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  • 1
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 24, No. Supplement_1 ( 2022-06-03), p. i99-i99
    Abstract: Pediatric low-grade gliomas (pLGGs) have excellent survival, however, with current standard of care, most patients suffer lifelong severe sequalae. pLGGs are almost exclusively driven by single activating mutations in the MAPK pathway. Clinical trials with small molecule inhibitors in BRAF-altered pLGGs are showing promising results in early clinical trials, and similar efforts are now underway for FGFR1-altered tumors, however the underlying biology and treatment response has not been thoroughly explored in a pre-clinical setting. To explore the genetic landscape of FGFR altered gliomas we assembled a cohort of 87 patients with FGFR1-4 altered gliomas across Dana-Farber Cancer Institute, Boston Children’s Hospital and Brigham and Women’s Hospital. Within this cohort we observed that pLGGs harboring FGFR1 kinase hotspot mutations (FGFR1-N546K or -K656E) frequently harbored a second alteration associated with activation of the MAPK or mTOR pathways, most commonly in the phosphatase PTPN11, NF1 or within the FGFR1 gene itself. Additionally, we observed two previously described structural variants of FGFR1, an FGFR1 internal kinase tandem duplication (FGFR-ITD) and a fusion with TACC1 (FGFR1:TACC1). The relative impact of the different FGFR1 alterations on oncogenicity, therapeutic response and resistance has not been previously explored. To address this, we have established mouse neural stem cell models overexpressing the structural variants and hot spot mutant FGFR1 alone or in combination with a second alteration. Immunoblotting revealed that the addition of a second alteration attenuated phosphorylation of ERK, AKT and S6 and influenced cell proliferation both in normal growth conditions and in absence of growth factor. Treatment with inhibitors of FGFR (Infigratinib) and MEK (Trametinib) revealed variable sensitivity both targeted therapies, suggesting that treatment of FGFR1 driven pLGG might require tailoring to the specific FGFR1 alteration.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 2094060-9
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  • 2
    In: Cell, Elsevier BV, Vol. 186, No. 19 ( 2023-09), p. 4172-4188.e18
    Type of Medium: Online Resource
    ISSN: 0092-8674
    RVK:
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 187009-9
    detail.hit.zdb_id: 2001951-8
    SSG: 12
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  • 3
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 25, No. Supplement_1 ( 2023-06-12), p. i17-i17
    Abstract: Diffuse midline gliomas (DMGs) are a universally fatal brain tumor of childhood. While histone mutations are a critical tumor initiating event, they are insufficient to drive gliomagenesis. Histone mutations co-occur with somatic alterations in other pathways including TP53, MAPK, and MYC signaling. However, the mechanisms through which these pathways are activated have not been fully elucidated. METHODS We applied an integrative approach using transcriptomics, epigenetics, proteomics, in vitro cancer models, and in vivo mouse models to systematically evaluate how FOXR2 mediates gliomagenesis. RESULTS We have recently found that a subset of DMGs aberrantly express FOXR2, a forkhead transcription factor. FOXR2 is both sufficient to enhance tumor formation, and necessary for FOXR2-expressing DMGs. While FOXR2 indeed enhances MYC protein stability, FOXR2 exerts oncogenesis through MYC-independent functions and specifically hijacks E26-transformation specific (ETS) transcriptional circuits and FOXR2 DNA-binding is highly enriched at ETS motifs. We have performed proteomic and phospho-proteomic analysis of FOXR2-expressing human neural stem cells to identify proteins and phospho-sites that are highly enriched in FOXR2-expressing cells. CONCLUSION Taken together, this study elucidates how FOXR2 interacts with ETS transcription factors to mediate oncogenesis in FOXR2-expressing diffuse midline gliomas.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2023
    detail.hit.zdb_id: 2094060-9
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  • 4
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 82, No. 17 ( 2022-09-02), p. 2980-3001
    Abstract: Forkhead box R2 (FOXR2) is a forkhead transcription factor located on the X chromosome whose expression is normally restricted to the testis. In this study, we performed a pan-cancer analysis of FOXR2 activation across more than 10,000 adult and pediatric cancer samples and found FOXR2 to be aberrantly upregulated in 70% of all cancer types and 8% of all individual tumors. The majority of tumors (78%) aberrantly expressed FOXR2 through a previously undescribed epigenetic mechanism that involves hypomethylation of a novel promoter, which was functionally validated as necessary for FOXR2 expression and proliferation in FOXR2-expressing cancer cells. FOXR2 promoted tumor growth across multiple cancer lineages and co-opted ETS family transcription circuits across cancers. Taken together, this study identifies FOXR2 as a potent and ubiquitous oncogene that is epigenetically activated across the majority of human cancers. The identification of hijacking of ETS transcription circuits by FOXR2 extends the mechanisms known to active ETS transcription factors and highlights how transcription factor families cooperate to enhance tumorigenesis. Significance: This work identifies a novel promoter that drives aberrant FOXR2 expression and delineates FOXR2 as a pan-cancer oncogene that specifically activates ETS transcriptional circuits across human cancers. See related commentary by Liu and Northcott, p. 2977
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
    detail.hit.zdb_id: 2036785-5
    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
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  • 5
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 13, No. 1 ( 2022-02-01)
    Abstract: The role of PPM1D mutations in de novo gliomagenesis has not been systematically explored. Here we analyze whole genome sequences of 170 pediatric high-grade gliomas and find that truncating mutations in PPM1D that increase the stability of its phosphatase are clonal driver events in 11% of Diffuse Midline Gliomas (DMGs) and are enriched in primary pontine tumors. Through the development of DMG mouse models, we show that PPM1D mutations potentiate gliomagenesis and that PPM1D phosphatase activity is required for in vivo oncogenesis. Finally, we apply integrative phosphoproteomic and functional genomics assays and find that oncogenic effects of PPM1D truncation converge on regulators of cell cycle, DNA damage response, and p53 pathways, revealing therapeutic vulnerabilities including MDM2 inhibition.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2553671-0
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  • 6
    Online Resource
    Online Resource
    Oxford University Press (OUP) ; 2021
    In:  Neuro-Oncology Vol. 23, No. Supplement_6 ( 2021-11-12), p. vi34-vi34
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 23, No. Supplement_6 ( 2021-11-12), p. vi34-vi34
    Abstract: Pediatric low-grade gliomas (pLGGs) have excellent survival, however, with current standard of care, most patients suffer lifelong severe sequalae. pLGGs are almost exclusively driven by single activating mutations in the mitogen-activated protein kinase (MAPK) pathway. As targeted molecular therapy clinical trials focusing on BRAF-altered pLGGs are showing promising results in early clinical trials, similar efforts are underway for FGFR1-altered tumors. In our cohort of FGFR1-4 altered gliomas, we observe frequent occurrence of a second alteration associated with activation of the MAPK or mammalian target of rapamycin (mTOR) pathways in pLGGs. Most commonly in the phosphatase NF1, PIK3CA, PIK3R1 PTPN11 or within the FGFR1 gene itself. However, the impact of second co-occurring mutations on therapeutic response and resistance has not been explored. To address this, we established mouse neural stem cell models over-expressing hot-spot mutated FGFR1 alone or in combination with a second alteration. Immunoblotting revealed that the addition of a second alteration attenuated phosphorylation of ERK, AKT and S6 and influenced cell proliferation both in normal growth conditions and in absence of growth factor. Treatment with an FGFR inhibitor (Infigratinib) showed reduced drug response in double mutant cells compared to hot-spot mutated FGFR1 alone. This was associated with less reduction of phosphorylation of ERK and S6 in the double mutant cells upon treatment. In conclusion, the presence of a second alteration influences proliferation and drug response in models of FGFR1-mutated pLGG, potentially by modulating MAPK and mTOR signaling.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2021
    detail.hit.zdb_id: 2094060-9
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  • 7
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 82, No. 12_Supplement ( 2022-06-15), p. 5730-5730
    Abstract: Background: Understanding how aberrant transcription factors (TFs) hijack normal development to induce oncogenesis is a critical question in oncology. Forkhead box (FOX) proteins are a superfamily of transcriptional regulators characterized by a forkhead DNA-binding domain. Within this family, Forkhead Box R2 (FOXR2) expression has been associated with a subset of cancers including CNS and peripheral neuroblastoma. While FOXR2 has been shown to stabilize MYC isoforms, the mechanistic details through which it enhances tumor formation and the true extent of its role as an oncogene across all cancers have not been systematically evaluated. Methods: We applied an integrative approach using transcriptomics, epigenetics, in vitro cancer models, and in vivo mouse models to systematically evaluate the mechanisms by which FOXR2 is activated across human cancers. Results: We performed a pan-cancer analysis of FOXR2 activation across over 10,000 adult and pediatric cancer samples, and found FOXR2 to be aberrantly upregulated in 70% of all cancer types, and 8% of all individual tumors. We identified genetic and epigenetic mechanisms that induce its expression, including hypomethylation of a novel promoter in the vast majority (78%) of FOXR2-expressing cases. We demonstrate that FOXR2 expression is both sufficient and necessary for transformation across multiple lineages, using both in vitro and in vivo models. Conclusion: Taken together, this study demonstrates the role of FOXR2 as a potent oncogene across human cancers, and highlights a novel mechanism by which its expression is activated. Citation Format: Jessica W. Tsai, Paloma Cejas, Dayle K. Wang, Smruti Patel, David W. Wu, Phonepasong Arounleut, Xin Wei, Ningxuan Zhou, Sudeepa Syamala, Frank P. Dubois, Kristine Pelton, Jayne Vogelzang, Cecilia Sousa, Audrey Baguette, Xiaolong Chen, Alexandra L. Condurat, Sarah E. Dixon-Clarke, Kevin N. Zhou, Sophie D. Lu, Elizabeth M. Gonzalez, Madison S. Chacon, Jeromy J. Digiacomo, Rushil Kumbhani, Dana Novikov, J'Ya Hunter, Maria Tsoli, David S. Ziegler, Uta Dirksen, Natalie Jager, Gnana Prakash Balasubramanian, Christof M. Kramm, Michaela Nathrath, Stefan Bielack, Suzanne J. Baker, Jinghui Zhang, James M. McFarland, Gad Getz, Francois Aguet, Nada Jabado, Olaf Witt, Stefan M. Pfister, Keith L. Ligon, Claudia Kleinman, Henry Long, David T. Jones, Pratiti Bandopadhayay, Timothy N. Phoenix. FOXR2 is an oncogenic driver across adult and pediatric cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5730.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
    detail.hit.zdb_id: 2036785-5
    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
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  • 8
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 83, No. 7_Supplement ( 2023-04-04), p. 3562-3562
    Abstract: Background: Diffuse midline gliomas (DMGs) are a universally fatal brain tumor of childhood. While histone mutations are a critical tumor initiating event, they are insufficient to drive gliomagenesis. Histone mutations co-occur with somatic alterations in other pathways including TP53, MAPK, and MYC signaling. However, the mechanisms through which these pathways are activated have not been fully elucidated. Methods: We applied an integrative approach using transcriptomics, epigenetics, proteomics, in vitro cancer models, and in vivo mouse models to systematically evaluate how FOXR2 mediates gliomagenesis. Results: We have recently found that a subset of DMGs aberrantly express FOXR2, a forkhead transcription factor. FOXR2 is both sufficient to enhance tumor formation, and necessary for FOXR2-expressing DMGs. While FOXR2 indeed enhances MYC protein stability, FOXR2 exerts oncogenesis through MYC-independent functions and specifically hijacks E26-transformation specific (ETS) transcriptional circuits and FOXR2 DNA-binding is highly enriched at ETS motifs. We have performed proteomic and phospho-proteomic analysis of FOXR2-expressing human neural stem cells to identify proteins and phospho-sites that are highly enriched in FOXR2-expressing cells. Conclusion: Taken together, this study elucidates how FOXR2 interacts with ETS transcription factors to mediate oncogenesis, and further highlights a role for FOXR2 in activating ETS and MAPK signaling. Citation Format: Jessica W. Tsai, Paloma Cejas, Marissa Coppola, Dayle K. Wang, Smruti Patel, David W. Wu, Phonepasong Arounleut, Xin Wei, Ningxuan Zhou, Sudeepa Syamala, Frank P. Dubois, Kristine Pelton, Jayne Vogelzang, Cecilia Sousa, Audrey Baguette, Xiaolong Chen, Alexandra L. Condurat, Sarah E. Dixon-Clarke, Annarah Charles, Kevin N. Zhou, Sophie D. Lu, Elizabeth M. Gonzalez, Madison S. Chacon, Jeromy J. Digiacomo, Rushil Kumbhani, Dana Novikov, Maria Tsoli, David S. Ziegler, Uta Dirksen, Natalie Jager, Gnana Prakash Balasubramanian, Christof M. Kramm, Michaela Nathrath, Stefan Bielack, Suzanne J. Baker, Jinghui Zhang, James M. McFarland, Gad Getz, Francois Aguet, Nada Jabado, Olaf Witt, Stefan M. Pfister, Keith L. Ligon, Volker Hovestadt, Claudia Kleinman, Henry Long, David T. Jones, Pratiti Bandopadhayay, Timothy N. Phoenix. Dissecting mechanisms underlying FOXR2-mediated gliomagenesis in diffuse midline gliomas. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3562.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2023
    detail.hit.zdb_id: 2036785-5
    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
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  • 9
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 24, No. Supplement_1 ( 2022-06-03), p. i101-i102
    Abstract: Pediatric low-grade gliomas (pLGGs) are the most frequent brain tumors in children and comprise a heterogeneous group of tumors with different locations, histologic subtypes, ages at presentation, and clinical behavior. Tumors frequently respond to treatment with chemotherapy or surgical removal, but they can regrow after a period of quiescence, requiring further therapy. Thus, a deeper understanding of the molecular processes involved in these tumors is required to develop therapeutic strategies that are effective against their disease mechanisms. To better understand the cellular behaviors of this heterogenous group of tumors, we have employed single-cell and single-nuclei RNA sequencing technologies to analyze a large-scale dataset ( & gt;250,000 cells) of pLGGs. Analysis of this data identified a heterogenous population of cell types and cell states, detecting mature and progenitor-like astrocytes and oligodendrocytes, as well as cells exhibiting senescence or cycling programs. Moreover, we identify a significant immune infiltrate, comprised primarily of microglia. In addition to heterogeneity within pLGG tumors, heterogeneity between LGG subtypes represents another layer that stratifies pLGG biology. We performed a compositional analysis of the cell types present in these tumors and compared transcription signatures and gene expression programs across shared cellular populations of histologically and genetically distinct pLGGs. Finally, we optimized our integration and batch correction analyses by using external 293T cells as spike in controls during our single-cell and single-nuclei data generation steps to determine the most suitable method for batch-effect removal. Our analysis of human pLGGs at the single-cell and single-nuclei resolution provides critical insight into the heterogenous biological activities that constitute these tumors.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 2094060-9
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  • 10
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 24, No. Supplement_1 ( 2022-06-03), p. i31-i31
    Abstract: TP53 is the most frequently mutated tumor suppressor with somatic alterations found in approximately 50% of all human cancers. In the remaining TP53 wild-type (WT) tumors, functional inactivation of the p53 pathway may be achieved through a variety of other mechanisms, including gene deletion, epigenetic silencing, and/or alterations in prominent negative regulators, including MDM2/MDM4 and PPM1D. These alterations block p53 activity and lead to uncontrolled cell proliferation and oncogenesis in a majority of cancers, including the highly aggressive, universally fatal glial cell tumors of childhood, known as Diffuse Intrinsic Pontine Gliomas (DIPGs). DIPGs are inoperable due to their location within the brainstem. Available treatment options, including radiotherapy, have had a palliative effect at best, with almost all children succumbing to the disease within 18 months of diagnosis. Recent advances have led to an improved understanding of the biological underpinnings of this disease and identification of recurrent genetic alterations that represent potential therapeutic targets for these patients. Prominent among these targets in DIPGs with WT p53 status (50%) are MDM2/4 and PPM1D, whose suppression lead to p53 reactivation specifically in the WT p53 context. We have undertaken a combination of approaches to better understand the therapeutic potential of MDM2 and PPM1D inhibition in DIPG, characterizing the genomic, transcriptomic, and cell-state changes that drive resistance, and identifying novel vulnerabilities that can be exploited with combination therapies towards a cure.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 2094060-9
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