EGAS00001000890-4-sc-20140725 - samples
Ontology highlight
ABSTRACT:
PROVIDER: EGAD00001000898 | EGA |
REPOSITORIES: EGA
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Project description:Cancers are ecosystems of genetically related clones, competing across space and time for limited resources. To understand the clonal structure of primary breast cancer, we applied genome and targeted sequencing to 295 samples from 49 patients’ tumors. The extent of subclonal diversification varied considerably among patients and encompassed many spatial patterns, including local growth, intraductal dissemination and clonal intermixture. Landmarks of disease progression, such as acquiring invasive or metastatic potential, arose within detectable subclones of antecedent lesions, suggesting that subclonal mutations could be relevant if actionable. No defined temporal order of mutation was evident, with the commonest genes, including PIK3CA, TP53, BRCA2, PTEN and MYC, mutated early in some, late in others, often exhibiting parallel evolution across subclones. Signatures of homologous recombination deficiency correlated with response to neoadjuvant chemotherapy. Thus, the interplay of mutation, growth and competition drives clonal structures of breast cancer that are complex, variable across patients and clinically relevant.
| EGAD00001000965 | EGA
Project description:Cancer evolves dynamically, as clonal expansions supersede or overlap one another, driven by shifting selective pressures, mutational processes and disrupted cancer genes. These processes mark the genome, such that a cancerÕs life history is encrypted in the timing, ploidy, clonality and patterns of somatic mutation. We developed bioinformatic algorithms to decipher this narrative, and applied them to 21 breast cancer genomes. We find that mutational processes evolve across the lifespan of a breast tumor, with cancer-specific signatures of point mutations and chromosomal instability often emerging late but contributing extensive genetic variation. Subclonal diversification is prominent, providing insight into the dynamics of clonal expansion in breast cancer. Most point mutations are found in just a fraction of tumor cells, together with frequent variegation in chromosomal copy number. Every tumor studied here has a dominant subclonal lineage, representing more than 50% of tumor cells. Minimal expansion of these subclones occurs until many hundreds to thousands of mutations have accumulated, implying the existence of long-lived, quiescent lineages of cells that are capable of substantial proliferation upon acquisition of enabling genomic changes. Expansion of the dominant subclone to an appreciable mass may therefore represent the final rate-limiting step in a breast cancer's development, triggering diagnosis.
2012-06-16 | E-MTAB-1087 | biostudies-arrayexpress
Project description:Cancer evolves dynamically, as clonal expansions supersede or overlap one another, driven by shifting selective pressures, mutational processes and disrupted cancer genes. These processes mark the genome, such that a cancerÕs life history is encrypted in the timing, ploidy, clonality and patterns of somatic mutation. We developed bioinformatic algorithms to decipher this narrative, and applied them to 21 breast cancer genomes. We find that mutational processes evolve across the lifespan of a breast tumor, with cancer-specific signatures of point mutations and chromosomal instability often emerging late but contributing extensive genetic variation. Subclonal diversification is prominent, providing insight into the dynamics of clonal expansion in breast cancer. Most point mutations are found in just a fraction of tumor cells, together with frequent variegation in chromosomal copy number. Every tumor studied here has a dominant subclonal lineage, representing more than 50% of tumor cells. Minimal expansion of these subclones occurs until many hundreds to thousands of mutations have accumulated, implying the existence of long-lived, quiescent lineages of cells that are capable of substantial proliferation upon acquisition of enabling genomic changes. Expansion of the dominant subclone to an appreciable mass may therefore represent the final rate-limiting step in a breast cancer's development, triggering diagnosis.
2012-06-29 | E-MTAB-1088 | biostudies-arrayexpress
Project description:Cell competition was originally described in Drosophila as a process for selection of the fittest cells. Using genetic mosaic mouse models and bone marrow chimeras, we have characterized a form of cell competition that selects for the least damaged cells. This competition is controlled by p53 but is distinct from the classical p53-mediated DNA damage response: it persists for months, is specific to the hematopoietic stem and progenitor cells, and depends on the relative rather than absolute level of p53 in competing cells. The competition appears to be mediated by a non-cell autonomous induction of growth arrest and senescence-related gene expression in outcompeted cells with higher p53 activity. p53-mediated cell competition of this type could potentially contribute to the clonal expansion of incipient cancer cells. This microarray experiment is aimed at identification of candidate genes that mediate this competition. It compares mRNA expression patterns of HSCs with different levels of p53 activity in either competitive or non-competitive conditions (isolated from either wild type, mutant p53, or mosaic wt/mutant p53 mice (R26-mp53mice) after irradiation).
2010-04-01 | GSE20912 | GEO
Project description:Activating mutations in kinase/PI3K/RAS signaling pathways are common in acute leukemia with KMT2A rearrangements (KMT2A-R). These mutations are often subclonal and their biological impact remain unclear. Using a retroviral acute myeloid leukemia model, we demonstrate that NRASG12D, FLT3ITD, and FLT3N676K accelerates KMT2A-MLLT3 leukemia onset. Importantly, also the presence of subclonal FLT3N676K in KMT2A-R leukemic cells shorten disease latency, possibly by providing stimulatory factors such as Mif. Acquired de novo mutations in Braf, Cbl, Kras, and Ptpn11 were identified in KMT2A-MLLT3 driven leukemia and favored clonal expansion. KMT2A-MLLT3 leukemia with an activating mutation enforce Myc- and Myb transcriptional modules, whereas KMT2A-MLLT3 leukemias lacking activating mutations displayed upregulation of signal transduction pathways. Our results provide new insight into the biology of KMT2A-R leukemia and highlights the importance of activated signaling as a contributing driver in this disease.
2018-05-02 | PXD008213 | Pride
Project description:Intratumor heterogeneity as a clinical challenge becomes most evident after several treatment lines, when multidrug-resistant subclones accumulate. To address this challenge, the characterization of resistance mechanisms at the subclonal level is key to identify common vulnerabilities. In this study, we integrate whole-genome sequencing, single-cell (sc) transcriptomics (scRNA sequencing), and chromatin accessibility (scATAC sequencing) together with mitochondrial DNA mutations to define subclonal architecture and evolution for longitudinal samples from 15 patients with relapsed or refractory multiple myeloma. We assess transcriptomic and epigenomic changes to resolve the multifactorial nature of therapy resistance and relate it to the parallel occurrence of different mechanisms: (1) preexisting epigenetic profiles of subclones associated with survival advantages, (2) converging phenotypic adaptation of genetically distinct subclones, and (3) subclone-specific interactions of myeloma and bone marrow microenvironment cells. Our study showcases how an integrative multiomics analysis can be applied to track and characterize distinct multidrug-resistant subclones over time for the identification of molecular targets against them.
2023-08-01 | GSE235783 | GEO
Project description:During meiosis in yeast, global splicing efficiency increases. The mechanism for this is relief of competition for the splicing machinery by repression of intron-containing ribosomal protein genes (RPGs). Repression of RPGs with rapamycin also increases splicing efficiency in vegetative cells. Reducing levels of an RPG-dedicated transcription factor globally improves splicing and suppresses the temperature-sensitive growth defect of a spliceosome mutation. These results indicate that the spliceosome is limiting and pre-mRNAs compete with each other. Under these conditions, splicing efficiency of a given pre-mRNA therefore depends on both its concentration and affinity for the limiting splicing factor(s) as well as those of the competing pre-mRNAs. We propose that trans-competition control of splicing helps repress meiotic gene expression in vegetative cells, and promotes efficient meiosis. Competition between RNAs for a limiting factor may be a general condition important for function of a variety of post-transcriptional control mechanisms. Splicing and gene expression profiles of 1) wild type yeast cells treated with rapamycin (2 biological replicates) relative to untreated cells and 2) prp4-1 pGAL-IFH1 (down-regulated expression of IFH1 transcription factor(specific for ribosomal protein genes)) relative to prp4-1 yeast.
2013-10-22 | E-GEOD-44219 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the following subset Series: GSE36822: Clonal competition with alternating dominance in multiple myeloma [244kCGH] GSE36823: Clonal competition with alternating dominance in multiple myeloma [44kCGH] GSE36824: Clonal competition with alternating dominance in multiple myeloma [GEP] Refer to individual Series
2012-03-27 | E-GEOD-36825 | biostudies-arrayexpress
Project description:To investigate the relationship between genetic and transcriptional heterogeneity in a context of cancer progression, we devised a computational approach called HoneyBADGER to identify copy number variation and loss-of-heterozygosity in individual cells from single-cell RNA-sequencing data. By combining allele frequency and expression magnitude deviations, HoneyBADGER is able to infer the presence of subclone-specific alterations in individual cells and reconstruct subclonal architecture. Also HoneyBADGER to analyze single cells from a progressive multiple myeloma (MM) patient to identify major genetic subclones that exhibit distinct transcriptional signatures relevant to cancer progression.
2018-05-24 | GSE110499 | GEO
Project description:Understanding the contribution of abnormal genetic and epigenetic programs to acute myeloid leukemia (AML) is necessary for the integrated design of targeted therapies. To investigate this, we determined the effect of epigenetic reprogramming on leukemic behavior by generating induced pluripotent stem cells (iPSCs) from AML patient samples harboring MLL rearrangements. AML-derived iPSCs (AML-iPSCs) retained leukemic mutations, but reset leukemic DNA methylation/gene expression patterns and lacked leukemic potential. However, when differentiated into hematopoietic cells, AML-iPSCs reacquired the ability to give rise to leukemia in vivo and reestablished leukemic methylation/gene expression patterns, including an aberrant MLL signature, indicating that epigenetic reprogramming was insufficient to eliminate leukemic behavior. In one case, we identified distinct AML-iPSC KRAS mutant and wildtype subclones that demonstrated differential growth properties and therapeutic susceptibilities, predicting KRAS wildtype clonal relapse due to increased cytarabine resistance. Increased cytarabine resistance was further observed in a cohort of KRAS wildtype MLL-rearranged AML samples, demonstrating the utility of AML-iPSCs in predicting subclonal relapse and facilitating clonal targeting in AML.
2016-11-14 | GSE89777 | GEO