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Ben-David, U.

Publications and source records attributed to Ben-David, U..

At least 19 recordsLinked to original sources

Mapping chromothripsis across human cancer cell lines reveals genome evolution and therapeutic vulnerabilities

Chromothripsis is a catastrophic chromosomal rearrangement found in ~40% of primary tumors, yet its landscape in cancer cell lines (CCLs) remains uncharacterized. To address this gap, we developed a pipeline to detect chromothripsis-like events from copy-number data alone, and mapped their occurrence across 1,646 human CCLs. Chromothripsis patterns were broadly conserved between primary tumors and CCLs, but CCLs displayed some distinct features and a significantly higher prevalence of chromothripsis. Chromothripsis continued to emerge during culture propagation, likely contributing to its increased prevalence in CCLs. Integrating genomic and functional data revealed selective vulnerabilities: chromothriptic cells were resistant to DNA damage-inducing agents but highly sensitive to histone deacetylase inhibitors (HDACi). Using isogenic models, we validated that HDACi could synergistically sensitize chromothriptic cells to DNA damage-inducing agents. Our study establishes the first comprehensive resource of chromothripsis in CCLs and reveals functional consequences and therapeutic vulnerabilities of chromothripsis-positive cancers.

cancer biology↗

The SKA complex is a mitotic vulnerability of chromosomally unstable cancers

Aneuploidy and chromosomal instability are common characteristics of cancer but remain underexploited therapeutically. Because chromosomally unstable cells exhibit altered mitotic control, they are selectively vulnerable to inhibition of the kinesin KIF18A. Here, we identify the spindle and kinetochore-associated (SKA) complex as a mitotic regulator that establishes a similar dependency. SKA loss is tolerated in cells with a defective mitotic checkpoint, but when mitosis is prolonged, it leads to mitotic errors and loss of viability. Genetic analysis reveals that SKA and KIF18A are epistatic, although they function through mechanistically distinct mitotic pathways. SKA depletion selectively impacts chromosomally unstable cancer cells and mirrors the effects of KIF18A inhibition. We thus identify a cellular vulnerability associated with prolonged mitosis in chromosomally unstable cancers.

cell biology↗

Pan-cancer analysis of single-cell RNA sequencing data from 304 human tumors sheds light on the aneuploidy paradox

Aneuploidy poses a central paradox in cancer biology: it impairs cellular fitness in normal cells but drives cancer progression. To resolve this, we analyzed single cell transcriptomes from >665,000 cells - including [~]288,000 malignant cells - across 304 tumors and 15 cancer types. Integrating transcriptomics with inferred aneuploidy profiles, we characterized cell-intrinsic programs and interactions with the tumor microenvironment. Unexpectedly, highly aneuploid single cells exhibited reduced proliferation and metabolism, contrasting sharply with tumor-bulk profiles. We show this divergence is driven by karyotypic heterogeneity: in highly heterogeneous tumors, aneuploid cells display signatures of acute stress and negative selection. Conversely, in clonally aneuploid tumors, these detrimental signatures are lost and replaced by signatures of increased proliferation and enhanced metabolism, reflecting adaptation. Additionally, we identified consistent transcriptional programs driven by recurrent chromosome-arm alterations across both single cells and bulk tumors. These findings illuminate the selective forces shaping tumor evolution and the aneuploidy paradox. Statement Of SignificanceBy jointly evaluating gene expression and aneuploidy at single-cell resolution, we demonstrate that karyotypic heterogeneity underlies the transcriptional impact of aneuploidy, reveal distinct cellular responses to emerging versus stable states, and identify recurrent chromosomal alterations that drive conserved transcriptional programs. Our findings capture the dynamics of aneuploidy evolution in human tumors, providing novel insights into the aneuploidy paradox.

cancer biology↗

Ribosome Quality Control Mitigates Proteotoxic Stress in Aneuploid Cells

Aneuploidy is widespread in tumors, but how cancer cells adapt to aneuploidy-induced cellular stresses remains poorly understood. Here, we focus on the mechanisms employed to cope with proteostasis disruption, a major stress caused by aneuploidy. We show that aneuploid cells exhibit a significant accumulation of ribosomes enclosed within autophagosomes, ultimately degraded through lysosome-mediated processes. Our data also indicate that limited folding capacity of newly synthesized polypeptides leads to lysosome-mediated degradation of ribosomes. We also found that the E3 ligase ZNF598 marks these ribosomes for degradation, thus clearing translationally-impaired ribosomes. Importantly, highly aneuploid tumors display a positive correlation with ZNF598 expression, while being negatively associated with ribosomal signatures. This suggests that ribosome-associated quality control is crucial for cancer cell survival under proteotoxic stress. Our study uncovers molecular events in response to proteotoxic stress in aneuploid cells and suggests that components of ribosome-associated quality control, including ZNF598, could serve as promising targets in cancer therapy.

cell biology↗

Pan-cancer analysis reveals genomic fidelity and evolution of patient-derived organoids

BackgroundPatient-derived organoids (PDOs) are gaining recognition as a promising ex vivo model for cancer research, offering advantages over traditional 2D cell lines by better recapitulating tumor biology. ResultsIn this study, we assess the genomic stability and evolution of PDOs by analyzing copy-number alterations (CNAs) in 300 PDO samples across 16 cancer types. These results are compared with data from previously analyzed patient-derived xenografts (PDXs). We observe that PDOs exhibit genomic evolution over passaging, with an increasing divergence from the original tumor genome over time. Importantly, across cancer types, PDOs maintain higher genomic fidelity and are more genetically similar to their tumors of origin than PDX models. Moreover, PDOs show greater genomic stability during culture passaging compared to PDXs. ConclusionsThese findings position PDOs as a reliable and representative model for cancer research, while highlighting the need to carefully track their genomic evolution in culture.

cancer biology↗

Chromosome-arm 17p Loss Renders Breast Cancer Cells Vulnerable to AURKB Inhibition

Loss of chromosome-arm 17p (Del17p) is a genetic hallmark of breast cancer. While TP53 loss is an established driver of Del17p, the potential therapeutically-relevant cellular vulnerabilities of this common aneuploidy remain unexplored. Here, we first analyzed genomic and clinical data from breast cancer patients using METABRIC and TCGA datasets. Del17p was prevalent across molecular subtypes and correlated with higher tumor grade, advanced stage, and worse survival. Gene expression profiling revealed reduced expression and activity of the chromosome 17p-residing gene Aurora Kinase B (AURKB) in Del17p tumors and cell lines. Moreover, functional dependency screens across breast cancer cell lines identified increased sensitivity of Del17p cells to genetic inhibition of AURKB, which we validated using chemical inhibition in matched breast cancer cell lines. Next, we generated an isogenic model of CAL51 breast cancer cells with/without heterozygous AURKB loss in TP53-WT and TP53-null backgrounds, and confirmed that heterozygous loss of AURKB resulted in its reduced expression and in increased sensitivity to the AURKB inhibitor barasertib. Notably, p53 inactivation increased AURKB expression and reduced drug sensitivity, as previously reported, but AURKB heterozygous knockout reverted these phenotypes, revealing opposite effects of common modes of p53 inactivation (Del17p vs. point mutations). Mechanistically, the phenotypes associated with barasertib treatment - mitotic aberrations, cytokinesis failure, whole-genome doubling and apoptosis - were exacerbated in Del17p cells. Our findings therefore suggest Del17p as a potential biomarker for identifying breast cancer patients who may benefit from AURKB inhibition and highlight its potential as a therapeutic target in Del17p breast tumors. SignificanceBreast cancer tumors with loss of chromosome-arm 17p (Del17p) exhibit reduced AURKB expression and increased sensitivity to AURKB inhibition, suggesting Del17p as a biomarker for AURKB-targeted therapy.

cancer biology↗

Cell and nuclear size are associated with chromosomal instability and tumorigenicity in cancer cells that undergo whole genome doubling

Whole genome doubling (WGD) is a frequent event in cancer evolution associated with chromosomal instability, metastasis, and poor prognosis. While the genomic consequences of WGD are well documented, the effects of non-genetic alterations that accompany WGD, such as changes to cell and nuclear size, on tetraploid (4N) cancer cell physiology are less understood. Here, we show that cell and nuclear volume do not always scale with DNA content after WGD in cancer cells, resulting in 4N cells that differ in size. We find that small size is associated with enhanced cell fitness, mitotic fidelity, and tumorigenicity in 4N cancer cells and with poor patient survival in WGD-positive human cancers. Overall, these results suggest that cell and nuclear size contribute to the tumorigenic potential of 4N cancer cells and could be an important prognostic marker in human tumors that undergo WGD. Statement of SignificanceWe report that WGD generates tetraploid cancer cells that vary in size, with larger cells displaying high chromosomal instability and smaller cells exhibiting high fitness and tumorigenicity. Furthermore, WGD status and cancer cell nuclear size in human tumors correlated with patient survival, demonstrating the clinical relevance of this association.

cancer biology↗

Integrating gene expression, mutation and copy number data to identify driver genes of recurrent chromosome-arm losses

Aneuploidy is a hallmark of cancer, yet the specific genes driving recurrent chromosome-arm losses remain largely unknown. Here, we present a systematic framework integrating gene expression, mutation, and copy number data to identify candidate driver genes of cancer type-specific recurrent chromosome-arm losses across 20 cancer types, using [~]7,500 tumors from The Cancer Genome Atlas. By analyzing focal deletions and point mutations that co-occur with, or are mutually exclusive with, chromosome-arm losses, we pinpoint 311 candidate drivers associated with 160 cancer type-specific recurrent events. Our approach identifies known aneuploidy drivers such as TP53 and PTEN, while revealing multiple novel candidates, including established tumor suppressor genes not previously linked to aneuploidy. Furthermore, we leverage gene expression changes associated with these chromosome-arm losses to propose pathway-level alterations that may drive cancer progression. Integrating these findings highlights key candidate drivers underlying the observed gene expression alterations, thereby reinforcing their biological relevance. This work provides the first comprehensive catalogue of candidate driver genes for recurrently lost chromosome-arms in human cancer.

cancer biology↗

Chromosome 7 to the rescue: overcoming chromosome 10 loss in gliomas

The co-occurrence of chromosome 10 loss and chromosome 7 gain in gliomas is the most frequent loss-gain co-aneuploidy pair in human cancers, a phenomenon that has been investigated without resolution since the late 1980s. Expanding beyond previous gene-centric studies, we investigate the co-occurrence in a genome-wide manner taking an evolutionary perspective. First, by mining large tumor aneuploidy data, we predict that the more likely order is 10 loss followed by 7 gain. Second, by analyzing extensive genomic and transcriptomic data from both patients and cell lines, we find that this co-occurrence can be explained by functional rescue interactions that are highly enriched on 7, which can possibly compensate for any detrimental consequences arising from the loss of 10. Finally, by analyzing transcriptomic data from normal, non-cancerous, human brain tissues, we provide a plausible reason why this co-occurrence happens preferentially in cancers originating in certain regions of the brain.

cancer biology↗

CDC20 determines the sensitivity to spindle assembly checkpoint (SAC) inhibitors

Spindle assembly checkpoint (SAC) inhibitors are a recently developed class of drugs that perturb the regulation of chromosome segregation during division, induce chromosomal instability (CIN), and eventually lead to cell death. While they are currently in clinical trials for solid cancers, biomarkers to predict the response to SAC inhibitors are still lacking. We recently reported that aneuploid cancer cells are preferentially sensitive to SAC inhibition. Here, we investigated the molecular determinants of the response to SAC inhibition that underlies the differential sensitivity of aneuploid cells to these drugs. We found that this response was largely driven by the expression of CDC20, a main activator of the anaphase-promoting complex (APC/C), rather than by APC/C itself. Mechanistically, we discovered that CDC20 depletion prolonged metaphase duration, diminished mitotic errors, and reduced sensitivity to SAC inhibition. Aneuploid cells expressed high levels of CDC20 and experienced shorter metaphases and multiple mitotic errors, resulting in increased long-term sensitivity to SAC inhibition. Our findings propose high CDC20 expression as a favorable biomarker for SAC inhibition therapy and as an aneuploidy-induced therapeutic vulnerability.

cancer biology↗

Inactivation of p53 drives breast cancer brain metastasis by altering fatty acid metabolism

Brain metastasis (BM) is a dire prognosis across cancer types. It is largely unknown why some tumors metastasize to the brain whereas others do not. We analyzed genomic and transcriptional data from clinical samples of breast cancer BM (BCBM) and found that nearly all of them carried p53-inactivating genetic alterations through mutations, copy-number loss, or both. Importantly, p53 pathway activity was already perturbed in primary tumors giving rise to BCBM, often by loss of the entire 17p chromosome-arm. This association was recapitulated across other carcinomas. Experimentally, p53 knockout was sufficient to drastically increase BCBM formation and growth in vivo, providing a causal link between p53 inactivation and brain tropism. Mechanistically, p53-deficient BC cells exhibited altered lipid metabolism, particularly increased fatty acid (FA) synthesis and uptake, which are characteristic of brain-metastasizing cancer cells. FA metabolism was further enhanced by astrocytes in a p53-dependent manner, as astrocyte-conditioned medium increased FASN, SCD1, and CD36 expression and activity, and enhanced the survival, proliferation and migration of p53-deficient cancer cells. Consequently, these cells were more sensitive than p53-competent cells to FA synthesis inhibitors, in isogenic cell cultures, in BCBM-derived spheroids, and across dozens of BC cell lines. Lastly, a significant association was observed between p53 inactivation, astrocyte infiltration, and SCD1 expression in clinical human BCBM samples. In summary, our study identifies p53 inactivation as a driver of BCBM and potentially of BM in general; suggests a p53-dependent effect of astrocytes on BC cell behavior; and reveals FA metabolism as an underlying, therapeutically-targetable molecular mechanism.

cancer biology↗

A compendium of Amplification-Related Gain Of Sensitivity (ARGOS) genes in human cancer

Chromosomal gains are among the most frequent somatic genetic alterations occurring in cancer. While the effect of sustained oncogene expression has been characterized, the impact of copy-number gains affecting collaterally-amplified "bystander" genes on cellular fitness remains less understood. To investigate this, we built a comprehensive map of dosage compensations across human cancers by integrating expression and copy number profiles from over 8,000 TCGA tumors and CCLE cell lines. Further, we analyzed the effect of gene overexpression across 17 human cancer ORF screens to provide an overview of genes that prove toxic to cancer cells when overexpressed. Combining these two independent approaches we propose a class of Amplification-Related Gain Of Sensitivity (ARGOS) genes. These genes are located in commonly amplified regions of the genome, have lower expression levels than expected by their copy-number status, and are toxic to cancer cells when overexpressed. We experimentally validated CDKN1A and RBM14 as high-confidence pan-cancer ARGOS genes in lung and breast cancer cell line models. We additionally suggest that RBM14s mechanism of toxicity involves altered DNA damage response and innate immune signaling processes following gene overexpression. Finally, we provide a comprehensive catalog of compensated, toxic, and ARGOS genes as a community resource.

cancer biology↗

Machine-learning analysis of factors that shape cancer aneuploidy landscapes reveals an important role for negative selection

Aneuploidy, an abnormal number of chromosomes within a cell, is considered a hallmark of cancer. Patterns of aneuploidy differ across cancers, yet are similar in cancers affecting closely-related tissues. The selection pressures underlying aneuploidy patterns are not fully understood, hindering our understanding of cancer development and progression. Here, we applied interpretable machine learning (ML) methods to study tissue-selective aneuploidy patterns. We defined 20 types of features of normal and cancer tissues, and used them to model gains and losses of chromosome-arms in 24 cancer types. In order to reveal the factors that shape the tissue-specific cancer aneuploidy landscapes, we interpreted the ML models by estimating the relative contribution of each feature to the models. While confirming known drivers of positive selection, our quantitative analysis highlighted the importance of negative selection for shaping the aneuploidy landscapes of human cancer. Tumor-suppressor gene density was a better predictor of gain patterns than oncogene density, and vice-versa for loss patterns. We identified the contribution of tissue-selective features and demonstrated them experimentally for chr13q gain in colon cancer. In line with an important role for negative selection in shaping the aneuploidy landscapes, we found compensation by paralogs to be a top predictor of chromosome-arm loss prevalence, and demonstrated this relationship for one such paralog interaction. Similar factors were found to shape aneuploidy patterns in human cancer cell lines, demonstrating their relevance for aneuploidy research. Overall, our quantitative, interpretable ML models improve the understanding of the genomic properties that shape cancer aneuploidy landscapes.

cancer biology↗

Computationally Engineered CRISPR-SpyCas9 High-Fidelity Variants with Improved Specificity and Reduced Non-specific DNA Damage

The CRISPR-Cas system holds great promise in the treatment of diseases caused by genetic variations. As wildtype SpyCas9 is known to generate many off-target effects, its use in the clinic remains controversial due to safety concerns. Several high-fidelity Cas9 variants with greater specificity have been developed using rational design and directed evolution. However, the enhancement of specificity by these methods is limited by factors like selection pressure and library diversity. Thus, in-silico protein engineering may provide a more efficient route for enhancing specificity, although computationally testing these proteins remains challenging. We recently demonstrated the advantage of normal mode analysis to simulate and predict the enzymatic function of SpyCas9 in the presence of mismatches. Here, we report several mathematical models describing the entropy and functionality relationships in the CRISPR-Cas9 system. We demonstrate the invariant characteristics of these models across different conformational structures. Based on these invariant models, we developed ComPE, a novel computational protein engineering method to modify the protein and measure the vibrational entropy of wildtype or variant SpyCas9 in complex with its sgRNA and target DNA. Using this platform, we discovered novel high-fidelity Cas9 variants with improved specificity. We functionally validated the improved specificity of four variants, and the intact on-target activity in one of them. Lastly, we demonstrate their reduced off-target editing and non-specific gRNA-independent DNA damage, highlighting their advantages for clinical applications. The described method could be applied to a wide range of proteins, from CRISPR-Cas orthologs to distinct proteins in any field where engineered proteins can improve biological processes.

bioengineering↗

Human aneuploid cells depend on the RAF/MEK/ERK pathway for overcoming increased DNA damage

Aneuploidy is a hallmark of human cancer, yet the cellular mechanisms that allow cells to cope with aneuploidy-induced cellular stresses remain largely unknown. Such coping mechanisms may present cellular vulnerabilities that can be harnessed for targeting cancer cells. Here, we induced aneuploidy in non-transformed RPE1-hTERT cells and derived multiple stable clones with various degrees of chromosome imbalances. We performed an unbiased genomic profiling of 6 isogenic clones, using whole-exome and RNA sequencing. We then functionally interrogated their cellular dependency landscapes, using genome-wide CRISPR/Cas9 screens and large-scale drug screens. We found that aneuploid clones activated the DNA damage response (DDR), and were consequently more resistant to further DNA damage induction. Interestingly, aneuploid cells also exhibited elevated RAF/MEK/ERK pathway activity, and were more sensitive to several clinically-relevant drugs targeting this pathway, and in particular to genetic and chemical CRAF inhibition. CRAF activity was functionally linked to the resistance to DNA damage induction, as CRAF inhibition sensitized aneuploid cells to DNA damage-inducing chemotherapies. The association between aneuploidy, RAF/MEK/ERK signaling, and DDR was independent of p53. The increased activity and dependency of aneuploid cells on the RAF/MEK/ERK pathway was validated in another isogenic aneuploid system, and across hundreds of human cancer cell lines, confirming their relevance to human cancer. Overall, our study provides a comprehensive resource for genetically-matched karyotypically-stable cells of various aneuploidy states, and reveals a novel therapeutically-relevant cellular dependency of aneuploid cells.

cancer biology↗

Increased RNA and protein degradation is required for counteracting transcriptional burden and proteotoxic stress in human aneuploid cells

Aneuploidy, an abnormal chromosome composition, results in a stoichiometric imbalance of protein complexes, which jeopardizes the fitness of aneuploid cells. Aneuploid cells thus need to compensate for the imbalanced DNA levels by regulating their RNA and protein levels, a phenomenon known as dosage compensation. However, the molecular mechanisms involved in dosage compensation in human cells - and whether they can be targeted to selectively kill aneuploid cancer cells - remain unknown. Here, we addressed this question via molecular dissection of multiple diploid vs. aneuploid cell models. Using genomic and functional profiling of a novel isogenic system of RPE1-hTERT cells with various degrees of aneuploidy, we found that aneuploid cells cope with both transcriptional burden and proteotoxic stress. At the mRNA level, aneuploid cells increased RNA synthesis, but concomitantly elevated several RNA degradation pathways, in particular the nonsense-mediated decay (NMD) and the microRNA-mediated mRNA silencing pathways. Consequently, aneuploid cells were more sensitive to the genetic or chemical perturbation of several key components of these RNA degradation pathways. At the protein level, aneuploid cells experienced proteotoxic stress, resulting in reduced translation and increased protein degradation, rendering them more sensitive to proteasome inhibition. These findings were recapitulated across hundreds of human cancer cell lines and primary tumors, confirming that both non-transformed and transformed cells alter their RNA and protein metabolism in order to adapt to the aneuploid state. Our results reveal that aneuploid cells are dependent on the over- or under-activation of several nodes along the gene expression process, identifying these pathways as clinically-actionable vulnerabilities of aneuploid cells.

cancer biology↗

Molecular origins of genome instability following a single chromosome mis-segregation event

Chromosome instability (CIN) is the most common form of genome instability and is a hallmark of cancer. CIN invariably leads to aneuploidy, a state of karyotype imbalance. Here, we show that aneuploidy can also trigger CIN. We found that aneuploid cells experience DNA replication stress in their first S-phase and precipitate in a state of continuous CIN. This generates a repertoire of genetically diverse cells that can either continue proliferating or stop dividing. Cycling aneuploid cells display lower karyotype complexity compared to the arrested ones and increased expression of DNA repair signatures. Interestingly, the same signatures were upregulated in highly-proliferative cancer cells, which might enable them to proliferate despite the disadvantage conferred by aneuploidy-induced CIN. Altogether, our study reveals the short-term origins of CIN following aneuploidy and indicates the aneuploid state of cancer cells as a point mutation-independent source of genome instability, providing an explanation for aneuploidy occurrence in tumors.

cell biology↗

Acute expression of human APOBEC3B in mice causes lethality associated with RNA editing

RNA editing has been described to promote heterogeneity leading to the development of multiple disorders including cancer. The cytosine deaminase APOBEC3B is known to fuel tumor evolution through DNA mutagenesis, but whether it may also function as an RNA editing enzyme has not been studied. Here, we engineered a novel doxycycline-inducible mouse model of human APOBEC3B-overexpression to understand the impact of this enzyme in tissue homeostasis and address a potential role in C-to-U RNA editing. Elevated and sustained levels of APOBEC3B led to rapid alteration of cellular fitness, major organ dysfunction, and ultimately lethality in mice. Importantly, extensive analyses of RNA-sequencing and WES from mouse tissues expressing high APOBEC3B levels reveal frequent UCC-to-UUC RNA editing events mainly localized in a specific hotspot. This work identifies, for the first time, a new function for APOBEC3B in RNA editing and presents a valuable preclinical tool to understand the emerging role of APOBEC3B as a potent driver of cancer and other diseases.

molecular biology↗