Transient endoreplication down-regulates the kinesin-14 HSET and contributes to genomic instability

Polyploid cancer cells exhibit chromosomal instability (CIN), which is associated with tumorigenesis and therapy resistance. The mechanisms that induce polyploidy and how these mechanisms contribute to CIN are not fully understood. Here we evaluate CIN in human cells that become polyploid through an experimentally induced endoreplication cycle. When these induced endoreplicating cells (iECs) returned to mitosis, it resulted in aneuploidy in daughter cells. This aneuploidy resulted from multipolar divisions, chromosome missegregation, and failure in cytokinesis. The iECs went through several rounds of division, ultimately spawning proliferative cells of reduced ploidy. iECs have reduced levels of the kinesin-14 HSET, which likely accounts for the multipolar divisions, and overexpression of HSET reduced spindle multipolarity. However, HSET overexpression had only mild effects on CIN, suggesting that additional defects must contribute to genomic instability in dividing iECs. Overall our results suggest that transient endoreplication cycles generate a diverse population of proliferative aneuploid cells that have the potential to contribute to tumor heterogeneity.

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The wages of CIN

The Journal of Cell Biology ◽

10.1083/jcb.200801030 ◽

2008 ◽

Vol 180 (4) ◽

pp. 661-663 ◽

Cited By ~ 12

Author(s):

Karen W. Yuen ◽

Arshad Desai

Keyword(s):

Cancer Cells ◽

Solid Tumors ◽

Chromosomal Instability ◽

Chromosome Instability ◽

Spindle Checkpoint ◽

Human Cells ◽

Normal Cells ◽

Chromosome Missegregation ◽

Cell Biol ◽

The Relationship

Aneuploidy and chromosome instability (CIN) are hallmarks of the majority of solid tumors, but the relationship between them is not well understood. In this issue, Thompson and Compton (Thompson, S.L., and D.A. Compton. 2008. Examining the link between chromosomal instability and aneuploidy in human cells. J. Cell. Biol. 180:665–672) investigate the mechanism of CIN in cancer cells and find that CIN arises primarily from defective kinetochore–spindle attachments that evade detection by the spindle checkpoint and persist into anaphase. They also explore the consequences of artificially elevating chromosome missegregation in otherwise karyotypically normal cells. Their finding that induced aneuploidy is rapidly selected against suggests that the persistence of aneuploid cells in tumors requires not only chromosome missegregation but also additional, as yet poorly defined events.

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The cGAS/STING/TBK1/IRF3 innate immunity pathway maintains chromosomal stability through regulation of p21 levels

Experimental & Molecular Medicine ◽

10.1038/s12276-020-0416-y ◽

2020 ◽

Vol 52 (4) ◽

pp. 643-657 ◽

Cited By ~ 6

Author(s):

Abdul Basit ◽

Min-Guk Cho ◽

Eui-Yun Kim ◽

Dohyeong Kwon ◽

Suk-Jo Kang ◽

...

Keyword(s):

Innate Immunity ◽

Adverse Effects ◽

Cancer Cells ◽

Chromosomal Instability ◽

Interferon Regulatory Factor ◽

Mitotic Arrest ◽

Regulatory Factor ◽

Chromosome Missegregation ◽

Sting Pathway ◽

Innate Immunity Pathway

Abstract Chromosomal instability (CIN) in cancer cells has been reported to activate the cGAS–STING innate immunity pathway via micronuclei formation, thus affecting tumor immunity and tumor progression. However, adverse effects of the cGAS/STING pathway as they relate to CIN have not yet been investigated. We addressed this issue using knockdown and add-back approaches to analyze each component of the cGAS/STING/TBK1/IRF3 pathway, and we monitored the extent of CIN by measuring micronuclei formation after release from nocodazole-induced mitotic arrest. Interestingly, knockdown of cGAS (cyclic GMP-AMP synthase) along with induction of mitotic arrest in HeLa and U2OS cancer cells clearly resulted in increased micronuclei formation and chromosome missegregation. Knockdown of STING (stimulator of interferon genes), TBK1 (TANK-binding kinase-1), or IRF3 (interferon regulatory factor-3) also resulted in increased micronuclei formation. Moreover, transfection with cGAMP, the product of cGAS enzymatic activity, as well as add-back of cGAS WT (but not catalytic-dead mutant cGAS), or WT or constitutively active STING (but not an inactive STING mutant) rescued the micronuclei phenotype, demonstrating that all components of the cGAS/STING/TBK1/IRF3 pathway play a role in preventing CIN. Moreover, p21 levels were decreased in cGAS-, STING-, TBK1-, and IRF3-knockdown cells, which was accompanied by the precocious G2/M transition of cells and the enhanced micronuclei phenotype. Overexpression of p21 or inhibition of CDK1 in cGAS-depleted cells reduced micronuclei formation and abrogated the precocious G2/M transition, indicating that the decrease in p21 and the subsequent precocious G2/M transition is the main mechanism underlying the induction of CIN through disruption of cGAS/STING signaling.

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Chromosome oscillation promotes Aurora A–dependent Hec1 phosphorylation and mitotic fidelity

The Journal of Cell Biology ◽

10.1083/jcb.202006116 ◽

2021 ◽

Vol 220 (7) ◽

Author(s):

Kenji Iemura ◽

Toyoaki Natsume ◽

Kayoko Maehara ◽

Masato T. Kanemaki ◽

Kozo Tanaka

Keyword(s):

Cancer Cells ◽

Cell Lines ◽

Cancer Cell ◽

Chromosomal Instability ◽

Oscillation Amplitude ◽

Cancer Cell Lines ◽

Aurora A ◽

Chromosome Missegregation ◽

Phosphorylation Level ◽

Chromosome Motion

Most cancer cells show chromosomal instability, a condition where chromosome missegregation occurs frequently. We found that chromosome oscillation, an iterative chromosome motion during metaphase, is attenuated in cancer cell lines. We also found that metaphase phosphorylation of Hec1 at serine 55, which is mainly dependent on Aurora A on the spindle, is reduced in cancer cell lines. The Aurora A–dependent Hec1-S55 phosphorylation level was regulated by the chromosome oscillation amplitude and vice versa: Hec1-S55 and -S69 phosphorylation by Aurora A is required for efficient chromosome oscillation. Furthermore, enhancement of chromosome oscillation reduced the number of erroneous kinetochore–microtubule attachments and chromosome missegregation, whereas inhibition of Aurora A during metaphase increased such errors. We propose that Aurora A–mediated metaphase Hec1-S55 phosphorylation through chromosome oscillation, together with Hec1-S69 phosphorylation, ensures mitotic fidelity by eliminating erroneous kinetochore–microtubule attachments. Attenuated chromosome oscillation and the resulting reduced Hec1-S55 phosphorylation may be a cause of CIN in cancer cell lines.

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Dormant replication origin firing links replication stress to whole chromosomal instability in human cancer

10.1101/2021.10.11.463929 ◽

2021 ◽

Author(s):

Ann-Kathrin Schmidt ◽

Nicolas Boehly ◽

Xiaoxiao Zhang ◽

Benjamin O. Slusarenko ◽

Magdalena Hennecke ◽

...

Keyword(s):

Cancer Cells ◽

Chromosomal Instability ◽

Replication Origin ◽

Human Cancer ◽

Chromosome Instability ◽

Replication Stress ◽

S Phase ◽

Origin Firing ◽

Human Cancer Cells ◽

Chromosome Missegregation

Chromosomal instability (CIN) is a hallmark of cancer and comprises structural CIN (S-CIN) and whole chromosome instability (W-CIN). Replication stress (RS), a condition of slowed or stalled DNA replication during S phase, has been linked to S-CIN, whereas defects in mitosis leading to chromosome missegregation and aneuploidy can account for W-CIN. It is well established that RS can activate additional replication origin firing that is considered as a rescue mechanism to suppress chromosomal instability in the presence of RS. In contrast, we show here that an increase in replication origin firing during S phase can contribute to W-CIN in human cancer cells. Increased origin firing can be specifically triggered by overexpression of origin firing genes including GINS1 and CDC45, whose elevated expression significantly correlates with W-CIN in human cancer specimens. Moreover, endogenous mild RS present in cancer cells characterized by W-CIN or modulation of the origin firing regulating ATR-CDK1-RIF1 axis induces dormant origin firing, which is sufficient to trigger chromosome missegregation and W-CIN. Importantly, chromosome missegregation upon increased dormant origin firing is mediated by increased microtubule growth rates leading to the generation of lagging chromosomes in mitosis, a condition prevalent in chromosomally unstable cancer cells. Thus, our study identified increased or dormant replication origin firing as a hitherto unrecognized, but cancer-relevant trigger for chromosomal instability.

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Examining the link between chromosomal instability and aneuploidy in human cells

The Journal of Cell Biology ◽

10.1083/jcb.200712029 ◽

2008 ◽

Vol 180 (4) ◽

pp. 665-672 ◽

Cited By ~ 321

Author(s):

Sarah L. Thompson ◽

Duane A. Compton

Keyword(s):

Chromosome Segregation ◽

Chromosomal Instability ◽

Live Cell Imaging ◽

Cell Imaging ◽

Human Cells ◽

Phenotypic Changes ◽

Chromosome Missegregation ◽

Chromosome Attachment ◽

Diploid Cells ◽

The Relationship

Solid tumors can be highly aneuploid and many display high rates of chromosome missegregation in a phenomenon called chromosomal instability (CIN). In principle, aneuploidy is the consequence of CIN, but the relationship between CIN and aneuploidy has not been clearly defined. In this study, we use live cell imaging and clonal cell analyses to evaluate the fidelity of chromosome segregation in chromosomally stable and unstable human cells. We show that improper microtubule–chromosome attachment (merotely) is a cause of chromosome missegregation in unstable cells and that increasing chromosome missegregation rates by elevating merotely during consecutive mitoses generates CIN in otherwise stable, near-diploid cells. However, chromosome missegregation compromises the proliferation of diploid cells, indicating that phenotypic changes that permit the propagation of nondiploid cells must combine with elevated chromosome missegregation rates to generate aneuploid cells with CIN.

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SHH-N non-canonically sustains androgen receptor activity in androgen-independent prostate cancer cells

Scientific Reports ◽

10.1038/s41598-021-93971-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Diana Trnski ◽

Maja Sabol ◽

Sanja Tomić ◽

Ivan Štefanac ◽

Milanka Mrčela ◽

...

Keyword(s):

Prostate Cancer ◽

Androgen Receptor ◽

Cancer Cells ◽

Therapy Resistance ◽

Androgen Deprivation ◽

Prostate Cancer Cells ◽

Androgen Independence ◽

Androgen Receptor Activity ◽

Signaling Activation ◽

Androgen Independent

AbstractProstate cancer is the second most frequent cancer diagnosed in men worldwide. Localized disease can be successfully treated, but advanced cases are more problematic. After initial effectiveness of androgen deprivation therapy, resistance quickly occurs. Therefore, we aimed to investigate the role of Hedgehog-GLI (HH-GLI) signaling in sustaining androgen-independent growth of prostate cancer cells. We found various modes of HH-GLI signaling activation in prostate cancer cells depending on androgen availability. When androgen was not deprived, we found evidence of non-canonical SMO signaling through the SRC kinase. After short-term androgen deprivation canonical HH-GLI signaling was activated, but we found little evidence of canonical HH-GLI signaling activity in androgen-independent prostate cancer cells. We show that in androgen-independent cells the pathway ligand, SHH-N, non-canonically binds to the androgen receptor through its cholesterol modification. Inhibition of this interaction leads to androgen receptor signaling downregulation. This implies that SHH-N activates the androgen receptor and sustains androgen-independence. Targeting this interaction might prove to be a valuable strategy for advanced prostate cancer treatment. Also, other non-canonical aspects of this signaling pathway should be investigated in more detail and considered when developing potential therapies.

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Targeting E-selectin to Tackle Cancer Using Uproleselan

Cancers ◽

10.3390/cancers13020335 ◽

2021 ◽

Vol 13 (2) ◽

pp. 335

Author(s):

Barbara Muz ◽

Anas Abdelghafer ◽

Matea Markovic ◽

Jessica Yavner ◽

Anupama Melam ◽

...

Keyword(s):

Bone Marrow ◽

Tumor Microenvironment ◽

Cancer Cells ◽

Metastatic Tumor ◽

Therapy Resistance ◽

Surface Proteins ◽

Cell Trafficking ◽

Primary Role ◽

Novel Therapy ◽

Tumor Dissemination

E-selectin is a vascular adhesion molecule expressed mainly on endothelium, and its primary role is to facilitate leukocyte cell trafficking by recognizing ligand surface proteins. E-selectin gained a new role since it was demonstrated to be involved in cancer cell trafficking, stem-like properties and therapy resistance. Therefore, being expressed in the tumor microenvironment, E-selectin can potentially be used to eradicate cancer. Uproleselan (also known as GMI-1271), a specific E-selectin antagonist, has been tested on leukemia, myeloma, pancreatic, colon and breast cancer cells, most of which involve the bone marrow as a primary or as a metastatic tumor site. This novel therapy disrupts the tumor microenvironment by affecting the two main steps of metastasis—extravasation and adhesion—thus blocking E-selectin reduces tumor dissemination. Additionally, uproleselan mobilized cancer cells from the protective vascular niche into the circulation, making them more susceptible to chemotherapy. Several preclinical and clinical studies summarized herein demonstrate that uproleselan has favorable safety and pharmacokinetics and is a tumor microenvironment-disrupting agent that improves the efficacy of chemotherapy, reduces side effects such as neutropenia, intestinal mucositis and infections, and extends overall survival. This review highlights the critical contribution of E-selectin and its specific antagonist, uproleselan, in the regulation of cancer growth, dissemination, and drug resistance in the context of the bone marrow microenvironment.

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Aberrant Bcl-x splicing in cancer: from molecular mechanism to therapeutic modulation

Journal of Experimental & Clinical Cancer Research ◽

10.1186/s13046-021-02001-w ◽

2021 ◽

Vol 40 (1) ◽

Author(s):

Zhihui Dou ◽

Dapeng Zhao ◽

Xiaohua Chen ◽

Caipeng Xu ◽

Xiaodong Jin ◽

...

Keyword(s):

Cancer Cells ◽

Human Cancer ◽

Structural Characteristics ◽

Therapy Resistance ◽

Regulatory Elements ◽

Aberrant Splicing ◽

Clinical Role ◽

Splicing Isoforms ◽

The Impact ◽

Splicing Patterns

AbstractBcl-x pre-mRNA splicing serves as a typical example to study the impact of alternative splicing in the modulation of cell death. Dysregulation of Bcl-x apoptotic isoforms caused by precarious equilibrium splicing is implicated in genesis and development of multiple human diseases, especially cancers. Exploring the mechanism of Bcl-x splicing and regulation has provided insight into the development of drugs that could contribute to sensitivity of cancer cells to death. On this basis, we review the multiple splicing patterns and structural characteristics of Bcl-x. Additionally, we outline the cis-regulatory elements, trans-acting factors as well as epigenetic modifications involved in the splicing regulation of Bcl-x. Furthermore, this review highlights aberrant splicing of Bcl-x involved in apoptosis evade, autophagy, metastasis, and therapy resistance of various cancer cells. Last, emphasis is given to the clinical role of targeting Bcl-x splicing correction in human cancer based on the splice-switching oligonucleotides, small molecular modulators and BH3 mimetics. Thus, it is highlighting significance of aberrant splicing isoforms of Bcl-x as targets for cancer therapy.

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Human papillomavirus E7 oncoprotein targets RNF168 to hijack the host DNA damage response

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1906102116 ◽

2019 ◽

Vol 116 (39) ◽

pp. 19552-19562 ◽

Cited By ~ 7

Author(s):

Justine Sitz ◽

Sophie Anne Blanchet ◽

Steven F. Gameiro ◽

Elise Biquand ◽

Tia M. Morgan ◽

...

Keyword(s):

Cervical Cancer ◽

Dna Damage ◽

Cancer Cells ◽

Genomic Instability ◽

E3 Ligase ◽

Human Papillomaviruses ◽

Double Strand Breaks ◽

Nuclear Bodies ◽

Dna Double Strand Breaks ◽

Strand Breaks

High-risk human papillomaviruses (HR-HPVs) promote cervical cancer as well as a subset of anogenital and head and neck cancers. Due to their limited coding capacity, HPVs hijack the host cell’s DNA replication and repair machineries to replicate their own genomes. How this host–pathogen interaction contributes to genomic instability is unknown. Here, we report that HPV-infected cancer cells express high levels of RNF168, an E3 ubiquitin ligase that is critical for proper DNA repair following DNA double-strand breaks, and accumulate high numbers of 53BP1 nuclear bodies, a marker of genomic instability induced by replication stress. We describe a mechanism by which HPV E7 subverts the function of RNF168 at DNA double-strand breaks, providing a rationale for increased homology-directed recombination in E6/E7-expressing cervical cancer cells. By targeting a new regulatory domain of RNF168, E7 binds directly to the E3 ligase without affecting its enzymatic activity. As RNF168 knockdown impairs viral genome amplification in differentiated keratinocytes, we propose that E7 hijacks the E3 ligase to promote the viral replicative cycle. This study reveals a mechanism by which tumor viruses reshape the cellular response to DNA damage by manipulating RNF168-dependent ubiquitin signaling. Importantly, our findings reveal a pathway by which HPV may promote the genomic instability that drives oncogenesis.

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