Project description:Copy number alteration (CNA) profiling of human tumors has revealed recurrent patterns of DNA amplifications and deletions. These patterns are indicative of conserved selection pressures, but cannot be fully explained by known oncogenes and tumor suppressor genes. Using integrative analysis of CNA data from patient tumors and experimental systems, we report that principal component analysis-defined CNA signatures are predictive of glycolytic phenotypes, including FDG-avidity of patient tumors, and increased proliferation. The primary glycolysis-linked CNA signature is associated with p53 mutation and shows coordinate amplification of glycolytic genes and other cancer-linked metabolic enzymes including TIGAR and RPIA. In contrast, alternative signatures involve both different mechanisms of tumor suppression loss (eg, MDM2 amplification) and different glycolysis enzyme isoforms. Furthermore, a cross-species CNA comparison identified 21 conserved CNA regions, containing 13 enzymes in the glycolysis and pentose phosphate pathways in addition to known cancer driving genes. In validation experiments, exogenous expression of hexokinase and enolase enzymes resulted in reduced propensities for amplifications at the corresponding endogenous loci. Our findings support metabolic stress as a selective pressure underlying the recurrent CNAs observed in human tumors, and further cast genomic instability as an enabling event in tumorigenesis and metabolic evolution.
Project description:Aneuploidy results in decreased cellular fitness in many different species and model systems. However, aneuploidy is commonly found in cancer cells and often correlates with aggressive growth and poor prognosis, suggesting that the impact of aneuploidy on cellular fitness is context dependent. The BRG1 (SMARCA4) subunit of the SWI/SNF chromatin remodelling complex is a tumour suppressor that is frequently lost in cancer cells. Here, we used a chromosomally stable cell line to test the effect of BRG1 loss on the evolution of aneuploidy. We find that BRG1 deletion leads to an initial loss of fitness in this cell line that improves over time. The improved fitness correlates with a gain of extra copies of chromosome 18. Notably, changes in pathways that are known to promote tolerance to aneuploidy are evident immediately upon loss of BRG1, providing an environment where karyotype changes associated with a fitness advantage can be explored. At least in some genetic backgrounds, therefore, loss of the SWI/SNF complex can contribute to tumourigenesis through tolerance of aneuploidy.
Project description:Aneuploidy is a hallmark of tumor cells, and yet the precise relationship between aneuploidy and a cell’s proliferative ability, or cellular fitness, has remained elusive. In this study, we have combined a detailed analysis of aneuploid clones isolated from laboratory-evolved populations of Saccharomyces cerevisiae with a systematic, genome-wide screen for the fitness effects of telomeric amplifications to address the relationship between aneuploidy and cellular fitness. We found that aneuploid clones rise to high population frequencies in nutrient-limited evolution experiments and show increased fitness relative to wild type. Direct competition experiments confirmed that three out of four aneuploid events isolated from evolved populations were themselves sufficient to improve fitness. To expand the scope beyond this small number of exemplars, we created a genome-wide collection of >1,800 diploid yeast strains, each containing a different telomeric amplicon (Tamp), ranging in size from 0.4 to 1,000 kb. Using pooled competition experiments in nutrient-limited chemostats followed by high-throughput sequencing of strain-identifying barcodes, we determined the fitness effects of these >1,800 Tamps under three different conditions. Our data revealed that the fitness landscape explored by telomeric amplifications is much broader than that explored by single-gene amplifications. As also observed in the evolved clones, we found the fitness effects of most Tamps to be condition specific, with a minority showing common effects in all three conditions. By integrating our data with previous work that examined the fitness effects of single-gene amplifications genome-wide, we found that a small number of genes within each Tamp are centrally responsible for each Tamp’s fitness effects. Our genome-wide Tamp screen confirmed that telomeric amplifications identified in laboratory-evolved populations generally increased fitness. Our results show that Tamps are mutations that produce large, typically condition-dependent changes in fitness that are important drivers of increased fitness in asexually evolving populations.
Project description:Aneuploidy causes a proliferative disadvantage in all normal cells analyzed to date, yet this condition is associated with a disease characterized by unabated proliferative potential, cancer. The mechanisms that allow cancer cells to tolerate the adverse effects of aneuploidy are not known. To probe this question, we identified aneuploid yeast strains with improved proliferative abilities. Their molecular characterization revealed strain-specific genetic alterations as well as mutations shared between different aneuploid strains. Among the latter, a loss-of-function mutation in the gene encoding the deubiquitinating enzyme Ubp6 improves growth rates in four different aneuploid yeast strains by attenuating the changes in intracellular protein composition caused by aneuploidy. Our results demonstrate the existence of aneuploidy-tolerating mutations that improve the fitness of multiple different aneuploidies and highlight the importance of ubiquitin-proteasomal degradation in suppressing the adverse effects of aneuploidy.
Project description:Aneuploidy is a frequent feature of human tumors. Germline mutations leading to aneuploidy are very rare in humans, and their tumor-promoting properties are mostly unknown at the molecular level. We report here novel germline biallelic mutations in MAD1L1, the gene encoding the Spindle Assembly Checkpoint (SAC) protein MAD1, in a 36-year-old female with a dozen of neoplasias, including five malignant tumors. Functional studies in peripheral blood cells demonstrated lack of full-length protein and deficient SAC response, resulting in ~30-40% of aneuploid cells as detected by cytogenetic and single-cell (sc) DNA analysis. scRNA-seq analysis of proband blood cells identified mitochondrial stress accompanied by systemic inflammation with enhanced interferon and NFkB signaling. The inference of chromosomal aberrations from scRNA-seq analysis detected inflammatory signals both in aneuploid and euploid cells, suggesting a non-cell autonomous response to aneuploidy. In addition to random aneuploidies, MAD1L1 mutations resulted in specific clonal expansions of T-cells with chromosome 18 gains and enhanced cytotoxic profile, as well as intermediate B-cells with chromosome 12 gains and transcriptomic signatures characteristic of chronic lymphocytic leukemia cells. These data point to MAD1L1 mutations as the cause of a new variant of mosaic variegated aneuploidy syndrome (MVA) with systemic inflammation and unprecedented tumor susceptibility.
Project description:Aneuploidy causes severe developmental defects and is a near universal feature of tumor cells. Despite its profound effects, the cellular processes affected by aneuploidy are not well characterized. Here, we examined the consequences of aneuploidy on the proteome of aneuploid budding yeast strains. We show that although protein levels largely scale with gene copy number, subunits of multi-protein complexes are notable exceptions. Posttranslational mechanisms attenuate their expression when their encoding genes are in excess. Our proteomic analyses further revealed a novel aneuploidy-associated protein expression signature characteristic of altered metabolism and redox homeostasis. Indeed aneuploid cells harbor increased levels of reactive oxygen species (ROS). Interestingly, increased protein turnover attenuates ROS levels and this novel aneuploidy-associated signature and improves the fitness of most aneuploid strains. Our results show that aneuploidy causes alterations in metabolism and redox homeostasis. Cells respond to these alterations through both transcriptional and posttranscriptional mechanisms.
Project description:Aneuploidy causes a proliferative disadvantage in all cells analyzed to date, yet this condition is associated with a disease characterized by unabated proliferative potential, cancer. The mechanisms that allow cancer cells to tolerate the adverse effects of aneuploidy are not known. To probe this question, we identified aneuploid yeast strains with high proliferative abilities and characterized their genetic alterations. We found both strain-specific genetic alterations and mutations shared between different aneuploid strains. One such mutation, a loss of function mutation in the gene encoding the deubiquitinating enzyme UBP6, improves growth rates in four different aneuploid yeast strains. Our data further suggest that deletion of UBP6 attenuates the effects of aneuploidy on cellular protein composition. Our results demonstrate the existence of aneuploidy-tolerating mutations that improve the fitness of multiple different aneuploidies and highlight the importance of ubiquitin-proteasomal degradation in suppressing the adverse effects of aneuploidy. This dataset contains both expression analysis and CGH of yeast strains bearing extra chromosomes. In all cases, the wt euploid strain grown under the same conditions was used as the reference sample. Reference nucleic acid was generally labeled with Cy3, though some were labeled with Cy5 as indicated in the associated annotations for each array. No replicate arrays are included. Expression Samples: GSM513249-GSM513277 CGH Samples: GSM513278-GSM513369
Project description:Aneuploidy, the presence of chromosome gains or losses, is a hallmark of cancer and congenital syndromes. Here, we describe KaryoCreate (Karyotype CRISPR Engineered Aneuploidy Technology), a system that enables generation of chromosome-specific aneuploidies by co-expression of a sgRNA targeting chromosome-specific CENPA-binding ɑ-satellite repeats together with dCas9 fused to a mutant form of KNL1. We designed unique and highly specific sgRNAs for 19 out of 24 chromosomes. Expression of these sgRNAs with KNL1Mut-dCas9 leads to missegregation and induction of gains or losses of the targeted chromosome in cellular progeny with an average efficiency of 8% and 12% for gains and losses, respectively (up to 20%), tested and validated across 9 chromosomes. Using KaryoCreate in colon epithelial cells, we show that chromosome 18q loss, a frequent occurrence in gastrointestinal cancers, promotes resistance to TGFβ, likely due to synergistic hemizygous deletion of multiple genes. Altogether, we describe a novel technology to create and study chromosome missegregation and aneuploidy in the context of cancer and beyond.
Project description:Aneuploidy, the presence of chromosome gains or losses, is a hallmark of cancer and congenital syndromes. Here, we describe KaryoCreate (Karyotype CRISPR Engineered Aneuploidy Technology), a system that enables generation of chromosome-specific aneuploidies by co-expression of a sgRNA targeting chromosome-specific CENPA-binding ɑ-satellite repeats together with dCas9 fused to a mutant form of KNL1. We designed unique and highly specific sgRNAs for 19 out of 24 chromosomes. Expression of these sgRNAs with KNL1Mut-dCas9 leads to missegregation and induction of gains or losses of the targeted chromosome in cellular progeny with an average efficiency of 8% and 12% for gains and losses, respectively (up to 20%), tested and validated across 9 chromosomes. Using KaryoCreate in colon epithelial cells, we show that chromosome 18q loss, a frequent occurrence in gastrointestinal cancers, promotes resistance to TGFβ, likely due to synergistic hemizygous deletion of multiple genes. Altogether, we describe a novel technology to create and study chromosome missegregation and aneuploidy in the context of cancer and beyond.
Project description:Esophageal adenocarcinoma is characterized by complex chromosomal alterations. Tumors were evaluated to identify regions of recurrent copy gains and losses and to determine the prognositic significance of the degree of segmental aneuploidy as measured by SNP array.