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  • Proceedings of the National Academy of Sciences  (3)
  • Biodiversity Research  (3)
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  • Proceedings of the National Academy of Sciences  (3)
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  • 1
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2018
    In:  Proceedings of the National Academy of Sciences Vol. 115, No. 22 ( 2018-05-29), p. 5774-5779
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 115, No. 22 ( 2018-05-29), p. 5774-5779
    Abstract: A growing body of evidence suggests that a subset of human cancers grows as single clonal expansions. In such a nearly neutral evolution scenario, it is possible to infer the early ancestral tree of a full-grown tumor. We hypothesized that early tree reconstruction can provide insights into the mobility phenotypes of tumor cells during their first few cell divisions. We explored this hypothesis by means of a computational multiscale model of tumor expansion incorporating the glandular structure of colorectal tumors. After calibrating the model to multiregional and single gland data from 19 human colorectal tumors using approximate Bayesian computation, we examined the role of early tumor cell mobility in shaping the private mutation patterns of the final tumor. The simulations showed that early cell mixing in the first tumor gland can result in side-variegated patterns where the same private mutations could be detected on opposite tumor sides. In contrast, absence of early mixing led to nonvariegated, sectional mutation patterns. These results suggest that the patterns of detectable private mutations in colorectal tumors may be a marker of early cell movement and hence the invasive and metastatic potential of the tumor at the start of the growth. In alignment with our hypothesis, we found evidence of early abnormal cell movement in 9 of 15 invasive colorectal carcinomas (“born to be bad”), but in none of 4 benign adenomas. If validated with a larger dataset, the private mutation patterns may be used for outcome prediction among screen-detected lesions with unknown invasive potential.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2018
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2012
    In:  Proceedings of the National Academy of Sciences Vol. 109, No. 48 ( 2012-11-27), p. 19673-19678
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 109, No. 48 ( 2012-11-27), p. 19673-19678
    Abstract: Histone H3 lysine-9 methyltransferase G9a/EHMT2/KMT1C is a key corepressor of gene expression. However, activation of a limited number of genes by G9a (independent of its catalytic activity) has also been observed, although the precise molecular mechanisms are unknown. By using RNAi in combination with gene expression microarray analysis, we found that G9a functions as a positive and a negative transcriptional coregulator for discrete subsets of genes that are regulated by the hormone-activated Glucocorticoid Receptor (GR). G9a was recruited to GR-binding sites (but not to the gene body) of its target genes and interacted with GR, suggesting recruitment of G9a by GR. In contrast to its corepressor function, positive regulation of gene expression by G9a involved G9a-mediated enhanced recruitment of coactivators CARM1 and p300 to GR target genes. Further supporting a role for G9a as a molecular scaffold for its coactivator function, the G9a-specific methyltransferase inhibitor UNC0646 did not affect G9a coactivator function but selectively decreased G9a corepressor function for endogenous target genes. Overall, G9a functioned as a coactivator for hormone-activated genes and as a corepressor in support of hormone-induced gene repression, suggesting that the positive or negative actions of G9a are determined by the gene-specific regulatory environment and chromatin architecture. These findings indicate distinct mechanisms of G9a coactivator vs. corepressor functions in transcriptional regulation and provide insight into the molecular mechanisms of G9a coactivator function. Our results also suggest a physiological role of G9a in fine tuning the set of genes that respond to glucocorticoids.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2012
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2009
    In:  Proceedings of the National Academy of Sciences Vol. 106, No. 12 ( 2009-03-24), p. 4828-4833
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 106, No. 12 ( 2009-03-24), p. 4828-4833
    Abstract: Cancers are clonal expansions, but how a single, transformed human cell grows into a billion-cell tumor is uncertain because serial observations are impractical. Potentially, this history is surreptitiously recorded within genomes that become increasingly numerous, polymorphic, and physically separated after transformation. To correlate physical with epigenetic pairwise distances, small 2,000- to 10,000-cell gland fragments were sampled from left and right sides of 12 primary colorectal cancers, and passenger methylation at 2 CpG-rich regions was measured by bisulfite sequencing. Methylation patterns were polymorphic but differences were similar between different parts of the same tumor, consistent with relatively isotropic or “flat” clonal expansions that could be simulated by rapid initial population expansions. Methylation patterns were too diverse to be consistent with very rare cancer stem cells but were more consistent with multiple (≈4 to 1,000) long-lived cancer stem cell lineages per cancer gland. Our study illustrates the potential to reconstruct the unperturbed biology of human cancers from epigenetic passenger variations in their present-day genomes.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2009
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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