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Genomic analysis of hESC pedigrees enables identification of de novo genetic alterations and determination of the timing and origin of mutational events

ABSTRACT: Given the association between mutational load and cancer, the observation that genetic aberrations are frequently found in human pluripotent stem cells (hPSCs) is of concern. Prior studies in hiPSCs have shown that deletions and regions of loss-of-heterozygosity (LOH) tend to arise during reprogramming and early culture, while duplications more frequently occur during long-term culture. For the corresponding experiments in hESCs, we studied two sets of hESC lines: one including the corresponding parental DNA; and the other generated from single blastomeres from four sibling embryos. Here, we show for the first time that genetic aberrations observed in hESCs can originate during preimplantation embryo development and/or early derivation. These early aberrations are mainly deletions and LOH, while aberrations arising during long-term culture of hESCs are more frequently duplications. Our results highlight the importance of close monitoring of genomic integrity and the development of improved methods for derivation and culture of hPSCs.

ORGANISM(S): Homo sapiens

PROVIDER: GSE49452 | GEO | 2014/04/21

SECONDARY ACCESSION(S): PRJNA213967

REPOSITORIES: GEO

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Genomic analysis of hESC pedigrees enables identification of de novo genetic alterations and determination of the timing and origin of mutational events

Project description:Given the association between mutational load and cancer, the observation that genetic aberrations are frequently found in human pluripotent stem cells (hPSCs) is of concern. Prior studies in hiPSCs have shown that deletions and regions of loss-of-heterozygosity (LOH) tend to arise during reprogramming and early culture, while duplications more frequently occur during long-term culture. For the corresponding experiments in hESCs, we studied two sets of hESC lines: one including the corresponding parental DNA; and the other generated from single blastomeres from four sibling embryos. Here, we show for the first time that genetic aberrations observed in hESCs can originate during preimplantation embryo development and/or early derivation. These early aberrations are mainly deletions and LOH, while aberrations arising during long-term culture of hESCs are more frequently duplications. Our results highlight the importance of close monitoring of genomic integrity and the development of improved methods for derivation and culture of hPSCs. Total DNA extracted at from human embryonic stem cells originated independently

2014-04-21 | E-GEOD-49452 | biostudies-arrayexpress

8p Loss of Heterozygosity triggers metastasis and drug resistance

Project description:Chromosome arm deletions are frequently observed in human cancers. Such large-scale aberrations may trigger phenotypes distinct from those that arise by loss of single genes. Using TALEN-based genomic engineering, we generated cell models with targeted 8p loss-of-heterozygosity (LOH) that mimics an 8p deletion commonly found in breast cancer patients. 8p LOH triggered up-regulation of the mevalonate pathway. The alterations in lipid metabolism led to increased metastatic potential and drug resistance of 8p-deleted cells that are in agreement with poorer survival rates of breast cancer patients harbouting 8p LOH. Our findings also suggest novel therapeutic strategies for treatment of 8p LOH tumors.

2015-05-21 | GSE68042 | GEO

8p Loss of Heterozygosity triggers metastasis and drug resistance

2015-05-21 | E-GEOD-68042 | biostudies-arrayexpress

Modulation of Wnt and Activin/Nodal supports efficient derivation, cloning and suspension expansion of human pluripotent stem cells

Project description:Various culture systems have been used to derive and maintain human pluripotent stem cells (hPSCs), but they are inefficient in sustaining cloning and suspension expansion of hPSCs. Through systematically modulating Wnt and Activin/Nodal signaling, we developed a defined medium (termed AIC), which enables efficient cloning and long-term expansion of hPSCs (AIC-hPSCs) through single-cell passage on feeders, matrix or in suspension (25-fold expansion in 4 days) and maintains genomic stability of hPSCs over extensive expansion. Moreover, the AIC medium supports efficient derivation of hPSCs from blastocysts or somatic cells under feeder-free conditions. Compared to conventional-culture hPSCs, AIC-hPSCs have similar gene expression profiles but down-regulated differentiation genes and display higher metabolic activity. The AIC medium shows a good compatibility for suspension expansion of different hPSC lines. Our study provides a robust culture system for derivation, cloning and suspension expansion of high-quality hPSCs that benefits GMP production and processing of therapeutic hPSC products

2020-04-23 | GSE145163 | GEO

Copy-number alterations correlate to high-risk genomic aberrations and survival in chronic lymphocytic leukemia

Project description:Large but not small copy-number alterations correlate to high-risk genomic aberrations and survival in chronic lymphocytic leukemia: a high-resolution genomic screening of newly diagnosed patients. Single nucleotide polymorphism (SNP)-arrays allow simultaneous detection of copy-number aberrations (CNAs) and copy-number neutral loss-of-heterozygosity (CNN-LOH). In this study we investigated the presence of CNAs and CNN-LOH in newly diagnosed CLL samples from a Swedish chronic lymphocytic leukemia (CLL) cohort. In this study we could detect the known recurrent aberrations in CLL (i.e. deletions of 13q, 11q, 17p and trisomy 12). We also detected other both large and small CNAs which were mostly non-recurrent. CNN-LOH was detected on chromosome 13q in patients that carried homozygous deletion of 13q.

2009-11-23 | GSE16406 | GEO

Identification of Candidate Genes for Sporadic Amyotrophic Lateral Sclerosis by Array Comparative Genomic Hybridisation

Project description:Background: Amyotrophic lateral sclerosis (ALS) is a devastating disorder of the central nervous system that leads to progressive loss of upper and lower motor neurons. Most cases are sporadic and of unknown aetiology. In this study, we screened 71 patients with sporadic ALS for the presence of DNA copy number variations, in order to identify novel candidate disease genes. Methods: We have used sub-megabase resolution BAC array comparative genomic hybridisation to detect genomic imbalances in our ALS patient cohort. In order to distinguish phenotypically neutral copy number variations occurring frequently in the normal population from disease-associated aberrations, we screened our results against both the Database of Genomic Variants and a reference data set of approximately 700 normal individuals and probands with other disorders analysed in our laboratory. Aberrations with potential relevance for disease aetiology were verified by oligo array CGH. Findings: In 71 patients with sporadic ALS, we identified a total of six duplications and seven deletions that scored above our threshold. Twelve of these thirteen variations were smaller than 1Mb. Seven were observed exclusively in ALS patients and thus likely play causal roles in the disorder. Analysis of these regions highlighted, for example, the SLC1A7 (EAAT5) glutamate transporter and the kinesin family member KIF9 as good positional and functional candidate genes for ALS. Interpretation: Non-polymorphic sub-microscopic duplications and deletions observable by array CGH are frequent in patients with sporadic ALS. Analysis of such aberrations serves as an excellent starting point in deciphering the aetiology of this complex disease. Keywords: array CGH A cohort of 71 ALS patients was analysed by means of a submegabase resolution BAC array. No replicates were included. Experiments were done without dye swap.

2008-12-24 | E-GEOD-7950 | biostudies-arrayexpress

Expression data from diploid human pluripotent stem cells

Project description:Human pluripotent stem cells (hPSCs) tend to acquire chromosomal aberrations in culture, which may increase their tumorigenicity. However, the cellular mechanism(s) underlying these aberrations are largely unknown. Here we show that the DNA replication in aneuploid hPSCs is perturbed, resulting in high prevalence of defects in chromosome condensation and segregation. Global gene expression analyses in aneuploid hPSCs revealed decreased levels of actin cytoskeleton genes and their common transcription factor SRF. Down-regulation of SRF or chemical perturbation of actin cytoskeleton organization in diploid hPSCs resulted in increased replication stress and perturbation of chromosome condensation, recapitulating the findings in aneuploid hPSCs. Altogether, our results revealed that in hPSCs DNA replication stress results in a distinctive defect in chromosome condensation, underlying their ongoing chromosomal instability. Our results shed a new light on the mechanisms leading to ongoing chromosomal instability in hPSCs, and may be relevant to tumor development as well. Expression data from diploid human pluripotent stem cells Total RNA was isolated from undifferentiated human pluripotent stem cells grown under standard human ES conditions or under condition media

2015-11-12 | E-GEOD-64647 | biostudies-arrayexpress

Primary mediastinal large B-cell lymphoma is hallmarked by large-scale copy-neutral loss of heterozygosity

Project description:Development of primary mediastinal B-cell lymphoma (PMBL) is driven by cumulative genomic aberrations. It is unknown whether copy-neutral loss of heterozygosity (CN-LOH) contributes to the pathogenesis of this tumor. To get insight into the CN-LOH landscape of PMBL, we performed Single Nucleotide Polymorphism array (SNPa) analysis of two PMBL-derived cell lines and 33 primary tumors. The study uncovered large-scale CN-LOH lesions in both cell lines and 90.9% (30/33) of primary tumors. The latter cases showed 133 CN-LOH stretches of size >25Mb which affected up to 14 chromosomes per case (mean of 4.4). Involvement of chromosomal segments was predominant (81.2%), which, in a heterozygous diploid context, suggests the implication of B-cell specific crossover events. Further analysis indicated that the CN-LOH lesions were triggered by one or two consecutive molecular hits. Notably, CN-LOH segments were non-randomly clustered on chromosome 6p (60%), 15 (37.2%) and 17q (40%). Preliminary whole-exome sequencing data yielded coincidence of these lesions with mutations in MHC I and histon-related genes (6p21), B2M (15q15) and GNA13 (17q23), respectively. We hypothesize that CN-LOH-associated hits occurred early during lymphomagenesis, following mutagenesis but preceding genomic gains. Screening of the cohort of 2,658 cancer whole-genomes revealed that the CN-LOH landscape in PMBL is unique and distinguishes this tumor from other malignancies. Altogether, CN-LOH lesions rank as the most frequent genetic defect identified so far in this disease and the CN-LOH landscape suggest a hitherto undescribed mitotic recombinational driver. The aberrations affect the expression of key driver genes and functionally alternate genomic deletions which are infrequent in PMBL.

2021-09-16 | GSE184212 | GEO

Human cleavage stage embryos are chromosomally unstable

Project description:Embryonic chromosome aberrations cause birth defects and reduce human fertility. However, neither their nature nor incidence are known. Here, we develop a method to assess genome-wide copy number variation and loss of heterozygosity in single cells and apply it to screen blastomeres from in vitro fertilized preimplantation embryos. Complex patterns of chromosome-arm imbalances or segmental deletions, duplications or amplifications that were reciprocal in sister blastomeres were detected in a large proportion of the embryos. In addition, aneuploidies and uniparental isodisomies were frequently observed. Since these embryos were derived from young fertile couples, the data indicate that chromosomal instability is common to human embryogenesis. Keywords: comparative genomic hybridisation

2009-04-26 | GSE11663 | GEO

Increased Risk of Genetic and Epigenetic Instability in Human Embryonic Stem Cells Associated with Specific Culture Conditions II

Project description:The self-renewal and differentiation capacities of human pluripotent stem cells (hPSCs) make them good sources of cells for cell transplantation therapy, drug development, and studies of cellular differentiation and development. However, the large numbers of cells necessary for many of these applications require extensive expansion of hPSC cultures, a process that has been associated with genetic and epigenetic alterations. We have performed a combinatorial study on both hESCs and hiPSCs to compare the effects of enzymatic vs. mechanical passaging, and feeder-free vs. mouse embryonic fibroblast feeder substrate, to on the genetic and epigenetic stability and the phenotypic characteristics of hPSCs. In extensive experiments in hEScs involving over 100 continuous passages, , we observed that both enzymatic passaging and feeder-free culture were associated with genetic instability, higher cell proliferation, and persistence of OCT4-positive cells in teratomas, with enzymatic passaging having the stronger effect. In all combinations of culture conditions except for mechanical passaging on feeder layers, we noted recurrent deletions in the genomic region containing the tumor suppressor gene TP53, which was associated with decreased mRNA expression of TP53, as well as alterations in the expression of several downstream genes consistent with a decrease in the activity of the TP53 pathway. Among the hESC cultures, we also observedculture-dependent variations in global gene expression and DNA methylation. Verification of the negative effects of enzymatic passaging and feeder-free conditions was performed in hiPSC cultures. Our results highlight the need for careful assessment of effects of culture conditions on cells intended for clinical therapies. Three independent hiPSC clones reprogrammed from human fetal dermal fibroblasts: HDF51iPS1, HDF51iPS7, and HDF51iPS11.

2015-03-29 | E-GEOD-56834 | biostudies-arrayexpress

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