1
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Cai Z, Jiang Y, Tong H, Liang M, Huang Y, Fang L, Liang F, Hu Y, Shi X, Wang J, Wang Z, Ji Q, Huo H, Shen L, He B. Cellular and molecular characteristics of stromal Lkb1 deficiency-induced gastrointestinal polyposis based on single-cell RNA sequencing. J Pathol 2024; 263:47-60. [PMID: 38389501 DOI: 10.1002/path.6259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 10/17/2023] [Accepted: 01/04/2024] [Indexed: 02/24/2024]
Abstract
Liver kinase B1 (Lkb1), encoded by serine/threonine kinase (Stk11), is a serine/threonine kinase and tumor suppressor that is strongly implicated in Peutz-Jeghers syndrome (PJS). Numerous studies have shown that mesenchymal-specific Lkb1 is sufficient for the development of PJS-like polyps in mice. However, the cellular origin and components of these Lkb1-associated polyps and underlying mechanisms remain elusive. In this study, we generated tamoxifen-inducible Lkb1flox/flox;Myh11-Cre/ERT2 and Lkb1flox/flox;PDGFRα-Cre/ERT2 mice, performed single-cell RNA sequencing (scRNA-seq) and imaging-based lineage tracing, and aimed to investigate the cellular complexity of gastrointestinal polyps associated with PJS. We found that Lkb1flox/+;Myh11-Cre/ERT2 mice developed gastrointestinal polyps starting at 9 months after tamoxifen treatment. scRNA-seq revealed aberrant stem cell-like characteristics of epithelial cells from polyp tissues of Lkb1flox/+;Myh11-Cre/ERT2 mice. The Lkb1-associated polyps were further characterized by a branching smooth muscle core, abundant extracellular matrix deposition, and high immune cell infiltration. In addition, the Spp1-Cd44 or Spp1-Itga8/Itgb1 axes were identified as important interactions among epithelial, mesenchymal, and immune compartments in Lkb1-associated polyps. These characteristics of gastrointestinal polyps were also demonstrated in another mouse model, tamoxifen-inducible Lkb1flox/flox;PDGFRα-Cre/ERT2 mice, which developed obvious gastrointestinal polyps as early as 2-3 months after tamoxifen treatment. Our findings further confirm the critical role of mesenchymal Lkb1/Stk11 in gastrointestinal polyposis and provide novel insight into the cellular complexity of Lkb1-associated polyp biology. © 2024 The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Zhaohua Cai
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Yangjing Jiang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Huan Tong
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Min Liang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Yijie Huang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Liang Fang
- Department of Cardiac Surgery, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Feng Liang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Yunwen Hu
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Xin Shi
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Jian Wang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Zi Wang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Qingqi Ji
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Huanhuan Huo
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Linghong Shen
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
| | - Ben He
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China
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Trembath HE, Yeh JJ, Lopez NE. Gastrointestinal Malignancy: Genetic Implications to Clinical Applications. Cancer Treat Res 2024; 192:305-418. [PMID: 39212927 DOI: 10.1007/978-3-031-61238-1_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Advances in molecular genetics have revolutionized our understanding of the pathogenesis, progression, and therapeutic options for treating gastrointestinal (GI) cancers. This chapter provides a comprehensive overview of the molecular landscape of GI cancers, focusing on key genetic alterations implicated in tumorigenesis across various anatomical sites including GIST, colon and rectum, and pancreas. Emphasis is placed on critical oncogenic pathways, such as mutations in tumor suppressor genes, oncogenes, chromosomal instability, microsatellite instability, and epigenetic modifications. The role of molecular biomarkers in predicting prognosis, guiding treatment decisions, and monitoring therapeutic response is discussed, highlighting the integration of genomic profiling into clinical practice. Finally, we address the evolving landscape of precision oncology in GI cancers, considering targeted therapies and immunotherapies.
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Affiliation(s)
- Hannah E Trembath
- Division of Colon and Rectal Surgery, Department of Surgery, University of California San Diego, 4303 La Jolla Village Drive Suite 2110, San Diego, CA, 92122, USA
- Division of Surgical Oncology, Department of Surgery, University of North Carolina, 170 Manning Drive, CB#7213, 1150 Physician's Office Building, Chapel Hill, NC, 27599-7213, USA
| | - Jen Jen Yeh
- Division of Colon and Rectal Surgery, Department of Surgery, University of California San Diego, 4303 La Jolla Village Drive Suite 2110, San Diego, CA, 92122, USA
- Division of Surgical Oncology, Department of Surgery, University of North Carolina, 170 Manning Drive, CB#7213, 1150 Physician's Office Building, Chapel Hill, NC, 27599-7213, USA
| | - Nicole E Lopez
- Division of Colon and Rectal Surgery, Department of Surgery, University of California San Diego, 4303 La Jolla Village Drive Suite 2110, San Diego, CA, 92122, USA.
- Division of Surgical Oncology, Department of Surgery, University of North Carolina, 170 Manning Drive, CB#7213, 1150 Physician's Office Building, Chapel Hill, NC, 27599-7213, USA.
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3
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Compton SE, Kitchen-Goosen SM, DeCamp LM, Lau KH, Mabvakure B, Vos M, Williams KS, Wong KK, Shi X, Rothbart SB, Krawczyk CM, Jones RG. LKB1 controls inflammatory potential through CRTC2-dependent histone acetylation. Mol Cell 2023:S1097-2765(23)00288-5. [PMID: 37172591 DOI: 10.1016/j.molcel.2023.04.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 03/17/2023] [Accepted: 04/18/2023] [Indexed: 05/15/2023]
Abstract
Deregulated inflammation is a critical feature driving the progression of tumors harboring mutations in the liver kinase B1 (LKB1), yet the mechanisms linking LKB1 mutations to deregulated inflammation remain undefined. Here, we identify deregulated signaling by CREB-regulated transcription coactivator 2 (CRTC2) as an epigenetic driver of inflammatory potential downstream of LKB1 loss. We demonstrate that LKB1 mutations sensitize both transformed and non-transformed cells to diverse inflammatory stimuli, promoting heightened cytokine and chemokine production. LKB1 loss triggers elevated CRTC2-CREB signaling downstream of the salt-inducible kinases (SIKs), increasing inflammatory gene expression in LKB1-deficient cells. Mechanistically, CRTC2 cooperates with the histone acetyltransferases CBP/p300 to deposit histone acetylation marks associated with active transcription (i.e., H3K27ac) at inflammatory gene loci, promoting cytokine expression. Together, our data reveal a previously undefined anti-inflammatory program, regulated by LKB1 and reinforced through CRTC2-dependent histone modification signaling, that links metabolic and epigenetic states to cell-intrinsic inflammatory potential.
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Affiliation(s)
- Shelby E Compton
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI, USA
| | - Susan M Kitchen-Goosen
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI, USA; Metabolism and Nutrition (MeNu) Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Lisa M DeCamp
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI, USA; Metabolism and Nutrition (MeNu) Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Kin H Lau
- Bioinformatics and Biostatistics Core, Van Andel Institute, Grand Rapids, MI, USA
| | - Batsirai Mabvakure
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI, USA
| | - Matthew Vos
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI, USA; Metabolism and Nutrition (MeNu) Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Kelsey S Williams
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI, USA; Metabolism and Nutrition (MeNu) Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Kwok-Kin Wong
- Laura and Isaac Perlmutter Cancer Center, NYU Langone Health, New York, NY, USA
| | - Xiaobing Shi
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI, USA
| | - Scott B Rothbart
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI, USA
| | - Connie M Krawczyk
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI, USA; Metabolism and Nutrition (MeNu) Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Russell G Jones
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI, USA; Metabolism and Nutrition (MeNu) Program, Van Andel Institute, Grand Rapids, MI, USA.
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Rho SB, Byun HJ, Kim BR, Lee CH. Liver Kinase B1 Mediates Its Anti-Tumor Function by Binding to the N-Terminus of Malic Enzyme 3. Biomol Ther (Seoul) 2023; 31:330-339. [PMID: 37095735 PMCID: PMC10129855 DOI: 10.4062/biomolther.2023.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 03/18/2023] [Accepted: 03/24/2023] [Indexed: 04/26/2023] Open
Abstract
Liver kinase B1 (LKB1) is a crucial tumor suppressor involved in various cellular processes, including embryonic development, tumor initiation and progression, cell adhesion, apoptosis, and metabolism. However, the precise mechanisms underlying its functions remain elusive. In this study, we demonstrate that LKB1 interacts directly with malic enzyme 3 (ME3) through the N-terminus of the enzyme and identified the binding regions necessary for this interaction. The binding activity was confirmed to promote the expression of ME3 in an LKB1-dependent manner and was also shown to induce apoptosis activity. Furthermore, LKB1 and ME3 overexpression upregulated the expression of tumour suppressor proteins (p53 and p21) and downregulated the expression of antiapoptotic proteins (nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and B-cell lymphoma 2 (Bcl-2)). Additionally, LKB1 and ME3 enhanced the transcription of p21 and p53 and inhibited the transcription of NF-κB. Moreover, LKB1 and ME3 suppressed the phosphorylation of various components of the phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B signaling pathway. Overall, these results suggest that LKB1 promotes pro-apoptotic activities by inducing ME3 expression.
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Affiliation(s)
- Seung Bae Rho
- Division of Cancer Biology, Research Institute, National Cancer Center, Goyang 10408
| | - Hyun Jung Byun
- College of Pharmacy, Dongguk University, Goyang 10326, Republic of Korea
| | - Boh-Ram Kim
- College of Pharmacy, Dongguk University, Goyang 10326, Republic of Korea
| | - Chang Hoon Lee
- College of Pharmacy, Dongguk University, Goyang 10326, Republic of Korea
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Yehia L, Heald B, Eng C. Clinical Spectrum and Science Behind the Hamartomatous Polyposis Syndromes. Gastroenterology 2023; 164:800-811. [PMID: 36717037 DOI: 10.1053/j.gastro.2023.01.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 01/21/2023] [Accepted: 01/23/2023] [Indexed: 02/01/2023]
Abstract
The hamartomatous polyposis syndromes are a set of clinically distinct disorders characterized by the occurrence of hamartomatous polyps in the gastrointestinal tract. These syndromes include juvenile polyposis syndrome, Peutz-Jeghers syndrome, and PTEN hamartoma tumor syndrome. Although each of the syndromes has distinct phenotypes, the hamartomatous polyps can be challenging to differentiate histologically. Additionally, each of these syndromes is associated with increased lifetime risks of gene-specific and organ-specific cancers, including those outside of the gastrointestinal tract. Germline pathogenic variants can be identified in a subset of individuals with these syndromes, which facilitates molecular diagnosis and subsequent gene-enabled management in the setting of genetic counseling. Although the malignant potential of hamartomatous polyps remains elusive, timely recognition of these syndromes is important and enables presymptomatic cancer surveillance and management before symptom exacerbation. Presently, there are no standard agents to prevent the development of polyps and cancers in the hamartomatous polyposis syndromes.
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Affiliation(s)
- Lamis Yehia
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | | | - Charis Eng
- Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio; Center for Personalized Genetic Healthcare, Community Care, Cleveland Clinic, Cleveland, Ohio; Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio; Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio; Germline High Risk Cancer Focus Group, Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio.
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6
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Song Y, Zhao F, Ma W, Li G. Hotspots and trends in liver kinase B1 research: A bibliometric analysis. PLoS One 2021; 16:e0259240. [PMID: 34735498 PMCID: PMC8568265 DOI: 10.1371/journal.pone.0259240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 10/15/2021] [Indexed: 11/29/2022] Open
Abstract
Introduction In the past 22 years, a large number of publications have reported that liver kinase B1 (LKB1) can regulate a variety of cellular processes and play an important role in many diseases. However, there is no systematic bibliometric analysis on the publications of LKB1 to reveal the research hotspots and future direction. Methods Publications were retrieved from the Web of Science Core Collection (WoSCC), Scopus, and PubMed databases. CiteSpace and VOSviewer were used to analysis the top countries, institutions, authors, source journals, discipline categories, references, and keywords. Results In the past 22 years, the number of LKB1 publications has increased gradually by year. The country, institution, author, journals that have published the most articles and cited the most frequently were the United States, Harvard University, Prof. Benoit Viollet, Journal of Biochemistry and Plos One. The focused research hotspot was the molecular functions of LKB1. The emerging hotspots and future trends are the clinical studies about LKB1 and co-mutated genes as biomarkers in tumors, especially in lung adenocarcinoma. Conclusions Our research could provide knowledge base, frontiers, emerging hotspots and future trends associated with LKB1 for researchers in this field, and contribute to finding potential cooperation possibilities.
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Affiliation(s)
- Yaowen Song
- Department of Radiotherapy Oncology, The First Affiliated Hospital of China Medical University, Shenyan, China
| | - Fangkun Zhao
- Department of Ophthalmology, The Fourth Affiliated Hospital of China Medical University, Shenyang, China
| | - Wei Ma
- Department of Breast Surgery, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Guang Li
- Department of Radiotherapy Oncology, The First Affiliated Hospital of China Medical University, Shenyan, China
- * E-mail:
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7
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Gao Y, Yan Y, Tripathi S, Pentinmikko N, Amaral A, Päivinen P, Domènech-Moreno E, Andersson S, Wong IPL, Clevers H, Katajisto P, Mäkelä TP. LKB1 Represses ATOH1 via PDK4 and Energy Metabolism and Regulates Intestinal Stem Cell Fate. Gastroenterology 2020; 158:1389-1401.e10. [PMID: 31930988 DOI: 10.1053/j.gastro.2019.12.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 12/02/2019] [Accepted: 12/30/2019] [Indexed: 01/16/2023]
Abstract
BACKGROUND & AIMS In addition to the Notch and Wnt signaling pathways, energy metabolism also regulates intestinal stem cell (ISC) function. Tumor suppressor and kinase STK11 (also called LKB1) regulates stem cells and cell metabolism. We investigated whether loss of LKB1 alters ISC homeostasis in mice. METHODS We deleted LKB1 from ISCs in mice using Lgr5-regulated CRE-ERT2 (Lkb1Lgr5-KO mice) and the traced lineages by using a CRE-dependent TdTomato reporter. Intestinal tissues were collected and analyzed by immunohistochemical and immunofluorescence analyses. We purified ISCs and intestinal progenitors using flow cytometry and performed RNA-sequencing analysis. We measured organoid-forming capacity and ISC percentages using intestinal tissues from Lkb1Lgr5-KO mice. We analyzed human Ls174t cells with knockdown of LKB1 or other proteins by immunoblotting, real-time quantitative polymerase chain reaction, and the Seahorse live-cell metabolic assay. RESULTS Some intestinal crypts from Lkb1Lgr5-KO mice lost ISCs compared with crypts from control mice. However, most crypts from Lkb1Lgr5-KO mice contained functional ISCs that expressed increased levels of Atoh1 messenger RNA (mRNA), acquired a gene expression signature associated with secretory cells, and generated more cells in the secretory lineage compared with control mice. Knockdown of LKB1 in Ls174t cells induced expression of Atoh1 mRNA and a phenotype of increased mucin production; knockdown of ATOH1 prevented induction of this phenotype. The increased expression of Atoh1 mRNA after LKB1 loss from ISCs or Ls174t cells did not involve Notch or Wnt signaling. Knockdown of pyruvate dehydrogenase kinase 4 (PDK4) or inhibition with dichloroacetate reduced the up-regulation of Atoh1 mRNA after LKB1 knockdown in Ls174t cells. Cells with LKB1 knockdown had a reduced rate of oxygen consumption, which was partially restored by PDK4 inhibition with dichloroacetate. ISCs with knockout of LKB1 increased the expression of PDK4 and had an altered metabolic profile. CONCLUSIONS LKB1 represses transcription of ATOH1, via PDK4, in ISCs, restricting their differentiation into secretory lineages. These findings provide a connection between metabolism and the fate determination of ISCs.
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Affiliation(s)
- Yajing Gao
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland; HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Finland
| | - Yan Yan
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland; HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Finland.
| | - Sushil Tripathi
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland; HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Finland
| | - Nalle Pentinmikko
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland; HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Finland; Institute of Biotechnology, HiLIFE, University of Helsinki, Finland
| | - Ana Amaral
- Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden
| | - Pekka Päivinen
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland; HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Finland
| | - Eva Domènech-Moreno
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland; HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Finland
| | - Simon Andersson
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland; HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Finland; Institute of Biotechnology, HiLIFE, University of Helsinki, Finland
| | - Iris P L Wong
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland
| | - Hans Clevers
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and Cancer Genomics Netherlands, University Medical Center Utrecht and Princess Máxima Centre, Utrecht, The Netherlands
| | - Pekka Katajisto
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland; HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Finland; Institute of Biotechnology, HiLIFE, University of Helsinki, Finland; Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden
| | - Tomi P Mäkelä
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Finland; HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Finland.
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Han Y, Feng H, Sun J, Liang X, Wang Z, Xing W, Dai Q, Yang Y, Han A, Wei Z, Bi Q, Ji H, Kang T, Zou W. Lkb1 deletion in periosteal mesenchymal progenitors induces osteogenic tumors through mTORC1 activation. J Clin Invest 2019; 129:1895-1909. [PMID: 30830877 PMCID: PMC6486357 DOI: 10.1172/jci124590] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Bone osteogenic sarcoma has a poor prognosis as the exact cell of origin and the signaling pathways underling tumor formation remain undefined. Here, we report an osteogenic tumor mouse model based on the conditional knockout of liver kinase b1 (Lkb1; also known as Stk11) in Cathepsin K (Ctsk)-Cre expressing cells. Lineage tracing studies demonstrated that Ctsk-Cre could label a population of periosteal cells. The cells functioned as mesenchymal progenitors with regard to markers and functional properties. LKB1 deficiency increased proliferation and osteoblast differentiation of Ctsk+ periosteal cells, while downregulation of mTORC1 activity, using Raptor genetic mouse model or mTORC1 inhibitor treatment, ameliorated tumor progression of Ctsk-Cre Lkb1fllfl mice. Xenograft mouse models, using human osteosarcoma cell lines, also demonstrated that LKB1 deficiency promoted tumor formation, while mTOR inhibition suppressed xenograft tumor growth. In summary, we identified periosteum-derived Ctsk-Cre expressing cells as a cell of origin for osteogenic tumor and suggested the LKB1-mTORC1 pathway as a promising target for treatment of osteogenic tumor.
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Affiliation(s)
- Yujiao Han
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Heng Feng
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Jun Sun
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Xiaoting Liang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Zhuo Wang
- Department of Pathology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Wenhui Xing
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Qinggang Dai
- The Second Dental Center, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yang Yang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Anjia Han
- Department of Pathology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Zhanying Wei
- Department of Osteoporosis and Bone Diseases, Metabolic Bone Disease and Genetics Research Unit, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, Shanghai, China
| | - Qing Bi
- Zhejiang Provincial People’s Hospital, Hangzhou, China
| | - Hongbin Ji
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
| | - Tiebang Kang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Weiguo Zou
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
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9
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Abstract
The tumor suppressor LKB1 is an essential serine/threonine kinase, which regulates various cellular processes such as cell metabolism, cell proliferation, cell polarity, and cell migration. Germline mutations in the STK11 gene (encoding LKB1) are the cause of the Peutz-Jeghers syndrome, which is characterized by benign polyps in the intestine and a higher risk for the patients to develop intestinal and extraintestinal tumors. Moreover, mutations and misregulation of LKB1 have been reported to occur in most types of tumors and are among the most common aberrations in lung cancer. LKB1 activates several downstream kinases of the AMPK family by direct phosphorylation in the T-loop. In particular the activation of AMPK upon energetic stress has been intensively analyzed in various diseases, including cancer to induce a metabolic switch from anabolism towards catabolism to regulate energy homeostasis and cell survival. In contrast, the regulation of LKB1 itself has long been only poorly understood. Only in the last years, several proteins and posttranslational modifications of LKB1 have been analyzed to control its localization, activity and recognition of substrates. Here, we summarize the current knowledge about the upstream regulation of LKB1, which is important for the understanding of the pathogenesis of many types of tumors.
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10
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Ollila S, Domènech-Moreno E, Laajanen K, Wong IP, Tripathi S, Pentinmikko N, Gao Y, Yan Y, Niemelä EH, Wang TC, Viollet B, Leone G, Katajisto P, Vaahtomeri K, Mäkelä TP. Stromal Lkb1 deficiency leads to gastrointestinal tumorigenesis involving the IL-11-JAK/STAT3 pathway. J Clin Invest 2017; 128:402-414. [PMID: 29202476 DOI: 10.1172/jci93597] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 10/24/2017] [Indexed: 12/12/2022] Open
Abstract
Germline mutations in the gene encoding tumor suppressor kinase LKB1 lead to gastrointestinal tumorigenesis in Peutz-Jeghers syndrome (PJS) patients and mouse models; however, the cell types and signaling pathways underlying tumor formation are unknown. Here, we demonstrated that mesenchymal progenitor- or stromal fibroblast-specific deletion of Lkb1 results in fully penetrant polyposis in mice. Lineage tracing and immunohistochemical analyses revealed clonal expansion of Lkb1-deficient myofibroblast-like cell foci in the tumor stroma. Loss of Lkb1 in stromal cells was associated with induction of an inflammatory program including IL-11 production and activation of the JAK/STAT3 pathway in tumor epithelia concomitant with proliferation. Importantly, treatment of LKB1-defcient mice with the JAK1/2 inhibitor ruxolitinib dramatically decreased polyposis. These data indicate that IL-11-mediated induction of JAK/STAT3 is critical in gastrointestinal tumorigenesis following Lkb1 mutations and suggest that targeting this pathway has therapeutic potential in Peutz-Jeghers syndrome.
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Affiliation(s)
- Saara Ollila
- Research Programs Unit, Faculty of Medicine and.,HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.,Division of Digestive and Liver Diseases, Department of Medicine, Irving Cancer Research Center, Columbia University Medical Center, New York, New York, USA
| | - Eva Domènech-Moreno
- Research Programs Unit, Faculty of Medicine and.,HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Kaisa Laajanen
- Research Programs Unit, Faculty of Medicine and.,HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Iris Pl Wong
- Research Programs Unit, Faculty of Medicine and.,HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Sushil Tripathi
- Research Programs Unit, Faculty of Medicine and.,HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Nalle Pentinmikko
- Institute of Biotechnology, HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Yajing Gao
- Research Programs Unit, Faculty of Medicine and.,HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Yan Yan
- Research Programs Unit, Faculty of Medicine and.,HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Elina H Niemelä
- Research Programs Unit, Faculty of Medicine and.,HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Timothy C Wang
- Division of Digestive and Liver Diseases, Department of Medicine, Irving Cancer Research Center, Columbia University Medical Center, New York, New York, USA
| | - Benoit Viollet
- INSERM, U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, France
| | - Gustavo Leone
- Department of Cancer Biology and Genetics, College of Medicine, Department of Molecular Genetics, College of Biological Sciences, and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA
| | - Pekka Katajisto
- HiLIFE-Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.,Institute of Biotechnology, HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.,Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden
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11
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Sengupta S, Nagalingam A, Muniraj N, Bonner MY, Mistriotis P, Afthinos A, Kuppusamy P, Lanoue D, Cho S, Korangath P, Shriver M, Begum A, Merino VF, Huang CY, Arbiser JL, Matsui W, Győrffy B, Konstantopoulos K, Sukumar S, Marignani PA, Saxena NK, Sharma D. Activation of tumor suppressor LKB1 by honokiol abrogates cancer stem-like phenotype in breast cancer via inhibition of oncogenic Stat3. Oncogene 2017; 36:5709-5721. [PMID: 28581518 DOI: 10.1038/onc.2017.164] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 04/09/2017] [Accepted: 04/10/2017] [Indexed: 12/12/2022]
Abstract
Tumor suppressor and upstream master kinase Liver kinase B1 (LKB1) plays a significant role in suppressing cancer growth and metastatic progression. We show that low-LKB1 expression significantly correlates with poor survival outcome in breast cancer. In line with this observation, loss-of-LKB1 rendered breast cancer cells highly migratory and invasive, attaining cancer stem cell-like phenotype. Accordingly, LKB1-null breast cancer cells exhibited an increased ability to form mammospheres and elevated expression of pluripotency-factors (Oct4, Nanog and Sox2), properties also observed in spontaneous tumors in Lkb1-/- mice. Conversely, LKB1-overexpression in LKB1-null cells abrogated invasion, migration and mammosphere-formation. Honokiol (HNK), a bioactive molecule from Magnolia grandiflora increased LKB1 expression, inhibited individual cell-motility and abrogated the stem-like phenotype of breast cancer cells by reducing the formation of mammosphere, expression of pluripotency-factors and aldehyde dehydrogenase activity. LKB1, and its substrate, AMP-dependent protein kinase (AMPK) are important for HNK-mediated inhibition of pluripotency factors since LKB1-silencing and AMPK-inhibition abrogated, while LKB1-overexpression and AMPK-activation potentiated HNK's effects. Mechanistic studies showed that HNK inhibited Stat3-phosphorylation/activation in an LKB1-dependent manner, preventing its recruitment to canonical binding-sites in the promoters of Nanog, Oct4 and Sox2. Thus, inhibition of the coactivation-function of Stat3 resulted in suppression of expression of pluripotency factors. Further, we showed that HNK inhibited breast tumorigenesis in mice in an LKB1-dependent manner. Molecular analyses of HNK-treated xenografts corroborated our in vitro mechanistic findings. Collectively, these results present the first in vitro and in vivo evidence to support crosstalk between LKB1, Stat3 and pluripotency factors in breast cancer and effective anticancer modulation of this axis with HNK treatment.
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Affiliation(s)
- S Sengupta
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - A Nagalingam
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - N Muniraj
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - M Y Bonner
- Department of Dermatology, Emory University School of Medicine, Winship Cancer Institute, Atlanta, GA, USA
| | - P Mistriotis
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore MD, USA
| | - A Afthinos
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore MD, USA
| | - P Kuppusamy
- Department of Medicine, University of Maryland School of Medicine, Baltimore MD, USA
| | - D Lanoue
- Department of Biochemistry and Molecular Biology, Dalhousie University, Nova Scotia Canada
| | - S Cho
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - P Korangath
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - M Shriver
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - A Begum
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - V F Merino
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - C-Y Huang
- Division of Biostatistics and Bioinformatics, the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD, USA
| | - J L Arbiser
- Department of Dermatology, Emory University School of Medicine, Winship Cancer Institute, Atlanta, GA, USA.,Atlanta Veterans Administration Medical Center, Atlanta, GA, USA
| | - W Matsui
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - B Győrffy
- MTA TTK Momentum Cancer Biomarker Research Group, Budapest, Hungary.,Semmelweis University 2nd Department of Pediatrics, Budapest, Hungary
| | - K Konstantopoulos
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore MD, USA
| | - S Sukumar
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
| | - P A Marignani
- Department of Biochemistry and Molecular Biology, Dalhousie University, Nova Scotia Canada
| | - N K Saxena
- Department of Medicine, University of Maryland School of Medicine, Baltimore MD, USA
| | - D Sharma
- Department of Oncology, Johns Hopkins University School of Medicine and the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore MD, USA
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12
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Aberrant expression of Sonic hedgehog signaling in Peutz-Jeghers syndrome. Hum Pathol 2015; 50:153-61. [PMID: 26997450 DOI: 10.1016/j.humpath.2015.09.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 09/16/2015] [Accepted: 09/18/2015] [Indexed: 12/21/2022]
Abstract
The SHH signaling pathway is critical for gastrointestinal development and organic patterning, and dysregulation of SHH pathway molecules has been detected in multiple gastrointestinal neoplasms. This study investigated the role of the SHH signaling pathway in PJS. Expression of SHH, PTCH, and GLI1 was examined by real-time PCR and immunohistochemistry in 20 normal tissues and 75 colorectal lesions (25 PJPs, 25 adenomas, and 25 adenocarcinomas). Expression of SHH, PTCH, and GLI1 mRNA was higher in PJPs than in normal tissue (P < .05) and gradually increased along the PJP-adenoma-adenocarcinoma sequence (P < .05). Immunostaining indicated that SHH expression was present in 60% of PJPs, 72% of adenomas, and 84% of carcinomas, whereas 68% of PJPs, 72% of adenomas, and 88% of carcinomas exhibited cytoplasmic expression of PTCH. Moreover, high GLI1 expression was detected in 56% of PJPs, 64% of adenomas, and 80% of carcinomas; and high nuclear expression of GLI1 was observed in 8 adenomas with atypia and 15 carcinomas. Increased SHH, PTCH, and GLI1 protein correlated positively with tumor grade (P = .012, P = .003, and P = .007, respectively), tumor depth (P = .024, P = .007, and P = .01), and lymph node metastasis (P = .05, P = .015, and P = .005). This study identified aberrant expression of SHH pathway molecules in PJS, and the findings may supply a novel mechanism for the development of PJ polyps.
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13
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Momcilovic M, Shackelford DB. Targeting LKB1 in cancer - exposing and exploiting vulnerabilities. Br J Cancer 2015; 113:574-84. [PMID: 26196184 PMCID: PMC4647688 DOI: 10.1038/bjc.2015.261] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 06/02/2015] [Accepted: 06/07/2015] [Indexed: 12/13/2022] Open
Abstract
The LKB1 tumour suppressor is a serine/threonine kinase that functions as master regulator of cell growth, metabolism, survival and polarity. LKB1 is frequently mutated in human cancers and research spanning the last two decades have begun decoding the cellular pathways deregulated following LKB1 inactivation. This work has led to the identification of vulnerabilities present in LKB1-deficient tumour cells. Pre-clinical studies have now identified therapeutic strategies targeting this subset of tumours that promise to benefit this large patient population harbouring LKB1 mutations. Here, we review the current efforts that are underway to translate pre-clinical discovery of therapeutic strategies targeting LKB1 mutant cancers into clinical practice.
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Affiliation(s)
- M Momcilovic
- Department of Pulmonary and Critical Care Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - D B Shackelford
- Department of Pulmonary and Critical Care Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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14
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Gupta R, Liu AY, Glazer PM, Wajapeyee N. LKB1 preserves genome integrity by stimulating BRCA1 expression. Nucleic Acids Res 2014; 43:259-71. [PMID: 25488815 PMCID: PMC4288185 DOI: 10.1093/nar/gku1294] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Serine/threonine kinase 11 (STK11, also known as LKB1) functions as a tumor suppressor in many human cancers. However, paradoxically loss of LKB1 in mouse embryonic fibroblast results in resistance to oncogene-induced transformation. Therefore, it is unclear why loss of LKB1 leads to increased predisposition to develop a wide variety of cancers. Here, we show that LKB1 protects cells from genotoxic stress. Cells lacking LKB1 display increased sensitivity to irradiation, accumulates more DNA double-strand breaks, display defective homology-directed DNA repair (HDR) and exhibit increased mutation rate, compared with that of LKB1-expressing cells. Conversely, the ectopic expression of LKB1 in cells lacking LKB1 protects them against genotoxic stress-induced DNA damage and prevents the accumulation of mutations. We find that LKB1 post-transcriptionally stimulates HDR gene BRCA1 expression by inhibiting the cytoplasmic localization of the RNA-binding protein, HU antigen R, in an AMP kinase-dependent manner and stabilizes BRCA1 mRNA. Cells lacking BRCA1 similar to the cell lacking LKB1 display increased genomic instability and ectopic expression of BRCA1 rescues LKB1 loss-induced sensitivity to genotoxic stress. Collectively, our results demonstrate that LKB1 is a crucial regulator of genome integrity and reveal a novel mechanism for LKB1-mediated tumor suppression with direct therapeutic implications for cancer prevention.
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Affiliation(s)
- Romi Gupta
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Alex Y Liu
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Peter M Glazer
- Department of Therapeutic Radiology and Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Narendra Wajapeyee
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06510, USA
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15
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Recent progress on liver kinase B1 (LKB1): expression, regulation, downstream signaling and cancer suppressive function. Int J Mol Sci 2014; 15:16698-718. [PMID: 25244018 PMCID: PMC4200829 DOI: 10.3390/ijms150916698] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 08/12/2014] [Accepted: 08/28/2014] [Indexed: 12/15/2022] Open
Abstract
Liver kinase B1 (LKB1), known as a serine/threonine kinase, has been identified as a critical cancer suppressor in many cancer cells. It is a master upstream kinase of 13 AMP-activated protein kinase (AMPK)-related protein kinases, and possesses versatile biological functions. LKB1 gene is mutated in many cancers, and its protein can form different protein complexes with different cellular localizations in various cell types. The expression of LKB1 can be regulated through epigenetic modification, transcriptional regulation and post-translational modification. LKB1 dowcnstream pathways mainly include AMPK, microtubule affinity regulating kinase (MARK), salt-inducible kinase (SIK), sucrose non-fermenting protein-related kinase (SNRK) and brain selective kinase (BRSK) signalings, etc. This review, therefore, mainly discusses recent studies about the expression, regulation, downstream signaling and cancer suppressive function of LKB1, which can be helpful for better understanding of this molecular and its significance in cancers.
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16
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Zac-Varghese S, Trapp S, Richards P, Sayers S, Sun G, Bloom SR, Reimann F, Gribble FM, Rutter GA. The Peutz-Jeghers kinase LKB1 suppresses polyp growth from intestinal cells of a proglucagon-expressing lineage in mice. Dis Model Mech 2014; 7:1275-86. [PMID: 25190708 PMCID: PMC4213731 DOI: 10.1242/dmm.014720] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Liver kinase B1 (LKB1; also known as STK11) is a serine/threonine kinase and tumour suppressor that is mutated in Peutz-Jeghers syndrome (PJS), a premalignant syndrome associated with the development of gastrointestinal polyps. Proglucagon-expressing enteroendocrine cells are involved in the control of glucose homeostasis and the regulation of appetite through the secretion of gut hormones such as glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine (PYY). To determine the role of LKB1 in these cells, we bred mice bearing floxed alleles of Lkb1 against animals carrying Cre recombinase under proglucagon promoter control. These mice (GluLKB1KO) were viable and displayed near-normal growth rates and glucose homeostasis. However, they developed large polyps at the gastro-duodenal junction, and displayed premature mortality (death from 120 days of age). Histological analysis of the polyps demonstrated that they had a PJS-like appearance with an arborising smooth-muscle core. Circulating GLP-1 levels were normal in GluLKB1KO mice and the polyps expressed low levels of the peptide, similar to levels in the neighbouring duodenum. Lineage tracing using a Rosa26tdRFP transgene revealed, unexpectedly, that enterocytes within the polyps were derived from non-proglucagon-expressing precursors, whereas connective tissue was largely derived from proglucagon-expressing precursors. Developmental studies in wild-type mice suggested that a subpopulation of proglucagon-expressing cells undergo epithelial-mesenchymal transition (EMT) to become smooth-muscle-like cells. Thus, it is likely that polyps in the GluLKB1KO mice developed from a unique population of smooth-muscle-like cells derived from a proglucagon-expressing precursor. The loss of LKB1 within this subpopulation seems to be sufficient to drive tumorigenesis.
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Affiliation(s)
- Sagen Zac-Varghese
- Department of Investigative Medicine, Imperial College London, London, W12 ONN, UK
| | - Stefan Trapp
- Department of Surgery and Cancer, Imperial College London, London, W12 ONN, UK
| | - Paul Richards
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK
| | - Sophie Sayers
- Department of Cell Biology, Imperial College London, London, W12 ONN, UK
| | - Gao Sun
- Department of Cell Biology, Imperial College London, London, W12 ONN, UK
| | - Stephen R Bloom
- Department of Investigative Medicine, Imperial College London, London, W12 ONN, UK
| | - Frank Reimann
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK
| | - Fiona M Gribble
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, CB2 0XY, UK
| | - Guy A Rutter
- Department of Cell Biology, Imperial College London, London, W12 ONN, UK.
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17
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Shackelford DB. Unravelling the connection between metabolism and tumorigenesis through studies of the liver kinase B1 tumour suppressor. J Carcinog 2013; 12:16. [PMID: 24082825 PMCID: PMC3779404 DOI: 10.4103/1477-3163.116323] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 05/12/2013] [Indexed: 12/15/2022] Open
Abstract
The liver kinase B1 (LKB1) tumour suppressor functions as a master regulator of growth, metabolism and survival in cells, which is frequently mutated in sporadic human non-small cell lung and cervical cancers. LKB1 functions as a key upstream activator of the AMP-activated protein kinase (AMPK), a central metabolic switch found in all eukaryotes that govern glucose and lipid metabolism and autophagy in response to alterations in nutrients and intracellular energy levels. The LKB1/AMPK signalling pathway suppresses mammalian target of rapamycin complex 1 (mTORC1), an essential regulator of cell growth in all eukaryotes that is deregulated in a majority of human cancers. LKB1 inactivation in cancer leads to both tumorigenesis and metabolic deregulation through the AMPK and mTORC1-signalling axis and there remain critical challenges to elucidate the direct role LKB1 inactivation plays in driving aberrant metabolism and tumour growth. This review addresses past and current efforts to delineate the molecular mechanisms fueling metabolic deregulation and tumorigenesis following LKB1 inactivation as well as translational promise of therapeutic strategies aimed at targeting LKB1-deficient tumors.
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Affiliation(s)
- David B Shackelford
- Department of Pulmonary and Critical Care Medicine, David Geffen School of Medicine at University of California, Los Angeles, California, USA
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18
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Zhong DS, Sun LL, Dong LX. Molecular mechanisms of LKB1 induced cell cycle arrest. Thorac Cancer 2013; 4:229-233. [PMID: 28920233 DOI: 10.1111/1759-7714.12003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Accepted: 10/02/2012] [Indexed: 01/13/2023] Open
Abstract
LKB1 is a serine/threonine protein kinase mutated in patients with Peutz-Jeghers syndrome. Biallelic inactivation of LKB1 is present in up to 30% of cases of non-small cell lung cancer (NSCLC). As a tumor suppressor, LKB1 functions in arresting the cell cycle and inhibiting cell growth. LKB1 leads to induction of p21/WAF1 expression in a p53-dependent mechanism, which is mediated by cytoplasmic LKB1 initiating negative regulation of cell growth or nuclear LKB1 directly involved in transcriptional regulation of p21/WAF1. Alternatively, p53 and p21/WAF1-independent mechanism of regulating cell cycle by LKB1 is also reported.
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Affiliation(s)
- Dian-Sheng Zhong
- Department of Respiratory Medicine, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Lin-Lin Sun
- Tianjin Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Li-Xia Dong
- Department of Respiratory Medicine, Tianjin Medical University General Hospital, Tianjin, China
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19
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Udd L, Gao Y, Ristimäki AP, Mäkelä TP. N-methylnitrosourea aggravates gastrointestinal polyposis in Lkb1+/- mice. Carcinogenesis 2013; 34:2409-14. [PMID: 23722652 DOI: 10.1093/carcin/bgt188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Peutz-Jeghers patients develop hamartomatous polyps and carcinomas of the gastrointestinal tract. Cyclooxygenase-2 accelerates polyp growth in Lkb1 (+/-) mice modelling Peutz-Jeghers polyposis. In this study, we aimed to evaluate the effect of the mutagenic carcinogen N-methylnitrosourea (MNU) on gastrointestinal tumourigenesis in Lkb1 (+/-) mice and to investigate the role of cyclooxygenase-2 on the tumourigenesis. We treated 40 Lkb1 (+/-) and 51 wild-type mice with MNU, 10 mice from both groups received the cyclooxygenase-2 inhibitor celecoxib. Carcinogen-treated Lkb1 (+/-) mice displayed worse survival (60%) than treated wild-type (100%, P = 0.028) or untreated Lkb1 (+/-) mice (92%, P = 0.045). Also, the gastrointestinal tumour burden was almost 10-fold higher in carcinogen-treated (2181 mm(3)) than in untreated (237 mm(3), P = 0.00045) Lkb1 (+/-) mice. Celecoxib was much less efficient in reducing tumourigenesis in MNU-treated mice (by 23%; 1686 mm(3)) than in untreated mice (76%; 58 mm(3)). Surprisingly, the increase in tumour burden in MNU-treated mice was not accompanied by consistent histological changes, with only a single focus of epithelial dysplasia noted. This study suggests that MNU promotes Peutz-Jeghers polyposis independently from the acceleration by cyclooxygenase-2.
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Affiliation(s)
- Lina Udd
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland and
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20
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Lo B, Strasser G, Sagolla M, Austin CD, Junttila M, Mellman I. Lkb1 regulates organogenesis and early oncogenesis along AMPK-dependent and -independent pathways. ACTA ACUST UNITED AC 2013; 199:1117-30. [PMID: 23266956 PMCID: PMC3529533 DOI: 10.1083/jcb.201208080] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A combination of ex vivo embryonic tissue culture, genetic manipulation, and chemical genetics reveals novel details of Lkb1-mediated regulation of tissue morphogenesis. The tumor suppressor Lkb1/STK11/Par-4 is a key regulator of cellular energy, proliferation, and polarity, yet its mechanisms of action remain poorly defined. We generated mice harboring a mutant Lkb1 knockin allele that allows for rapid inhibition of Lkb1 kinase. Culturing embryonic tissues, we show that acute loss of kinase activity perturbs epithelial morphogenesis without affecting cell polarity. In pancreas, cystic structures developed rapidly after Lkb1 inhibition. In lung, inhibition resulted in cell-autonomous branching defects. Although the lung phenotype was rescued by an activator of the Lkb1 target adenosine monophosphate–activated kinase (AMPK), pancreatic cyst development was independent of AMPK signaling. Remarkably, the pancreatic phenotype evolved to resemble precancerous lesions, demonstrating that loss of Lkb1 was sufficient to drive the initial steps of carcinogenesis ex vivo. A similar phenotype was induced by expression of mutant K-Ras with p16/p19 deletion. Combining culture of embryonic tissues with genetic manipulation and chemical genetics thus provides a powerful approach to unraveling developmental programs and understanding cancer initiation.
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Affiliation(s)
- Bryan Lo
- Genentech, South San Francisco, CA 94080, USA
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21
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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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22
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Wei C, Bhattaram VK, Igwe JC, Fleming E, Tirnauer JS. The LKB1 tumor suppressor controls spindle orientation and localization of activated AMPK in mitotic epithelial cells. PLoS One 2012; 7:e41118. [PMID: 22815934 PMCID: PMC3399794 DOI: 10.1371/journal.pone.0041118] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 06/20/2012] [Indexed: 12/22/2022] Open
Abstract
Orientation of mitotic spindles plays an integral role in determining the relative positions of daughter cells in a tissue. LKB1 is a tumor suppressor that controls cell polarity, metabolism, and microtubule stability. Here, we show that germline LKB1 mutation in mice impairs spindle orientation in cells of the upper gastrointestinal tract and causes dramatic mislocalization of the LKB1 substrate AMPK in mitotic cells. RNAi of LKB1 causes spindle misorientation in three-dimensional MDCK cell cysts. Maintaining proper spindle orientation, possibly mediated by effects on the downstream kinase AMPK, could be an important tumor suppressor function of LKB1.
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Affiliation(s)
- Chongjuan Wei
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
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23
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Tanwar PS, Kaneko-Tarui T, Zhang L, Teixeira JM. Altered LKB1/AMPK/TSC1/TSC2/mTOR signaling causes disruption of Sertoli cell polarity and spermatogenesis. Hum Mol Genet 2012; 21:4394-405. [PMID: 22791749 DOI: 10.1093/hmg/dds272] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Male patients with Peutz-Jeghers syndrome (PJS) have defective spermatogenesis and are at increased risk of developing Sertoli cell tumors. Mutations in the Liver Kinase B1 (LKB1/STK11) gene are associated with the pathogenesis of PJS and have been identified in non-PJS patients with sporadic testicular cancers. The mechanisms controlled by LKB1 signaling in Sertoli cell functions and testicular biology have not been described. We have conditionally deleted the Lkb1 gene (Lkb1(cko)) in somatic testicular cells to define the molecular mechanisms involved in the development of the testicular phenotype observed in PJS patients. Focal vacuolization in some of the seminiferous tubules was observed in 4-week-old mutant testes but germ cell development appeared to be normal. However, similar to PJS patients, we observed progressive germ cell loss and Sertoli cell only tubules in Lkb1(cko) testes from mice older than 10 weeks, accompanied by defects in Sertoli cell polarity and testicular junctional complexes and decreased activation of the MAP/microtubule affinity regulating and focal adhesion kinases. Suppression of AMP kinase and activation of mammalian target of rapamycin (mTOR) signaling were also observed in Lkb1(cko) testes. Loss of Tsc1 or Tsc2 copies the progressive Lkb1(cko) phenotype, suggesting that dysregulated activation of mTOR contributes to the pathogenesis of the Lkb1(cko) testicular phenotype. Pten(cko) mice had a normal testicular phenotype, which could be explained by the comparative lack of mTOR activation detected. These studies describe the importance of LKB1 signaling in testicular biology and the possible molecular mechanisms driving the pathogenesis of the testicular defects observed in PJS patients.
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Affiliation(s)
- Pradeep S Tanwar
- Vincent Center For Reproductive Biology/Thier 931, Department of Obstetrics, Gynecology and Reproductive Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
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24
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Langeveld D, Jansen M, de Boer DV, van Sprundel M, Brosens LAA, Morsink FH, Giardiello FM, Offerhaus GJA, de Leng WWJ. Aberrant intestinal stem cell lineage dynamics in Peutz-Jeghers syndrome and familial adenomatous polyposis consistent with protracted clonal evolution in the crypt. Gut 2012; 61:839-46. [PMID: 21940722 PMCID: PMC3564664 DOI: 10.1136/gutjnl-2011-300622] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
OBJECTIVE Genetic predisposition to cancer in Peutz-Jeghers syndrome (PJS) and the role of germline serine-threonine kinase (LKB1) mutations are poorly understood. The authors studied the effect of germline LKB1 mutations on intestinal stem cell dynamics in unaffected flat PJS mucosa. Recent research has documented that the intestinal crypt houses multiple equipotent stem cell lineages. Lineages continuously compete through random drifts, while somatically inherited methylation patterns record clonal diversity. DESIGN To study the effect of germline LKB1 mutations on clonal expansion, the authors performed quantitative analyses of cardiac-specific homeobox methylation pattern diversity in crypts isolated from unaffected colonic mucosa obtained from archival PJS patient material. The authors compared methylation density and methylation pattern diversity in patients with PJS to those in patients with familial adenomatous polyposis and age-matched controls. RESULTS The percentage of total methylation is comparable between groups, but the number of unique methylation patterns is significantly increased for patients with familial adenomatous polyposis and patients with PJS compared to control subjects. CONCLUSIONS Monoallelic LKB1 loss is not silent and provokes a protracted clonal evolution in the crypt. The increased methylation pattern diversity observed in unaffected PJS mucosa predicts that premalignant lesions will arise at an accelerated pace compared to the general population.
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Affiliation(s)
- Danielle Langeveld
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands,Department of Pathology, Academic Medical Center, Amsterdam, The Netherlands
| | - Marnix Jansen
- Department of Pathology, Academic Medical Center, Amsterdam, The Netherlands
| | - D V de Boer
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mariska van Sprundel
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Lodewijk A A Brosens
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Folkert H Morsink
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Francis M Giardiello
- Division of Gastroenterology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - G Johan A Offerhaus
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands,Department of Pathology, Academic Medical Center, Amsterdam, The Netherlands
| | - Wendy W J de Leng
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
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25
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Abstract
The Peutz-Jeghers syndrome (PJS) culprit kinase LKB1 phosphorylates and activates multiple intracellular kinases regulating cell metabolism and polarity. The relevance of each of these pathways is highly variable depending on the tissue type, but typically represents functions of differentiated cells. These include formation and maintenance of specialized cell compartments in nerve axons, swift refunneling of metabolites and restructuring of cell architecture in response to environmental cues in committed lymphocytes, and ensuring energy-efficient oxygen-based energy expenditure. Such features are often lost or reduced in cancer cells, and indeed LKB1 defects in PJS-associated and sporadic cancers and even the benign PJS polyps lead to differentiation defects, including expansion of partially differentiated epithelial cells in PJS polyps and epithelial-to-mesenchymal transition in carcinomas. This review focuses on the involvement of LKB1 in the differentiation of epithelial, mesenchymal, hematopoietic and germinal lineages.
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Affiliation(s)
- Lina Udd
- Institute of Biotechnology and Genome-Scale Biology Research Program, University of Helsinki, P.O. Box 56 (Biocenter 1), 00014, Helsinki, Finland
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26
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Jansen M, Langeveld D, De Leng WWJ, Milne ANA, Giardiello FM, Offerhaus GJA. LKB1 as the ghostwriter of crypt history. Fam Cancer 2012; 10:437-46. [PMID: 21805166 PMCID: PMC3175351 DOI: 10.1007/s10689-011-9469-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Familial cancer syndromes present rare insights into malignant tumor development. The molecular background of polyp formation and the cancer prone state in Peutz-Jeghers syndrome remain enigmatic to this day. Previously, we proposed that Peutz-Jeghers polyps are not pre-malignant lesions, but an epiphenomenon to the malignant condition. However, Peutz-Jeghers polyp formation and the cancer-prone state must both be accounted for by the same molecular mechanism. Our contribution focuses on the histopathology of the characteristic Peutz-Jeghers polyp and recent research on stem cell dynamics and how these concepts relate to Peutz-Jeghers polyposis. We discuss a protracted clonal evolution scenario in Peutz-Jeghers syndrome due to a germline LKB1 mutation. Peutz-Jeghers polyp formation and malignant transformation are separately mediated through the same molecular mechanism played out on different timescales. Thus, a single mechanism accounts for the development of benign Peutz-Jeghers polyps and for malignant transformation in Peutz-Jeghers syndrome.
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Affiliation(s)
- Marnix Jansen
- Department of Pathology, Academic Medical Center, PO Box 22660, 1100 DD, Amsterdam, The Netherlands.
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27
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Ollila S, Mäkelä TP. The tumor suppressor kinase LKB1: lessons from mouse models. J Mol Cell Biol 2011; 3:330-40. [PMID: 21926085 DOI: 10.1093/jmcb/mjr016] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mutations in the tumor suppressor gene LKB1 are important in hereditary Peutz-Jeghers syndrome, as well as in sporadic cancers including lung and cervical cancer. LKB1 is a kinase-activating kinase, and a number of LKB1-dependent phosphorylation cascades regulate fundamental cellular and organismal processes in at least metabolism, polarity, cytoskeleton organization, and proliferation. Conditional targeting approaches are beginning to demonstrate the relevance and specificity of these signaling pathways in development and homeostasis of multiple organs. More than one of the pathways also appear to contribute to tumor growth following Lkb1 deficiencies based on a number of mouse tumor models. Lkb1-dependent activation of AMPK and subsequent inactivation of mammalian target of rapamycin signaling are implicated in several of the models, and other less well characterized pathways are also involved. Conditional targeting studies of Lkb1 also point an important role of LKB1 in epithelial-mesenchymal interactions, significantly expanding knowledge on the relevance of LKB1 in human disease.
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Affiliation(s)
- Saara Ollila
- Institute of Biotechnology, University of Helsinki, Viikki Biocenter, Viikinkaari 9B, FIN-00014, Helsinki, Finland
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28
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Liu JX, Zhou P, Hu ZM, Mao GP. Expression of Brg1, VEGF and COX-2 in Peutz-Jeghers syndrome. Shijie Huaren Xiaohua Zazhi 2011; 19:2461-2466. [DOI: 10.11569/wcjd.v19.i23.2461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To detect the expression of brahma-related gene 1 (Brg1), vascular endothelial growth factor (VEGF) and cyclooxygenase 2 (COX-2) proteins in Peutz-Jeghers syndrome (PJS) and to analyze their clinical significance.
METHODS: Immunohistochemistry was used to detect the expression of Brg1, VEGF and COX-2 proteins in 72 PJS samples, 12 normal small intestinal mucosal tissue samples and 30 cancer tissue samples.
RESULTS: The positive rates of Brg1, VEGF and COX-2 expression were significantly higher in PJS than in normal mucosal tissue (54.17% vs 16.67%, 58.33% vs 8.33%, 62.50% vs 25.00%, all P < 0.01) and in cancer tissue than in PJS (76.67% vs 54.17%, 80.00% vs 58.33%, 83.33% vs 62.50% all P < 0.01). In PJS, positive correlations were found between Brg1 and VEGF expression and between Brg1 and COX-2 expression.
CONCLUSION: Brg1, VEGF and COX-2 may play a role in the occurrence of PJS.
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29
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Lai C, Robinson J, Clark S, Stamp G, Poulsom R, Silver A. Elevation of WNT5A expression in polyp formation in Lkb1+/- mice and Peutz-Jeghers syndrome. J Pathol 2011; 223:584-92. [PMID: 21341271 DOI: 10.1002/path.2835] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 11/10/2010] [Accepted: 11/27/2010] [Indexed: 01/05/2023]
Abstract
Peutz-Jeghers syndrome (PJS) is a rare, inherited disease caused by germline mutation of the LKB1 gene. Patients with PJS develop characteristic polyps in the digestive tract and carry an elevated risk of cancers in multiple organs, including the intestinal tract. While LKB1 is capable of phosphorylating AMPK and regulates the mTOR pathway, it is also known to be a multitasking protein that can influence other cellular processes, including cell polarity. We hypothesized that there may be other biological pathways directly or indirectly affected by the loss of LKB1 in PJS and aimed to investigate this possibility through transcriptional profiling of polyps harvested from an Lkb1(+/-) mouse model of PJS and from PJS patients. We identified alterations in the mRNA level of a wide range of genes, including some that are involved in Wnt signalling (Wnt5a, Wif1, Dixdc1, Wnt11, Ccnd1, and Ccnd2), although we did not observe nuclear localization of β-catenin in over 93 human PJS intestinal polyps or in 24 gastric polyps from Lkb1(+/-) mice. Among these genes, WNT5A, a non-canonical and non-transforming Wnt, is consistently up-regulated in both Lkb1(+/-) mice and human PJS polyps at a high level. We performed in situ hybridization to further define the spatial expression pattern of WNT5A and observed a strong signal in the stroma of mouse and human polyps compared to no or very low expression in the mucosa. Our findings indicate that WNT5A plays an important role in PJS polyposis.
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Affiliation(s)
- Cecilia Lai
- Colorectal Cancer Genetics, Blizard Institute of Cell and Molecular Science, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, Whitechapel, London, UK
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30
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Shorning BY, Clarke AR. LKB1 loss of function studied in vivo. FEBS Lett 2011; 585:958-66. [DOI: 10.1016/j.febslet.2011.01.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 01/10/2011] [Accepted: 01/11/2011] [Indexed: 12/12/2022]
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31
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Duggan S, Prichard D, Kirca M, Kelleher D. Inherited Syndromes Predisposing to Inflammation and GI Cancer. Recent Results Cancer Res 2011; 185:35-50. [PMID: 21822818 DOI: 10.1007/978-3-642-03503-6_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cancers arising within the gastrointestinal (GI) tract are commonly associated with an immune component at their inception and later in their maintenance. While many of the immune factors and immune cell types surrounding these lesions have been highlighted, the underlying pre-dispositions in immunesupported carcinogenesis are not well characterised. Inherited Mendelian GI disorders such as polyposis syndromes, while classically due to germline mutations in non-immune genes, commonly demonstrate alterations in key immune and inflammatory genes. In some cases immune based therapies have been shown to provide at least some benefit in animal models of these syndromes. The advent of genome wide association studies has begun to powerfully examine the genetic nature of complex non-Mendelian GI diseases highlighting polymorphisms within immune related genes and their potential to provide the niche in which GI cancers may originate. Here in the role in which Mendelian and non-Mendelian genetics of immune related factors supporting GI malignancy will be presented and discussed.
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Affiliation(s)
- Shane Duggan
- Department of Clinical Medicine and Institute of Molecular Medicine, Trinity College Dublin, Ireland
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32
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Tervonen TA, Partanen JI, Saarikoski ST, Myllynen M, Marques E, Paasonen K, Moilanen A, Wohlfahrt G, Kovanen PE, Klefstrom J. Faulty epithelial polarity genes and cancer. Adv Cancer Res 2011; 111:97-161. [PMID: 21704831 DOI: 10.1016/b978-0-12-385524-4.00003-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Epithelial architecture is formed in tissues and organs when groups of epithelial cells are organized into polarized structures. The epithelial function and integrity as well as signaling across the epithelial layer is orchestrated by apical junctional complexes (AJCs), which are landmarks for PAR/CRUMBS and lateral SCRIB polarity modules and by dynamic interactions of the cells with underlying basement membrane (BM). These highly organized epithelial architectures are demolished in cancer. In all advanced epithelial cancers, malignant cells have lost polarity and connections to the basement membrane and they have become proliferative, motile, and invasive. Clearly, loss of epithelial integrity associates with tumor progression but does it contribute to tumor development? Evidence from studies in Drosophila and recently also in vertebrate models have suggested that even the oncogene-driven enforced cell proliferation can be conditional, dependant on the influence of cell-cell or cell-microenvironment contacts. Therefore, loss of epithelial integrity may not only be an obligate consequence of unscheduled proliferation of malignant cells but instead, malignant epithelial cells may need to acquire capacity to break free from the constraints of integrity to freely and autonomously proliferate. We discuss how epithelial polarity complexes form and regulate epithelial integrity, highlighting the roles of enzymes Rho GTPases, aPKCs, PI3K, and type II transmembrane serine proteases (TTSPs). We also discuss relevance of these pathways to cancer in light of genetic alterations found in human cancers and review molecular pathways and potential pharmacological strategies to revert or selectively eradicate disorganized tumor epithelium.
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33
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Molecular mechanisms of tumor suppression by LKB1. FEBS Lett 2010; 585:944-51. [PMID: 21192934 DOI: 10.1016/j.febslet.2010.12.034] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 12/21/2010] [Accepted: 12/22/2010] [Indexed: 01/19/2023]
Abstract
The LKB1 tumor suppressor gene is frequently mutated in sporadic lung adenocarcinomas and cervical cancers and germline mutations are causative for Peutz-Jeghers syndrome characterized by gastrointestinal polyposis. The intracellular LKB1 kinase is implicated in regulating polarity, metabolism, cell differentiation, and proliferation - all functions potentially contributing to tumor suppression. LKB1 acts as an activating kinase of at least 14 kinases mediating LKB1 functions in a complex signaling network with partial overlaps. Regulation of the LKB1 signaling network is highly context dependent, and spatially organized in various cellular compartments. Also the mechanisms by which LKB1 activity suppresses tumorigenesis is context dependent, where recent observations are providing hints on the molecular mechanisms involved.
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34
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Morton JP, Jamieson NB, Karim SA, Athineos D, Ridgway RA, Nixon C, McKay CJ, Carter R, Brunton VG, Frame MC, Ashworth A, Oien KA, Evans TJ, Sansom OJ. LKB1 haploinsufficiency cooperates with Kras to promote pancreatic cancer through suppression of p21-dependent growth arrest. Gastroenterology 2010; 139:586-97, 597.e1-6. [PMID: 20452353 PMCID: PMC3770904 DOI: 10.1053/j.gastro.2010.04.055] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 02/11/2010] [Accepted: 04/29/2010] [Indexed: 12/16/2022]
Abstract
BACKGROUND & AIMS Patients carrying germline mutations of LKB1 have an increased risk of pancreatic cancer; however, it is unclear whether down-regulation of LKB1 is an important event in sporadic pancreatic cancer. In this study, we aimed to investigate the impact of LKB1 down-regulation for pancreatic cancer in mouse and human and to elucidate the mechanism by which Lkb1 deregulation contributes to this disease. METHODS We first investigated the consequences of Lkb1 deficiency in a genetically modified mouse model of pancreatic cancer, both in terms of disease progression and at the molecular level. To test the relevance of our findings to human pancreatic cancer, we investigated levels of LKB1 and its potential targets in human pancreatic cancer. RESULTS We definitively show that Lkb1 haploinsufficiency can cooperate with oncogenic KrasG12D to cause pancreatic ductal adenocarcinoma (PDAC) in the mouse. Mechanistically, this was associated with decreased p53/p21-dependent growth arrest. Haploinsufficiency for p21 (Cdkn1a) also synergizes with KrasG12D to drive PDAC in the mouse. We also found that levels of LKB1 expression were decreased in around 20% of human PDAC and significantly correlated with low levels of p21 and a poor prognosis. Remarkably, all tumors that had low levels of LKB1 had low levels of p21, and these tumors did not express mutant p53. CONCLUSIONS We have identified a novel LKB1-p21 axis that suppresses PDAC following Kras mutation in vivo. Down-regulation of LKB1 may therefore serve as an alternative to p53 mutation to drive pancreatic cancer in vivo.
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MESH Headings
- AMP-Activated Protein Kinase Kinases
- AMP-Activated Protein Kinases
- Animals
- Carcinoma, Pancreatic Ductal/genetics
- Carcinoma, Pancreatic Ductal/metabolism
- Carcinoma, Pancreatic Ductal/mortality
- Carcinoma, Pancreatic Ductal/pathology
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- Cyclin-Dependent Kinase Inhibitor p21/deficiency
- Cyclin-Dependent Kinase Inhibitor p21/genetics
- Cyclin-Dependent Kinase Inhibitor p21/metabolism
- Disease Progression
- Genes, Tumor Suppressor
- Genotype
- Haplotypes
- Heterozygote
- Homeodomain Proteins/genetics
- Homozygote
- Humans
- Mice
- Mice, Knockout
- Pancreatic Neoplasms/genetics
- Pancreatic Neoplasms/metabolism
- Pancreatic Neoplasms/mortality
- Pancreatic Neoplasms/pathology
- Phenotype
- Prognosis
- Promoter Regions, Genetic
- Proportional Hazards Models
- Protein Serine-Threonine Kinases/deficiency
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Proto-Oncogene Proteins p21(ras)/deficiency
- Proto-Oncogene Proteins p21(ras)/genetics
- Proto-Oncogene Proteins p21(ras)/metabolism
- Risk Assessment
- Time Factors
- Trans-Activators/genetics
- Tumor Suppressor Protein p53/metabolism
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Affiliation(s)
- Jennifer P. Morton
- Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
- Centre for Oncology and Applied Pharmacology, Division of Cancer Sciences and Molecular Pathology, University of Glasgow, Glasgow, UK
| | - Nigel B. Jamieson
- Centre for Oncology and Applied Pharmacology, Division of Cancer Sciences and Molecular Pathology, University of Glasgow, Glasgow, UK
- West of Scotland Pancreatic Unit, Glasgow Royal Infirmary, Alexandra Parade, Glasgow, UK
| | - Saadia A. Karim
- Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
| | - Dimitris Athineos
- Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
- Centre for Oncology and Applied Pharmacology, Division of Cancer Sciences and Molecular Pathology, University of Glasgow, Glasgow, UK
| | | | - Colin Nixon
- Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
| | - Colin J. McKay
- West of Scotland Pancreatic Unit, Glasgow Royal Infirmary, Alexandra Parade, Glasgow, UK
| | - Ross Carter
- West of Scotland Pancreatic Unit, Glasgow Royal Infirmary, Alexandra Parade, Glasgow, UK
| | - Valerie G. Brunton
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Margaret C. Frame
- Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Alan Ashworth
- The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
| | - Karin A. Oien
- Centre for Oncology and Applied Pharmacology, Division of Cancer Sciences and Molecular Pathology, University of Glasgow, Glasgow, UK
| | - T.R. Jeffry Evans
- Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
- Centre for Oncology and Applied Pharmacology, Division of Cancer Sciences and Molecular Pathology, University of Glasgow, Glasgow, UK
| | - Owen J. Sansom
- Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK
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35
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Deguchi A, Miyoshi H, Kojima Y, Okawa K, Aoki M, Taketo MM. LKB1 suppresses p21-activated kinase-1 (PAK1) by phosphorylation of Thr109 in the p21-binding domain. J Biol Chem 2010; 285:18283-90. [PMID: 20400510 DOI: 10.1074/jbc.m109.079137] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serine/threonine protein kinase LKB1 is a tumor suppressor gene mutated in Peutz-Jeghers syndrome patients. The mutations are found also in several types of sporadic cancer. Although LKB1 is implicated in suppression of cell growth and metastasis, the detailed mechanisms have not yet been elucidated. In this study, we investigated the effect of LKB1 on cell motility, whose acquisition occurs in early metastasis. The knockdown of LKB1 enhanced cell migration and PAK1 activity in human colon cancer HCT116 cells, whereas forced expression of LKB1 in Lkb1-null mouse embryonic fibroblasts suppressed PAK1 activity and PAK1-mediated cell migration simultaneously. Notably, LKB1 directly phosphorylated PAK1 at Thr(109) in the p21-binding domain in vitro. The phosphomimetic T109E mutant showed significantly lower protein kinase activity than wild-type PAK1, suggesting that the phosphorylation at Thr(109) by LKB1 was responsible for suppression of PAK1. Consistently, the nonphosphorylatable T109A mutant was resistant to suppression by LKB1. Furthermore, we found that PAK1 was activated in the hepatocellular carcinomas and the precancerous liver lesions of Lkb1(+/-) mice. Taken together, these results suggest that PAK1 is a direct downstream target of LKB1 and plays an essential role in LKB1-induced suppression of cell migration.
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Affiliation(s)
- Atsuko Deguchi
- Department of Pharmacology, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
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36
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Udd L, Katajisto P, Kyyrönen M, Ristimäki AP, Mäkelä TP. Impaired gastric gland differentiation in Peutz-Jeghers syndrome. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:2467-76. [PMID: 20363912 DOI: 10.2353/ajpath.2010.090519] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Gastrointestinal hamartomatous polyps in the Peutz-Jeghers cancer predisposition syndrome and its mouse model (Lkb1(+/-)) are presumed to contain all cell types native to the site of their occurrence. This study aimed to explore the pathogenesis of Peutz-Jeghers syndrome polyposis by characterizing cell types and differentiation of the epithelium of gastric polyps and predisposed mucosa. Both antral and fundic polyps were characterized by a deficit of pepsinogen C-expressing differentiated gland cells (antral gland, mucopeptic, and chief cells); in large fundic polyps, parietal cells were also absent. Gland cell loss was associated with an increase in precursor neck cells, an expansion of the proliferative zone, and an increase in smooth muscle alpha-actin expressing myofibroblasts in the polyp stroma. Lack of pepsinogen C-positive gland cells identified incipient polyps, and even the unaffected mucosa of young predisposed mice displayed an increase in pepsinogen C negative glands (25%; P = 0045). In addition, in small intestinal polyps, gland cell differentiation was defective, with the absence of Paneth cells. There were no signs of metaplastic differentiation in any of the tissues studied, and both the gastric and small intestinal defects were seen in Lkb1(+/-) mice, as well as polyps from patients with Peutz-Jeghers syndrome. These results identify impaired epithelial differentiation as the earliest pathological sign likely to contribute to tumorigenesis in individuals with inherited Lkb1 mutations.
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Affiliation(s)
- Lina Udd
- Institute of Biotechnology and Genome-Scale Biology Research Program, University of Helsinki, Helsinki, Finland
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37
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McCarthy A, Lord CJ, Savage K, Grigoriadis A, Smith DP, Weigelt B, Reis-Filho JS, Ashworth A. Conditional deletion of the Lkb1 gene in the mouse mammary gland induces tumour formation. J Pathol 2010; 219:306-16. [PMID: 19681070 DOI: 10.1002/path.2599] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Heterozygous germline mutations in the LKB1 (STK11) gene cause Peutz-Jeghers syndrome (PJS), an autosomal dominant disorder characterized by hamartomatous polyposis of the gastrointestinal tract and an increased risk of colorectal, breast, and other cancers. To model the role of LKB1 mutation in mammary tumourigenesis, we have used a conditional gene targeting strategy to generate a mouse in which exons encoding the kinase domain of Lkb1 were deleted specifically in the mammary gland. Mammary gland tumours developed in these mice with a latency of 46-85 weeks and occurred in the thoracic or inguinal glands. These tumours were grade 2 invasive ductal carcinomas or solid papillary carcinomas with histological features similar to those described in breast cancers arising in patients with PJS. This mouse model of Lkb1 deficiency provides a potentially useful tool to investigate the role of Lkb1 in tumourigenesis and to guide the development of therapeutic approaches.
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Affiliation(s)
- Afshan McCarthy
- The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, Fulham Road, London SW3 6JB, UK
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Robinson J, Lai C, Martin A, Nye E, Tomlinson I, Silver A. Oral rapamycin reduces tumour burden and vascularization in Lkb1(+/-) mice. J Pathol 2009; 219:35-40. [PMID: 19434632 DOI: 10.1002/path.2562] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Patients with Peutz-Jeghers syndrome (PJS) are affected by hamartomatous intestinal polyposis and increased risk of cancers in multiple organs caused by germline mutations in the tumour suppressor gene LKB1. Murine models that recapitulate aspects of PJS have been created. Here we examine the therapeutic effect of rapamycin, a macrolide with anti-tumourigenic and anti-angiogenic properties, in reducing tumour incidence in a large cohort of Lkb1(+/-) mice. To study the influence of early intervention, the animals were dosed with rapamycin from the age of 8 weeks, well before the onset of polyposis. These mice continued to receive the drug, which was well tolerated, throughout their lives. At sacrifice, we observed a reduction in gastric tumour burden in the rapamycin-treated mice (p = 0.0001) compared with age- and sex-matched controls. Treated animals also have a lower number of polyps per mouse than controls. In the polyps from the treated mice, phosphorylation of ribosomal p70 S6 kinase was maintained, while the phosphorylation of AKT at serine-473 was elevated, suggesting that mTORC1 function is maintained at this dosage. Despite this, a significant reduction in microvessel density was seen in polyps from the rapamycin-treated mice compared to those from the control mice (p = 5 x 10(-5)), suggesting that the anti-angiogenic effect of rapamycin played a role in polyp reduction. Overall, we demonstrated that prolonged oral administration of rapamycin from an early age is effective in lowering tumour burden in the Lkb1(+/-) mice without evident side effects.
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Affiliation(s)
- James Robinson
- Colorectal Cancer Genetics, Institute of Cell and Molecular Sciences, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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39
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Jansen M, Ten Klooster JP, Offerhaus GJ, Clevers H. LKB1 and AMPK family signaling: the intimate link between cell polarity and energy metabolism. Physiol Rev 2009; 89:777-98. [PMID: 19584313 DOI: 10.1152/physrev.00026.2008] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Research on the LKB1 tumor suppressor protein mutated in cancer-prone Peutz-Jeghers patients has continued at a feverish pace following exciting developments linking energy metabolism and cancer development. This review summarizes the current state of research on the LKB1 tumor suppressor. The weight of the evidence currently indicates an evolutionary conserved role for the protein in the regulation of various aspects of cellular polarity and energy metabolism. We focus on studies examining the concept that both cellular polarity and energy metabolism are regulated through the conserved LKB1-AMPK signal transduction pathway. Recent studies from a variety of model organisms have given new insight into the mechanism of polyp development and cancer formation in Peutz-Jeghers patients and the role of LKB1 mutation in sporadic tumorigenesis. Conditional LKB1 mouse models have outlined a tissue-dependent context for pathway activation and suggest that LKB1 may affect different AMPK isoforms independently. Elucidation of the molecular mechanism responsible for Peutz-Jeghers syndrome will undoubtedly reveal important insight into cancer development in the larger population.
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Affiliation(s)
- Marnix Jansen
- Hubrecht Institute, Developmental Biology and Stem Cell Research, 3584 CT Utrecht, The Netherlands
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Abstract
In the past decade, studies of the human tumour suppressor LKB1 have uncovered a novel signalling pathway that links cell metabolism to growth control and cell polarity. LKB1 encodes a serine-threonine kinase that directly phosphorylates and activates AMPK, a central metabolic sensor. AMPK regulates lipid, cholesterol and glucose metabolism in specialized metabolic tissues, such as liver, muscle and adipose tissue. This function has made AMPK a key therapeutic target in patients with diabetes. The connection of AMPK with several tumour suppressors suggests that therapeutic manipulation of this pathway using established diabetes drugs warrants further investigation in patients with cancer.
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Affiliation(s)
- David B. Shackelford
- Dulbecco Center for Cancer Research, Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, USA 92037
| | - Reuben J. Shaw
- Dulbecco Center for Cancer Research, Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, USA 92037
- Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, CA, USA 92037
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41
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Xie Z, Dong Y, Zhang J, Scholz R, Neumann D, Zou MH. Identification of the serine 307 of LKB1 as a novel phosphorylation site essential for its nucleocytoplasmic transport and endothelial cell angiogenesis. Mol Cell Biol 2009; 29:3582-96. [PMID: 19414597 PMCID: PMC2698771 DOI: 10.1128/mcb.01417-08] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 10/17/2008] [Accepted: 04/26/2009] [Indexed: 11/20/2022] Open
Abstract
LKB1, a master kinase that controls at least 13 downstream protein kinases including the AMP-activated protein kinase (AMPK), resides mainly in the nucleus. A key step in LKB1 activation is its export from the nucleus to the cytoplasm. Here, we identified S307 of LKB1 as a putative novel phosphorylation site which is essential for its nucleocytoplasmic transport. In a cell-free system, recombinant PKC-zeta phosphorylates LKB1 at S307. AMPK-activating agents stimulate PKC-zeta activity and LKB1 phosphorylation at S307 in endothelial cells, hepatocytes, skeletal muscle cells, and vascular smooth muscle cells. Like the kinase-dead LKB1 D194A mutant (mutation of Asp194 to Ala), the constitutively nucleus-localized LKB1 SL26 mutant and the LKB1 S307A mutant (Ser307 to Ala) exhibit a decreased association with STRAD alpha. Interestingly, the PKC-zeta consensus sequence surrounding LKB1 S307 is disrupted in the LKB1 SL26 mutant, thus providing a likely molecular explanation for this mutation causing LKB1 dysfunction. In addition, LKB1 nucleocytoplasmic transport and AMPK activation in response to peroxynitrite are markedly reduced by pharmacological inhibition of CRM1, which normally facilitates nuclear export of LKB1-STRAD complexes. In comparison to the LKB1 wild type, the S307A mutant complexes show reduced association with CRM1. Finally, adenoviral overexpression of wild-type LKB1 suppresses, while the LKB1 S307A mutant increases, tube formation and hydrogen peroxide-enhanced apoptosis in cultured endothelial cells. Taken together, our results suggest that, in multiple cell types the signaling pathways engaged by several physiological stimuli converge upon PKC-zeta-dependent LKB1 phosphorylation at S307, which directs the nucleocytoplasmic transport of LKB1 and consequent AMPK activation.
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Affiliation(s)
- Zhonglin Xie
- Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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mTOR and HIF-1alpha-mediated tumor metabolism in an LKB1 mouse model of Peutz-Jeghers syndrome. Proc Natl Acad Sci U S A 2009; 106:11137-42. [PMID: 19541609 DOI: 10.1073/pnas.0900465106] [Citation(s) in RCA: 174] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Peutz-Jeghers syndrome (PJS) is a familial cancer disorder due to inherited loss of function mutations in the LKB1/ STK11 serine/threonine kinase. PJS patients develop gastrointestinal hamartomas with 100% penetrance often in the second decade of life, and demonstrate an increased predisposition toward the development of a number of additional malignancies. Among mitogenic signaling pathways, the mammalian-target of rapamycin complex 1 (mTORC1) pathway is hyperactivated in tissues and tumors derived from LKB1-deficient mice. Consistent with a central role for mTORC1 in these tumors, rapamycin as a single agent results in a dramatic suppression of preexisting GI polyps in LKB1+/- mice. However, the key targets of mTORC1 in LKB1-deficient tumors remain unknown. We demonstrate here that these polyps, and LKB1- and AMPK-deficient mouse embryonic fibroblasts, show dramatic up-regulation of the HIF-1alpha transcription factor and its downstream transcriptional targets in an rapamycin-suppressible manner. The HIF-1alpha targets hexokinase II and Glut1 are up-regulated in these polyps, and using FDG-PET, we demonstrate that LKB1+/- mice show increased glucose utilization in focal regions of their GI tract corresponding to these gastrointestinal hamartomas. Importantly, we demonstrate that polyps from human Peutz-Jeghers patients similarly exhibit up-regulated mTORC1 signaling, HIF-1alpha, and GLUT1 levels. Furthermore, like HIF-1alpha and its target genes, the FDG-PET signal in the GI tract of these mice is abolished by rapamycin treatment. These findings suggest a number of therapeutic modalities for the treatment and detection of hamartomas in PJS patients, and potential for the screening and treatment of the 30% of sporadic human lung cancers bearing LKB1 mutations.
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Rodriguez-Nieto S, Sanchez-Cespedes M. BRG1 and LKB1: tales of two tumor suppressor genes on chromosome 19p and lung cancer. Carcinogenesis 2009; 30:547-54. [PMID: 19176640 DOI: 10.1093/carcin/bgp035] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Losses of heterozygosity (LOH) of the short arm of chromosome 19 are frequent in lung cancer, suggesting that one or more tumor suppressor genes are present in this region. The LKB1 gene, also called STK11, is somatically inactivated through point mutations and large deletions in lung tumors, demonstrating that LKB1 is a target of the LOH of this chromosomal arm. Data from several independent groups have provided information about the profiles of lung tumors with LKB1 inactivation and it is generally agreed that this alteration strongly predominates in non-small cell lung cancer, in particular adenocarcinomas, in smokers. The LKB1 protein has serine-threonine kinase activity and is involved in the regulation of the cell energetic checkpoint through the phosphorylation and activation of adenosine monophosphate-dependent kinase (AMPK). LKB1 is also involved in other processes such as cell polarization, probably through substrates other than AMPK. Interestingly, another gene on chromosome 19p, BRG1, encoding a component of the SWI/SNF chromatin-remodeling complex, has emerged as a tumor suppressor gene that is altered in lung tumors. Similar to LKB1, BRG1 is somatically inactivated by point mutations or large deletions in lung tumors featuring LOH of chromosome 19p. These observations suggest an important role for BRG1 in lung cancer and highlight the need to further our understanding of the function of Brahma/SWI2-related gene 1 (BRG1) in cancer. Finally, simultaneous mutations at LKB1 and BRG1 are common in lung cancer cells, which exemplifies how a single event, LOH of chromosome 19p in this instance, targets two different tumor suppressors.
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Affiliation(s)
- Salvador Rodriguez-Nieto
- Genes and Cancer Group, Programa de Epigenetica y Biologia del Cancer (PEBC), Institut d'Investigacions Biomediques Bellvitge (IDIBELL), Hospital Durant i Reynals, 08907-L'Hospitalet de Llobregat, Barcelona, Spain
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Wei C, Amos CI, Zhang N, Zhu J, Wang X, Frazier ML. Chemopreventive efficacy of rapamycin on Peutz-Jeghers syndrome in a mouse model. Cancer Lett 2009; 277:149-54. [PMID: 19147279 DOI: 10.1016/j.canlet.2008.11.036] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 11/21/2008] [Accepted: 11/28/2008] [Indexed: 02/06/2023]
Abstract
Germline mutations in LKB1 cause Peutz-Jeghers syndrome (PJS), an autosomal dominant disorder with a predisposition to gastrointestinal polyposis and cancer. Hyperactivation of mTOR-signaling has been associated with PJS. We previously reported that rapamycin treatment of Lkb1(+/-) mice after the onset of polyposis reduced the polyp burden. Here we evaluated the preventive efficacy of rapamycin on Peutz-Jeghers polyposis. We found that rapamycin treatment of Lkb1(+/-) mice initiated before the onset of polyposis in Lkb1(+/-) mice led to a dramatic reduction in both polyp burden and polyp size and this reduction was associated with decreased phosphorylation levels of S6 and 4EBP1. Together, these findings support the use of rapamycin as an option for chemoprevention and treatment of PJS.
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Affiliation(s)
- Chongjuan Wei
- Department of Epidemiology, The University of Texas M.D. Anderson Cancer Center, 1155 Pressler Boulevard, Houston, TX 77030, USA
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Abstract
Germ line mutations in the LKB1 tumor suppressor gene are associated with the Peutz-Jeghers polyposis and cancer syndrome. Somatic mutations in Lkb1 are observed in sporadic pulmonary, pancreatic and biliary cancers and melanomas. The LKB1 serine-threonine kinase functionally and biochemically links control of cellular structure and energy utilization through activation of the AMPK family of kinases. Lkb1 regulates cell polarity through downstream kinases including AMPKs, MARKs and BRSKs, and nutrient utilization and cellular metabolism through the AMPK-mTOR pathway. LKB1 has been shown to affect normal chromosomal segregation, TGF-beta signaling in the mesenchyme and WNT and p53 activity. Although each of the LKB1-dependent processes and downstream pathways have been individually delineated through work across a range of experimental systems, how they relate to Lkb1's role as a tumor suppressor remains to be fully explored and elucidated. The recent development of mouse cancer models harboring engineered mutations in Lkb1 have offered insights into how LKB1 may be functioning to restrain tumorigenesis and how its role as a master regulator of polarity and metabolism could contribute to its tumor suppressor function.
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Zhang J, Bowden GT. UVB irradiation regulates Cox-2 mRNA stability through AMPK and HuR in human keratinocytes. Mol Carcinog 2008; 47:974-83. [PMID: 18449856 DOI: 10.1002/mc.20450] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Considerable evidence has demonstrated that UVB irradiation is a strong carcinogen for nonmelanoma skin cancer. Up-regulation of cyclooxygenase-2 (Cox-2) has been shown to be a crucial event in human keratinocytes in their responses to UVB irradiation. To further understand the molecular mechanisms governing Cox-2 regulation, we found that UVB irradiation significantly increased Cox-2 mRNA stability by inducing cytoplasmic localization and protein abundance of human antigen R (HuR). We also found that AMP-activated kinase (AMPK) mediates these events and that UVB reduces AMPK activity by down-regulating LKB1 kinase. Finally, we propose a novel model in which UVB regulates Cox-2 mRNA stability through the LKB1/AMPK pathway.
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Affiliation(s)
- Jack Zhang
- Arizona Cancer Center, Tucson, Arizona 85724, USA
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47
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Hosogi H, Nagayama S, Kawamura J, Koshiba Y, Nomura A, Itami A, Okabe H, Satoh S, Watanabe G, Sakai Y. Molecular insights into Peutz-Jeghers syndrome: two probands with a germline mutation of LKB1. J Gastroenterol 2008; 43:492-7. [PMID: 18600394 DOI: 10.1007/s00535-008-2185-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Accepted: 03/10/2008] [Indexed: 02/04/2023]
Abstract
LKB1 encodes a serine/threonine protein kinase that is defective in patients with Peutz-Jeghers syndrome (PJS), a hereditary disorder characterized by gastrointestinal hamartomatous polyposis and an increased risk of cancer development. Although a tentative molecular classification of PJS patients was recently made according to their LKB1 mutation status, it is difficult to clarify the genotype-phenotype relationship because of the rarity and genetic heterogeneity of this disease. Here we report on two probands with PJS whose intestinal hamartomatous polyposis was treated by laparoscopyassisted polypectomy. Direct sequencing analyses revealed a nonsense mutation at codon 240 in exon 5 in one patient, and a mutation at a splicing donor site in intron 5 in the other patient. No additional somatic mutations were detected in the resected hamartomas in either case. Immunohistochemical analysis revealed an elevated expression of cyclooxygenase-2, and almost complete loss of LKB1 expression in the polyps, suggesting that a biallelic inactivation of the LKB1 gene was responsible for the hamartoma formation. Methylation-specific polymerase chain reaction analysis revealed no hypermethylation of the LKB1 promoter. Mutation analysis is useful in making a precise diagnosis of PJS in candidate probands, and may in the near future provide valuable information for predicting cancer risk based on genotype-phenotype correlations.
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Affiliation(s)
- Hisahiro Hosogi
- Department of Surgery, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
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48
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Vaahtomeri K, Ventelä E, Laajanen K, Katajisto P, Wipff PJ, Hinz B, Vallenius T, Tiainen M, Mäkelä TP. Lkb1 is required for TGFbeta-mediated myofibroblast differentiation. J Cell Sci 2008; 121:3531-40. [PMID: 18840652 DOI: 10.1242/jcs.032706] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Inactivating mutations of the tumor-suppressor kinase gene LKB1 underlie Peutz-Jeghers syndrome (PJS), which is characterized by gastrointestinal hamartomatous polyps with a prominent smooth-muscle and stromal component. Recently, it was noted that PJS-type polyps develop in mice in which Lkb1 deletion is restricted to SM22-expressing mesenchymal cells. Here, we investigated the stromal functions of Lkb1, which possibly underlie tumor suppression. Ablation of Lkb1 in primary mouse embryo fibroblasts (MEFs) leads to attenuated Smad activation and TGFbeta-dependent transcription. Also, myofibroblast differentiation of Lkb1(-/-) MEFs is defective, resulting in a markedly decreased formation of alpha-smooth muscle actin (SMA)-positive stress fibers and reduced contractility. The myofibroblast differentiation defect was not associated with altered serum response factor (SRF) activity and was rescued by exogenous TGFbeta, indicating that inactivation of Lkb1 leads to defects in myofibroblast differentiation through attenuated TGFbeta signaling. These results suggest that tumorigenesis by Lkb1-deficient SM22-positive cells involves defective myogenic differentiation.
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Affiliation(s)
- Kari Vaahtomeri
- Genome-Scale Biology Program, Institute of Biomedicine, Biomedicum Helsinki, P.O. Box 63, 00014 University of Helsinki, Finland
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Londesborough A, Vaahtomeri K, Tiainen M, Katajisto P, Ekman N, Vallenius T, Mäkelä TP. LKB1 in endothelial cells is required for angiogenesis and TGFbeta-mediated vascular smooth muscle cell recruitment. Development 2008; 135:2331-8. [PMID: 18539926 DOI: 10.1242/dev.017038] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Inactivation of the tumor suppressor kinase Lkb1 in mice leads to vascular defects and midgestational lethality at embryonic day 9-11 (E9-E11). Here, we have used conditional targeting to investigate the defects underlying the Lkb1(-/-) phenotype. Endothelium-restricted deletion of Lkb1 led to embryonic death at E12.5 with a loss of vascular smooth muscle cells (vSMCs) and vascular disruption. Transforming growth factor beta (TGFbeta) pathway activity was reduced in Lkb1-deficient endothelial cells (ECs), and TGFbeta signaling from Lkb1(-/-) ECs to adjacent mesenchyme was defective, noted as reduced SMAD2 phosphorylation. The addition of TGFbeta to mutant yolk sac explants rescued the loss of vSMCs, as evidenced by smooth muscle alpha actin (SMA) expression. These results reveal an essential function for endothelial Lkb1 in TGFbeta-mediated vSMC recruitment during angiogenesis.
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Affiliation(s)
- Anou Londesborough
- Genome-Scale Biology Program and Institute of Biomedicine, Biomedicum Helsinki, 00014 University of Helsinki, Finland
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50
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Makowski L, Hayes DN. Role of LKB1 in lung cancer development. Br J Cancer 2008; 99:683-8. [PMID: 18728656 PMCID: PMC2528145 DOI: 10.1038/sj.bjc.6604515] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 06/03/2008] [Accepted: 06/25/2008] [Indexed: 12/12/2022] Open
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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Affiliation(s)
- L Makowski
- Division of Endocrinology, Department of Medicine, Sarah W Stedman Nutrition and Metabolism Center, Duke University Medical Center, Metabolism, and Nutrition, Durham, NC, USA
| | - D N Hayes
- Division of Medical Oncology, Department of Internal Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
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