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  • 1
  • 2
    In: Neuro-Oncology, 2017, Vol. 19(suppl6), pp.vi200-vi200
    Description: Pilocytic astrocytoma (PA) is the most frequent pediatric brain tumor. This single-pathway disease exhibits aberrant activation of the MAPK pathway driving the tumor into oncogene-induced senescence (OIS). OIS is proposed to be the source of the unstable however benign growth observed in PA patients. Senescence is thought to be regulated by the senescence-associated secretory phenotype (SASP) which comprises a variety of cytokines, growth factors and proteases. Markers of senescence have been detected in PA, but the functional relevance of the SASP and its relation to OIS in PA is unknown. The first patient-derived PA cell culture model DKFZ-BT66 was utilized for the characterization of OIS and the role of the SASP in PA. The model allows experimental switching between senescent and proliferating states by modulation of the p53/RB pathway. Both conditions were analyzed by gene-expression profiling (GEP), Western Blot, real-time qPCR, ELISA, cell counts and viability by automated trypan blue exclusion staining. A significant increase of the SASP could be detected by GEP in the OIS state of the PA cell line. Moreover, the OIS expression signature was associated with improved progression free survival in a cohort of n=112 PA patients. Upregulation of IL-6 and IL-1B, two representative SASP factors, could be demonstrated on mRNA and protein level in DKFZ-BT66 during OIS. Both cytokine receptors are expressed and activation of the respective pathways was confirmed. Activation of the IL-1 pathway led to decreased growth of proliferating PA cells. Overall, the novel primary PA tumor model provides functional evidence of the presence of OIS in PA and exhibits increased activity of the SASP during the senescent state. In order to find an explanation for the clinically observed spontaneous on/off growth behavior, current studies aim to investigate the disruption of the OIS-characteristic growth arrest by inhibition of inflammatory signaling pathways.
    Keywords: Medicine;
    ISSN: 1522-8517
    E-ISSN: 1523-5866
    Source: Oxford University Press
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  • 3
    Language: English
    In: Cancer Cell, 01/2015, Vol.27(1), pp.85-96
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ccell.2014.11.006 Byline: Maria Romina Girotti, Filipa Lopes, Natasha Preece, Dan Niculescu-Duvaz, Alfonso Zambon, Lawrence Davies, Steven Whittaker, Grazia Saturno, Amaya Viros, Malin Pedersen, Bart M.J.M. Suijkerbuijk, Delphine Menard, Robert McLeary, Louise Johnson, Laura Fish, Sarah Ejiama, Berta Sanchez-Laorden, Juliane Hohloch, Neil Carragher, Kenneth Macleod, Garry Ashton, Anna A. Marusiak, Alberto Fusi, John Brognard, Margaret Frame, Paul Lorigan, Richard Marais, Caroline Springer Abstract: BRAF and MEK inhibitors are effective in BRAF mutant melanoma, but most patients eventually relapse with acquired resistance, and others present intrinsic resistance to these drugs. Resistance is often mediated by pathway reactivation through receptor tyrosine kinase (RTK)/SRC-family kinase (SFK) signaling or mutant NRAS, which drive paradoxical reactivation of the pathway. We describe pan-RAF inhibitors (CCT196969, CCT241161) that also inhibit SFKs. These compounds do not drive paradoxical pathway activation and inhibit MEK/ERK in BRAF and NRAS mutant melanoma. They inhibit melanoma cells and patient-derived xenografts that are resistant to BRAF and BRAF/MEK inhibitors. Thus, paradox-breaking pan-RAF inhibitors that also inhibit SFKs could provide first-line treatment for BRAF and NRAS mutant melanomas and second-line treatment for patients who develop resistance. Author Affiliation: (1) Molecular Oncology Group, Cancer Research UK Manchester Institute, Manchester M20 4BX, UK (2) Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London SM2 5NG, UK (3) Targeted Therapy Team, The Institute of Cancer Research, London SW3 6JB, UK (4) Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, UK (5) Histology Unit, Cancer Research UK Manchester Institute, Manchester M20 4BX, UK (6) Signalling Networks in Cancer Group, Cancer Research UK Manchester Institute, Manchester M20 4BX, UK (7) University of Manchester, Christie NHS Foundation Trust, Manchester M20 4BX, UK Article History: Received 17 May 2014; Revised 11 August 2014; Accepted 7 November 2014 Article Note: (footnote) This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).
    Keywords: Drug Resistance – Drug Therapy ; Melanoma – Drug Therapy;
    ISSN: 15356108
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  • 4
    Language: English
    In: Cancer Cell, 12 January 2015, Vol.27(1), pp.85-96
    Description: BRAF and MEK inhibitors are effective in BRAF mutant melanoma, but most patients eventually relapse with acquired resistance, and others present intrinsic resistance to these drugs. Resistance is often mediated by pathway reactivation through receptor tyrosine kinase (RTK)/SRC-family kinase (SFK) signaling or mutant NRAS, which drive paradoxical reactivation of the pathway. We describe pan-RAF inhibitors (CCT196969, CCT241161) that also inhibit SFKs. These compounds do not drive paradoxical pathway activation and inhibit MEK/ERK in BRAF and NRAS mutant melanoma. They inhibit melanoma cells and patient-derived xenografts that are resistant to BRAF and BRAF/MEK inhibitors. Thus, paradox-breaking pan-RAF inhibitors that also inhibit SFKs could provide first-line treatment for BRAF and NRAS mutant melanomas and second-line treatment for patients who develop resistance. Girotti et al. describe two pan-RAF inhibitors that also inhibit SRC-family kinases. These compounds do not drive paradoxical MEK/ERK activation and can inhibit MEK in NRAS mutant cells. Moreover, the agents can overcome resistance to clinical BRAF or combination BRAF/MEK inhibitors in patient-derived xenografts.
    Keywords: Medicine
    ISSN: 1535-6108
    E-ISSN: 1878-3686
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  • 5
    Language: English
    In: Cancer Cell, 13 March 2017, Vol.31(3), pp.466-466
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ccell.2017.02.007 Byline: Maria Romina Girotti, Filipa Lopes, Natasha Preece, Dan Niculescu-Duvaz, Alfonso Zambon, Lawrence Davies, Steven Whittaker, Grazia Saturno, Amaya Viros, Malin Pedersen, Bart M.J.M. Suijkerbuijk, Delphine Menard, Robert McLeary, Louise Johnson, Laura Fish, Sarah Ejiama, Berta Sanchez-Laorden, Juliane Hohloch, Neil Carragher, Kenneth Macleod, Garry Ashton, Anna A. Marusiak, Alberto Fusi, John Brognard, Margaret Frame, Paul Lorigan, Richard Marais, Caroline Springer
    Keywords: Medicine
    ISSN: 1535-6108
    E-ISSN: 1878-3686
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  • 6
    Language: English
    In: Oncotarget, 14 February 2017, Vol.8(7), pp.11460-11479
    Description: Pilocytic astrocytoma (PA) is the most frequent pediatric brain tumor. Activation of the MAPK pathway is well established as the oncogenic driver of the disease. It is most frequently caused by KIAA1549:BRAF fusions, and leads to oncogene induced senescence (OIS). OIS is thought to be a major reason for growth arrest of PA cells in vitro and in vivo, preventing establishment of PA cultures. Hence, valid preclinical models are currently very limited, but preclinical testing of new compounds is urgently needed. We transduced the PA short-term culture DKFZ-BT66 derived from the PA of a 2-year old patient with a doxycycline-inducible system coding for Simian Vacuolating Virus 40 Large T Antigen (SV40-TAg). SV40-TAg inhibits TP53/CDKN1A and CDKN2A/RB1, two pathways critical for OIS induction and maintenance. DNA methylation array and KIAA1549:BRAF fusion analysis confirmed pilocytic astrocytoma identity of DKFZ-BT66 cells after establishment. Readouts were analyzed in proliferating as well as senescent states, including cell counts, viability, cell cycle analysis, expression of SV40-Tag, CDKN2A (p16), CDKN1A (p21), and TP53 (p53) protein, and gene-expression profiling. Selected MAPK inhibitors (MAPKi) including clinically available MEK inhibitors (MEKi) were tested in vitro. Expression of SV40-TAg enabled the cells to bypass OIS and to resume proliferation with a mean doubling time of 45h allowing for propagation and long-term culture. Withdrawal of doxycycline led to an immediate decrease of SV40-TAg expression, appearance of senescent morphology, upregulation of CDKI proteins and a subsequent G1 growth arrest in line with the re-induction of senescence. DKFZ-BT66 cells still underwent replicative senescence that was overcome by TERT expression. Testing of a set of MAPKi revealed differential responses in DKFZ-BT66. MEKi efficiently inhibited MAPK signaling at clinically achievable concentrations, while BRAF V600E- and RAF Type II inhibitors showed paradoxical activation. Taken together, we have established the first patient-derived long term expandable PA cell line expressing the KIAA1549:BRAF-fusion suitable for preclinical drug testing.
    Keywords: Kiaa1549:Braf-Fusion ; Mapk-Inhibitors ; Oncogene-Induced Senescence (Ois) ; Pediatric Low Grade Glioma ; Pilocytic Astrocytoma ; Astrocytoma ; Brain Neoplasms ; Cell Culture Techniques ; Cell Line, Tumor ; Cellular Senescence -- Physiology
    E-ISSN: 1949-2553
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  • 7
    Language: English
    In: Neuro-Oncology, 06/2017, 06/01/2017, Vol.19(suppl_4), pp.iv41-iv42
    Keywords: Medicine;
    ISSN: 1522-8517
    E-ISSN: 1523-5866
    Source: Oxford University Press (via CrossRef)
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  • 8
    Language: English
    In: Neuro-Oncology, 06/2017, 06/01/2017, Vol.19(suppl_4), pp.iv33-iv33
    Keywords: Medicine;
    ISSN: 1522-8517
    E-ISSN: 1523-5866
    Source: Oxford University Press (via CrossRef)
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