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  • Oxford University Press (OUP)  (3)
  • Fischer, Johannes C  (3)
  • 1
    Online Resource
    Online Resource
    Label-Free Enrichment and Molecular Characterization of Viable Circulating Tumor Cells from Diagnostic Leukapheresis Products
    Oxford University Press (OUP) ; 2019
    In:  Clinical Chemistry Vol. 65, No. 4 ( 2019-04-01), p. 549-558
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    In: Clinical Chemistry, Oxford University Press (OUP), Vol. 65, No. 4 ( 2019-04-01), p. 549-558
    Abstract: Circulating tumor cells (CTCs) may be used to improve cancer diagnosis, prognosis, and treatment. However, because knowledge regarding CTC biology is limited and the numbers of CTCs and CTC-positive cancer patients are low, progress in this field is slow. We addressed this limitation by combining diagnostic leukapheresis (DLA) and microfluidic enrichment to obtain large numbers of viable CTCs from metastasized breast cancer patients. METHODS DLA was applied to 9 patients, and 7.5 mL of peripheral blood was drawn. CTCs were enriched with the Parsortix™ system. The quality of CTCs from fresh and cryopreserved DLA products was tested, and CTCs were cultured in vitro. Single uncultured and cultured CTCs were isolated by micromanipulation to determine different parameters, such as genomic aberrations and mutation profiles of selected tumor-associated genes. Expression levels of estrogen receptor and HER2/neu were monitored during in vitro culture. RESULTS Viable CTCs from peripheral blood and fresh or frozen DLA products could be enriched. DLA increased the likelihood of successful CTC culture. Cryopreserved DLA products could be stored with minimal CTC loss and no overt reduction in the tumor cell quality and viability during an observation period of up to 3 years. The analyzed parameters did not change during in vitro culture. DLA samples with high CTC numbers and lower ratios of apoptotic CTCs were more likely to grow in culture. CONCLUSIONS The increased CTC numbers from fresh or cryopreserved DLA products facilitate multiple functional and molecular analyses and, thus, could improve our knowledge of their biology.
    Type of Medium: Online Resource
    ISSN: 0009-9147 , 1530-8561
    URL: Article
    DOI: 10.1373/clinchem.2018.296814
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2019
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  • 2
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    Identification of new RAD51D-regulating microRNAs that also emerge as potent inhibitors of the Fanconi anemia/homologous recombination pathways
    Oxford University Press (OUP) ; 2022
    In:  Human Molecular Genetics Vol. 31, No. 24 ( 2022-12-16), p. 4241-4254
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    In: Human Molecular Genetics, Oxford University Press (OUP), Vol. 31, No. 24 ( 2022-12-16), p. 4241-4254
    Abstract: The Fanconi anemia (FA) and homologous recombination (HR) pathways, which partially overlap and include RAD51 and its paralogs, are key for the repair of different types of DNA damage, such as DNA interstrand crosslinks. First, to broadly assess the impact of microRNA-mediated regulation, we examined microRNA expression profiles in five isogenic fibroblast cell pairs, either deficient in DNA repair due to germline mutations in FANCA, FANCB, FANCC, FANCI or BRIP1/FANCJ or proficient due to correction with retroviral vectors. In each pair, we observed lower abundance of specific microRNAs in the FA-deficient cells. From the list of microRNAs, we experimentally confirmed the effects of miR-141-3p and miR-369-3p targeting RAD51B and miR-15a-5p, miR-494-3p as well as miR-544a targeting RAD51D. However, by western blotting, only RAD51D protein was reduced by a mixture of its regulating microRNAs. Gene ontology analyses and identification of additional FA/HR factors as targets of miR-15a-5p, miR-494-3p and miR-544a strongly suggested the widespread influence of these microRNAs on HR. Interestingly, only miR-494-3p directly reduced RAD51 foci formation, while a mixture of miR-15a-5p, miR-494-3p and miR-544a strongly reduced HR activity in green fluorescent protein (GFP) repair assays. In summary, by successfully employing this novel loss- and gain-of-function strategy, we have identified new microRNAs strongly inhibiting HR in mammalian cells. Understanding and modulating such miRNA regulation of DNA repair genes/pathways might help to overcome the reduced repair capacity of FA patients with biallelic hypomorphic mutations or help to engineer synthetic lethality strategies for patients with mutations in cancer-associated FA/HR genes.
    Type of Medium: Online Resource
    ISSN: 0964-6906 , 1460-2083
    URL: Article
    DOI: 10.1093/hmg/ddac177
    RVK:
    XA 10000
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 1474816-2
    SSG: 12
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  • 3
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    Genomic High-Resolution Profiling of Single CKpos/CD45neg Flow-Sorting Purified Circulating Tumor Cells from Patients with Metastatic Breast Cancer
    Oxford University Press (OUP) ; 2014
    In:  Clinical Chemistry Vol. 60, No. 10 ( 2014-10-01), p. 1290-1297
    Details
    In: Clinical Chemistry, Oxford University Press (OUP), Vol. 60, No. 10 ( 2014-10-01), p. 1290-1297
    Abstract: Circulating tumor cells (CTCs) are promising surrogate markers for systemic disease, and their molecular characterization might be relevant to guide more individualized cancer therapies. To enable fast and efficient purification of individual CTCs, we developed a work flow from CellSearchTM cartridges enabling high-resolution genomic profiling on the single-cell level. METHODS Single CTCs were sorted from 40 CellSearch samples from patients with metastatic breast cancer using a MoFlo XDP cell sorter. Genomes of sorted single cells were amplified using an adapter–linker PCR. Amplification products were analyzed by array-based comparative genomic hybridization, a gene-specific quantitative PCR (qPCR) assay for cyclin D1 (CCND1) locus amplification, and genomic sequencing to screen for mutations in exons 1, 9, and 20 of the phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) gene and exons 5, 7, and 8 of the tumor protein p53 (TP53) gene. RESULTS One common flow-sorting protocol was appropriate for 90% of the analyzed CellSearch cartridges, and the detected CTC numbers correlated positively with those originally detected with the CellSearch system (R2 = 0.9257). Whole genome amplification was successful in 72.9% of the sorted single CTCs. Over 95% of the cells displayed chromosomal aberrations typical for metastatic breast cancers, and amplifications at the CCND1 locus were validated by qPCR. Aberrant CTCs from 2 patients harbored mutations in exon 20 of the PIK3CA gene. CONCLUSIONS This work flow enabled effective CTC isolation and provided insights into genomic alterations of CTCs in metastatic breast cancer. This approach might facilitate further molecular characterization of rare CTCs to increase understanding of their biology and as a basis for their molecular screening in the clinical setting.
    Type of Medium: Online Resource
    ISSN: 0009-9147 , 1530-8561
    URL: Article
    DOI: 10.1373/clinchem.2014.222331
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2014
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