bims-micesi 2022-04-24 papers

bims-micesi

Biomed News

on Mitotic cell signalling

Issue of 2022–04–24
seventeen papers selected by
Valentina Piano, Max Planck Institute of Molecular Physiology

Tension can directly suppress Aurora B kinase-triggered release of kinetochore-microtubule attachments.
Kinesin-5 Eg5 mediates centrosome separation to control spindle assembly in spermatocytes.
Integrin-Mediated Adhesion Promotes Centrosome Separation in Early Mitosis.
BRAF Inhibitor Resistance Confers Increased Sensitivity to Mitotic Inhibitors.
The phosphorylation and dephosphorylation switch of VCP/p97 regulates the architecture of centrosome and spindle.
Maintaining Transcriptional Specificity Through Mitosis.
Mitotic drive in asymmetric epigenetic inheritance.
Vasa nucleates asymmetric translation along the mitotic spindle during unequal cell divisions.
Mitotic Spindle Positioning (MISP) is an actin bundler that selectively stabilizes the rootlets of epithelial microvilli.
The mitochondrial poison carbonyl cyanide 3-chlorophenyl hydrazone (CCCP) induces aneugenic effects in primary human fibroblasts: a possible link between mitochondrial dysfunction and chromosomal loss.
Regulated interaction of ID2 with the anaphase-promoting complex links progression through mitosis with reactivation of cell-type-specific transcription.
Methylglyoxal Impairs Sister Chromatid Separation in Lymphocytes.
Pathogenic BRCA1 variants disrupt PLK1-regulation of mitotic spindle orientation.
Primary acute lymphoblastic leukemia cells are susceptible to microtubule depolymerization in G1 and M phases through distinct cell death pathways.
Bioinformatics Analysis Highlight Differentially Expressed CCNB1 and PLK1 Genes as Potential Anti-Breast Cancer Drug Targets and Prognostic Markers.
A Novel Allosteric Inhibitor Targets PLK1 in Triple Negative Breast Cancer Cells.
Cell division in tissues enables macrophage infiltration.

Nat Commun. 2022 Apr 20. 13(1): 2152

Tension can directly suppress Aurora B kinase-triggered release of kinetochore-microtubule attachments.

Anna K de Regt, Cordell J Clark, Charles L Asbury, Sue Biggins.

Chromosome segregation requires sister kinetochores to attach microtubules emanating from opposite spindle poles. Proper attachments come under tension and are stabilized, but defective attachments lacking tension are released, giving another chance for correct attachments to form. This error correction process depends on Aurora B kinase, which phosphorylates kinetochores to destabilize their microtubule attachments. However, the mechanism by which Aurora B distinguishes tense versus relaxed kinetochores remains unclear because it is difficult to detect kinase-triggered detachment and to manipulate kinetochore tension in vivo. To address these challenges, we apply an optical trapping-based assay using soluble Aurora B and reconstituted kinetochore-microtubule attachments. Strikingly, the tension on these attachments suppresses their Aurora B-triggered release, suggesting that tension-dependent changes in the conformation of kinetochores can regulate Aurora B activity or its outcome. Our work uncovers the basis for a key mechano-regulatory event that ensures accurate segregation and may inform studies of other mechanically regulated enzymes.

DOI: https://doi.org/10.1038/s41467-022-29542-8
Chromosoma. 2022 Apr 18.

Kinesin-5 Eg5 mediates centrosome separation to control spindle assembly in spermatocytes.

Zhen-Yu She, Ning Zhong, Ya-Lan Wei.

  Timely and accurate centrosome separation is critical for bipolar spindle organization and faithful chromosome segregation during cell division. Kinesin-5 Eg5 is essential for centrosome separation and spindle organization in somatic cells; however, the detailed functions and mechanisms of Eg5 in spermatocytes remain unclear. In this study, we show that Eg5 proteins are located at spindle microtubules and centrosomes in spermatocytes both in vivo and in vitro. We reveal that the spermatocytes are arrested at metaphase I in seminiferous tubules after Eg5 inhibition. Eg5 ablation results in cell cycle arrest, the formation of monopolar spindle, and chromosome misalignment in cultured GC-2 spd cells. Importantly, we find that the long-term inhibition of Eg5 results in an increased number of centrosomes and chromosomal instability in spermatocytes. Our findings indicate that Eg5 mediates centrosome separation to control spindle assembly and chromosome alignment in spermatocytes, which finally contribute to chromosome stability and faithful cell division of the spermatocytes.

Keywords:  Centrosome; Eg5; Kinesin-5; Microtubule; Spermatocytes; Spindle

DOI:  https://doi.org/10.1007/s00412-022-00772-5
Cells. 2022 Apr 16. pii: 1360. [Epub ahead of print]11(8):

Integrin-Mediated Adhesion Promotes Centrosome Separation in Early Mitosis.

Siamak A Kamranvar, Deepesh Kumar Gupta, Anishia Wasberg, Liangwen Liu, Joan Roig, Staffan Johansson.

  Integrin-mediated adhesion to the extracellular matrix is a key regulator of the cell cycle, as demonstrated for the passage of the G1/S checkpoint and the completion of cytokinetic abscission. Here, integrin-dependent regulation of the cell cycle in G2 and early M phases was investigated. The progression through the G2 and M phases was monitored by live-cell imaging and immunofluorescence staining in adherent and non-adherent fibroblast cells. Non-adherent cells, as well as adherent cells lacking FAK activity due to suppressed expression or pharmacological inhibition, exhibited a prolonged G2 phase and severely defect centrosome separation, resulting in delayed progress through the early mitotic stages. The activation of the critical mitotic regulator PLK1 and its indirect target Eg5, a kinesin-family motor protein driving the centrosome separation, were reduced in the cells lacking FAK activity. Furthermore, the absence of integrin adhesion or FAK activity destabilized the structural integrity of centrosomes and often caused detachment of pericentriolar material from the centrioles. These data identify a novel adhesion-dependent mechanism by which integrins via FAK and PLK1 contribute to the regulation of the cell cycle in the G2 and early M phases, and to the maintenance of genome integrity.

Keywords:  Eg5; FAK; PLK1; centrosome; integrin; mitosis

DOI:  https://doi.org/10.3390/cells11081360
Front Oncol. 2022 ;12 766794

BRAF Inhibitor Resistance Confers Increased Sensitivity to Mitotic Inhibitors.

Sean A Misek, Bardees M Foda, Thomas S Dexheimer, Maisah Akram, Susan E Conrad, Jens C Schmidt, Richard R Neubig, Kathleen A Gallo.

  Single agent and combination therapy with BRAFV600E/K and MEK inhibitors have remarkable efficacy against melanoma tumors with activating BRAF mutations, but in most cases BRAF inhibitor (BRAFi) resistance eventually develops. One resistance mechanism is reactivation of the ERK pathway. However, only about half of BRAFi resistance is due to ERK reactivation. The purpose of this study is to uncover pharmacological vulnerabilities of BRAFi-resistant melanoma cells, with the goal of identifying new therapeutic options for patients whose tumors have developed resistance to BRAFi/MEKi therapy. We screened a well-annotated compound library against a panel of isogenic pairs of parental and BRAFi-resistant melanoma cell lines to identify classes of compounds that selectively target BRAFi-resistant cells over their BRAFi-sensitive counterparts. Two distinct patterns of increased sensitivity to classes of pharmacological inhibitors emerged. In two cell line pairs, BRAFi resistance conferred increased sensitivity to compounds that share the property of cell cycle arrest at M-phase, including inhibitors of aurora kinase (AURK), polo-like kinase (PLK), tubulin, and kinesin. Live cell microscopy, used to track mitosis in real time, revealed that parental but not BRAFi-resistant melanoma cells were able to exit from compound-induced mitotic arrest through mitotic slippage, thus escaping death. Consistent with the key role of Cyclin B1 levels in regulating mitosis at the spindle checkpoint in arrested cells, we found lower Cyclin B1 levels in parental compared with BRAFi-resistant melanoma cells, suggesting that inability to down-regulate Cyclin B1 expression levels may explain the increased vulnerability of resistant cells to mitotic inhibitors. Another BRAFi-resistant cell line showed increased sensitivity to Chk1/2 inhibitors, which was associated with an accumulation of DNA damage, resulting in mitotic failure. This study demonstrates that BRAFi-resistance, in at least a subset of melanoma cells, confers vulnerability to pharmacological disruption of mitosis and suggests a targeted synthetic lethal approach for overcoming resistance to BRAF/MEK-directed therapies.

Keywords:  BRAF; compound screen; inhibitor; melanoma; mitosis; pharmacology; resistance; vemurafenib

DOI:  https://doi.org/10.3389/fonc.2022.766794
Cell Death Differ. 2022 Apr 16.

The phosphorylation and dephosphorylation switch of VCP/p97 regulates the architecture of centrosome and spindle.

Kaiyuan Zhu, Yang Cai, Xiaotong Si, Zuodong Ye, Yuanzhu Gao, Chuang Liu, Rui Wang, Zhibin Ma, Huazhang Zhu, Liang Zhang, Shengjin Li, Hongmin Zhang, Jianbo Yue.

The proper orientation of centrosome and spindle is essential for genome stability; however, the mechanism that governs these processes remains elusive. Here, we demonstrated that polo-like kinase 1 (Plk1), a key mitotic kinase, phosphorylates residue Thr76 in VCP/p97 (an AAA-ATPase), at the centrosome from prophase to anaphase. This phosphorylation process recruits VCP to the centrosome and in this way, it regulates centrosome orientation. VCP exhibits strong co-localization with Eg5 (a mitotic kinesin motor), at the mitotic spindle, and the dephosphorylation of Thr76 in VCP is required for the enrichment of both VCP and Eg5 at the spindle, thus ensuring proper spindle architecture and chromosome segregation. We also showed that the phosphatase, PTEN, is responsible for the dephosphorylation of Thr76 in VCP; when PTEN was knocked down, the normal spread of VCP from the centrosome to the spindle was abolished. Cryo-EM structures of VCPT76A and VCPT76E, which represent dephosphorylated and phosphorylated states of VCP, respectively, revealed that the Thr76 phosphorylation modulates VCP by altering the inter-domain and inter-subunit interactions, and ultimately the nucleotide-binding pocket conformation. Interestingly, the tumor growth in nude mice implanted with VCPT76A-reconstituted cancer cells was significantly slower when compared with those implanted with VCPWT-reconstituted cancer cells. Collectively, our findings demonstrate that the phosphorylation and dephosphorylation switch of VCP regulates the architecture of centrosome and spindle for faithful chromosome segregation.

DOI: https://doi.org/10.1038/s41418-022-01000-4
Annu Rev Genomics Hum Genet. 2022 Apr 19.

Maintaining Transcriptional Specificity Through Mitosis.

Kenji Ito, Kenneth S Zaret.

Virtually all cell types have the same DNA, yet each type exhibits its own cell-specific pattern of gene expression. During the brief period of mitosis, the chromosomes exhibit changes in protein composition and modifications, a marked condensation, and a consequent reduction in transcription. Yet as cells exit mitosis, they reactivate their cell-specific programs with high fidelity. Initially, the field focused on the subset of transcription factors that are selectively retained in, and hence bookmark, chromatin in mitosis. However, recent studies show that many transcription factors can be retained in mitotic chromatin and that, surprisingly, such retention can be due to nonspecific chromatin binding. Here, we review the latest studies focusing on low-level transcription via promoters, rather than enhancers, as contributing to mitotic memory, as well as new insights into chromosome structure dynamics, histone modifications, cell cycle signaling, and nuclear envelope proteins that together ensure the fidelity of gene expression through a round of mitosis. Expected final online publication date for the Annual Review of Genomics and Human Genetics, Volume 23 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

DOI: https://doi.org/10.1146/annurev-genom-121321-094603
Biochem Soc Trans. 2022 Apr 19. pii: BST20200267. [Epub ahead of print]

Mitotic drive in asymmetric epigenetic inheritance.

Rajesh Ranjan, Xin Chen.

  Asymmetric cell division (ACD) produces two daughter cells with distinct cell fates. This division mode is widely used during development and by adult stem cells during tissue homeostasis and regeneration, which can be regulated by both extrinsic cues such as signaling molecules and intrinsic factors such as epigenetic information. While the DNA replication process ensures that the sequences of sister chromatids are identical, how epigenetic information is re-distributed during ACD has remained largely unclear in multicellular organisms. Studies of Drosophila male germline stem cells (GSCs) have revealed that sister chromatids incorporate pre-existing and newly synthesized histones differentially and segregate asymmetrically during ACD. To understand the underlying molecular mechanisms of this phenomenon, two key questions must be answered: first, how and when asymmetric histone information is established; and second, how epigenetically distinct sister chromatids are distinguished and segregated. Here, we discuss recent advances which help our understanding of this interesting and important cell division mode.

Keywords:  DNA replication; and asymmetric cell division (ACD); and cell fate determination; centromere and kinetochore; epigenetic inheritance; mitotic drive; nonrandom sister chromatid segregation; stem cell

DOI:  https://doi.org/10.1042/BST20200267
Nat Commun. 2022 Apr 20. 13(1): 2145

Vasa nucleates asymmetric translation along the mitotic spindle during unequal cell divisions.

Ana Fernandez-Nicolas, Alicia Uchida, Jessica Poon, Mamiko Yajima.

mRNA translation on the spindle is hypothesized to be an essential strategy for the localized production of cell regulators. This mechanism may be important particularly in early embryonic cells, which have a large diffusion volume and that undergo rapid cell divisions. Evidence to test such a hypothesis has been, however, limited. Here, we use an embryo with both symmetric and asymmetric cell divisions and manipulate Vasa protein, an RNA-helicase, on the spindle in live sea urchin embryos. We learned that the spindle serves as a major site of translation and that protein synthesis within a single spindle can be unequal and help drive asymmetric cell divisions during embryogenesis. Recruiting Vasa to the ectopic sub-cellular region induced a new site of translation, disturbed asymmetric translation on the spindle, and changed the cell fate. Based on these observations, we conclude that Vasa functions in localized translation, which provides a spatiotemporal control in protein synthesis and is essential for rapidly developing embryonic cells.

DOI: https://doi.org/10.1038/s41467-022-29855-8
Cell Rep. 2022 Apr 19. pii: S2211-1247(22)00450-8. [Epub ahead of print]39(3): 110692

Mitotic Spindle Positioning (MISP) is an actin bundler that selectively stabilizes the rootlets of epithelial microvilli.

E Angelo Morales, Cayetana Arnaiz, Evan S Krystofiak, Marija Zanic, Matthew J Tyska.

  Microvilli are conserved actin-based surface protrusions that have been repurposed throughout evolution to fulfill diverse cell functions. In the case of transporting epithelia, microvilli are supported by a core of actin filaments bundled in parallel by villin, fimbrin, and espin. Remarkably, microvilli biogenesis persists in mice lacking all three of these factors, suggesting the existence of unknown bundlers. We identified Mitotic Spindle Positioning (MISP) as an actin-binding factor that localizes specifically to the rootlet end of the microvillus. MISP promotes rootlet elongation in cells, and purified MISP exhibits potent filament bundling activity in vitro. MISP-bundled filaments also recruit fimbrin, which further elongates and stabilizes bundles. MISP confinement to the rootlet is enforced by ezrin, which prevents decoration of the membrane-wrapped distal end of the core bundle. These discoveries reveal how epithelial cells optimize apical membrane surface area and offer insight on the remarkable robustness of microvilli biogenesis.

Keywords:  CP: Cell biology; brush border; cytoskeleton; ezrin; fimbrin; membrane; protrusion; rootlet

DOI:  https://doi.org/10.1016/j.celrep.2022.110692
Mutagenesis. 2022 Apr 20. pii: geac008. [Epub ahead of print]

The mitochondrial poison carbonyl cyanide 3-chlorophenyl hydrazone (CCCP) induces aneugenic effects in primary human fibroblasts: a possible link between mitochondrial dysfunction and chromosomal loss.

Francesca Marcon, Francesca De Battistis, Ester Siniscalchi, Riccardo Crebelli, Roberta Meschini.

  An association between proper chromosome segregation and intact mitochondria has been extensively reported. This could be related to the effects on the progression of cell division of altered energy production, increased oxidative stress, and deregulated calcium homeostasis. However, evidence for a direct relationship is still lacking. The present study was aimed at investigating the possible effect of mitochondrial dysfunction on chromosomal instability as detected in primary human cells treated with the mitochondrial poison carbonyl cyanide 3-chlorophenyl hydrazone (CCCP). Chromosome instability was analyzed in anaphase and interphase cells to follow the fate of chromosome damage during the progression of mitosis and the subsequent cell cycle. Through the combination of cytogenetic approaches and molecular analyses, i.e. morphological cell analysis, formation and characterization of micronucleus content, Comet assay, and gene expression, it was demonstrated that the prevalent DNA damage associated with CCCP treatment was the induction of chromosome loss, while primary DNA damage was not detected. No alterations in the shape of anaphase cells were observed nor induction of multipolar spindles. The proper activation of mitotic checkpoint was maintained. A linear dose-response curve characterizing the CCCP effects suggested that multiple cellular targets could be affected by the CCCP-induced mitochondrial dysfunctions triggering aneuploidy. Conversely, a steep increase was induced by the positive control vinblastine, known to have tubulin as a unique target. In addition, the effect of CCCP on mitochondrial function was demonstrated by changes in mitochondrial DNA copy number and in the expression of genes involved in mitochondrial maintenance. Overall, these results indicate that the mitochondrial poison CCCP may induce aneugenic effects.

Keywords:  aneuploidy in somatic cells; mechanisms of genotoxicity; mitochondria

DOI:  https://doi.org/10.1093/mutage/geac008
Nat Commun. 2022 Apr 19. 13(1): 2089

Regulated interaction of ID2 with the anaphase-promoting complex links progression through mitosis with reactivation of cell-type-specific transcription.

Sang Bae Lee, Luciano Garofano, Aram Ko, Fulvio D'Angelo, Brulinda Frangaj, Danika Sommer, Qiwen Gan, KyeongJin Kim, Timothy Cardozo, Antonio Iavarone, Anna Lasorella.

Tissue-specific transcriptional activity is silenced in mitotic cells but it remains unclear whether the mitotic regulatory machinery interacts with tissue-specific transcriptional programs. We show that such cross-talk involves the controlled interaction between core subunits of the anaphase-promoting complex (APC) and the ID2 substrate. The N-terminus of ID2 is independently and structurally compatible with a pocket composed of core APC/C subunits that may optimally orient ID2 onto the APCCDH1 complex. Phosphorylation of serine-5 by CDK1 prevented the association of ID2 with core APC, impaired ubiquitylation and stabilized ID2 protein at the mitosis-G1 transition leading to inhibition of basic Helix-Loop-Helix (bHLH)-mediated transcription. The serine-5 phospho-mimetic mutant of ID2 that inefficiently bound core APC remained stable during mitosis, delayed exit from mitosis and reloading of bHLH transcription factors on chromatin. It also locked cells into a "mitotic stem cell" transcriptional state resembling the pluripotent program of embryonic stem cells. The substrates of APCCDH1 SKP2 and Cyclin B1 share with ID2 the phosphorylation-dependent, D-box-independent interaction with core APC. These results reveal a new layer of control of the mechanism by which substrates are recognized by APC.

DOI: https://doi.org/10.1038/s41467-022-29502-2
Int J Mol Sci. 2022 Apr 08. pii: 4139. [Epub ahead of print]23(8):

Methylglyoxal Impairs Sister Chromatid Separation in Lymphocytes.

Leigh Donnellan, Clifford Young, Bradley S Simpson, Varinderpal S Dhillon, Maurizio Costabile, Peter Hoffmann, Michael Fenech, Permal Deo.

  The accurate segregation of sister chromatids is complex, and errors that arise throughout this process can drive chromosomal instability and tumorigenesis. We recently showed that methylglyoxal (MGO), a glycolytic by-product, can cause chromosome missegregation events in lymphocytes. However, the underlying mechanisms of this were not explored. Therefore, in this study, we utilised shotgun proteomics to identify MGO-modified proteins, and label-free quantitation to measure changes in protein abundance following exposure to MGO. We identified numerous mitotic proteins that were modified by MGO, including those involved in the separation and cohesion of sister chromatids. Furthermore, the protein abundance of Securin, an inhibitor of sister chromatid separation, was increased following treatment with MGO. Cytological examination of chromosome spreads showed MGO prevented sister chromatid separation, which was associated with the formation of complex nuclear anomalies. Therefore, results from this study suggest MGO may drive chromosomal instability by preventing sister chromatid separation.

Keywords:  chromosomal instability; methylglyoxal; proteomics; sister chromatid separation

DOI:  https://doi.org/10.3390/ijms23084139
Nat Commun. 2022 Apr 22. 13(1): 2200

Pathogenic BRCA1 variants disrupt PLK1-regulation of mitotic spindle orientation.

Zhengcheng He, Ryan Ghorayeb, Susanna Tan, Ke Chen, Amanda C Lorentzian, Jack Bottyan, Syed Mohammed Musheer Aalam, Miguel Angel Pujana, Philipp F Lange, Nagarajan Kannan, Connie J Eaves, Christopher A Maxwell.

Preneoplastic mammary tissues from human female BRCA1 mutation carriers, or Brca1-mutant mice, display unexplained abnormalities in luminal differentiation. We now study the division characteristics of human mammary cells purified from female BRCA1 mutation carriers or non-carrier donors. We show primary BRCA1 mutant/+ cells exhibit defective BRCA1 localization, high radiosensitivity and an accelerated entry into cell division, but fail to orient their cell division axis. We also analyse 15 genetically-edited BRCA1 mutant/+ human mammary cell-lines and find that cells carrying pathogenic BRCA1 mutations acquire an analogous defect in their division axis accompanied by deficient expression of features of mature luminal cells. Importantly, these alterations are independent of accumulated DNA damage, and specifically dependent on elevated PLK1 activity induced by reduced BRCA1 function. This essential PLK1-mediated role of BRCA1 in controlling the cell division axis provides insight into the phenotypes expressed during BRCA1 tumorigenesis.

DOI: https://doi.org/10.1038/s41467-022-29885-2
J Biol Chem. 2022 Apr 15. pii: S0021-9258(22)00379-9. [Epub ahead of print] 101939

Primary acute lymphoblastic leukemia cells are susceptible to microtubule depolymerization in G1 and M phases through distinct cell death pathways.

Magdalena Delgado, Randall R Rainwater, Billie Heflin, Alicja Urbaniak, Kaitlynn Butler, Mari Davidson, Reine M Protacio, Giulia Baldini, Andrea Edwards, Megan R Reed, Kevin D Raney, Timothy C Chambers.

  Microtubule targeting agents (MTAs) are widely used cancer chemotherapeutics which conventionally exert their effects during mitosis, leading to mitotic or post-mitotic death. However, accumulating evidence suggests that MTAs can also generate death signals during interphase, which may represent a key mechanism in the clinical setting. We reported previously that vincristine and other microtubule destabilizers induce death not only in M phase, but also in G1 phase in primary acute lymphoblastic leukemia (ALL) cells. Here, we sought to investigate and compare the pathways responsible for phase-specific cell death. Primary ALL cells were subjected to centrifugal elutriation, and cell populations enriched in G1 phase (97%) or G2/M phases (80%) were obtained and treated with vincristine. We found death of M phase cells was associated with established features of mitochondrial-mediated apoptosis, including Bax activation, loss of mitochondrial transmembrane potential, caspase-3 activation, and nucleosomal DNA fragmentation. In contrast, death of G1 phase cells was not associated with pronounced Bax or caspase-3 activation but was associated with loss of mitochondrial transmembrane potential, parylation, nuclear translocation of apoptosis-inducing factor and EndoG, and supra-nucleosomal DNA fragmentation, which was enhanced by inhibition of autophagy. The results indicate that microtubule depolymerization induces distinct cell death pathways depending on during which phase of the cell cycle microtubule perturbation occurs. The observation that a specific type of drug can enter a single cell type and induce two different modes of death is novel and intriguing. These findings provide a basis for advancing knowledge of clinical mechanisms of MTAs.

Keywords:  Bcl-2 proteins; EndoG; Microtubule depolymerization; acute lymphoblastic leukemia; apoptosis; apoptosis inducing factor; autophagy; cell death; parylation

DOI:  https://doi.org/10.1016/j.jbc.2022.101939
Genes (Basel). 2022 Apr 07. pii: 654. [Epub ahead of print]13(4):

Bioinformatics Analysis Highlight Differentially Expressed CCNB1 and PLK1 Genes as Potential Anti-Breast Cancer Drug Targets and Prognostic Markers.

Leiming Fang, Qi Liu, Hongtu Cui, Yunji Zheng, Chengjun Wu.

  Breast cancer is one of the most common malignant tumors in women worldwide. Early diagnosis, treatment, and prognosis of breast cancer are global challenges. Identification of valid predictive diagnosis and prognosis biomarkers and drug targets are crucial for breast cancer prevention. This study characterizes differentially expressed genes (DEGs) based on the TCGA database by using DESeq2, edgeR, and limma. A total of 2032 DEGs, including 1026 up-regulated genes and 1006 down-regulated genes were screened. Followed with WGCNA, PPI analysis, GEPIA 2, and HPA database verification, thirteen hub genes including CDK1, BUB1, BUB1B, CDC20, CCNB2, CCNB1, KIF2C, NDC80, CDCA8, CENPF, BIRC5, AURKB, PLK1, MAD2L1, and CENPE were obtained, and they may serve as potential therapeutic targets of breast cancer. Especially, overexpression of CCNB1 and PLK1 are strongly associated with the low survival rate of breast cancer patients, demonstrating their potentiality as prognostic markers. Moreover, CCNB1 and PLK1 are highly expressed in all breast cancer stages, suggesting that they could be further studied as potential drug targets. Taken together, our study highlights CCNB1 and PLK1 as potential anti-breast cancer drug targets and prognostic markers.

Keywords:  CCNB1; DEGs; PLK1; breast cancer; hub genes

DOI:  https://doi.org/10.3390/genes13040654
Biomolecules. 2022 Mar 31. pii: 531. [Epub ahead of print]12(4):

A Novel Allosteric Inhibitor Targets PLK1 in Triple Negative Breast Cancer Cells.

Jankiben R Patel, Prasad Thangavelu, Renee M Terrell, Bridg'ette Israel, Arindam Basu Sarkar, A Michael Davidson, Kun Zhang, Rahul Khupse, Syreeta L Tilghman.

  While Polo-like kinase 1 (PLK1) inhibitors have shown promise in clinical settings for treating triple-negative breast cancer tumors and other solid tumors, they are limited by their ability to bind non-selectively to the ATP kinase domain. Therefore, we sought to develop a PLK1 allosteric inhibitor targeting the PLK1 T-loop (a switch responsible for activation) and evaluate its effects in triple-negative breast cancer cells. A novel compound, RK-10, was developed based on an in silico model, and its effects on specificity, viability, migration, and cell cycle regulation in MCF-10A and MDA-MB 231 cells were evaluated. When MDA-MB 231 cells were treated with 0-50 µg/mL RK-10, phospho-PLK1 (Thr-210) was decreased in cells cultured adherently and cells cultured as mammospheres. RK-10 significantly inhibited viability after 24 h; however, by 48 h, 25-50 µM RK-10 caused >50% reduction. RK-10 attenuated wound healing by up to 99.7% and caused S and G2/M cell cycle arrest, which was associated with increased p21 expression. We developed a novel allosteric inhibitor which mediates anti-proliferative and anti-migratory properties through targeting phospho-PLK1 (Thr-210) in mammospheres and causing S phase and G2/M cell cycle arrest. Further development of PLK1 allosteric inhibitors may be a promising approach for TNBC treatment.

Keywords:  allosteric inhibitor; mammospheres; polo-like kinase 1; triple-negative breast cancer

DOI:  https://doi.org/10.3390/biom12040531
Science. 2022 Apr 22. 376(6591): 394-396

Cell division in tissues enables macrophage infiltration.

Maria Akhmanova, Shamsi Emtenani, Daniel Krueger, Attila Gyoergy, Mariana Guarda, Mikhail Vlasov, Fedor Vlasov, Andrei Akopian, Aparna Ratheesh, Stefano De Renzis, Daria E Siekhaus.

Cells migrate through crowded microenvironments within tissues during normal development, immune response, and cancer metastasis. Although migration through pores and tracks in the extracellular matrix (ECM) has been well studied, little is known about cellular traversal into confining cell-dense tissues. We find that embryonic tissue invasion by Drosophila macrophages requires division of an epithelial ectodermal cell at the site of entry. Dividing ectodermal cells disassemble ECM attachment formed by integrin-mediated focal adhesions next to mesodermal cells, allowing macrophages to move their nuclei ahead and invade between two immediately adjacent tissues. Invasion efficiency depends on division frequency, but reduction of adhesion strength allows macrophage entry independently of division. This work demonstrates that tissue dynamics can regulate cellular infiltration.

DOI: https://doi.org/10.1126/science.abj0425