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Dzung A, Saltari A, Tiso N, Lyck R, Dummer R, Levesque MP. STK11 Prevents Invasion through Signal Transducer and Activator of Transcription 3/5 and FAK Repression in Cutaneous Melanoma. J Invest Dermatol 2022; 142:1171-1182.e10. [PMID: 34757069 DOI: 10.1016/j.jid.2021.09.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 08/23/2021] [Accepted: 09/01/2021] [Indexed: 11/18/2022]
Abstract
The STK11/LKB1 is a tumor suppressor involved in metabolism and cell motility. In BRAFV600E melanoma, STK11 is inactivated by extracellular signal‒regulated kinase and RSK, preventing it from binding and activating adenosine monophosphate-activated protein kinase and promoting melanoma cell proliferation. Although STK11 mutations occur in 5‒10% of cutaneous melanoma, few functional studies have been performed. By knocking out STK11 with CRISPR/Cas9 in two human BRAF-mutant melanoma cell lines, we found that STK11 loss reduced the sensitivity to a BRAF inhibitor. More strikingly, STK11 loss led to an increased invasive phenotype in both three-dimensional spheroids and in vivo zebrafish xenograft models. STK11 overexpression consistently reversed the invasive phenotype. Interestingly, STK11 knockout increased invasion also in an NRAS-mutant melanoma cell line. Furthermore, although STK11 was expressed in primary human melanoma tumors, its expression significantly decreased in melanoma metastases, especially in brain metastases. In the STK11-knockout cells, we observed increased activating phosphorylation of signal transducer and activator of transcription 3/5 and FAK. Using inhibitors of signal transducer and activator of transcription 3/5 and FAK, we reversed the invasive phenotype in both BRAF- and NRAS-mutated cells. Our findings confirm an increased invasive phenotype on STK11 inactivation in BRAF- and NRAS-mutant cutaneous melanoma that can be targeted by signal transducer and activator of transcription 3/5 and FAK inhibition.
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Affiliation(s)
- Andreas Dzung
- Department of Dermatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Annalisa Saltari
- Department of Dermatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Natascia Tiso
- Laboratory of Developmental Genetics, Department of Biology, University of Padova, Padova, Italy
| | - Ruth Lyck
- Theodor Kocher Institute, University of Bern, Bern, Switzerland
| | - Reinhard Dummer
- Department of Dermatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Mitchell P Levesque
- Department of Dermatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
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2
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Caja L, Dadras MS, Mezheyeuski A, Rodrigues-Junior DM, Liu S, Webb AT, Gomez-Puerto MC, Ten Dijke P, Heldin CH, Moustakas A. The protein kinase LKB1 promotes self-renewal and blocks invasiveness in glioblastoma. J Cell Physiol 2021; 237:743-762. [PMID: 34350982 DOI: 10.1002/jcp.30542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 07/10/2021] [Accepted: 07/24/2021] [Indexed: 12/13/2022]
Abstract
The role of liver kinase B1 (LKB1) in glioblastoma (GBM) development remains poorly understood. LKB1 may regulate GBM cell metabolism and has been suggested to promote glioma invasiveness. After analyzing LKB1 expression in GBM patient mRNA databases and in tumor tissue via multiparametric immunohistochemistry, we observed that LKB1 was localized and enriched in GBM tumor cells that co-expressed SOX2 and NESTIN stemness markers. Thus, LKB1-specific immunohistochemistry can potentially reveal subpopulations of stem-like cells, advancing GBM patient molecular pathology. We further analyzed the functions of LKB1 in patient-derived GBM cultures under defined serum-free conditions. Silencing of endogenous LKB1 impaired 3D-gliomasphere frequency and promoted GBM cell invasion in vitro and in the zebrafish collagenous tail after extravasation of circulating GBM cells. Moreover, loss of LKB1 function revealed mitochondrial dysfunction resulting in decreased ATP levels. Treatment with the clinically used drug metformin impaired 3D-gliomasphere formation and enhanced cytotoxicity induced by temozolomide, the primary chemotherapeutic drug against GBM. The IC50 of temozolomide in the GBM cultures was significantly decreased in the presence of metformin. This combinatorial effect was further enhanced after LKB1 silencing, which at least partially, was due to increased apoptosis. The expression of genes involved in the maintenance of tumor stemness, such as growth factors and their receptors, including members of the platelet-derived growth factor (PDGF) family, was suppressed after LKB1 silencing. The defect in gliomasphere growth caused by LKB1 silencing was bypassed after supplementing the cells with exogenous PFDGF-BB. Our data support the parallel roles of LKB1 in maintaining mitochondrial homeostasis, 3D-gliomasphere survival, and hindering migration in GBM. Thus, the natural loss of, or pharmacological interference with LKB1 function, may be associated with benefits in patient survival but could result in tumor spread.
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Affiliation(s)
- Laia Caja
- Department of Medical Biochemistry and Microbiology and Ludwig Institute for Cancer Research, Science for Life Laboratory, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Mahsa Shahidi Dadras
- Department of Medical Biochemistry and Microbiology and Ludwig Institute for Cancer Research, Science for Life Laboratory, Biomedical Center, Uppsala University, Uppsala, Sweden.,Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Artur Mezheyeuski
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Dorival Mendes Rodrigues-Junior
- Department of Medical Biochemistry and Microbiology and Ludwig Institute for Cancer Research, Science for Life Laboratory, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Sijia Liu
- Department of Cell and Chemical Biology, Oncode Institute, Leiden University Medical Center, Leiden, The Netherlands
| | - Anna Taylor Webb
- Department of Medical Biochemistry and Microbiology and Ludwig Institute for Cancer Research, Science for Life Laboratory, Biomedical Center, Uppsala University, Uppsala, Sweden.,Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Maria Catalina Gomez-Puerto
- Department of Cell and Chemical Biology, Oncode Institute, Leiden University Medical Center, Leiden, The Netherlands
| | - Peter Ten Dijke
- Department of Cell and Chemical Biology, Oncode Institute, Leiden University Medical Center, Leiden, The Netherlands
| | - Carl-Henrik Heldin
- Department of Medical Biochemistry and Microbiology and Ludwig Institute for Cancer Research, Science for Life Laboratory, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Aristidis Moustakas
- Department of Medical Biochemistry and Microbiology and Ludwig Institute for Cancer Research, Science for Life Laboratory, Biomedical Center, Uppsala University, Uppsala, Sweden
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Drakouli S, Lyberopoulou A, Papathanassiou M, Mylonis I, Georgatsou E. Enhancer of rudimentary homologue interacts with scaffold attachment factor B at the nuclear matrix to regulate SR protein phosphorylation. FEBS J 2017. [DOI: 10.1111/febs.14141] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Sotiria Drakouli
- Laboratory of Biochemistry; Faculty of Medicine; University of Thessaly; Volos Greece
| | - Aggeliki Lyberopoulou
- Laboratory of Biochemistry; Faculty of Medicine; University of Thessaly; Volos Greece
- Laboratory of Internal Medicine; Faculty of Medicine; University of Thessaly; Volos Greece
| | - Maria Papathanassiou
- Laboratory of Biochemistry; Faculty of Medicine; University of Thessaly; Volos Greece
- Department of Pathology; Faculty of Medicine; University of Thessaly; Volos Greece
| | - Ilias Mylonis
- Laboratory of Biochemistry; Faculty of Medicine; University of Thessaly; Volos Greece
| | - Eleni Georgatsou
- Laboratory of Biochemistry; Faculty of Medicine; University of Thessaly; Volos Greece
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Presneau N, Duhamel LA, Ye H, Tirabosco R, Flanagan AM, Eskandarpour M. Post-translational regulation contributes to the loss of LKB1 expression through SIRT1 deacetylase in osteosarcomas. Br J Cancer 2017. [PMID: 28632727 PMCID: PMC5537492 DOI: 10.1038/bjc.2017.174] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Background: The most prevalent form of bone cancer is osteosarcoma (OS), which is associated with poor prognosis in case of metastases formation. Mice harbouring liver kinase B1 (LKB1+/−) develop osteoblastoma-like tumours. Therefore, we asked whether loss of LKB1 gene has a role in the pathogenesis of human OS. Methods: Osteosarcomas (n=259) were screened for LKB1 and sirtuin 1 (SIRT1) protein expression using immunohistochemistry and western blot. Those cases were also screened for LKB1 genetic alterations by next-generation sequencing, Sanger sequencing, restriction fragment length polymorphism and fluorescence in situ hybridisation approaches. We studied LKB1 protein degradation through SIRT1 expression. MicroRNA expression investigations were also conducted to identify the microRNAs involved in the SIRT1/LKB1 pathway. Results: Forty-one per cent (106 out of 259) OS had lost LKB1 protein expression with no evident genetic anomalies. We obtained evidence that SIRT1 impairs LKB1 protein stability, and that SIRT1 depletion leads to accumulation of LKB1 in OS cell lines resulting in growth arrest. Further investigations revealed the role of miR-204 in the regulation of SIRT1 expression, which impairs LKB1 stability. Conclusions: We demonstrated the involvement of sequential regulation of miR-204/SIRT1/LKB1 in OS cases and showed a mechanism for the loss of expression of LKB1 tumour suppressor in this malignancy.
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Affiliation(s)
- Nadège Presneau
- University College London Cancer Institute, 72 Huntley Street, London WC1E 6BT, UK
| | - Laure Alice Duhamel
- University College London Cancer Institute, 72 Huntley Street, London WC1E 6BT, UK
| | - Hongtao Ye
- Department of Histopathology, Royal National Orthopaedic, Stanmore, Middlesex HA7 4LP, UK
| | - Roberto Tirabosco
- Department of Histopathology, Royal National Orthopaedic, Stanmore, Middlesex HA7 4LP, UK
| | - Adrienne M Flanagan
- University College London Cancer Institute, 72 Huntley Street, London WC1E 6BT, UK.,Department of Histopathology, Royal National Orthopaedic, Stanmore, Middlesex HA7 4LP, UK
| | - Malihe Eskandarpour
- University College London Cancer Institute, 72 Huntley Street, London WC1E 6BT, UK
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Daly CS, Shaw P, Ordonez LD, Williams GT, Quist J, Grigoriadis A, Van Es JH, Clevers H, Clarke AR, Reed KR. Functional redundancy between Apc and Apc2 regulates tissue homeostasis and prevents tumorigenesis in murine mammary epithelium. Oncogene 2017; 36:1793-1803. [PMID: 27694902 PMCID: PMC5219933 DOI: 10.1038/onc.2016.342] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 08/02/2016] [Accepted: 08/05/2016] [Indexed: 02/08/2023]
Abstract
Aberrant Wnt signaling within breast cancer is associated with poor prognosis, but regulation of this pathway in breast tissue remains poorly understood and the consequences of immediate or long-term dysregulation remain elusive. The exact contribution of the Wnt-regulating proteins adenomatous polyposis coli (APC) and APC2 in the pathogenesis of human breast cancer are ill-defined, but our analysis of publically available array data sets indicates that tumors with concomitant low expression of both proteins occurs more frequently in the 'triple negative' phenotype, which is a subtype of breast cancer with particularly poor prognosis. We have used mouse transgenics to delete Apc and/or Apc2 from mouse mammary epithelium to elucidate the significance of these proteins in mammary homeostasis and delineate their influences on Wnt signaling and tumorigenesis. Loss of either protein alone failed to affect Wnt signaling levels or tissue homeostasis. Strikingly, concomitant loss led to local disruption of β-catenin status, disruption in epithelial integrity, cohesion and polarity, increased cell division and a distinctive form of ductal hyperplasia with 'squamoid' ghost cell nodules in young animals. Upon aging, the development of Wnt activated mammary carcinomas with squamous differentiation was accompanied by a significantly reduced survival. This novel Wnt-driven mammary tumor model highlights the importance of functional redundancies existing between the Apc proteins both in normal homeostasis and in tumorigenesis.
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Affiliation(s)
- C S Daly
- European Cancer Stem Cell Research Institute, Cardiff University School of Biosciences, Cardiff, Wales, UK
| | - P Shaw
- European Cancer Stem Cell Research Institute, Cardiff University School of Biosciences, Cardiff, Wales, UK
| | - L D Ordonez
- European Cancer Stem Cell Research Institute, Cardiff University School of Biosciences, Cardiff, Wales, UK
| | - G T Williams
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, UK
| | - J Quist
- Breast Cancer Now Unit, King's College London, Guy's Hospital London, London, UK
- Cancer Bioinformatics, King's College London, Guy's Hospital London, London, UK
| | - A Grigoriadis
- Breast Cancer Now Unit, King's College London, Guy's Hospital London, London, UK
- Cancer Bioinformatics, King's College London, Guy's Hospital London, London, UK
| | - J H Van Es
- Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
| | - H Clevers
- Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
| | - A R Clarke
- European Cancer Stem Cell Research Institute, Cardiff University School of Biosciences, Cardiff, Wales, UK
| | - K R Reed
- European Cancer Stem Cell Research Institute, Cardiff University School of Biosciences, Cardiff, Wales, UK
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LRF maintains genome integrity by regulating the non-homologous end joining pathway of DNA repair. Nat Commun 2015. [DOI: 10.1038/ncomms9325 and 1880=1880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
AbstractLeukemia/lymphoma-related factor (LRF) is a POZ/BTB and Krüppel (POK) transcriptional repressor characterized by context-dependent key roles in cell fate decision and tumorigenesis. Here we demonstrate an unexpected transcription-independent function for LRF in the classical non-homologous end joining (cNHEJ) pathway of double-strand break (DSB) repair. We find that LRF loss in cell lines and mouse tissues results in defective cNHEJ, genomic instability and hypersensitivity to ionizing radiation. Mechanistically, we show that LRF binds and stabilizes DNA-PKcs on DSBs, in turn favouring DNA-PK activity. Importantly, LRF loss restores ionizing radiation sensitivity to p53 null cells, making LRF an attractive biomarker to direct p53-null LRF-deficient tumours towards therapeutic treatments based on genotoxic agents or PARP inhibitors following a synthetic lethal strategy.
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7
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LRF maintains genome integrity by regulating the non-homologous end joining pathway of DNA repair. Nat Commun 2015. [DOI: 10.1038/ncomms9325 order by 1-- #] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
AbstractLeukemia/lymphoma-related factor (LRF) is a POZ/BTB and Krüppel (POK) transcriptional repressor characterized by context-dependent key roles in cell fate decision and tumorigenesis. Here we demonstrate an unexpected transcription-independent function for LRF in the classical non-homologous end joining (cNHEJ) pathway of double-strand break (DSB) repair. We find that LRF loss in cell lines and mouse tissues results in defective cNHEJ, genomic instability and hypersensitivity to ionizing radiation. Mechanistically, we show that LRF binds and stabilizes DNA-PKcs on DSBs, in turn favouring DNA-PK activity. Importantly, LRF loss restores ionizing radiation sensitivity to p53 null cells, making LRF an attractive biomarker to direct p53-null LRF-deficient tumours towards therapeutic treatments based on genotoxic agents or PARP inhibitors following a synthetic lethal strategy.
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8
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LRF maintains genome integrity by regulating the non-homologous end joining pathway of DNA repair. Nat Commun 2015. [DOI: 10.1038/ncomms9325 order by 8029-- -] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
AbstractLeukemia/lymphoma-related factor (LRF) is a POZ/BTB and Krüppel (POK) transcriptional repressor characterized by context-dependent key roles in cell fate decision and tumorigenesis. Here we demonstrate an unexpected transcription-independent function for LRF in the classical non-homologous end joining (cNHEJ) pathway of double-strand break (DSB) repair. We find that LRF loss in cell lines and mouse tissues results in defective cNHEJ, genomic instability and hypersensitivity to ionizing radiation. Mechanistically, we show that LRF binds and stabilizes DNA-PKcs on DSBs, in turn favouring DNA-PK activity. Importantly, LRF loss restores ionizing radiation sensitivity to p53 null cells, making LRF an attractive biomarker to direct p53-null LRF-deficient tumours towards therapeutic treatments based on genotoxic agents or PARP inhibitors following a synthetic lethal strategy.
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LRF maintains genome integrity by regulating the non-homologous end joining pathway of DNA repair. Nat Commun 2015; 6:8325. [PMID: 26446488 PMCID: PMC4633636 DOI: 10.1038/ncomms9325] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 08/11/2015] [Indexed: 12/29/2022] Open
Abstract
Leukemia/lymphoma-related factor (LRF) is a POZ/BTB and Krüppel (POK) transcriptional repressor characterized by context-dependent key roles in cell fate decision and tumorigenesis. Here we demonstrate an unexpected transcription-independent function for LRF in the classical non-homologous end joining (cNHEJ) pathway of double-strand break (DSB) repair. We find that LRF loss in cell lines and mouse tissues results in defective cNHEJ, genomic instability and hypersensitivity to ionizing radiation. Mechanistically, we show that LRF binds and stabilizes DNA-PKcs on DSBs, in turn favouring DNA-PK activity. Importantly, LRF loss restores ionizing radiation sensitivity to p53 null cells, making LRF an attractive biomarker to direct p53-null LRF-deficient tumours towards therapeutic treatments based on genotoxic agents or PARP inhibitors following a synthetic lethal strategy.
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10
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LRF maintains genome integrity by regulating the non-homologous end joining pathway of DNA repair. Nat Commun 2015. [DOI: 10.1038/ncomms9325 order by 8029-- #] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
AbstractLeukemia/lymphoma-related factor (LRF) is a POZ/BTB and Krüppel (POK) transcriptional repressor characterized by context-dependent key roles in cell fate decision and tumorigenesis. Here we demonstrate an unexpected transcription-independent function for LRF in the classical non-homologous end joining (cNHEJ) pathway of double-strand break (DSB) repair. We find that LRF loss in cell lines and mouse tissues results in defective cNHEJ, genomic instability and hypersensitivity to ionizing radiation. Mechanistically, we show that LRF binds and stabilizes DNA-PKcs on DSBs, in turn favouring DNA-PK activity. Importantly, LRF loss restores ionizing radiation sensitivity to p53 null cells, making LRF an attractive biomarker to direct p53-null LRF-deficient tumours towards therapeutic treatments based on genotoxic agents or PARP inhibitors following a synthetic lethal strategy.
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Liu XS, Chandramouly G, Rass E, Guan Y, Wang G, Hobbs RM, Rajendran A, Xie A, Shah JV, Davis AJ, Scully R, Lunardi A, Pandolfi PP. LRF maintains genome integrity by regulating the non-homologous end joining pathway of DNA repair. Nat Commun 2015. [DOI: 10.1038/ncomms9325 order by 1-- -] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
AbstractLeukemia/lymphoma-related factor (LRF) is a POZ/BTB and Krüppel (POK) transcriptional repressor characterized by context-dependent key roles in cell fate decision and tumorigenesis. Here we demonstrate an unexpected transcription-independent function for LRF in the classical non-homologous end joining (cNHEJ) pathway of double-strand break (DSB) repair. We find that LRF loss in cell lines and mouse tissues results in defective cNHEJ, genomic instability and hypersensitivity to ionizing radiation. Mechanistically, we show that LRF binds and stabilizes DNA-PKcs on DSBs, in turn favouring DNA-PK activity. Importantly, LRF loss restores ionizing radiation sensitivity to p53 null cells, making LRF an attractive biomarker to direct p53-null LRF-deficient tumours towards therapeutic treatments based on genotoxic agents or PARP inhibitors following a synthetic lethal strategy.
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12
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Liu XS, Chandramouly G, Rass E, Guan Y, Wang G, Hobbs RM, Rajendran A, Xie A, Shah JV, Davis AJ, Scully R, Lunardi A, Pandolfi PP. LRF maintains genome integrity by regulating the non-homologous end joining pathway of DNA repair. Nat Commun 2015. [DOI: 10.1038/ncomms9325 order by 1-- gadu] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
AbstractLeukemia/lymphoma-related factor (LRF) is a POZ/BTB and Krüppel (POK) transcriptional repressor characterized by context-dependent key roles in cell fate decision and tumorigenesis. Here we demonstrate an unexpected transcription-independent function for LRF in the classical non-homologous end joining (cNHEJ) pathway of double-strand break (DSB) repair. We find that LRF loss in cell lines and mouse tissues results in defective cNHEJ, genomic instability and hypersensitivity to ionizing radiation. Mechanistically, we show that LRF binds and stabilizes DNA-PKcs on DSBs, in turn favouring DNA-PK activity. Importantly, LRF loss restores ionizing radiation sensitivity to p53 null cells, making LRF an attractive biomarker to direct p53-null LRF-deficient tumours towards therapeutic treatments based on genotoxic agents or PARP inhibitors following a synthetic lethal strategy.
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13
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Liu XS, Chandramouly G, Rass E, Guan Y, Wang G, Hobbs RM, Rajendran A, Xie A, Shah JV, Davis AJ, Scully R, Lunardi A, Pandolfi PP. LRF maintains genome integrity by regulating the non-homologous end joining pathway of DNA repair. Nat Commun 2015. [DOI: 10.1038/ncomms9325 order by 8029-- awyx] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
AbstractLeukemia/lymphoma-related factor (LRF) is a POZ/BTB and Krüppel (POK) transcriptional repressor characterized by context-dependent key roles in cell fate decision and tumorigenesis. Here we demonstrate an unexpected transcription-independent function for LRF in the classical non-homologous end joining (cNHEJ) pathway of double-strand break (DSB) repair. We find that LRF loss in cell lines and mouse tissues results in defective cNHEJ, genomic instability and hypersensitivity to ionizing radiation. Mechanistically, we show that LRF binds and stabilizes DNA-PKcs on DSBs, in turn favouring DNA-PK activity. Importantly, LRF loss restores ionizing radiation sensitivity to p53 null cells, making LRF an attractive biomarker to direct p53-null LRF-deficient tumours towards therapeutic treatments based on genotoxic agents or PARP inhibitors following a synthetic lethal strategy.
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Alterations of LKB1 and KRAS and risk of brain metastasis: comprehensive characterization by mutation analysis, copy number, and gene expression in non-small-cell lung carcinoma. Lung Cancer 2014; 86:255-61. [PMID: 25224251 DOI: 10.1016/j.lungcan.2014.08.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 08/17/2014] [Accepted: 08/19/2014] [Indexed: 12/29/2022]
Abstract
BACKGROUND Brain metastases are one of the most malignant complications of lung cancer and constitute a significant cause of cancer related morbidity and mortality worldwide. Recent years of investigation suggested a role of LKB1 in NSCLC development and progression, in synergy with KRAS alteration. In this study, we systematically analyzed how LKB1 and KRAS alteration, measured by mutation, gene expression (GE) and copy number (CN), are associated with brain metastasis in NSCLC. MATERIALS AND METHODS Patients treated at University of North Carolina Hospital from 1990 to 2009 with NSCLC provided frozen, surgically extracted tumors for analysis. GE was measured using Agilent 44,000 custom-designed arrays, CN was assessed by Affymetrix GeneChip Human Mapping 250K Sty Array or the Genome-Wide Human SNP Array 6.0 and gene mutation was detected using ABI sequencing. Integrated analysis was conducted to assess the relationship between these genetic markers and brain metastasis. A model was proposed for brain metastasis prediction using these genetic measurements. RESULTS 17 of the 174 patients developed brain metastasis. LKB1 wild type tumors had significantly higher LKB1 CN (p<0.001) and GE (p=0.002) than the LKB1 mutant group. KRAS wild type tumors had significantly lower KRAS GE (p<0.001) and lower CN, although the latter failed to be significant (p=0.295). Lower LKB1 CN (p=0.039) and KRAS mutation (p=0.007) were significantly associated with more brain metastasis. The predictive model based on nodal (N) stage, patient age, LKB1 CN and KRAS mutation had a good prediction accuracy, with area under the ROC curve of 0.832 (p<0.001). CONCLUSION LKB1 CN in combination with KRAS mutation predicted brain metastasis in NSCLC.
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Thirumurthi U, Shen J, Xia W, LaBaff AM, Wei Y, Li CW, Chang WC, Chen CH, Lin HK, Yu D, Hung MC. MDM2-mediated degradation of SIRT6 phosphorylated by AKT1 promotes tumorigenesis and trastuzumab resistance in breast cancer. Sci Signal 2014; 7:ra71. [PMID: 25074979 DOI: 10.1126/scisignal.2005076] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Sirtuin 6 (SIRT6) is associated with longevity and is also a tumor suppressor. Identification of molecular regulators of SIRT6 might enable its activation therapeutically in cancer patients. In various breast cancer cell lines, we found that SIRT6 was phosphorylated at Ser(338) by the kinase AKT1, which induced the interaction and ubiquitination of SIRT6 by MDM2, targeting SIRT6 for protease-dependent degradation. The survival of breast cancer patients positively correlated with the abundance of SIRT6 and inversely correlated with the phosphorylation of SIRT6 at Ser(338). In a panel of breast tumor biopsies, SIRT6 abundance inversely correlated with the abundance of phosphorylated AKT. Inhibiting AKT or preventing SIRT6 phosphorylation by mutating Ser(338) prevented the degradation of SIRT6 mediated by MDM2, suppressed the proliferation of breast cancer cells in culture, and inhibited the growth of breast tumor xenografts in mice. Overexpressing MDM2 decreased the abundance of SIRT6 in cells, whereas overexpressing an E3 ligase-deficient MDM2 or knocking down endogenous MDM2 increased SIRT6 abundance. Trastuzumab (known as Herceptin) is a drug that targets a specific receptor common in some breast cancers, and knocking down SIRT6 increased the survival of a breast cancer cell exposed to trastuzumab. Overexpression of a nonphosphorylatable SIRT6 mutant increased trastuzumab sensitivity in a resistant breast cancer cell line. Thus, stabilizing SIRT6 may be a clinical strategy for overcoming trastuzumab resistance in breast cancer patients.
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Affiliation(s)
- Umadevi Thirumurthi
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA
| | - Jia Shen
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA
| | - Weiya Xia
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Adam M LaBaff
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA
| | - Yongkun Wei
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Chia-Wei Li
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Wei-Chao Chang
- Center for Molecular Medicine and Graduate Institute of Cancer Biology, China Medical University, Taichung 404, Taiwan
| | - Chung-Hsuan Chen
- Genomics Research Center, Academia Sinica, Nankang, Taipei 106, Taiwan. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan. Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
| | - Hui-Kuan Lin
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA
| | - Dihua Yu
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA
| | - Mien-Chie Hung
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA. Center for Molecular Medicine and Graduate Institute of Cancer Biology, China Medical University, Taichung 404, Taiwan. Department of Biotechnology, Asia University, Taichung 413, Taiwan.
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16
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Rewiring cell polarity signaling in cancer. Oncogene 2014; 34:939-50. [PMID: 24632617 DOI: 10.1038/onc.2014.59] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 02/07/2014] [Accepted: 02/11/2014] [Indexed: 02/08/2023]
Abstract
Disrupted cell polarity is a feature of epithelial cancers. The Crumbs, Par and Scribble polarity complexes function to specify and maintain apical and basolateral membrane domains, which are essential to organize intracellular signaling pathways that maintain epithelial homeostasis. Disruption of apical-basal polarity proteins facilitates rewiring of oncogene and tumor suppressor signaling pathways to deregulate proliferation, apoptosis, invasion and metastasis. Moreover, apical-basal polarity integrates intracellular signaling with the microenvironment by regulating metabolic signaling, extracellular matrix remodeling and tissue level organization. In this review, we discuss recent advances in our understanding of how polarity proteins regulate diverse signaling pathways throughout cancer progression from initiation to metastasis.
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17
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Azad AKM, Lee H. Voting-based cancer module identification by combining topological and data-driven properties. PLoS One 2013; 8:e70498. [PMID: 23940583 PMCID: PMC3734239 DOI: 10.1371/journal.pone.0070498] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 06/19/2013] [Indexed: 12/19/2022] Open
Abstract
Recently, computational approaches integrating copy number aberrations (CNAs) and gene expression (GE) have been extensively studied to identify cancer-related genes and pathways. In this work, we integrate these two data sets with protein-protein interaction (PPI) information to find cancer-related functional modules. To integrate CNA and GE data, we first built a gene-gene relationship network from a set of seed genes by enumerating all types of pairwise correlations, e.g. GE-GE, CNA-GE, and CNA-CNA, over multiple patients. Next, we propose a voting-based cancer module identification algorithm by combining topological and data-driven properties (VToD algorithm) by using the gene-gene relationship network as a source of data-driven information, and the PPI data as topological information. We applied the VToD algorithm to 266 glioblastoma multiforme (GBM) and 96 ovarian carcinoma (OVC) samples that have both expression and copy number measurements, and identified 22 GBM modules and 23 OVC modules. Among 22 GBM modules, 15, 12, and 20 modules were significantly enriched with cancer-related KEGG, BioCarta pathways, and GO terms, respectively. Among 23 OVC modules, 19, 18, and 23 modules were significantly enriched with cancer-related KEGG, BioCarta pathways, and GO terms, respectively. Similarly, we also observed that 9 and 2 GBM modules and 15 and 18 OVC modules were enriched with cancer gene census (CGC) and specific cancer driver genes, respectively. Our proposed module-detection algorithm significantly outperformed other existing methods in terms of both functional and cancer gene set enrichments. Most of the cancer-related pathways from both cancer data sets found in our algorithm contained more than two types of gene-gene relationships, showing strong positive correlations between the number of different types of relationship and CGC enrichment -values (0.64 for GBM and 0.49 for OVC). This study suggests that identified modules containing both expression changes and CNAs can explain cancer-related activities with greater insights.
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Affiliation(s)
- A. K. M. Azad
- School of Information and Communications, Gwangju Institute of Science and Technology, Gwangju, South Korea
| | - Hyunju Lee
- School of Information and Communications, Gwangju Institute of Science and Technology, Gwangju, South Korea
- * E-mail:
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18
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Okochi-Takada E, Hattori N, Tsukamoto T, Miyamoto K, Ando T, Ito S, Yamamura Y, Wakabayashi M, Nobeyama Y, Ushijima T. ANGPTL4 is a secreted tumor suppressor that inhibits angiogenesis. Oncogene 2013; 33:2273-8. [PMID: 23686315 DOI: 10.1038/onc.2013.174] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 02/14/2013] [Accepted: 03/28/2013] [Indexed: 12/12/2022]
Abstract
Tumor suppressors with extracellular function are likely to have advantages as targets for cancer therapy, but few are known. Here, we focused on angiopoietin-like 4 (ANGPTL4), which is a secreted glycoprotein involved in lipoprotein metabolism and angiogenesis, is methylation-silenced in human cancers, but has unclear roles in cancer development and progression. We found a deletion mutation in its coiled-coil domain at its N-terminal in human gastric cancers, in addition to hypermethylation of the ANGPTL4 promoter CpG islands. Forced expression of wild-type ANGPTL4, but not ANGPTL4 with the deletion, at physiological levels markedly suppressed in vivo tumorigenicity and tumor angiogenesis, indicating that the latter caused the former. Tumor-derived ANGPTL4 suppressed in vitro vascular tube formation and proliferation of human umbilical vascular endothelial cells, partly due to suppression of ERK signaling. These showed that ANGPTL4 is a genetically and epigenetically inactivated secreted tumor suppressor that inhibits tumor angiogenesis.
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Affiliation(s)
- E Okochi-Takada
- Division of Epigenomics, National Cancer Center Research Institute, Tokyo, Japan
| | - N Hattori
- Division of Epigenomics, National Cancer Center Research Institute, Tokyo, Japan
| | - T Tsukamoto
- Oncological Pathology Division, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - K Miyamoto
- Division of Molecular Oncology, National Hospital Organization Kure Medical Center and Chugoku Cancer Center, Kureshi, Japan
| | - T Ando
- 1] Division of Epigenomics, National Cancer Center Research Institute, Tokyo, Japan [2] Third Department of Internal Medicine, University of Toyama, Toyama, Japan
| | - S Ito
- Department of Gastroenterological Surgery, Aichi Cancer Center Central Hospital, Nagoya, Japan
| | - Y Yamamura
- Department of Gastroenterological Surgery, Aichi Cancer Center Central Hospital, Nagoya, Japan
| | - M Wakabayashi
- Division of Epigenomics, National Cancer Center Research Institute, Tokyo, Japan
| | - Y Nobeyama
- 1] Division of Epigenomics, National Cancer Center Research Institute, Tokyo, Japan [2] Department of Dermatology, The Jikei University School of Medicine, Tokyo, Japan
| | - T Ushijima
- Division of Epigenomics, National Cancer Center Research Institute, Tokyo, Japan
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19
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Zhou W, Marcus AI, Vertino PM. Dysregulation of mTOR activity through LKB1 inactivation. CHINESE JOURNAL OF CANCER 2013; 32:427-33. [PMID: 23668926 PMCID: PMC3845579 DOI: 10.5732/cjc.013.10086] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mammalian target of rapamycin (mTOR) is aberrantly activated in many cancer types, and two rapamycin derivatives are currently approved by the Food and Drug Administration (FDA) of the United States for treating renal cell carcinoma. Mechanistically, mTOR is hyperactivated in human cancers either due to the genetic activation of its upstream activating signaling pathways or the genetic inactivation of its negative regulators. The tumor suppressor liver kinase B1 (LKB1), also known as serine/threonine kinase 11 (STK11), is involved in cell polarity, cell detachment and adhesion, tumor metastasis, and energetic stress response. A key role of LKB1 is to negatively regulate the activity of mTOR complex 1 (mTORC1). This review summarizes the molecular basis of this negative interaction and recent research progress in this area.
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Affiliation(s)
- Wei Zhou
- The Winship Cancer Institute, Department of Hematology and Oncology, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
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20
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Korsse SE, Peppelenbosch MP, van Veelen W. Targeting LKB1 signaling in cancer. Biochim Biophys Acta Rev Cancer 2012; 1835:194-210. [PMID: 23287572 DOI: 10.1016/j.bbcan.2012.12.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 12/18/2012] [Accepted: 12/20/2012] [Indexed: 12/13/2022]
Abstract
The serine/threonine kinase LKB1 is a master kinase involved in cellular responses such as energy metabolism, cell polarity and cell growth. LKB1 regulates these crucial cellular responses mainly via AMPK/mTOR signaling. Germ-line mutations in LKB1 are associated with the predisposition of the Peutz-Jeghers syndrome in which patients develop gastrointestinal hamartomas and have an enormously increased risk for developing gastrointestinal, breast and gynecological cancers. In addition, somatic inactivation of LKB1 has been associated with sporadic cancers such as lung cancer. The exact mechanisms of LKB1-mediated tumor suppression remain so far unidentified; however, the inability to activate AMPK and the resulting mTOR hyperactivation has been detected in PJS-associated lesions. Therefore, targeting LKB1 in cancer is now mainly focusing on the activation of AMPK and inactivation of mTOR. Preclinical in vitro and in vivo studies show encouraging results regarding these approaches, which have even progressed to the initiation of a few clinical trials. In this review, we describe the functions, regulation and downstream signaling of LKB1, and its role in hereditary and sporadic cancers. In addition, we provide an overview of several AMPK activators, mTOR inhibitors and additional mechanisms to target LKB1 signaling, and describe the effect of these compounds on cancer cells. Overall, we will explain the current strategies attempting to find a way of treating LKB1-associated cancer.
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Affiliation(s)
- S E Korsse
- Dept. of Gastroenterology and Hepatology, Erasmus Medical University Center, Rotterdam, The Netherlands
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21
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Bonanno L, Favaretto A, Rugge M, Taron M, Rosell R. Role of genotyping in non-small cell lung cancer treatment: current status. Drugs 2012; 71:2231-46. [PMID: 22085382 DOI: 10.2165/11597700-000000000-00000] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Non-small cell lung cancer (NSCLC) is a common malignant disease with an extremely poor prognosis. Chemotherapeutic treatment for advanced disease is currently based on histological subtyping, but recent discoveries of genetic alterations in subsets of NSCLC have already changed clinical practice with regard to Egfr mutations as predictive markers of response to gefitinib and erlotinib. This has also paved the way for the integration of molecular analyses into early phase clinical trials, as demonstrated by the clinical development of crizotinib, effective in lung cancer harbouring Alk rearrangements. Similarly, other subgroups of NSCLC carry potentially targetable molecular alterations and their study has the potential to change the diagnostic and therapeutic approach to lung cancer in the near future. In contrast to a wealth of knowledge surrounding genomic alterations in lung adenocarcinomas, fewer data are available concerning squamous cell lung cancer (SCC), although recent data demonstrate that genotyping can provide new therapeutic perspectives in SCC treatment. Moreover, the study of molecular predictive markers of response to chemotherapy aims to improve chemotherapeutic treatment, increasing efficacy and limiting toxicity.
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Affiliation(s)
- Laura Bonanno
- Medical Oncology 2, Instituto Oncologico Veneto-IRCCS, Padua, Italy
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22
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Genomic dissection of the epidermal growth factor receptor (EGFR)/PI3K pathway reveals frequent deletion of the EGFR phosphatase PTPRS in head and neck cancers. Proc Natl Acad Sci U S A 2011; 108:19024-9. [PMID: 22065749 DOI: 10.1073/pnas.1111963108] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Activation of the PI3K and epidermal growth factor receptor (EGFR) pathway is able to drive oncogenesis in multiple human cancers, including head and neck squamous cell carcinoma. Targeted agents such as cetuximab and erlotinib are currently used in patients with head and neck squamous cell carcinoma, but, in this disease, the genomic alterations that cause pathway activation and determine response to pharmacologic inhibition remain ill-defined. Here, we present a detailed dissection of the EGFR/PI3K pathway, composed of sequencing of the core pathway components, and high-resolution genomic copy number assessment. Mutations were found in PIK3CA (6%), but no point mutations were observed in other pathway genes such as PTEN and EGFR. In contrast, we observed frequent copy number alterations of genes in the pathway, including PIK3CA, EGFR, protein tyrosine phosphatase receptor S (PTPRS), and RICTOR. In total, activating genetic pathway alterations were identified in 74% of head and neck tumors. Importantly, intragenic microdeletions of the EGFR phosphatase PTPRS were frequent (26%), identifying this gene as a target of 19p13 loss. PTPRS loss promoted EGFR/PI3K pathway activation, modulated resistance to EGFR inhibition, and strongly determined survival in lung cancer patients with activating EGFR mutations. These findings have important implications for our understanding of head and neck cancer tumorigenesis and for the use of targeted agents for this malignancy.
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23
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Gao Y, Ge G, Ji H. LKB1 in lung cancerigenesis: a serine/threonine kinase as tumor suppressor. Protein Cell 2011; 2:99-107. [PMID: 21380642 PMCID: PMC4875258 DOI: 10.1007/s13238-011-1021-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 02/12/2011] [Indexed: 01/01/2023] Open
Abstract
Lung cancer is featured with high mortality, with a 15% five-year survival rate worldwide. Genetic alterations, such as loss of function of tumor suppressor genes, frequently contribute to lung cancer initiation, progression and metastasis. Liver kinase B1 (LKB1), as a serine/threonine kinase and tumor suppressor, is frequently mutated and inactivated in non-small cell lung cancer (NSCLC). Recent studies have provided strong evidences that LKB1 loss promotes lung cancerigenesis process, especially lung cancer progression and metastasis. This review will summarize recent progress on how LKB1 modulates the process of lung cancerigenesis, emphasizing on LKB1 downstream signaling pathways and biological functions. We will further discuss the potential development of prognostic biomarkers or therapeutic targets in lung cancer clinic based on the molecular alteration associated with deregulated LKB1 signaling.
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Affiliation(s)
- Yijun Gao
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Gaoxiang Ge
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Hongbin Ji
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
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24
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Polymorphisms of the apoptosis-associated gene DP1L1 (deleted in polyposis 1-like 1) in colon cancer and inflammatory bowel disease. J Cancer Res Clin Oncol 2009; 136:795-802. [DOI: 10.1007/s00432-009-0719-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 10/26/2009] [Indexed: 01/21/2023]
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25
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Low SAFB levels are associated with worse outcome in breast cancer patients. Breast Cancer Res Treat 2009; 121:503-9. [PMID: 19137425 DOI: 10.1007/s10549-008-0297-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 12/23/2008] [Indexed: 10/21/2022]
Abstract
The scaffold attachment factors SAFB1 and SAFB2 have been shown to function as estrogen receptor (ERalpha) co-repressors in breast cancer cells, and to affect many cellular processes such as stress response, RNA processing, and apoptosis. SAFB1 and SAFB2 have also been implicated in breast tumorigenesis: Their shared chromosomal locus at 19p13 is frequently lost in breast cancer, mutations have been identified, and overexpression results in growth inhibition. The purpose of this study was to determine SAFB1/SAFB2 protein expression in human breast tumors, to correlate their expression with either natural progression ("prognostic factor") or with response to Tamoxifen ("predictive factor"), and to analyze potential correlations with tumor characteristics. SAFB1/SAFB2 protein were measured by immunoblotting using a pan-SAFB antibody in tumor extracts from patients with long-term clinical follow-up (n = 289), a subset of whom had received no adjuvant systemic therapy after breast cancer surgery (n = 117) and another subset of whom were treated with adjuvant Tamoxifen (n = 172). SAFB levels were correlated with clinico-pathological variables and patient outcome. SAFB levels varied widely, with 25 tumors not expressing detectable levels of SAFB. SAFB expression was significantly correlated with ERalpha, HER-2, bcl-2 and with expression of other ERalpha coregulators such as SRC-3. There was no association between SAFB expression and disease free survival, however, low SAFB expression was significantly associated with worse overall survival in patients who did not receive adjuvant therapy. This study shows that low SAFB protein levels predict poor prognosis of breast cancer patients, suggesting critical functions of SAFB1 and SAFB2 in breast cancer cells.
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26
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27
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Zhong D, Liu X, Khuri FR, Sun SY, Vertino PM, Zhou W. LKB1 is necessary for Akt-mediated phosphorylation of proapoptotic proteins. Cancer Res 2008; 68:7270-7. [PMID: 18794113 DOI: 10.1158/0008-5472.can-08-1484] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
LKB1 plays the role of tumor suppressor, opposite to Akt, by negatively regulating mammalian target of rapamycin through the activation of AMP-activated protein kinase and TSC signaling. We have discovered a novel, potentially oncogenic role for LKB1 as a supporter of Akt-mediated phosphorylation of proapoptotic proteins. We found that Akt activation led to increased phosphorylation of FoxO3a at Thr(32) in LKB1 wild-type cells but not in LKB1-null cells. Depletion of LKB1 in the cells with wild-type LKB1 resulted in attenuation of that phosphorylation of FoxO3a by activated Akt, whereas the restoration of LKB1 function in LKB1-null cells reestablished Akt-mediated FoxO3a phosphorylation. On expanding our analysis to other Akt targets, using isogenic LKB1 knockdown cell line pairs and a phospho-specific antibody microarray, we observed that there was a requirement for LKB1 in the phosphorylation of other Akt downstream targets, including Ask1 (Ser(83)), Bad (Ser(136)), FoxO1 (Ser(319)), FoxO4 (Ser(197)), and glycogen synthase kinase 3beta (GSK3beta; Ser(9)). Because the phosphorylation of these sites by Akt suppresses apoptosis, the requirement of LKB1 suggests that LKB1 may have an antiapoptotic role in tumor cells with constitutively active Akt. Indeed, we found that the suppression of LKB1 expression led to apoptosis in three cell lines in which Akt is constitutively active but not in two cell lines without Akt activation. This observation may explain the lack of LKB1 somatic mutations in brain, breast, and colon cancers, where Akt is frequently activated due to mutations in phosphatidylinositol 3-kinase, PTEN, or Akt itself.
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Affiliation(s)
- Diansheng Zhong
- The Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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28
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Abstract
Three phenotypically related genetic syndromes and their lesions (LKB1, PTEN, and TSC1/2) are identified as frequently altered in lung cancer. LKB1, a kinase inactivated in 30% of lung cancers, is discussed in this review. Loss of LKB1 regulation often coincident with KRAS activation allows for unchecked growth and the metabolic capacity to accommodate the proliferation.
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29
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Kam M, Massare J, Gallinger S, Kinzie J, Weaver D, Dingell JD, Esufali S, Bapat B, Tobi M. Peutz-Jeghers syndrome diagnosed in a schizophrenic patient with a large deletion in the STK11 gene. Dig Dis Sci 2006; 51:1567-70. [PMID: 16927138 DOI: 10.1007/s10620-006-9102-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Accepted: 10/26/2005] [Indexed: 01/29/2023]
Affiliation(s)
- Michael Kam
- VAMC, Department of Medicine, Division of Gastroenterology and Surgery, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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30
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Katajisto P, Vallenius T, Vaahtomeri K, Ekman N, Udd L, Tiainen M, Mäkelä TP. The LKB1 tumor suppressor kinase in human disease. Biochim Biophys Acta Rev Cancer 2006; 1775:63-75. [PMID: 17010524 DOI: 10.1016/j.bbcan.2006.08.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 07/25/2006] [Accepted: 08/12/2006] [Indexed: 12/31/2022]
Abstract
Inactivating germline mutations in the LKB1 gene underlie Peutz-Jeghers syndrome characterized by hamartomatous polyps and an elevated risk for cancer. Recent studies suggest the involvement of LKB1 also in more common human disorders including diabetes and in a significant fraction of lung adenocarcinomas. These observations have increased the interest towards signaling pathways of this tumor suppressor kinase. The recent breakthroughs in understanding the molecular functions of the LKB1 indicate its contribution as a regulator of cell polarity, energy metabolism and cell proliferation. Here we review how the substrates and cellular functions of LKB1 may be linked to Peutz-Jeghers syndrome and other diseases, and discuss how some of the molecular changes associated with altered LKB1 signaling might be used in therapeutic approaches.
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Affiliation(s)
- Pekka Katajisto
- Molecular Cancer Biology Program, Translational Genome-Scale Biology and Institute of Biomedicine, Biomedicum Helsinki, University of Helsinki, Finland
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31
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Zhong D, Guo L, de Aguirre I, Liu X, Lamb N, Sun SY, Gal AA, Vertino PM, Zhou W. LKB1 mutation in large cell carcinoma of the lung. Lung Cancer 2006; 53:285-94. [PMID: 16822578 DOI: 10.1016/j.lungcan.2006.05.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 05/17/2006] [Accepted: 05/20/2006] [Indexed: 10/24/2022]
Abstract
Germline inactivation of LKB1 is responsible for Peutz-Jeghers syndrome, an autosomal dominant disorder characterized by benign hamartomas of the GI tract and an increased predisposition to certain cancers, including lung. Acquired mutations in LKB1 are rarely observed in most sporadic tumor types except for adenocarcinomas of the lung where up to 50% harbor inactivating mutations. In this study, we focused on LKB1 mutations in lung cancer cell lines originating from large cell carcinomas. We identified a novel 1.5kb interstitial deletion within LKB1 gene in H157 cancer cells. Homozygosity mapping-of-deletion analysis (HOMOD) analysis showed that the deletion is accompanied by LOH of one parental allele, indicating biallelic inactivation of LKB1. This deletion results in an LKB1 transcript lacking exons 2 and 3 and a predicted in-frame deletion of 58 amino acids within the kinase domain of the LKB1 protein. The truncated transcript was expressed at relatively low levels, and the truncated LKB1 protein was virtually undetectable in this cell line. To determine the impact of LKB1 protein truncation on its function, we examined AMPK-alpha, a downstream target of LKB1 kinase activity triggered by low energy stress conditions. Phosphorylation of AMPK-alpha was attenuated in H157 cells treated with 2-deoxyglucose, and could be rescued by expression of an exogenous GFP-LKB1 fusion protein. Therefore, our data suggest that LKB1 function is compromised in H157. Of the four cell lines and six primary tumors of large cell lung carcinoma origin that have been evaluated in this and other studies, LKB1 mutations have been found in three cases. These results suggest that, in addition to adenocarcinomas, acquired loss of function mutations in LKB1 may also be frequently involved in the pathogenesis of large cell lung carcinomas.
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Affiliation(s)
- Diansheng Zhong
- The Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 32322, USA
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32
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Grützmann R, McFaul C, Bartsch DK, Sina-Frey M, Rieder H, Koch R, McCarthy E, Greenhalf W, Neoptolemos JP, Saeger HD, Pilarsky C. No evidence for germline mutations of the LKB1/STK11 gene in familial pancreatic carcinoma. Cancer Lett 2004; 214:63-8. [PMID: 15331174 DOI: 10.1016/j.canlet.2004.06.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Revised: 05/25/2004] [Accepted: 06/01/2004] [Indexed: 01/02/2023]
Abstract
Familial pancreatic cancer (FPC) (approximately 3% of all cases) has not been linked to defects in any specific gene. Germline inactivation of the gene LKB1/STK11 have been shown to cause Peutz-Jeghers syndrome (PJS) associated with a approximately 100-fold higher risk for the development of pancreatic cancer. We have analysed 39 index patients from European FPC families for mutations of LKB1/STK11 by sequencing of their DNA. No germline mutation was found within the complete coding region. Therefore, our results indicate that LKB1/STK11 is not altered in the germline of patients with hereditary pancreatic cancer.
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Affiliation(s)
- Robert Grützmann
- Department of Visceral, Thoracic and Vascular Surgery, University Hospital Carl Gustav Carus, Technical University of Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
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33
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Oesterreich S. Scaffold attachment factors SAFB1 and SAFB2: Innocent bystanders or critical players in breast tumorigenesis? J Cell Biochem 2003; 90:653-61. [PMID: 14587024 DOI: 10.1002/jcb.10685] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Scaffold attachment factor B1 (SAFB1) and SAFB2 are large, multifunctional proteins that have been implicated in numerous cellular processes including chromatin organization, transcriptional regulation, RNA splicing, and stress response. While the two homologous proteins show high similarity, and functional domains are highly conserved, evidence suggests that they also have unique properties. For example, SAFB2 can be found in both the nucleus and cytoplasm, whereas SAFB1 seems to be mainly localized in the nucleus. In breast cancer cells, SAFBs function as estrogen receptor corepressors and growth inhibitors. SAFB protein expression is lost in approximately 20% of breast cancers. Interestingly, the two genes reside in close proximity, oriented head-to-head, on chromosome 19p13, a locus which is frequently lost in clinical breast cancer specimens. Furthermore, SAFB1 mutations have been identified in breast tumors that were not present in adjacent normal tissue. The possibility that SAFB1 and SAFB2 are novel breast tumor suppressor genes, and how they might function in this role, are discussed.
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Affiliation(s)
- Steffi Oesterreich
- Department of Medicine and Molecular and Cellular Biology, The Breast Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
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