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Canis M.,Ludwig Maximilians University of Munich | Canis M.,University of Gottingen | Lechner A.,Ludwig Maximilians University of Munich | MacK B.,Ludwig Maximilians University of Munich | And 5 more authors.
Tumor Biology | Year: 2013

The pentaspan protein CD133 (Prominin-1) is part of the signature of tumour-initiating cells for various cancer entities. The aim of the present study was to investigate the impact of ectopic CD133 expression on tumourigenic properties of otherwise CD133-negative, non-tumourigenic cells in vitro and in vivo. CD133 was stably transfected into human embryonic kidney 293 (HEK293) which was then sorted for the expression of CD133. The effects of CD133 on cell proliferation were assessed upon standard cell counting of sorted cells at various time points. Severe combined immunodeficient (SCID) mice (n = 30) were injected with HEK293 CD133high and CD133low transfectants (5 × 103, 1 × 105, or 5 × 106 cells per injection). The expression of CD133, Ki67, CD44s, CD44v6, and EpCAM was analysed upon immunohistochemical staining of cryosections with specific antibodies. In vitro, ectopic expression of CD133 did influence neither cell proliferation nor cell cycle distribution of otherwise CD133-negative HEK293 cells. However, CD133high cells generated tumours in vivo in SCID mice with at least 1,000-fold increased frequency compared to CD133 low cells. Tumour load was also significantly increased in CD133 high cells as compared to those tumours formed by high numbers of CD133low cells. Immunohistochemistry stainings disclosed no changes in Ki67, CD44s, CD44v6, or EpCAM once tumours were formed by either cell type. CD133 induces tumour-initiating properties in HEK293 cells in vivo and is potentially involved in the regulation of tumourigenicity. Future research will aim at the elucidation of molecular mechanisms of CD133-induced tumourigenicity. © 2012 The Author(s).

Fledrich R.,Max Planck Institute for Experimental Medicine | Schlotter-Weigel B.,Ludwig Maximilians University of Munich | Schnizer T.J.,Max Planck Institute for Experimental Medicine | Wichert S.P.,Max Planck Institute for Experimental Medicine | And 11 more authors.
Brain | Year: 2012

Charcot-Marie-Tooth disease is the most common inherited neuropathy and a duplication of the peripheral myelin protein 22 gene causes the most frequent subform Charcot-Marie-Tooth 1A. Patients develop a slowly progressive dysmyelinating and demyelinating peripheral neuropathy and distally pronounced muscle atrophy. The amount of axonal loss determines disease severity. Although patients share an identical monogenetic defect, the disease progression is strikingly variable and the impending disease course can not be predicted in individual patients. Despite promising experimental data, recent therapy trials have failed. Established clinical outcome measures are thought to be too insensitive to detect amelioration within trials. Surrogate biomarkers of disease severity in Charcot-Marie-Tooth 1A are thus urgently needed. Peripheral myelin protein 22 transgenic rats harbouring additional copies of the peripheral myelin protein 22 gene ('Charcot-Marie-Tooth rats'), which were kept on an outbred background mimic disease hallmarks and phenocopy the variable disease severity of patients with Charcot-Marie-Tooth 1A. Hence, we used the Charcot-Marie-Tooth rat to dissect prospective and surrogate markers of disease severity derived from sciatic nerve and skin tissue messenger RNA extracts. Gene set enrichment analysis of sciatic nerve transcriptomes revealed that dysregulation of lipid metabolism associated genes such as peroxisome proliferator-activated receptor gamma constitutes a modifier of present and future disease severity. Importantly, we directly validated disease severity markers from the Charcot-Marie-Tooth rats in 46 patients with Charcot-Marie-Tooth 1A. Our data suggest that the combination of age and cutaneous messenger RNA levels of glutathione S-transferase theta 2 and cathepsin A composes a strong indicator of disease severity in patients with Charcot-Marie-Tooth 1A, as quantified by the Charcot-Marie-Tooth Neuropathy Score. This translational approach, utilizing a transgenic animal model, demonstrates that transcriptional analysis of skin biopsy is suitable to identify biomarkers of Charcot-Marie-Tooth 1A. © 2011 The Author.

Derakhshandeh-Peykar P.,Tehran University of Medical Sciences | Alivi J.,Tehran University of Medical Sciences | Hosseinnejad A.,Tehran University of Medical Sciences | Rautenstrauss B.,Medizinisch Genetisches Zentrum MGZ | And 2 more authors.
Journal of Neurogenetics | Year: 2011

Glioblastoma multiform (GBM; World Health Organization (WHO) grade IV) and anaplastic astrocytomas (AA; WHO grade III) are highly aggressive and lethal astrocytic brain tumors. To detect cancer-specific somatic mutations in two hot-spot regions of PIK3CA gene, the helical and kinase domains (encoded by exons 9 and 20, respectively) in GBM and AA, the authors examined the respective sequences 31 paraffin-embedded samples (23 GBM and 8 AA). The samples were obtained from a group of Iranian patients affected with high-grade glioblastoma (HGG). The overall prevalence of PIK3CA mutations was 23% (7/31) for both tumor types (22% in GBM, and 25% in AA). Five mutations were detected in exon 20, p.Arg992Gln (c.2976G→A), p.Met1005Val (c.3014A→G), p.Ile1019→Val (c.3056A→G), p.Ser1008Cys (c.3024C→G), and p.Asn1044Asp (c.3130A→G), and one mutation in exon 9, p.Glu545Ala (c.1634A→C). Additionally exons 48 of P53 gene in four unrelated young patients, who showed no mutations in PIK3CA exons 9 and 20, were analyzed. Three mutations were identified: p.Pro72Ala (c.214C→G), g.11608G→T (homozygote splice mutation), and p.Thr170Thr (c.510G→A silent mutation). In conclusion, mutation detection in PIK3CA in patients with a high degree of malignancy and early age at diagnosis should be included in molecular diagnostic protocols, also with regard to possible upcoming therapies. © 2011 Informa Healthcare USA, Inc.

Thompson B.A.,QIMR Berghofer Medical Research Institute | Thompson B.A.,University of Queensland | Spurdle A.B.,QIMR Berghofer Medical Research Institute | Plazzer J.-P.,Royal Melbourne Hospital | And 142 more authors.
Nature Genetics | Year: 2014

The clinical classification of hereditary sequence variants identified in disease-related genes directly affects clinical management of patients and their relatives. The International Society for Gastrointestinal Hereditary Tumours (InSiGHT) undertook a collaborative effort to develop, test and apply a standardized classification scheme to constitutional variants in the Lynch syndrome-associated genes MLH1, MSH2, MSH6 and PMS2. Unpublished data submission was encouraged to assist in variant classification and was recognized through microattribution. The scheme was refined by multidisciplinary expert committee review of the clinical and functional data available for variants, applied to 2,360 sequence alterations, and disseminated online. Assessment using validated criteria altered classifications for 66% of 12,006 database entries. Clinical recommendations based on transparent evaluation are now possible for 1,370 variants that were not obviously protein truncating from nomenclature. This large-scale endeavor will facilitate the consistent management of families suspected to have Lynch syndrome and demonstrates the value of multidisciplinary collaboration in the curation and classification of variants in public locus-specific databases. © 2014 Nature America, Inc.

Kenngott S.,Internistische Klinik Dr. Muller | Olze R.,Internistische Klinik Dr. Muller | Kollmer M.,Internistische Klinik Dr. Muller | Bottheim H.,Internistische Klinik Dr. Muller | And 3 more authors.
European Journal of Medical Research | Year: 2010

Background: Dual therapy with aspirin and clopidogrel increases the risk of gastrointestinal bleeding. Therefore, co-therapy with a proton pump inhibitor (PPI) is recommended by most guidelines. However, there are warnings against combining PPIs with clopidogrel because of their interactions with cytochrome P450 isoenzyme 2C19 (CYP2C19). Methods: The effects of the combined or separate intake of 20 mg of omeprazole and 75 mg of clopidogrel on the clopidogrel-induced inhibition of platelet aggregation were measured in four healthy subjects whose CYP2C19 exon sequences were determined. The effects of co-therapy with 10 mg of rabeprazole were also examined. Results: Two subjects showed the wild-type CYP2C19 sequence. The concurrent intake of omeprazole had no effect on clopidogrel-induced platelet inhibition in these subjects. Two subjects were heterozygous for the *2 allele, with predicted reduced CYP2C19 activity. One of them was a clopidogrel non-responder. In the second heterozygous subject, omeprazole co-therapy reduced the clopidogrel anti-platelet effect when taken simultaneously or separately. However, the simultaneous intake of rabeprazole did not reduce the clopidogrel effect. Conclusion: The clopidogrel-PPI interaction does not seem to be a PPI class effect. Rabeprazole did not affect the clopidogrel effect in a subject with a clear omeprazole-clopidogrel interaction. The separate intake of PPI and clopidogrel may not be sufficient to prevent their interaction. © I. Holzapfel Publishers 2010.

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