell proliferation, cell communication, and reshaping the tumor microenvironment across different cancers.

Keywords:  Cancer; Single-cell; Spatial transcriptome; TME; ZWILCH

DOI:  https://doi.org/10.1007/s12672-025-02981-7