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Hu G, Huang N, Zhang J, Zhang D, Wang S, Zhang Y, Wang L, Du Y, Kuang S, Ma K, Zhu H, Xu N, Liu M. LKB1 loss promotes colorectal cancer cell metastasis through regulating TNIK expression and actin cytoskeleton remodeling. Mol Carcinog 2023; 62:1659-1672. [PMID: 37449799 DOI: 10.1002/mc.23606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 05/19/2023] [Accepted: 07/05/2023] [Indexed: 07/18/2023]
Abstract
Colorectal cancer (CRC) is one of the most common malignant tumors. Approximately 5%-6% of CRC cases are associated with hereditary CRC syndromes, including the Peutz-Jeghers syndrome (PJS). Liver kinase B1 (LKB1), also known as STK11, is the major gene responsible for PJS. LKB1 heterozygotic deficiency is involved in intestinal polyps in mice, while the mechanism of LKB1 in CRC remains elusive. In this study, we generated LKB1 knockout (KO) CRC cell lines by using CRISPR-Cas9. LKB1 KO promoted CRC cell motility in vitro and tumor metastases in vivo. LKB1 attenuated expression of TRAF2 and NCK-interacting protein kinase (TNIK) as accessed by RNA-seq and western blots, and similar suppression was also detected in the tumor tissues of azoxymethane/dextran sodium sulfate-induced intestinal-specific LKB1-KO mice. LKB1 repressed TNIK expression through its kinase activity. Moreover, attenuating TNIK by shRNA inhibited cell migration and invasion of CRC cells. LKB1 loss-induced high metastatic potential of CRC cells was depended on TNIK upregulation. Furthermore, TNIK interacted with ARHGAP29 and further affected actin cytoskeleton remodeling. Taken together, LKB1 deficiency promoted CRC cell metastasis via TNIK upregulation and subsequently mediated cytoskeleton remodeling. These results suggest that LKB1-TNIK axis may play a crucial role in CRC progression.
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Affiliation(s)
- Guanghui Hu
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Ning Huang
- Department of Hepatobiliary Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jing Zhang
- Department of Hepatobiliary Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Die Zhang
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Shuren Wang
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yuanyuan Zhang
- Department of Gynecologic Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Panjiayuan, Chaoyang District, Beijing, People's Republic of China
| | - Liming Wang
- Department of Hepatobiliary Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yingxi Du
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Shuwen Kuang
- Department of Hepatobiliary Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Kai Ma
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Hongxia Zhu
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Ningzhi Xu
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Mei Liu
- Laboratory of Cell and Molecular Biology & State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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2
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Chiraphapphaiboon W, Thongnoppakhun W, Limjindaporn T, Sawasdichai S, Roothumnong E, Prangphan K, Pamornpol B, Limwongse C, Pithukpakorn M. STK11 Causative Variants and Copy Number Variations Identified in Thai Patients With Peutz-Jeghers Syndrome. Cureus 2023; 15:e34495. [PMID: 36874343 PMCID: PMC9983355 DOI: 10.7759/cureus.34495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2023] [Indexed: 02/04/2023] Open
Abstract
Introduction Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disorder caused by germline mutations in the serine-threonine kinase 11 (STK11) tumor suppressor gene. This syndrome is characterized by hamartomatous gastrointestinal polyps, mucocutaneous melanin pigmentation, and a higher risk of developing various cancers. Methods We summarized the clinical and molecular characteristics of five unrelated Thai patients with PJS. Denaturing high-performance liquid chromatography (DHPLC) screening, coupled with direct DNA sequencing and multiplex ligation-dependent probe amplification (MLPA), were applied for the molecular analysis of STK11. Results A total of four STK11 pathogenic changeswere identified in the five PJS patients, including two frameshift variants (a novel c.199dup, p.Leu67ProfsTer96 and a known c.834_835del, p.Cys278TrpfsTer6) and two types of copy number variations (CNV), exon 1 deletion and exons 2-3 deletion. Among reported STK11 exonic deletions, exon 1 and exons 2-3 deletions were found to be the two most commonly deleted exons. Conclusion All identified STK11 mutations were null mutations that were associated with more severe PJS phenotypes and cancers. This study broadens the phenotypic and mutational spectrum of STK11 in PJS.
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Affiliation(s)
| | - Wanna Thongnoppakhun
- Siriraj Genomics, Office of the Dean, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, THA
| | | | - Sunisa Sawasdichai
- Siriraj Genomics, Office of the Dean, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, THA
| | - Ekkapong Roothumnong
- Division of Medical Genetics, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, THA
| | - Kanjana Prangphan
- Siriraj Genomics, Office of the Dean, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, THA
| | - Benjaporn Pamornpol
- Department of Anatomy, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, THA
| | - Chanin Limwongse
- Siriraj Genomics, Office of the Dean, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, THA.,Division of Medical Genetics, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, THA
| | - Manop Pithukpakorn
- Siriraj Genomics, Office of the Dean, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, THA.,Division of Medical Genetics, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, THA
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3
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Will We Unlock the Benefit of Metformin for Patients with Lung Cancer? Lessons from Current Evidence and New Hypotheses. Pharmaceuticals (Basel) 2022; 15:ph15070786. [PMID: 35890085 PMCID: PMC9318003 DOI: 10.3390/ph15070786] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/15/2022] [Accepted: 06/16/2022] [Indexed: 11/16/2022] Open
Abstract
Metformin has been under basic and clinical study as an oncological repurposing pharmacological agent for several years, stemming from observational studies which consistently evidenced that subjects who were treated with metformin had a reduced risk for development of cancer throughout their lives, as well as improved survival outcomes when diagnosed with neoplastic diseases. As a result, several basic science studies have attempted to dissect the relationship between metformin’s metabolic mechanism of action and antineoplastic cellular signaling pathways. Evidence in this regard was compelling enough that a myriad of randomized clinical trials was planned and conducted in order to establish the effect of metformin treatment for patients with diverse neoplasms, including lung cancer. As with most novel antineoplastic agents, early results from these studies have been mostly discouraging, though a recent analysis that incorporated body mass index may provide significant information regarding which patient subgroups might derive the most benefit from the addition of metformin to their anticancer treatment. Much in line with the current pipeline for anticancer agents, it appears that the benefit of metformin may be circumscribed to a specific patient subgroup. If so, addition of metformin to antineoplastic agents could prove one of the most cost-effective interventions proposed in the context of precision oncology. Currently published reviews mostly rely on a widely questioned mechanism of action by metformin, which fails to consider the differential effects of the drug in lean vs. obese subjects. In this review, we analyze the pre-clinical and clinical information available to date regarding the use of metformin in various subtypes of lung cancer and, further, we present evidence as to the differential metabolic effects of metformin in lean and obese subjects where, paradoxically, the obese subjects have reported more benefit with the addition of metformin treatment. The novel mechanisms of action described for this biguanide may explain the different results observed in clinical trials published in the last decade. Lastly, we present novel hypothesis regarding potential biomarkers to identify who might reap benefit from this intervention, including the role of prolyl hydroxylase domain 3 (PHD3) expression to modify metabolic phenotypes in malignant diseases.
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4
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AMPKα-like proteins as LKB1 downstream targets in cell physiology and cancer. J Mol Med (Berl) 2021; 99:651-662. [PMID: 33661342 DOI: 10.1007/s00109-021-02040-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/28/2020] [Accepted: 01/12/2021] [Indexed: 12/13/2022]
Abstract
One of the key events in cancer development is the ability of tumor cells to overcome nutrient deprivation and hypoxia. Among proteins performing metabolic adaptation to the various cellular nutrient conditions, liver kinase B 1 (LKB1) and its main downstream target adenosine monophosphate (AMP)-activated protein kinase α (AMPKα) are important sensors of energy requirements within the cell. Although LKB1 was originally described as a tumor suppressor, given its role in metabolism, it potentially acts as a double-edged sword. AMPKα, a master regulator of cell energy demands, is activated when ATP level drops under a certain threshold, responding accordingly through its downstream targets. Twelve downstream kinase targets of LKB1 have been described as AMPKα-like proteins. This group is comprised of novel (nua) kinase family (NUAK) kinases (NUAK1 and 2) linked to cell cycle progression and ultraviolet (UV)-damage; microtubule affinity regulating kinases (MARKs) (MARK1, MARK2, MARK3, and MARK4) that are involved in cell polarity; salt inducible kinases (SIK) (SIK1, SIK2, also known as Qin-induced kinase or QIK and SIK3) that are implicated in cell metabolism and adipose tissue development and mitotic regulation; maternal embryonic leuzine zipper kinase (MELK) that regulate oocyte maturation; and finally brain selective kinases (BRSKs) (BRSK1 and 2), which have been mainly characterized in the brain due to their role in neuronal polarization. Thus, many efforts have been made in order to harness LKB1 kinase and its downstream targets as a possible therapeutic hub in tumor development and propagation. In this review, we describe LKB1 and its downstream target AMPK summarize major functions of various AMPK-like proteins, while focusing on biological functions of BRSK1 and 2 in different models.
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5
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Faisal M, Kim JH, Yoo KH, Roh EJ, Hong SS, Lee SH. Development and Therapeutic Potential of NUAKs Inhibitors. J Med Chem 2020; 64:2-25. [PMID: 33356242 DOI: 10.1021/acs.jmedchem.0c00533] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
NUAK isoforms, NUAK1 (ARK5) and NUAK2 (SNARK), are important members of the AMPK family of protein kinases. They are involved in a broad spectrum of physiological and cellular events, and sometimes their biological roles overlap. NUAK isoform dysregulation is associated with numerous pathological disorders, including neurodegeneration, metastatic cancer, and diabetes. Therefore, they are promising therapeutic targets in metabolic diseases and cancers; consequently, various NUAK-targeted inhibitors have been disclosed. The first part of this review comprises a brief discussion of the homology, expression, structure, and characteristics of NUAK isoforms. The second part focuses on NUAK isoforms' involvement in crucial biological operations, including mechanistic findings, highlighting how their abnormal functioning contributes to disease progression and quality of life. The third part summarizes the key findings and applications of targeting NUAK isoforms for treating multiple cancers and neurodegenerative disorders. The final part systematically presents a critical review and analysis of the literature on NUAK isoform inhibitions through small molecules.
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Affiliation(s)
- Muhammad Faisal
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology (UST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - Jae Ho Kim
- Chemical Kinomics Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - Kyung Ho Yoo
- Chemical Kinomics Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - Eun Joo Roh
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology (UST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea.,Chemical Kinomics Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - Soon Sun Hong
- Department of Biomedical Sciences, College of Medicine, and Program in Biomedical Science & Engineering, Inha University, Incheon 22212, Republic of Korea
| | - So Ha Lee
- Chemical Kinomics Research Center, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea
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6
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Kalinin S, Meares GP, Lin SX, Pietruczyk EA, Saher G, Spieth L, Nave KA, Boullerne AI, Lutz SE, Benveniste EN, Feinstein DL. Liver kinase B1 depletion from astrocytes worsens disease in a mouse model of multiple sclerosis. Glia 2019; 68:600-616. [PMID: 31664743 PMCID: PMC7337013 DOI: 10.1002/glia.23742] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 09/19/2019] [Accepted: 10/05/2019] [Indexed: 12/15/2022]
Abstract
Liver kinase B1 (LKB1) is a ubiquitously expressed kinase involved in the regulation of cell metabolism, growth, and inflammatory activation. We previously reported that a single nucleotide polymorphism in the gene encoding LKB1 is a risk factor for multiple sclerosis (MS). Since astrocyte activation and metabolic function have important roles in regulating neuroinflammation and neuropathology, we examined the serine/threonine kinase LKB1 in astrocytes in a chronic experimental autoimmune encephalomyelitis mouse model of MS. To reduce LKB1, a heterozygous astrocyte-selective conditional knockout (het-cKO) model was used. While disease incidence was similar, disease severity was worsened in het-cKO mice. RNAseq analysis identified Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enriched in het-cKO mice relating to mitochondrial function, confirmed by alterations in mitochondrial complex proteins and reductions in mRNAs related to astrocyte metabolism. Enriched pathways included major histocompatibility class II genes, confirmed by increases in MHCII protein in spinal cord and cerebellum of het-cKO mice. We observed increased numbers of CD4+ Th17 cells and increased neuronal damage in spinal cords of het-cKO mice, associated with reduced expression of choline acetyltransferase, accumulation of immunoglobulin-γ, and reduced expression of factors involved in motor neuron survival. In vitro, LKB1-deficient astrocytes showed reduced metabolic function and increased inflammatory activation. These data suggest that metabolic dysfunction in astrocytes, in this case due to LKB1 deficiency, can exacerbate demyelinating disease by loss of metabolic support and increase in the inflammatory environment.
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Affiliation(s)
- Sergey Kalinin
- Department of Anesthesiology, University of Illinois, Chicago, Illinois
| | - Gordon P Meares
- Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, West Virginia
| | - Shao Xia Lin
- Department of Anesthesiology, University of Illinois, Chicago, Illinois
| | | | - Gesine Saher
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Gottingen, Germany
| | - Lena Spieth
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Gottingen, Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Gottingen, Germany
| | - Anne I Boullerne
- Department of Anesthesiology, University of Illinois, Chicago, Illinois
| | - Sarah E Lutz
- Department of Anatomy and Cell Biology, University of Illinois, Chicago, Illinois
| | - Etty N Benveniste
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Douglas L Feinstein
- Department of Anesthesiology, University of Illinois, Chicago, Illinois.,Department of Veterans Affairs, Jesse Brown VA Medical Center, Chicago, Illinois
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7
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Kuwako KI, Okano H. Versatile Roles of LKB1 Kinase Signaling in Neural Development and Homeostasis. Front Mol Neurosci 2018; 11:354. [PMID: 30333724 PMCID: PMC6176002 DOI: 10.3389/fnmol.2018.00354] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 09/11/2018] [Indexed: 01/01/2023] Open
Abstract
Kinase signaling pathways orchestrate a majority of cellular structures and functions across species. Liver kinase B1 (LKB1, also known as STK11 or Par-4) is a ubiquitously expressed master serine/threonine kinase that plays crucial roles in numerous cellular events, such as polarity control, proliferation, differentiation and energy homeostasis, in many types of cells by activating downstream kinases of the AMP-activated protein kinase (AMPK) subfamily members. In contrast to the accumulating evidence for LKB1 functions in nonneuronal tissues, its functions in the nervous system have been relatively less understood until recently. In the brain, LKB1 initially emerged as a principal regulator of axon/dendrite polarity in forebrain neurons. Thereafter, recent investigations have rapidly uncovered diverse and essential functions of LKB1 in the developing and mature nervous system, such as migration, neurite morphogenesis, myelination and the maintenance of neural integrity, demonstrating that LKB1 is also a multifunctional master kinase in the nervous system. In this review article, we summarize the expanding knowledge about the functional aspects of LKB1 signaling in neural development and homeostasis.
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Affiliation(s)
- Ken-Ichiro Kuwako
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
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8
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The mTOR-S6K pathway links growth signalling to DNA damage response by targeting RNF168. Nat Cell Biol 2018; 20:320-331. [PMID: 29403037 PMCID: PMC5826806 DOI: 10.1038/s41556-017-0033-8] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 12/22/2017] [Indexed: 01/03/2023]
Abstract
Growth signals, such as extracellular nutrients and growth factors, have substantial effects on genome integrity; however, the direct underlying link remains unclear. Here, we show that the mechanistic target of rapamycin (mTOR)-ribosomal S6 kinase (S6K) pathway, a central regulator of growth signalling, phosphorylates RNF168 at Ser60 to inhibit its E3 ligase activity, accelerate its proteolysis and impair its function in the DNA damage response, leading to accumulated unrepaired DNA and genome instability. Moreover, loss of the tumour suppressor liver kinase B1 (LKB1; also known as STK11) hyperactivates mTOR complex 1 (mTORC1)-S6K signalling and decreases RNF168 expression, resulting in defects in the DNA damage response. Expression of a phospho-deficient RNF168-S60A mutant rescues the DNA damage repair defects and suppresses tumorigenesis caused by Lkb1 loss. These results reveal an important function of mTORC1-S6K signalling in the DNA damage response and suggest a general mechanism that connects cell growth signalling to genome stability control.
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9
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LKB1 loss cooperating with BRAF V600E promotes melanoma cell invasion and migration by up-regulation MMP-2 via PI3K/Akt/mTOR pathway. Oncotarget 2017; 8:113847-113857. [PMID: 29371951 PMCID: PMC5768368 DOI: 10.18632/oncotarget.22943] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 08/04/2017] [Indexed: 11/25/2022] Open
Abstract
The serine/threonine kinase LKB1, act as a tumor suppressor, has been reported in several sporadic cancers. However, how the loss of LKB1 promotes melanoma invasion and metastasis remains incompletely understood. In this study, we inactivated LKB1expression by RNA interference in BRAF mutation and wild type melanoma cells respectively. We found LKB1 inactivation cooperate with BRAF V600E lead to melanoma cells more aggressive by a series of experiments including wound scratch test, Transwell assay. While single alteration, either LKB1 loss or BRAF V600E, fails to enhance melanoma cells invasion ability. Mechanistically, LKB1 loss synergism with BRAF V600E resulted in the activation of the PI3K/Akt/mTOR signaling pathway and significant up-regulation expression of MMP-2. In addition, LKB1 expression in human melanoma tissues was negatively associated with MMP-2 expression in the presence of BRAF V600E. Thus, our findings indicate a probable explanation on LKB1 function as a tumor suppressor in melanoma and a new therapeutic strategy for melanoma by targeting on BRAF and LKB1 together.
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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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Zhang W, Li X, Song G, Luo D. Prognostic significance of LKB1 promoter methylation in cutaneous malignant melanoma. Oncol Lett 2017; 14:2075-2080. [PMID: 28781649 PMCID: PMC5530115 DOI: 10.3892/ol.2017.6431] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 04/13/2017] [Indexed: 11/07/2022] Open
Abstract
Liver kinase B1 (LKB1) loss is a common occurrence in various types of human cancer, and promoter methylation has been hypothesized to be a major mechanism of LKB1 inactivation. The association between LKB1 gene promoter methylation status and tumor progression in cutaneous malignant melanoma (CMM) remains unknown. In the present study, the methylation status of the LKB1 promoter region was examined in 57 human cutaneous malignant melanomas and 50 benign skin lesion controls by methylation-specific polymerase chain reaction. Consequently, 12 (12/57) melanoma tissues exhibited LKB1 promoter methylation, while only 2 (2/50) benign lesions presented with LKB1 hypermethylation. The frequency of LKB1 promoter methylation in melanoma was significantly increased compared with the benign controls (P<0.05). Additional statistical analysis demonstrated that hypermethylation of the LKB1 gene was correlated with Breslow's thickness, presence of ulceration and American Joint Committee on Cancer stage (P<0.05). Additionally, Kaplan-Meier analysis revealed that LKB1 hypermethylation was significantly associated with poorer survival (P<0.01). Multivariate COX regression analysis indicated that LKB1 promoter methylation was an independent prognostic factor for overall survival in patients with melanoma.
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Affiliation(s)
- Weiming Zhang
- Department of Pathology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Xiao Li
- Department of Pathology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Guoxin Song
- Department of Pathology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Dan Luo
- Department of Dermatology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
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12
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Haikala HM, Anttila JM, Klefström J. MYC and AMPK-Save Energy or Die! Front Cell Dev Biol 2017; 5:38. [PMID: 28443281 PMCID: PMC5386972 DOI: 10.3389/fcell.2017.00038] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 03/27/2017] [Indexed: 12/12/2022] Open
Abstract
MYC sustains non-stop proliferation by altering metabolic machinery to support growth of cell mass. As part of the metabolic transformation MYC promotes lipid, nucleotide and protein synthesis by hijacking citric acid cycle to serve biosynthetic processes, which simultaneously exhausts ATP production. This leads to the activation of cellular energy sensing protein, AMP-activated protein kinase (AMPK). Cells with normal growth control can stop cell proliferation machinery to replenish ATP reservoirs whereas MYC prevents such break by blocking the cell cycle exit. The relentless cell cycle activation, accompanied by sustained metabolic stress and AMPK activity, switches the energy-saving AMPK to pro-apoptotic AMPK. The AMPK-involving metabolic side of MYC apoptosis may provide novel avenues for therapeutic development. Here we first review the role of anabolic MYC and catabolic AMPK pathways in context of cancer and then discuss how the concomitant activity of both pathways in tumor cells may result in targetable synthetic lethal vulnerabilities.
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Affiliation(s)
- Heidi M Haikala
- Research Programs Unit/Translational Cancer Biology, Cancer Cell Circuitry Laboratory, Institute of Biomedicine, University of HelsinkiHelsinki, Finland
| | - Johanna M Anttila
- Research Programs Unit/Translational Cancer Biology, Cancer Cell Circuitry Laboratory, Institute of Biomedicine, University of HelsinkiHelsinki, Finland
| | - Juha Klefström
- Research Programs Unit/Translational Cancer Biology, Cancer Cell Circuitry Laboratory, Institute of Biomedicine, University of HelsinkiHelsinki, Finland
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13
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Deletion of endothelial cell-specific liver kinase B1 increases angiogenesis and tumor growth via vascular endothelial growth factor. Oncogene 2017; 36:4277-4287. [PMID: 28346429 PMCID: PMC5532072 DOI: 10.1038/onc.2017.61] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 01/18/2017] [Accepted: 02/09/2017] [Indexed: 12/25/2022]
Abstract
Liver kinase B1 (LKB1) is a serine/threonine protein kinase ubiquitously expressed in mammalian cells. It was first identified in Peutz-Jeghers syndrome as a tumor suppressor gene. Whether endothelial LKB1 regulates angiogenesis and tumor growth is unknown. In this study, we generated endothelial cell-specific LKB1-knockout (LKB1endo−/−) mice by crossbreeding vascular endothelial-cadherin-Cre mice with LKB1flox/flox mice. Vascular endothelial growth factor (VEGF) level was highly co-stained in endothelial cells but not macrophages in LKB1endo−/− mice. Consistently, LKB1endo−/− mouse tissues including the lung, skin, kidney, and liver showed increased vascular permeability. Tumors implanted in LKB1endo−/− mice but not macrophage-specific LKB1-knockout mice grew faster and showed enhanced vascular permeability and increased angiogenesis as compared with those implanted in wild-type mice. Injection of VEGF-neutralizing antibody but not the isotype-matched control antibody decreased endothelial-cell angiogenesis and tumor growth in vivo. Furthermore, LKB1 deletion enhanced mouse retinal and cell angiogenesis, and knockdown of VEGF by small-interfering RNA decreased endothelial cell proliferation and migration. Re-expression of LKB1 or knockdown of VEGF receptor 2 decreased the over-proliferation and -migration observed in LKB1endo−/− cells. Mechanistically, LKB1 could bind to the VEGF transcription factor, specificity protein 1 (Sp1), which then inhibited the binding of Sp1 to the VEGF promoter to reduce VEGF expression. Endothelial LKB1 may regulate endothelial angiogenesis and tumor growth by modulating Sp1-mediated VEGF expression.
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14
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Gudipaty SA, Rosenblatt J. Epithelial cell extrusion: Pathways and pathologies. Semin Cell Dev Biol 2016; 67:132-140. [PMID: 27212253 DOI: 10.1016/j.semcdb.2016.05.010] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 05/13/2016] [Accepted: 05/17/2016] [Indexed: 02/06/2023]
Abstract
To remove dying or unwanted cells from an epithelium while preserving the barrier function of the layer, epithelia use a unique process called cell extrusion. To extrude, the cell fated to die emits the lipid Sphingosine 1 Phosphate (S1P), which binds the G-protein-coupled receptor Sphingosine 1 Phosphate receptor 2 (S1P2) in the neighboring cells that activates Rho-mediated contraction of an actomyosin ring circumferentially and basally. This contraction acts to squeeze the cell out apically while drawing together neighboring cells and preventing any gaps to the epithelial barrier. Epithelia can extrude out cells targeted to die by apoptotic stimuli to repair the barrier in the face of death or extrude live cells to promote cell death when epithelial cells become too crowded. Indeed, because epithelial cells naturally turn over by cell death and division at some of the highest rates in the body, epithelia depend on crowding-induced live cell extrusion to preserve constant cell numbers. If extrusion is defective, epithelial cells rapidly lose contact inhibition and form masses. Additionally, because epithelia act as the first line of defense in innate immunity, preservation of this barrier is critical for preventing pathogens from invading the body. Given its role in controlling constant cell numbers and maintaining barrier function, a number of different pathologies can result when extrusion is disrupted. Here, we review mechanisms and signaling pathways that control epithelial extrusion and discuss how defects in these mechanisms can lead to multiple diseases. We also discuss tactics pathogens have devised to hijack the extrusion process to infect and colonize epithelia.
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Affiliation(s)
- Swapna Aravind Gudipaty
- Department of Oncological Sciences, Huntsman Cancer Institute, University Of Utah, 2000 Circle of Hope Drive, Salt Lake City, UT 84112, USA
| | - Jody Rosenblatt
- Department of Oncological Sciences, Huntsman Cancer Institute, University Of Utah, 2000 Circle of Hope Drive, Salt Lake City, UT 84112, USA.
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15
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Abstract
The AMP-protein kinase (AMPK) pathway is very versatile as it regulates cellular energetic homeostasis in many different tissue types. An appreciation for the importance of AMPK signalling and regulation in cardiovascular and tumor biology is increasing. Recently, a link has been established between anti-cancer therapy and susceptibility to cardiac disease. It has been shown that some anti-cancer drugs lead to an increased risk of cardiac disease, underlined by de-regulation of AMPK signalling. This review explores the AMPK signalling axis in both cardiac and tumor metabolism. We then examine off-target AMPK inhibition by cancer drugs and how this may translate into increased risk of cardiovascular disease. Finally, we discuss the implication of deregulated AMPK signalling during different stages of cardiac hypertrophy. Better understanding of the molecular pathways behind pathological processes will lead to the development of more effective therapeutics for cancer and cardiovascular diseases.
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Affiliation(s)
- Yulia Lipovka
- Department of Physiology, University of Arizona, Sarver Molecular Cardiovascular Research Program, USA
| | - John P Konhilas
- Department of Physiology, University of Arizona, Sarver Molecular Cardiovascular Research Program, USA
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16
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Rhodes LV, Tate CR, Hoang VT, Burks HE, Gilliam D, Martin EC, Elliott S, Miller DB, Buechlein A, Rusch D, Tang H, Nephew KP, Burow ME, Collins-Burow BM. Regulation of triple-negative breast cancer cell metastasis by the tumor-suppressor liver kinase B1. Oncogenesis 2015; 4:e168. [PMID: 26436950 PMCID: PMC4632088 DOI: 10.1038/oncsis.2015.27] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 10/16/2014] [Accepted: 11/02/2014] [Indexed: 12/17/2022] Open
Abstract
Liver kinase B1 (LKB1), also known as serine/threonine kinase 11 (STK11), has been identified as a tumor suppressor in many cancers including breast. Low LKB1 expression has been associated with poor prognosis of breast cancer patients, and we report here a significant association between loss of LKB1 expression and reduced patient survival specifically in the basal subtype of breast cancer. Owing to the aggressive nature of the basal subtype as evidenced by high incidences of metastasis, the purpose of this study was to determine if LKB1 expression could regulate the invasive and metastatic properties of this specific breast cancer subtype. Induction of LKB1 expression in basal-like breast cancer (BLBC)/triple-negative breast cancer cell lines, MDA-MB-231 and BT-549, inhibited invasiveness in vitro and lung metastatic burden in an orthotopic xenograft model. Further analysis of BLBC cells overexpressing LKB1 by unbiased whole transcriptomics (RNA-sequencing) revealed striking regulation of metastasis-associated pathways, including cell adhesion, extracellular matrix remodeling, and epithelial-to-mesenchymal transition (EMT). In addition, LKB1 overexpression inhibited EMT-associated genes (CDH2, Vimentin, Twist) and induced the epithelial cell marker CDH1, indicating reversal of the EMT phenotype in the MDA-MB-231 cells. We further demonstrated marked inhibition of matrix metalloproteinase 1 expression and activity via regulation of c-Jun through inhibition of p38 signaling in LKB1-expressing cells. Taken together, these data support future development of LKB1 inducing therapeutics for the suppression of invasion and metastasis of BLBC.
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Affiliation(s)
- L V Rhodes
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
| | - C R Tate
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
| | - V T Hoang
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
| | - H E Burks
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
| | - D Gilliam
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
| | - E C Martin
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
| | - S Elliott
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
| | - D B Miller
- Department of Cellular and Integrative Physiology, Bloomington, IN, USA
| | - A Buechlein
- Center for Genomics and Bioinformatics, College of Arts and Sciences, Indiana University School of Medicine and Simon Cancer Center, Bloomington, IN, USA
| | - D Rusch
- Center for Genomics and Bioinformatics, College of Arts and Sciences, Indiana University School of Medicine and Simon Cancer Center, Bloomington, IN, USA
| | - H Tang
- Center for Genomics and Bioinformatics, College of Arts and Sciences, Indiana University School of Medicine and Simon Cancer Center, Bloomington, IN, USA
| | - K P Nephew
- Department of Cellular and Integrative Physiology, Bloomington, IN, USA
| | - M E Burow
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
| | - B M Collins-Burow
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
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17
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Oestrogen receptors interact with the α-catalytic subunit of AMP-activated protein kinase. Biosci Rep 2015; 35:BSR20150074. [PMID: 26374855 PMCID: PMC4626870 DOI: 10.1042/bsr20150074] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 09/10/2015] [Indexed: 01/19/2023] Open
Abstract
We identified a novel interaction between the classical oestrogen receptors (ERα and ERβ) and the catalytic subunit of AMP-activated protein kinase (AMPK) in several cell types. In addition, we demonstrate that oestradiol (E2) activates AMPK through ERα and requires the upstream kinase complex liver kinase B (LKB1). Normal and pathological stressors engage the AMP-activated protein kinase (AMPK) signalling axis to protect the cell from energetic pressures. Sex steroid hormones also play a critical role in energy metabolism and significantly modify pathological progression of cardiac disease, diabetes/obesity and cancer. AMPK is targeted by 17β-oestradiol (E2), the main circulating oestrogen, but the mechanism by which E2 activates AMPK is currently unknown. Using an oestrogen receptor α/β (ERα/β) positive (T47D) breast cancer cell line, we validated E2-dependent activation of AMPK that was mediated through ERα (not ERβ) by using three experimental strategies. A series of co-immunoprecipitation experiments showed that both ERs associated with AMPK in cancer and striated (skeletal and cardiac) muscle cells. We further demonstrated direct binding of ERs to the α-catalytic subunit of AMPK within the βγ-subunit-binding domain. Finally, both ERs interacted with the upstream liver kinase B 1 (LKB1) kinase complex, which is required for E2-dependent activation of AMPK. We conclude that E2 activates AMPK through ERα by direct interaction with the βγ-binding domain of AMPKα.
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18
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Boullerne AI, Skias D, Hartman EM, Testai FD, Kalinin S, Polak PE, Feinstein DL. A single-nucleotide polymorphism in serine-threonine kinase 11, the gene encoding liver kinase B1, is a risk factor for multiple sclerosis. ASN Neuro 2015; 7:1759091415568914. [PMID: 25694554 PMCID: PMC4342367 DOI: 10.1177/1759091415568914] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
We identified a family in which five siblings were diagnosed with multiple sclerosis (MS) or clinically isolated syndrome. Several women in the maternal lineage have comorbidities typically associated with Peutz Jeghers Syndrome, a rare autosomal-dominant disease caused by mutations in the serine-threonine-kinase 11 (STK11) gene, which encodes liver kinase B1. Sequence analysis of DNA from one sibling identified a single-nucleotide polymorphism (SNP) within STK11 intron 5. This SNP (dbSNP ID: rs9282860) was identified by TaqMan polymerase chain reaction (PCR) assays in DNA samples available from two other siblings. Further screening was carried out in samples from 654 relapsing-remitting MS patients, 100 primary progressive MS patients, and 661 controls. The STK11-SNP has increased frequency in all female patients versus controls (odds ratio = 1.66, 95% CI = 1.05, 2.64, p = .032). The STK11-SNP was not associated with disease duration or onset; however, it was significantly associated with reduced severity (assessed by MS severity scores), with the lowest scores in patients who also harbored the HLA-DRB1*1501 allele. In vitro studies showed that peripheral blood mononuclear cells from members of the family were more sensitive to the mitochondrial inhibitor metformin than cells from MS patients with the major STK11 allele. The increased association of SNP rs9282860 in women with MS defines this variant as a genetic risk factor. The lower disease severity observed in the context of HLA-DRB1*1501 combined with limited in vitro studies raises the provocative possibility that cells harboring the STK11-SNP could be targeted by drugs which increase metabolic stress.
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Affiliation(s)
- Anne I Boullerne
- Department of Anesthesiology, University of Illinois at Chicago, IL, USA
| | - Demetrios Skias
- Department of Veterans Affairs, Jesse Brown VA Medical Center, Chicago, IL, USA Department of Neurology, University of Illinois at Chicago, IL, USA
| | | | | | - Sergey Kalinin
- Department of Anesthesiology, University of Illinois at Chicago, IL, USA
| | - Paul E Polak
- Department of Anesthesiology, University of Illinois at Chicago, IL, USA
| | - Douglas L Feinstein
- Department of Anesthesiology, University of Illinois at Chicago, IL, USA Department of Veterans Affairs, Jesse Brown VA Medical Center, Chicago, IL, USA
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19
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Shen YAA, Chen Y, Dao DQ, Mayoral SR, Wu L, Meijer D, Ullian EM, Chan JR, Lu QR. Phosphorylation of LKB1/Par-4 establishes Schwann cell polarity to initiate and control myelin extent. Nat Commun 2014; 5:4991. [PMID: 25255972 PMCID: PMC4334370 DOI: 10.1038/ncomms5991] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 08/14/2014] [Indexed: 12/31/2022] Open
Abstract
The Schwann cell (SC)-axon interface represents a membrane specialization that integrates axonal signals to coordinate cytoskeletal dynamics resulting in myelination. Here we show that LKB1/Par-4 is asymmetrically localized to the SC-axon interface and colocalizes with the polarity protein Par-3. Using purified SCs and myelinating cocultures, we demonstrate that localization is dependent on the phosphorylation of LKB1 at serine-431. SC-specific deletion of LKB1 significantly attenuates developmental myelination, delaying the initiation and altering the myelin extent into adulthood, resulting in a 30% reduction in the conduction velocity along adult sciatic nerves. Phosphorylation of LKB1 by protein kinase A is essential to establish the asymmetric localization of LKB1 and Par-3 and rescues the delay in myelination observed in the SC-specific knockout of LKB1. Our findings suggest that SC polarity may coordinate multiple signaling complexes that couple SC-axon contact to the redistribution of specific membrane components necessary to initiate and control myelin extent.
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Affiliation(s)
- Yun-An A Shen
- Department of Neurology and Program in Neurosciences, University of California, San Francisco, California 94158, USA
| | - Yan Chen
- 1] Department of Pediatrics, Brain Cancer Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229 [2] Department of Pediatrics and Obstetrics/Gynecology, State Key Laboratory of Biotherapy, Cancer Center, West China Second Hospital, Sichuan University, Chengdu 61004, China
| | - Dang Q Dao
- Department of Ophthalmology and Physiology and Programs in Neurosciences, University of California, San Francisco, California 94143, USA
| | - Sonia R Mayoral
- Department of Neurology and Program in Neurosciences, University of California, San Francisco, California 94158, USA
| | - Laiman Wu
- Department of Pediatrics, Brain Cancer Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
| | - Dies Meijer
- Department of Cellular Neurobiology, Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Erik M Ullian
- Department of Ophthalmology and Physiology and Programs in Neurosciences, University of California, San Francisco, California 94143, USA
| | - Jonah R Chan
- Department of Neurology and Program in Neurosciences, University of California, San Francisco, California 94158, USA
| | - Q Richard Lu
- Department of Pediatrics, Brain Cancer Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
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20
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Xia C, Ye F, Hu X, Li Z, Jiang B, Fu Y, Cheng X, Shao Z, Zhuang Z. Liver kinase B1 enhances chemoresistance to gemcitabine in breast cancer MDA-MB-231 cells. Oncol Lett 2014; 8:2086-2092. [PMID: 25295095 PMCID: PMC4186618 DOI: 10.3892/ol.2014.2446] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 06/19/2014] [Indexed: 11/08/2022] Open
Abstract
Liver kinase B1 (LKB1) is a well-known tumor suppressor gene in a variety of human cancers, including breast cancer. However, its role in gemcitabine resistance is unclear. Since gemcitabine in combination with other chemotherapeutic reagents is the first-line treatment in advanced breast cancer, the aim of the present study was to determine the effect of ectopic expression of LKB1 on chemosensitivity to gemcitabine in the breast cancer MDA-MB-231 cell line. Increasing the expression of LKB1 was found to directly correlate with gemcitabine chemoresistance. Although LKB1 suppressed the cell proliferation rate and clonogenicity in the absence of gemcitabine, it increased the median inhibitory concentration of gemcitabine and clonogenicity of cells in the presence of gemcitabine. Mechanistic analysis indicated that LKB1 was able to protect cells from DNA damage caused by gemcitabine. Furthermore, it was found that LKB1 induced a significant upregulation of cytidine deaminase expression, an important enzyme that accelerates gemcitabine catabolization. Overall, dual characteristics of LKB1 were identified: Suppressing cell growth in normal conditions and enhancing chemoresisitance to gemcitabine, possibly by accelerating degradation of gemcitabine, and protecting cells from DNA damage caused by gemcitabine.
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Affiliation(s)
- Chen Xia
- Department of Breast Surgery, Shanghai First Maternity and Infant Hospital, Tongji University, School of Medicine, Shanghai 200040, P.R. China
| | - Fugui Ye
- Department of General Surgery, Affiliated Union Hospital of Fujian Medical University, Union Clinical School, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Xin Hu
- Department of Breast Surgery, Cancer Center and Cancer Institute, Shanghai Medical College, Fudan University, Shanghai 200032, P.R. China
| | - Zhengdong Li
- Department of Breast Surgery, Shanghai First Maternity and Infant Hospital, Tongji University, School of Medicine, Shanghai 200040, P.R. China
| | - Beiqi Jiang
- Department of Breast Surgery, Shanghai First Maternity and Infant Hospital, Tongji University, School of Medicine, Shanghai 200040, P.R. China
| | - Yun Fu
- Department of Breast Surgery, Shanghai First Maternity and Infant Hospital, Tongji University, School of Medicine, Shanghai 200040, P.R. China
| | - Xiaolin Cheng
- Department of Breast Surgery, Shanghai First Maternity and Infant Hospital, Tongji University, School of Medicine, Shanghai 200040, P.R. China
| | - Zhiming Shao
- Department of Breast Surgery, Cancer Center and Cancer Institute, Shanghai Medical College, Fudan University, Shanghai 200032, P.R. China
| | - Zhigang Zhuang
- Department of Breast Surgery, Shanghai First Maternity and Infant Hospital, Tongji University, School of Medicine, Shanghai 200040, P.R. China
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21
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Zhang W, Wang Q, Wu Y, Moriasi C, Liu Z, Dai X, Wang Q, Liu W, Yuan ZY, Zou MH. Endothelial cell-specific liver kinase B1 deletion causes endothelial dysfunction and hypertension in mice in vivo. Circulation 2014; 129:1428-39. [PMID: 24637557 DOI: 10.1161/circulationaha.113.004146] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Liver kinase B1 (LKB1), a tumor suppressor, is a central regulator of cell polarity and energy homeostasis. The role of LKB1 in endothelial function in vivo has not been explored. METHODS AND RESULTS Endothelium-specific LKB1 knockout (LKB1(endo-/-)) mice were generated by cross-breeding LKB1(flox/flox) mice with VE-Cadherin-Cre mice. LKB1(endo-/-) mice exhibited hypertension, cardiac hypertrophy, and impaired endothelium-dependent relaxation. LKB1(endo-/-) endothelial cells exhibited reduced endothelial nitric oxide synthase activity and AMP kinase (a downstream enzyme of LKB1) phosphorylation at Thr172 compared with wild-type (WT) cells. In addition, the levels of caveolin-1 were higher in the endothelial cells of LKB1(endo-/-) mice, and knockdown of caveolin-1 by siRNA normalized endothelial nitric oxide synthase activity. Human antigen R bound with the adenylate-uridylate-rich elements of caveolin-1 mRNA 3' untranslated region, resulting in the increased stability of caveolin-1, and genetic knockdown of human antigen R decreased the expression of caveolin-1 in LKB1-deficient endothelial cells. Finally, adenoviral overexpression of constitutively active AMP kinase, but not green fluorescent protein, decreased caveolin-1, lowered blood pressure, and improved endothelial function in LKB1(endo-/-) mice in vivo. CONCLUSIONS Our findings indicate that endothelial LKB1 regulates endothelial nitric oxide synthase activity, endothelial function, and blood pressure by modulating AMP kinase-mediated caveolin-1 expression.
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Affiliation(s)
- Wencheng Zhang
- Section of Molecular Medicine, Department of Medicine (W.Z., Q.W., Y.W., C.M., Z.L., X.D., Q.W., M.-H.Z.) and Department of Biochemistry and Molecular Biology (Z.L., M.-H.Z.), University of Oklahoma Health Sciences Center, Oklahoma City; Department of Cardiology, First Affiliated Hospital of Xi'an Jiaotong University Health Science Center, Xi'an, China (Y.W., W.L., Z.-Y.Y., M.-H.Z.); and Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Qilu Hospital of Shandong University, Jinan, Shandong, China (M.-H.Z.)
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22
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Swierczynski J, Hebanowska A, Sledzinski T. Role of abnormal lipid metabolism in development, progression, diagnosis and therapy of pancreatic cancer. World J Gastroenterol 2014; 20:2279-303. [PMID: 24605027 PMCID: PMC3942833 DOI: 10.3748/wjg.v20.i9.2279] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 12/25/2013] [Accepted: 01/03/2014] [Indexed: 02/07/2023] Open
Abstract
There is growing evidence that metabolic alterations play an important role in cancer development and progression. The metabolism of cancer cells is reprogrammed in order to support their rapid proliferation. Elevated fatty acid synthesis is one of the most important aberrations of cancer cell metabolism. An enhancement of fatty acids synthesis is required both for carcinogenesis and cancer cell survival, as inhibition of key lipogenic enzymes slows down the growth of tumor cells and impairs their survival. Based on the data that serum fatty acid synthase (FASN), also known as oncoantigen 519, is elevated in patients with certain types of cancer, its serum level was proposed as a marker of neoplasia. This review aims to demonstrate the changes in lipid metabolism and other metabolic processes associated with lipid metabolism in pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic neoplasm, characterized by high mortality. We also addressed the influence of some oncogenic factors and tumor suppressors on pancreatic cancer cell metabolism. Additionally the review discusses the potential role of elevated lipid synthesis in diagnosis and treatment of pancreatic cancer. In particular, FASN is a viable candidate for indicator of pathologic state, marker of neoplasia, as well as, pharmacological treatment target in pancreatic cancer. Recent research showed that, in addition to lipogenesis, certain cancer cells can use fatty acids from circulation, derived from diet (chylomicrons), synthesized in liver, or released from adipose tissue for their growth. Thus, the interactions between de novo lipogenesis and uptake of fatty acids from circulation by PDAC cells require further investigation.
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23
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Mohseni M, Sun J, Lau A, Curtis S, Goldsmith J, Fox VL, Wei C, Frazier M, Samson O, Wong KK, Wong KK, Kim C, Camargo FD. A genetic screen identifies an LKB1-MARK signalling axis controlling the Hippo-YAP pathway. Nat Cell Biol 2013; 16:108-17. [PMID: 24362629 DOI: 10.1038/ncb2884] [Citation(s) in RCA: 232] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 10/28/2013] [Indexed: 12/11/2022]
Abstract
The Hippo-YAP pathway is an emerging signalling cascade involved in the regulation of stem cell activity and organ size. To identify components of this pathway, we performed an RNAi-based kinome screen in human cells. Our screen identified several kinases not previously associated with Hippo signalling that control multiple cellular processes. One of the hits, LKB1, is a common tumour suppressor whose mechanism of action is only partially understood. We demonstrate that LKB1 acts through its substrates of the microtubule affinity-regulating kinase family to regulate the localization of the polarity determinant Scribble and the activity of the core Hippo kinases. Our data also indicate that YAP is functionally important for the tumour suppressive effects of LKB1. Our results identify a signalling axis that links YAP activation with LKB1 mutations, and have implications for the treatment of LKB1-mutant human malignancies. In addition, our findings provide insight into upstream signals of the Hippo-YAP signalling cascade.
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Affiliation(s)
- Morvarid Mohseni
- 1] Stem Cell Program, Boston Children's Hospital, Boston, Massachusetts 02115, USA [2] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts 02138, USA [3] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA
| | - Jianlong Sun
- 1] Stem Cell Program, Boston Children's Hospital, Boston, Massachusetts 02115, USA [2] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts 02138, USA [3] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA
| | - Allison Lau
- 1] Stem Cell Program, Boston Children's Hospital, Boston, Massachusetts 02115, USA [2] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA
| | - Stephen Curtis
- 1] Stem Cell Program, Boston Children's Hospital, Boston, Massachusetts 02115, USA [2] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA [3] Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Jeffrey Goldsmith
- Center for Pediatric Polyposis, Boston Children's Hospital, Boston, Massachusetts 02115, USA
| | - Victor L Fox
- Division of Gastroenterology and Nutrition, Boston Children's Hospital, Boston, Massachusetts 02115, USA
| | - Chongjuan Wei
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Marsha Frazier
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Owen Samson
- Wnt Signaling and Colorectal Cancer Group, The Beatson Institute for Cancer Research, Cancer Research UK, Glasgow G61 1BD, UK
| | | | - Kwok-Kim Wong
- 1] Genetics Division, Department of Medicine Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA [2] Ludwig Center at Dana-Farber/Harvard Cancer Center, Boston, Massachusetts 02115, USA
| | - Carla Kim
- 1] Stem Cell Program, Boston Children's Hospital, Boston, Massachusetts 02115, USA [2] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA [3] Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Fernando D Camargo
- 1] Stem Cell Program, Boston Children's Hospital, Boston, Massachusetts 02115, USA [2] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts 02138, USA [3] Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA
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Soares H, Marinho HS, Real C, Antunes F. Cellular polarity in aging: role of redox regulation and nutrition. GENES AND NUTRITION 2013; 9:371. [PMID: 24306961 DOI: 10.1007/s12263-013-0371-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 11/19/2013] [Indexed: 02/06/2023]
Abstract
Cellular polarity concerns the spatial asymmetric organization of cellular components and structures. Such organization is important not only for biological behavior at the individual cell level, but also for the 3D organization of tissues and organs in living organisms. Processes like cell migration and motility, asymmetric inheritance, and spatial organization of daughter cells in tissues are all dependent of cell polarity. Many of these processes are compromised during aging and cellular senescence. For example, permeability epithelium barriers are leakier during aging; elderly people have impaired vascular function and increased frequency of cancer, and asymmetrical inheritance is compromised in senescent cells, including stem cells. Here, we review the cellular regulation of polarity, as well as the signaling mechanisms and respective redox regulation of the pathways involved in defining cellular polarity. Emphasis will be put on the role of cytoskeleton and the AMP-activated protein kinase pathway. We also discuss how nutrients can affect polarity-dependent processes, both by direct exposure of the gastrointestinal epithelium to nutrients and by indirect effects elicited by the metabolism of nutrients, such as activation of antioxidant response and phase-II detoxification enzymes through the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2). In summary, cellular polarity emerges as a key process whose redox deregulation is hypothesized to have a central role in aging and cellular senescence.
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Affiliation(s)
- Helena Soares
- Departamento de Química e Bioquímica, Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
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Partanen JI, Tervonen TA, Klefström J. Breaking the epithelial polarity barrier in cancer: the strange case of LKB1/PAR-4. Philos Trans R Soc Lond B Biol Sci 2013; 368:20130111. [PMID: 24062587 DOI: 10.1098/rstb.2013.0111] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The PAR clan of polarity regulating genes was initially discovered in a genetic screen searching for genes involved in asymmetric cell divisions in the Caenorhabditis elegans embryo. Today, investigations in worms, flies and mammals have established PAR proteins as conserved and fundamental regulators of animal cell polarization in a broad range of biological phenomena requiring cellular asymmetries. The human homologue of invertebrate PAR-4, a serine-threonine kinase LKB1/STK11, has caught attention as a gene behind Peutz-Jeghers polyposis syndrome and as a bona fide tumour suppressor gene commonly mutated in sporadic cancer. LKB1 functions as a master regulator of AMP-activated protein kinase (AMPK) and 12 other kinases referred to as the AMPK-related kinases, including four human homologues of PAR-1. The role of LKB1 as part of the energy sensing LKB1-AMPK module has been intensively studied, whereas the polarity function of LKB1, in the context of homoeostasis or cancer, has gained less attention. Here, we focus on the PAR-4 identity of LKB1, discussing the weight of evidence indicating a role for LKB1 in regulation of cell polarity and epithelial integrity across species and highlight recent investigations providing new insight into the old question: does the PAR-4 identity of LKB1 matter in cancer?
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Affiliation(s)
- Johanna I Partanen
- Cancer Cell Circuitry Laboratory, Translational Cancer Biology Research Program and Institute of Biomedicine, University of Helsinki, , Biomedicum Helsinki, Rm B507b, PO Box 63, Haartmaninkatu 8, 00014 Helsinki, Finland
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Par-1 regulates tissue growth by influencing hippo phosphorylation status and hippo-salvador association. PLoS Biol 2013; 11:e1001620. [PMID: 23940457 PMCID: PMC3735459 DOI: 10.1371/journal.pbio.1001620] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 06/19/2013] [Indexed: 01/07/2023] Open
Abstract
The evolutionarily conserved Hippo (Hpo) signaling pathway plays a pivotal role in organ size control by balancing cell proliferation and cell death. Here, we reported the identification of Par-1 as a regulator of the Hpo signaling pathway using a gain-of-function EP screen in Drosophila melanogaster. Overexpression of Par-1 elevated Yorkie activity, resulting in increased Hpo target gene expression and tissue overgrowth, while loss of Par-1 diminished Hpo target gene expression and reduced organ size. We demonstrated that par-1 functioned downstream of fat and expanded and upstream of hpo and salvador (sav). In addition, we also found that Par-1 physically interacted with Hpo and Sav and regulated the phosphorylation of Hpo at Ser30 to restrict its activity. Par-1 also inhibited the association of Hpo and Sav, resulting in Sav dephosphorylation and destabilization. Furthermore, we provided evidence that Par-1-induced Hpo regulation is conserved in mammalian cells. Taken together, our findings identified Par-1 as a novel component of the Hpo signaling network.
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Abstract
White adipose tissue (WAT) is not only a lipogenic and fat storage tissue but also an important endocrine organ that regulates energy homeostasis, lipid metabolism, appetite, fertility, and immune and stress responses. Liver kinase B1 (LKB1), a tumor suppressor, is a key regulator in energy metabolism. However, the role of LKB1 in adipogenesis is unknown. The current study aimed to determine the contributions of LKB1 to adipogenesis in vivo. Using the Fabp4-Cre/loxP system, we generated adipose tissue-specific LKB1 knockout (LKB1(ad-/-)) mice. LKB1(ad-/-) mice exhibited a reduced amount of WAT, postnatal growth retardation, and early death before weaning. Further, LKB1 deletion markedly reduced the levels of insulin receptor substrate 1 (IRS1), peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein α, and phosphorylated AMP-activated protein kinase (AMPK). Consistent with these results, overexpression of constitutively active AMPK partially ablated IRS1 degradation in LKB1-deficient cells. LKB1 deletion increased the levels of F-box/WD repeat-containing protein (Fbw) 8, the IRS1 ubiquitination E3 ligase. Silencing of Fbw8 increased IRS1 levels. Finally, promoter analysis and DNA chromatin immunoprecipitation analysis identified three sterol regulatory element (SRE) sites in the Fbw8 promoter, where SRE-binding protein 1c binds and induces the expression of Fbw8. Taken together, these data indicate that LKB1 controls IRS1-dependent adipogenesis via AMPK in WAT.
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Affiliation(s)
- Wencheng Zhang
- Section of Molecule Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Qilong Wang
- Section of Molecule Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Ping Song
- Section of Molecule Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Ming-Hui Zou
- Section of Molecule Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Corresponding author: Ming-Hui Zou,
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He J, Zhou Y, Xing J, Wang Q, Zhu H, Zhu Y, Zou MH. Liver kinase B1 is required for thromboxane receptor-dependent nuclear factor-κB activation and inflammatory responses. Arterioscler Thromb Vasc Biol 2013; 33:1297-305. [PMID: 23539217 DOI: 10.1161/atvbaha.113.301296] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
OBJECTIVE Thromboxane A2 receptor (TPr) has been reported to trigger vascular inflammation. Nuclear factor κ B (NF-κB) is a known transcription factor. The aims of the present study were to determine the contributions of NF-κB activation to TPr-triggered vascular inflammation and elucidate the mechanism(s) underlying TPr activation of NF-κB. APPROACH AND RESULTS The effects of TPr activators, [1S-[1 alpha,2 alpha(Z),3beta(1E,3S*), 4 alpha]]-7-[3-[3-hydroxy-4-(4-iodophenoxy)-1-butenyl]-7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid (I-BOP) and U46619, on NF-κB activation, phosphorylation of rhoA/rho-associated kinases and liver kinase B1, cell adhesion and migration, proliferation, and endothelium-dependent vasorelaxation were assayed in cultured human umbilical vein endothelial cells, human monocytes, or isolated mouse aortas. Exposure of human umbilical vein endothelial cells to TPr agonists I-BOP and U46619 induced dose-dependent and time-dependent phosphorylation of inhibitor of κB α in parallel with aberrant expression of inflammatory markers cyclooxygenase-2, inducible nitric oxide synthase, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1. Inhibition of NF-κB by pharmacological or genetic means abolished TPr-triggered expression of inflammatory markers. Consistently, exposure of human umbilical vein endothelial cells to either I-BOP or U46619 significantly increased phosphorylation of inhibitor of κB α, I kappaB kinase, rhoA, rho-associated kinases, and liver kinase B1. Pretreatment of human umbilical vein endothelial cells with the TPr antagonist SQ29548 or rho-associated kinases inhibitor Y27632 or silencing of the LKB1 blocked TPr-enhanced phosphorylation of inhibitor of κB α and its upstream kinase, I kappaB kinase. Finally, exposure of isolated mouse aortas to either U46619 or I-BOP enhanced NF-κB activation and vascular inflammation in parallel with reduced endothelium-dependent relaxation in intact vessels. CONCLUSIONS TPr stimulation instigates aberrant inflammation and endothelial dysfunction via rho-associated kinases/liver kinase B1/I kappaB kinase-dependent NF-κB activation in vascular endothelial cells.
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Affiliation(s)
- Jinlong He
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China
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Daikoku T, Yoshie M, Xie H, Sun X, Cha J, Ellenson LH, Dey SK. Conditional deletion of Tsc1 in the female reproductive tract impedes normal oviductal and uterine function by enhancing mTORC1 signaling in mice. Mol Hum Reprod 2013; 19:463-72. [PMID: 23475984 DOI: 10.1093/molehr/gat016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Heightened mammalian target of rapamycin complex 1 (mTORC1) activity by genetic deletion of its direct inhibitor, Tsc1, is associated with aberrant development and dysfunction of the female reproductive tract in mice. Here, we compared the phenotypes of mice with conditional deletion of Tsc1 in the female reproductive tract by either progesterone receptor (PR)-Cre (Tsc1(PR(d/d))), which inactivates Tsc1 in all major cell types in the uterus (epithelium, stroma and myometrium), or anti-Mullerian hormone type 2 receptor (Amhr2)-Cre (Tsc1(Amhr2(d/d))), which inactivates stromal and myometrial Tsc1. Tsc1(PR(d/d)) and Tsc1(Amhr2(d/d)) females are infertile resulting from oviductal hyperplasia, retention of embryos in the oviduct and implantation failure. In contrast to the appropriate embryonic development after fertilization seen in Tsc1(Amhr2(d/d)) females, embryo development was disrupted in Tsc1(PR(d/d)) females. In addition, uteri in Tsc1(PR(d/d)) and Tsc1(Amhr2(d/d)) females showed epithelial hyperplasia but not endometrial cancer. In conclusion, Tsc1(PR(d/d)) and Tsc1(Amhr2(d/d)) have overlapping yet distinct phenotypes in the context of compartment-specific deletion of Tsc1.
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Affiliation(s)
- Takiko Daikoku
- Division of Reproductive Sciences, The Perinatal Institute, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, MLC 7045, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
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Feng Y, Wang Y, Wang Z, Fang Z, Li F, Gao Y, Liu H, Xiao T, Li F, Zhou Y, Zhai Q, Liu X, Sun Y, Bardeesy N, Wong KK, Chen H, Xiong ZQ, Ji H. The CRTC1-NEDD9 signaling axis mediates lung cancer progression caused by LKB1 loss. Cancer Res 2012; 72:6502-11. [PMID: 23074285 DOI: 10.1158/0008-5472.can-12-1909] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Somatic mutation of the tumor suppressor gene LKB1 occurs frequently in lung cancer where it causes tumor progression and metastasis, but the underlying mechanisms remain mainly unknown. Here, we show that the oncogene NEDD9 is an important downstream mediator of lung cancer progression evoked by LKB1 loss. In de novo mouse models, RNAi-mediated silencing of Nedd9 inhibited lung tumor progression, whereas ectopic NEDD9 expression accelerated this process. Mechanistically, LKB1 negatively regulated NEDD9 transcription by promoting cytosolic translocation of CRTC1 from the nucleus. Notably, ectopic expression of either NEDD9 or CRTC1 partially reversed the inhibitory function of LKB1 on metastasis of lung cancer cells. In clinical specimens, elevated expression of NEDD9 was associated with malignant progression and metastasis. Collectively, our results decipher the mechanism through which LKB1 deficiency promotes lung cancer progression and metastasis, and provide a mechanistic rationale for therapeutic attack of these processes.
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Affiliation(s)
- Yan Feng
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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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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Martin MJ, Hayward R, Viros A, Marais R. Metformin accelerates the growth of BRAF V600E-driven melanoma by upregulating VEGF-A. Cancer Discov 2012; 2:344-55. [PMID: 22576211 PMCID: PMC3364710 DOI: 10.1158/2159-8290.cd-11-0280] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
UNLABELLED The antidiabetic drug metformin has antitumor activity in a variety of cancers because it blocks cell growth by inhibiting TORC1. Here, we show that melanoma cells that are driven by oncogenic BRAF are resistant to the growth-inhibitory effects of metformin because RSK sustains TORC1 activity even when AMP-activated protein kinase (AMPK) is activated. We further show that AMPK targets the dual-specificity protein phosphatase DUSP6 for degradation and this increases ERK activity, which then upregulates the VEGF-A protein. Critically, this drives angiogenesis and accelerates the growth of BRAF-driven tumors in mice. Unexpectedly, however, when VEGF signaling is inhibited, instead of accelerating tumor growth, metformin inhibits tumor growth. Thus, we show that BRAF-driven melanoma cells are resistant to the antigrowth effects of AMPK and that AMPK mediates cell-autonomous and cell-nonautonomous effects that accelerate the growth of these cells in vivo. SIGNIFICANCE Metformin inhibits the growth of most tumor cells, but BRAF-mutant melanoma cells are resistant to metformin in vitro, and metformin accelerates their growth in vivo. Unexpectedly, VEGF inhibitors and metformin synergize to suppress the growth of BRAF-mutant tumors, revealing a combination of drugs that may be effective in these patients.
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Affiliation(s)
- Matthew J. Martin
- Division of Tumour Biology, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, United Kingdom
| | - Robert Hayward
- Division of Tumour Biology, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, United Kingdom
| | - Amaya Viros
- Division of Tumour Biology, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, United Kingdom
| | - Richard Marais
- Division of Tumour Biology, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, United Kingdom
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Energy metabolism and proliferation in pancreatic carcinogenesis. Langenbecks Arch Surg 2012; 397:507-12. [PMID: 22430298 DOI: 10.1007/s00423-012-0933-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 02/15/2012] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer entity with a high proliferative potential. Uncontrolled cell proliferation is mediated by a number of core signaling pathways. Recently, novel data of PDAC biology suggest that these core signal pathways affect cell proliferation and metabolism simultaneously. METHODS Here, we reviewed the literature on core metabolic signaling pathways in pancreatic carcinogenesis. RESULTS Results obtained from mouse genetics and in vitro experiments have demonstrated the significance of the Kras, p53, c-Myc, and Lkb1 networks in the proliferation of pancreatic epithelial and cancer cells. At the same time, these major pathways also affect energy metabolism by influencing glucose and glutamine utilization. In particular, Kras-mediated metabolic changes seem to be directly involved in carcinogenesis. However, there is a lack of solid evidence on how metabolism and proliferation are connected in pancreatic carcinogenesis. CONCLUSION Understanding early and subtle changes in cellular metabolism of pancreatic epithelial-and specifically of acinar-cells, which accompany or directly influence malignant transformation and uncontrolled proliferation, will be paramount to define novel imaging and other modalities for earlier detection of PDAC.
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Mian I, Pierre-Louis WS, Dole N, Gilberti RM, Dodge-Kafka K, Tirnauer JS. LKB1 destabilizes microtubules in myoblasts and contributes to myoblast differentiation. PLoS One 2012; 7:e31583. [PMID: 22348111 PMCID: PMC3279410 DOI: 10.1371/journal.pone.0031583] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 01/09/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Skeletal muscle myoblast differentiation and fusion into multinucleate myotubes is associated with dramatic cytoskeletal changes. We find that microtubules in differentiated myotubes are highly stabilized, but premature microtubule stabilization blocks differentiation. Factors responsible for microtubule destabilization in myoblasts have not been identified. FINDINGS We find that a transient decrease in microtubule stabilization early during myoblast differentiation precedes the ultimate microtubule stabilization seen in differentiated myotubes. We report a role for the serine-threonine kinase LKB1 in both microtubule destabilization and myoblast differentiation. LKB1 overexpression reduced microtubule elongation in a Nocodazole washout assay, and LKB1 RNAi increased it, showing LKB1 destabilizes microtubule assembly in myoblasts. LKB1 levels and activity increased during myoblast differentiation, along with activation of the known LKB1 substrates AMP-activated protein kinase (AMPK) and microtubule affinity regulating kinases (MARKs). LKB1 overexpression accelerated differentiation, whereas RNAi impaired it. CONCLUSIONS Reduced microtubule stability precedes myoblast differentiation and the associated ultimate microtubule stabilization seen in myotubes. LKB1 plays a positive role in microtubule destabilization in myoblasts and in myoblast differentiation. This work suggests a model by which LKB1-induced microtubule destabilization facilitates the cytoskeletal changes required for differentiation. Transient destabilization of microtubules might be a useful strategy for enhancing and/or synchronizing myoblast differentiation.
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Affiliation(s)
- Isma Mian
- Center for Molecular Medicine and University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Willythssa Stéphie Pierre-Louis
- Center for Molecular Medicine and University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Neha Dole
- Center for Molecular Medicine and University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Renée M. Gilberti
- Center for Molecular Medicine and University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Kimberly Dodge-Kafka
- Calhoun Center for Cardiology, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Jennifer S. Tirnauer
- Center for Molecular Medicine and University of Connecticut Health Center, Farmington, Connecticut, United States of America
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Tumor suppressor function of Liver kinase B1 (Lkb1) is linked to regulation of epithelial integrity. Proc Natl Acad Sci U S A 2012; 109:E388-97. [PMID: 22308451 DOI: 10.1073/pnas.1120421109] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although loss of epithelial integrity is a hallmark of advanced cancer, it remains poorly understood whether genetic alterations corrupting this integrity causally facilitate tumorigenesis. We show that conditional deletion of tumor suppressor gene Lkb1 (Par-4) in the mammary gland compromises epithelial integrity manifested by mislocalization of cell polarity markers, lateralization of tight junctions, deterioration of desmosomes and basement membrane (BM), and hyperbranching of the mammary ductal tree. We identify the desmosomal BM remodelling serine protease Hepsin as a key factor mediating Lkb1 loss-induced structural alterations in mammary epithelium and BM fragmentation. Although loss of Lkb1 alone does not promote mammary tumorigenesis, combination of Lkb1 deficiency with oncogenic c-Myc leads to dramatic acceleration in tumor formation. The results coupling Lkb1 loss-mediated epithelial integrity defects to mislocalization of serine protease Hepsin and to oncogenic synergy with c-Myc imply that Lkb1 loss facilitates oncogenic proliferation by releasing epithelial cells from structural BM boundaries.
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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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EL-MASRY OMARS, BROWN BARRYL, DOBSON PAULINER. Effects of activation of AMPK on human breast cancer cell lines with different genetic backgrounds. Oncol Lett 2012; 3:224-228. [PMID: 22740885 PMCID: PMC3362498 DOI: 10.3892/ol.2011.458] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 10/04/2011] [Indexed: 11/06/2022] Open
Abstract
Breast cancer remains a therapeutic challenge, and this has intensified the search for new drug targets. The AMP-activated protein kinase (AMPK) signalling pathway is emerging as having potential for intervention. We assessed the possible different effects of AMPK action on breast cancer cells by studying their impact on proliferation, apoptosis and the mitochondrial membrane potential in three breast cancer cell lines (MCF-7, MDA-MB-231 and T47D) differing in their p53 and estrogen receptor (ER) status. Activation of AMPK by 5-aminoimidazole carboxamide ribonucleotide (AICAR) and phenformin elicited clear anti-proliferative effects in all breast cancer cell lines, but with differences in sensitivity. However, the anti-proliferative effects were accompanied by varying responses between the different cells, with a marked cell cycle arrest effect in T47D cells and an apoptotic effect in MCF-7 and MDA-MB-231 cells. The mitochondrial apoptotic pathway was potentially involved in all cell lines. These results suggest that AMPK potentially serves as a therapeutic target in breast cancer, but one which may be dependent on the genetic background of the cancer cells.
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Affiliation(s)
- OMAR S. EL-MASRY
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - BARRY L. BROWN
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - PAULINE R.M. DOBSON
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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Abstract
The mechanistic (or mammalian) target of rapamycin (mTOR), an evolutionarily conserved protein kinase, orchestrates cellular responses to growth, metabolic and stress signals. mTOR processes various extracellular and intracellular inputs as part of two mTOR protein complexes, mTORC1 or mTORC2. The mTORCs have numerous cellular targets but members of a family of protein kinases, the protein kinase (PK)A/PKG/PKC (AGC) family are the best characterized direct mTOR substrates. The AGC kinases control multiple cellular functions and deregulation of many members of this family underlies numerous pathological conditions. mTOR phosphorylates conserved motifs in these kinases to allosterically augment their activity, influence substrate specificity, and promote protein maturation and stability. Activation of AGC kinases in turn triggers the phosphorylation of diverse, often overlapping, targets that ultimately control cellular response to a wide spectrum of stimuli. This review will highlight recent findings on how mTOR regulates AGC kinases and how mTOR activity is feedback regulated by these kinases. We will discuss how this regulation can modulate downstream targets in the mTOR pathway that could account for the varied cellular functions of mTOR.
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Affiliation(s)
- Bing Su
- Department of Immunobiology and The Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT, USA.
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Yang HR, Ko JS, Seo JK. Germline mutation analysis of STK11 gene using direct sequencing and multiplex ligation-dependent probe amplification assay in Korean children with Peutz-Jeghers syndrome. Dig Dis Sci 2011. [PMID: 20393878 DOI: 10.1007/s10620-010-1194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/01/2023]
Abstract
Background and Aims Peutz-Jeghers syndrome is an autosomal, dominantly inherited disease characterized by mucocutaneous hyperpigmentation and hamartomatous polyps of the gastrointestinal tract. In this study, mutation analysis of the STK11 gene was performed to establish the genetic background of Peutz-Jeghers syndrome in Korean children.Methods This study included 17 children who were diagnosed with Peutz-Jeghers syndrome based on clinical diagnostic criteria between July 2006 and December 2007.The clinical records of these children were reviewed retrospectively.Genomic DNA was extracted from the blood samples of each patient and used for direct sequencing and the MLPA (multiplex ligation-dependent probe amplification)assay.Results By direct sequencing, mutations in the STK11 gene were observed in five of 17 (29.4%) children with Peutz-Jeghers syndrome. Missense mutations were observed in four, and a frameshift mutation in one. All these mutations were present in the kinase domain of the STK11 gene. By MLPA analysis, mutations in the STK11 gene were observed in six (35.3%) children—exonic deletions were observed in five and exonic duplication in one. Conclusions The detection rate of STK11 gene mutations by direct sequencing is relatively low, even in children clinically diagnosed with Peutz-Jeghers syndrome. With the introduction of the MLPA assay as a new cytogenetic technique, large deletions and exonic duplications could also be detected in children with PJS. In the future, these results may be useful for the genetic diagnosis of Peutz-Jeghers syndrome in Korean children.
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Affiliation(s)
- Hye Ran Yang
- Department of Pediatrics, Seoul National University Collegeof Medicine, Seoul, Korea
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Herrmann JL, Byekova Y, Elmets CA, Athar M. Liver kinase B1 (LKB1) in the pathogenesis of epithelial cancers. Cancer Lett 2011; 306:1-9. [PMID: 21450399 DOI: 10.1016/j.canlet.2011.01.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 01/16/2011] [Accepted: 01/19/2011] [Indexed: 12/26/2022]
Abstract
LKB1 acts as a master kinase, with its major protein targets being the family of AMPKs. Through activation of multiple signaling pathways, LKB1's main physiologic functions involve regulating cellular growth, metabolism, and polarity. Germline mutations in LKB1 result in Peutz-Jeghers Syndrome, a rare cancer susceptibility syndrome. In addition, multiple LKB1 mutations have been identified in sporadic cancers, especially those of the lung. Recent studies from a variety of murine models have helped characterize LKB1's role in the pathogenesis of epithelial cancers. In some tumor types, LKB1 might function chiefly to suppress cell growth or invasion, while in other cases, it may serve to prevent metastasis. Moreover, molecular signatures of individual tumors likely influence LKB1's operational role, as multiple studies have shown that LKB1 can synergize with other tumor suppressors and/or oncogenes to accelerate tumorigenesis. To date, LKB1 has been considered mainly a tumor suppressor; however, some studies have suggested its potential oncogenic role, mainly through the suppression of apoptosis. In short, LKB1 is a tissue and context-specific kinase. This review aims to summarize our current understanding of its role in the pathogenesis of epithelial cancers.
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Gao Y, Ge G, Ji H. LKB1 in lung cancerigenesis: a serine/threonine kinase as tumor suppressor. Protein Cell 2011; 2:99-107. [PMID: 21380642 PMCID: PMC4875258 DOI: 10.1007/s13238-011-1021-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 02/12/2011] [Indexed: 01/01/2023] Open
Abstract
Lung cancer is featured with high mortality, with a 15% five-year survival rate worldwide. Genetic alterations, such as loss of function of tumor suppressor genes, frequently contribute to lung cancer initiation, progression and metastasis. Liver kinase B1 (LKB1), as a serine/threonine kinase and tumor suppressor, is frequently mutated and inactivated in non-small cell lung cancer (NSCLC). Recent studies have provided strong evidences that LKB1 loss promotes lung cancerigenesis process, especially lung cancer progression and metastasis. This review will summarize recent progress on how LKB1 modulates the process of lung cancerigenesis, emphasizing on LKB1 downstream signaling pathways and biological functions. We will further discuss the potential development of prognostic biomarkers or therapeutic targets in lung cancer clinic based on the molecular alteration associated with deregulated LKB1 signaling.
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Affiliation(s)
- Yijun Gao
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Gaoxiang Ge
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Hongbin Ji
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
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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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Chaiyapan W, Sangkhathat S, Kanngurn S, Phukaoloun M, Chiengkriwate P, Patrapinyokul S. Immunohistological evidence for Wnt-signaling activation in Peutz-Jeghers polyposis. Pediatr Surg Int 2010; 26:173-7. [PMID: 20020146 DOI: 10.1007/s00383-009-2547-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/28/2009] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Molecular pathogenesis of gastrointestinal polyposis in Peutz-Jegher's syndrome (PJS) has been linked to the loss-of-function mutation of LKB1. Recent functional genetic studies have pointed out that LKB1 plays a physiological role in controlling the Wnt-signaling pathway and activation of the pathway as a consequence of LKB1 haploinsufficiency might be responsible for the development of harmatomatous polyps. This study aimed to look for immunohistochemical evidence of Wnt-signaling activation in PJS polyps. METHOD Beta-catenin immunohistochemistry patterns were evaluated in gastrointestinal polyps from five cases of PJS. All patients were also evaluated for germline mutations of LKB1 and somatic mutations of beta-catenin in the polyps. RESULTS Four of the five cases had germline mutations of LKB1, including two novel mutations, a one-base insertion at codon 53 and a large deletion encompassing exon 3 (codon 136-155). PJS polyps from all patients showed generalized membrane and cytoplasmic localizations of beta-catenin along the mucosal endothelium. Polyps from two cases with LKB1 mutations revealed moderate-intensity nuclear staining in approximately 20 and 70% of the polyps. CONCLUSION The study offers additional evidence of Wnt-signaling activation in PJS polyp development at the tissue level, although the degree of up-regulation was not as high as has been found in Wnt-associated neoplasms.
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Affiliation(s)
- Walawee Chaiyapan
- Tumor Biology Research Unit, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla, 90110, Thailand
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Komiya T, Coxon A, Park Y, Chen WD, Zajac-Kaye M, Meltzer P, Karpova T, Kaye FJ. Enhanced activity of the CREB co-activator Crtc1 in LKB1 null lung cancer. Oncogene 2009; 29:1672-80. [PMID: 20010869 PMCID: PMC7227613 DOI: 10.1038/onc.2009.453] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Activation of Crtc1 (also known as Mect1/Torc1) by a t(11;19) chromosomal rearrangement underlies the etiology of malignant salivary gland tumors. As LKB1 is a target for mutational inactivation in lung cancer and was recently shown to regulate hepatic Crtc2/CREB transcriptional activity in mice, we now present evidence suggesting disruption of an LKB1/Crtc pathway in cancer. Although Crtc1 is preferentially expressed in adult brain tissues, we observed elevated levels of steady-state Crtc1 in thoracic tumors. In addition, we show that somatic loss of LKB1 is associated with underphosphorylation of endogenous Crtc1, enhanced Crtc1 nuclear localization and enhanced expression of the Crtc prototypic target gene, NR4A2/Nurr1. Inhibition of NR4A2 was associated with growth suppression of LKB1 null tumors, but showed little effect on LKB1-wildtype cells. These data strengthen the role of dysregulated Crtc as a bona fide cancer gene, present a new element to the complex LKB1 tumorigenic axis, and suggest that Crtc genes may be aberrantly activated in a wider range of common adult malignancies.
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Affiliation(s)
- T Komiya
- Genetics Branch, National Cancer Institute and National Naval Medical Center, Bethesda, MD, USA
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45
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Kopacova M, Tacheci I, Rejchrt S, Bures J. Peutz-Jeghers syndrome: Diagnostic and therapeutic approach. World J Gastroenterol 2009; 15:5397-408. [PMID: 19916169 PMCID: PMC2778095 DOI: 10.3748/wjg.15.5397] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [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
Peutz-Jeghers syndrome (PJS) is an inherited, autosomal dominant disorder distinguished by hamartomatous polyps in the gastrointestinal tract and pigmented mucocutaneous lesions. Prevalence of PJS is estimated from 1 in 8300 to 1 in 280 000 individuals. PJS predisposes sufferers to various malignancies (gastrointestinal, pancreatic, lung, breast, uterine, ovarian and testicular tumors). Bleeding, obstruction and intussusception are common complications in patients with PJS. Double balloon enteroscopy (DBE) allows examination and treatment of the small bowel. Polypectomy using DBE may obviate the need for repeated urgent operations and small bowel resection that leads to short bowel syndrome. Prophylaxis and polypectomy of the entire small bowel is the gold standard in PJS patients. Intraoperative enteroscopy (IOE) was the only possibility for endoscopic treatment of patients with PJS before the DBE era. Both DBE and IOE facilitate exploration and treatment of the small intestine. DBE is less invasive and more convenient for the patient. Both procedures are generally safe and useful. An overall recommendation for PJS patients includes not only gastrointestinal multiple polyp resolution, but also regular lifelong cancer screening (colonoscopy, upper endoscopy, computed tomography, magnetic resonance imaging or ultrasound of the pancreas, chest X-ray, mammography and pelvic examination with ultrasound in women, and testicular examination in men). Although the incidence of PJS is low, it is important for clinicians to recognize these disorders to prevent morbidity and mortality in these patients, and to perform presymptomatic testing in the first-degree relatives of PJS patients.
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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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47
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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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Zheng B, Jeong JH, Asara JM, Yuan YY, Granter SR, Chin L, Cantley LC. Oncogenic B-RAF negatively regulates the tumor suppressor LKB1 to promote melanoma cell proliferation. Mol Cell 2009; 33:237-47. [PMID: 19187764 DOI: 10.1016/j.molcel.2008.12.026] [Citation(s) in RCA: 283] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Revised: 08/28/2008] [Accepted: 12/30/2008] [Indexed: 10/21/2022]
Abstract
The LKB1-AMPK signaling pathway serves as a critical cellular sensor coupling energy homeostasis to cell growth, proliferation, and survival. However, how tumor cells suppress this signaling pathway to gain growth advantage under conditions of energy stress is largely unknown. Here, we show that AMPK activation is suppressed in melanoma cells with the B-RAF V600E mutation and that downregulation of B-RAF signaling activates AMPK. We find that in these cells LKB1 is phosphorylated by ERK and Rsk, two kinases downstream of B-RAF, and that this phosphorylation compromises the ability of LKB1 to bind and activate AMPK. Furthermore, expression of a phosphorylation-deficient mutant of LKB1 allows activation of AMPK and inhibits melanoma cell proliferation and anchorage-independent cell growth. Our findings provide a molecular linkage between the LKB1-AMPK and the RAF-MEK-ERK pathways and suggest that suppression of LKB1 function by B-RAF V600E plays an important role in B-RAF V600E-driven tumorigenesis.
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Affiliation(s)
- Bin Zheng
- Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA.
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Sebbagh M, Santoni MJ, Hall B, Borg JP, Schwartz MA. Regulation of LKB1/STRAD localization and function by E-cadherin. Curr Biol 2008; 19:37-42. [PMID: 19110428 DOI: 10.1016/j.cub.2008.11.033] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 11/10/2008] [Accepted: 11/11/2008] [Indexed: 01/06/2023]
Abstract
LKB1 kinase is a tumor suppressor that is causally linked to Peutz-Jeghers syndrome. In complex with the pseudokinase STRAD and the scaffolding protein MO25, LKB1 phosphorylates and activates AMPK family kinases, which mediate many cellular processes. The prototypical family member AMPK regulates cell energy metabolism and epithelial apicobasal polarity. This latter event is also dependent on E-cadherin-mediated adherens junctions (AJs) at lateral borders. Strikingly, overexpression of LKB1/STRAD can also trigger establishment of epithelial polarity in the absence of cell-cell or cell-matrix contacts. However, the upstream factors that normally govern LKB1/STRAD function are unknown. Here we show by immunostaining and fluorescence resonance energy transfer that active LKB1/STRAD kinase complex colocalizes with E-cadherin at AJs. LKB1/STRAD localization and AMPK phosphorylation require E-cadherin-dependent maturation of AJs. However, LKB1/STRAD complex kinase activity is E-cadherin independent. These data suggest that in polarized epithelial cells, E-cadherin regulates AMPK phosphorylation by controlling the localization of the LKB1 complex. The LKB1 complex therefore appears to function downstream of E-cadherin in tumor suppression.
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Affiliation(s)
- Michael Sebbagh
- Cardiovascular Research Center and Department of Microbiology, University of Virginia, Charlottesville, VA 22908, USA.
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50
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Wu J, Vallenius T, Ovaska K, Westermarck J, Mäkelä TP, Hautaniemi S. Integrated network analysis platform for protein-protein interactions. Nat Methods 2008; 6:75-7. [PMID: 19079255 DOI: 10.1038/nmeth.1282] [Citation(s) in RCA: 220] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Accepted: 11/18/2008] [Indexed: 12/13/2022]
Abstract
There is an increasing demand for network analysis of protein-protein interactions (PPIs). We introduce a web-based protein interaction network analysis platform (PINA), which integrates PPI data from six databases and provides network construction, filtering, analysis and visualization tools. We demonstrated the advantages of PINA by analyzing two human PPI networks; our results suggested a link between LKB1 and TGFbeta signaling, and revealed possible competitive interactors of p53 and c-Jun.
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Affiliation(s)
- Jianmin Wu
- Genome-Scale Biology Program, Institute of Biomedicine, University of Helsinki, Haartmaninkatu 8, Helsinki, Finland.
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