DNA methylation alterations exhibit striking intra-individual stability and inter-individual heterogeneity across metastatic dissemination
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE38242 | GEO | 2013/02/04
SECONDARY ACCESSION(S): PRJNA167520
REPOSITORIES: GEO
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2013-02-04 | E-GEOD-38242 | biostudies-arrayexpress
Project description:Human cancers almost ubiquitously harbor epigenetic alterations. Although such alterations in epigenetic marks, including DNA methylation, are potentially heritable, they can also be dynamically altered. Given this potential for plasticity, the degree to which epigenetic changes can be subject to selection and act as drivers of neoplasia has been questioned. We carried out genome-scale analyses of DNA methylation alterations in lethal metastatic prostate cancer and created DNA methylation "cityscape" plots to visualize these complex data. We show that somatic DNA methylation alterations, despite showing marked interindividual heterogeneity among men with lethal metastatic prostate cancer, were maintained across all metastases within the same individual. The overall extent of maintenance in DNA methylation changes was comparable to that of genetic copy number alterations. Regions that were frequently hypermethylated across individuals were markedly enriched for cancer- and development/differentiation-related genes. Additionally, regions exhibiting high consistency of hypermethylation across metastases within individuals, even if variably hypermethylated across individuals, showed enrichment for cancer-related genes. Whereas some regions showed intraindividual metastatic tumor heterogeneity in promoter methylation, such methylation alterations were generally not correlated with gene expression. This was despite a general tendency for promoter methylation patterns to be strongly correlated with gene expression, particularly at regions that were variably methylated across individuals. These findings suggest that DNA methylation alterations have the potential for producing selectable driver events in carcinogenesis and disease progression and highlight the possibility of targeting such epigenome alterations for development of longitudinal markers and therapeutic strategies.
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Project description:There is growing evidence that sperm DNA methylation is important in maintaining proper sperm health and function. Previous studies have associated sperm DNA methylation levels with sperm quality and function, however, little is known regarding the intra- and inter-individual variability in sperm methylation levels. This study characterizes this variation. Sperm epigenetic differences between successive semen samples from 12 patients were examined to identify the intra- and inter-individual differences globally across the genome, and in specifically defined genomic regions using the Illumina Infinium HumanMethylation450 BeadChips. Methylation analysis identified a bimodal distribution in the methylation levels that were non-uniformly distributed across the different genomic regions. The methylation levels were highly correlated in both the intra- and inter-individual comparisons. The intra-individual methylation levels were more highly correlated than the inter-individual comparison both globally and across the defined genomic regions, demonstrating that sperm DNA methylation levels are relatively stable between semen sample collections.
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Project description:Mixed-effects models for repeated measures and longitudinal data include random coefficients that are unique to the individual, and thus permit subject-specific growth trajectories, as well as direct study of how the coefficients of a growth function vary as a function of covariates. Although applications of these models often assume homogeneity of the within-subject residual variance that characterizes within-person variation after accounting for systematic change and the variances of the random coefficients of a growth model that quantify individual differences in aspects of change, alternative covariance structures can be considered. These include allowing for serial correlations between the within-subject residuals to account for dependencies in data that remain after fitting a particular growth model or specifying the within-subject residual variance to be a function of covariates or a random subject effect to address between-subject heterogeneity due to unmeasured influences. Further, the variances of the random coefficients can be functions of covariates to relax the assumption that these variances are constant across subjects and to allow for the study of determinants of these sources of variation. In this paper, we consider combinations of these structures that permit flexibility in how mixed-effects models are specified to understand within- and between-subject variation in repeated measures and longitudinal data. Data from three learning studies are analyzed using these different specifications of mixed-effects models.
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Project description:MAPK inhibitors (MAPKi) are active in BRAF-mutant metastatic melanoma patients, but the extent of response and progression-free survival (PFS) is variable, and complete responses are rare. We sought to examine the patterns of response and progression in patients treated with targeted therapy.MAPKi-naïve patients treated with combined dabrafenib and trametinib had all metastases ?5 mm (lymph nodes ?15 mm in short axis) visible on computed tomography measured at baseline and throughout treatment.24 patients had 135 measured metastases (median 4.5/patient, median diameter 16 mm). Time to best response (median 5.5 mo, range 1.7-20.1 mo), and the degree of best response (median -70%, range +9 to -100%) varied amongst patients. 17% of patients achieved complete response (CR), whereas 53% of metastases underwent CR, including 42% ?10 mm. Metastases that underwent CR were smaller than non-CR metastases (median 11 vs 20 mm, P<0.001). PFS was variable among patients (median 8.2 mo, range 2.6-18.3 mo), and 50% of patients had disease progression in new metastases only. Only 1% (1/71) of CR-metastases subsequently progressed. Twelve-month overall survival was poorer in those with a more heterogeneous initial response to therapy than less heterogeneous (67% vs 93%, P?=?0.009).Melanoma response and progression with MAPKi displays marked inter- and intra-patient heterogeneity. Most metastases undergo complete response, yet only a small proportion of patients achieve an overall complete response. Similarly, disease progression often occurs only in a subset of the tumor burden, and often in new metastases alone. Clinical heterogeneity, likely reflecting molecular heterogeneity, remains a barrier to the effective treatment of melanoma patients.
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Project description:We report the application of single molecule-based sequencing technology in combination with MBD affinity purifcation (MAP-seq) to generate methylation maps in a panel of human brain samples. Here we assay the methylation status of the human genome in eight distinct brain regions from three individuals in addition to a further thirty six hippocampal samples. The cerebellum was a consistent outlier compared to all other regions, showing over 16,000 differentially methylated regions (DMRs). Unexpectedly, the sequence properties of hypo- and hyper- methylated domains in cerebellum were distinct. In contrast we found very few DMRs that could distinguish between regions of the cortex, limbic system and brain stem. Inter-individual DMRs were readily detectable, however with the exception of cerebellum, DNA methylation patterns are more similar between different brain regions from the same individual, than they are for a single brain region between different individuals.
2014-12-01 | GSE50960 | GEO
Project description:The plasticity and heterogeneity of cancer cells are known to play a major role in malignant progression, yet the precise molecular drivers of metastases remain elusive. We performed single-cell RNA-Seq (scRNA-Seq) on tumours and matched lung macrometastases of patient-derived xenografts (PDXs) of breast cancer to identify molecular mechanisms of metastasis during colonization.
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Project description:Metastatic prostate cancer (mPC) comprises a spectrum of diverse phenotypes. However, the extent of inter- and intra-tumor heterogeneity is not established. Here we use digital spatial profiling (DSP) technology to quantitate transcript and protein abundance in spatially-distinct regions of mPCs. By assessing multiple discrete areas across multiple metastases, we find a high level of intra-patient homogeneity with respect to tumor phenotype. However, there are notable exceptions including tumors comprised of regions with high and low androgen receptor (AR) and neuroendocrine activity. While the vast majority of metastases examined are devoid of significant inflammatory infiltrates and lack PD1, PD-L1 and CTLA4, the B7-H3/CD276 immune checkpoint protein is highly expressed, particularly in mPCs with high AR activity. Our results demonstrate the utility of DSP for accurately classifying tumor phenotype, assessing tumor heterogeneity, and identifying aspects of tumor biology involving the immunological composition of metastases.
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Project description:Prostate cancers exhibit a spectrum of molecular aberrations of which a substantial subset are amenable to targeted therapeutics. To determine the diversity of somatic alterations present in metastasis within and between individuals we characterized the genomic landscapes of 176 tumors acquired from 63 men. In contrast to the considerable variation across individuals, the molecular diversity of tumors within an individual was substantially less: alterations in putative drivers of cancer growth and cell cycle progression status were highly concordant. While androgen receptor activity was inversely related to proliferation, the expression of Fanconi Anemia complex genes was strongly associated with increased cell cycle progression. Inhibition of FANCA, FANCC, FANCD2 and BRCA2 expression reduced prostate cancer growth. The limited molecular diversity across metastases may result from bottlenecks imposed by the dissemination process, limited evolutionary time between metastatic seeding and tumor sampling, intermixing of tumor clones, and selection resulting from treatment pressures. Though exceptions exist, evaluating a single metastasis provides a reasonable assessment of the key molecular processes that occur throughout the spectrum of disseminated tumors within an individual, and may be used for selecting treatments based on predicted molecular vulnerabilities. Custom Agilent 44K whole human genome expression oligonucleotide microarrays were used to profile 171 CRPC tumors from 63 patients. RNA was amplified prior to hybridization against a common reference pool of prostate tumor cell lines.
2015-12-18 | E-GEOD-74685 | biostudies-arrayexpress