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Bourouh M, Marignani PA. The Tumor Suppressor Kinase LKB1: Metabolic Nexus. Front Cell Dev Biol 2022; 10:881297. [PMID: 35573694 PMCID: PMC9097215 DOI: 10.3389/fcell.2022.881297] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022] Open
Abstract
Liver kinase B1 (LKB1) is a multitasking tumor suppressor kinase that is implicated in multiple malignancies such as lung, gastrointestinal, pancreatic, and breast. LKB1 was first identified as the gene responsible for Peutz-Jeghers syndrome (PJS) characterized by hamartomatous polyps and oral mucotaneous pigmentation. LKB1 functions to activate AMP-activated protein kinase (AMPK) during energy stress to shift metabolic processes from active anabolic pathways to active catabolic pathways to generate ATP. Genetic loss or inactivation of LKB1 promotes metabolic reprogramming and metabolic adaptations of cancer cells that fuel increased growth and division rates. As a result, LKB1 loss is associated with increased aggressiveness and treatment options for patients with LKB1 mutant tumors are limited. Recently, there has been new insights into the role LKB1 has on metabolic regulation and the identification of potential vulnerabilities in LKB1 mutant tumors. In this review, we discuss the tumor suppressive role of LKB1 and the impact LKB1 loss has on metabolic reprograming in cancer cells, with a focus on lung cancer. We also discuss potential therapeutic avenues to treat malignancies associated with LKB1 loss by targeting aberrant metabolic pathways associated with LKB1 loss.
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Affiliation(s)
- Mohammed Bourouh
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University Halifax, Halifax, NS, Canada
| | - Paola A Marignani
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University Halifax, Halifax, NS, Canada
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2
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Forte G, Cariola F, De Marco K, Manghisi A, Guglielmi FA, Armentano R, Lippolis G, Giorgio P, Simone C, Disciglio V. A novel STK11 gene mutation (c.388dupG, p.Glu130Glyfs∗33) in a Peutz-Jeghers family and evidence of higher gastric cancer susceptibility associated with alterations in STK11 region aa 107-170. Genes Dis 2022; 9:288-291. [PMID: 35224145 PMCID: PMC8843985 DOI: 10.1016/j.gendis.2021.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/18/2021] [Accepted: 11/07/2021] [Indexed: 11/21/2022] Open
Affiliation(s)
- Giovanna Forte
- Medical Genetics, National Institute of Gastroenterology “S. de Bellis” Research Hospital, Castellana Grotte, Bari 70013, Italy
| | - Filomena Cariola
- Medical Genetics, National Institute of Gastroenterology “S. de Bellis” Research Hospital, Castellana Grotte, Bari 70013, Italy
| | - Katia De Marco
- Medical Genetics, National Institute of Gastroenterology “S. de Bellis” Research Hospital, Castellana Grotte, Bari 70013, Italy
| | - Andrea Manghisi
- Medical Genetics, National Institute of Gastroenterology “S. de Bellis” Research Hospital, Castellana Grotte, Bari 70013, Italy
| | - Filomena Anna Guglielmi
- Medical Genetics, National Institute of Gastroenterology “S. de Bellis” Research Hospital, Castellana Grotte, Bari 70013, Italy
| | - Raffaele Armentano
- Histopathology Unit, National Institute of Gastroenterology “S. de Bellis,” Research Hospital, Castellana Grotte, Bari 70013, Italy
| | - Giuseppe Lippolis
- Department of General Surgery, National Institute of Gastroenterology “S. de Bellis” Research Hospital, Castellana Grotte, Bari 70013, Italy
| | - Pietro Giorgio
- Gastroenterology and Digestive Endoscopy Unit, National Institute of Gastroenterology “S. de Bellis” Research Hospital, Castellana Grotte, Bari 70013, Italy
| | - Cristiano Simone
- Medical Genetics, National Institute of Gastroenterology “S. de Bellis” Research Hospital, Castellana Grotte, Bari 70013, Italy
- Department of Biomedical Sciences and Human Oncology (DIMO), Medical Genetics, University of Bari Aldo Moro, Piazza Umberto I, Bari 70124, Italy
| | - Vittoria Disciglio
- Medical Genetics, National Institute of Gastroenterology “S. de Bellis” Research Hospital, Castellana Grotte, Bari 70013, Italy
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Koseoglu H, Celebi A, Galamiyeva G, Dalay N, Ozkardes H, Buyru N. No Tumor Suppressor Role for LKB1 in Prostate Cancer. DNA Cell Biol 2021; 40:1222-1229. [PMID: 34370601 DOI: 10.1089/dna.2021.0274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
To elucidate the pathogenesis of prostate diseases, following in silico analysis, the LKB1 gene was selected for further investigation. The LKB1 gene has been associated with poor prognosis and is frequently mutated in different types of cancers. In this study, 50 benign prostatic hyperplasia (BPH) and 57 prostate cancer (PCa) tissues, including matched normal tissue for the patients, were analyzed by qRT-PCR and DNA sequencing for LKB1 expression and the mutation profile, respectively. Expression of LKB1 was increased in 60.7% of the PCa tissues compared with noncancerous tissue samples (p ≤ 0.001). However, LKB1 expression was lower when compared with normal tissues in BPH (p = 0.920). Four coding sequence alterations were detected in BPH. Three silent mutations were located in codons 9, 32, and 275 and a missense mutation was observed in codon 384. Six alterations were identified in the intronic regions of the LKB1 gene in both PCa and BPH. Five mutations were observed in both patient groups. A new alteration in intron 6 was observed in a patient with PCa. The LKB1 gene may be associated with benign transformations rather than the tumors in prostate pathogenesis when its expression and mutation status are considered. However, the mechanism of LKB1 in PCa needs further studies.
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Affiliation(s)
- Hikmet Koseoglu
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Asuman Celebi
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Gunay Galamiyeva
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Nejat Dalay
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Hakan Ozkardes
- Department of Urology, Medical Faculty, Baskent University, Istanbul, Turkey
| | - Nur Buyru
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
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Holloway RW, Marignani PA. Targeting mTOR and Glycolysis in HER2-Positive Breast Cancer. Cancers (Basel) 2021; 13:2922. [PMID: 34208071 PMCID: PMC8230691 DOI: 10.3390/cancers13122922] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/09/2021] [Accepted: 06/10/2021] [Indexed: 12/18/2022] Open
Abstract
Up to one third of all breast cancers are classified as the aggressive HER2-positive subtype, which is associated with a higher risk of recurrence compared to HER2-negative breast cancers. The HER2 hyperactivity associated with this subtype drives tumor growth by up-regulation of mechanistic target of rapamycin (mTOR) pathway activity and a metabolic shift to glycolysis. Although inhibitors targeting the HER2 receptor have been successful in treating HER2-positive breast cancer, anti-HER2 therapy is associated with a high risk of recurrence and drug resistance due to stimulation of the PI3K-Akt-mTOR signaling pathway and glycolysis. Combination therapies against HER2 with inhibition of mTOR improve clinical outcomes compared to HER2 inhibition alone. Here, we review the role of the HER2 receptor, mTOR pathway, and glycolysis in HER2-positive breast cancer, along with signaling mechanisms and the efficacy of treatment strategies of HER2-positive breast cancer.
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Affiliation(s)
| | - Paola A. Marignani
- Department of Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada;
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Abstract
Hydrogen sulfide (H2S) has been considered the third gaseous signaling molecule that plays important roles in a wide range of physiological and pathological conditions. However, there has been some controversy on the role of H2S in autophagy. Recent studies indicate that a number of signaling pathways are involved in the pro-autophagy effect of H2S, such as PI3K/Akt/mTOR, AMPK/mTOR, LKB1/STRAD/MO25, and miR-30c signaling pathways. On the other hand, there are many signaling pathways that play important roles in the anti-autophagy effect of H2S, including SR-A, PI3K/SGK1/GSK3β, PI3K/AKT/mTOR, Nrf2-ROS-AMPK, AMPK/mTOR, and JNK1 signaling pathways. Novel H2S-releasing donors/drugs could be designed and identified in order to increase the therapeutic effects by mediating autophagy in human diseases. In this review, the H2S metabolism in mammals is summarized and the effects of signaling pathways in H2S-mediated autophagy are further discussed.
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Lin R, Elf S, Shan C, Kang HB, Ji Q, Zhou L, Hitosugi T, Zhang L, Zhang S, Seo JH, Xie J, Tucker M, Gu TL, Sudderth J, Jiang L, Mitsche M, DeBerardinis RJ, Wu S, Li Y, Mao H, Chen PR, Wang D, Chen GZ, Hurwitz SJ, Lonial S, Arellano ML, Khoury HJ, Khuri FR, Lee BH, Lei Q, Brat DJ, Ye K, Boggon TJ, He C, Kang S, Fan J, Chen J. 6-Phosphogluconate dehydrogenase links oxidative PPP, lipogenesis and tumour growth by inhibiting LKB1-AMPK signalling. Nat Cell Biol 2015; 17:1484-96. [PMID: 26479318 PMCID: PMC4628560 DOI: 10.1038/ncb3255] [Citation(s) in RCA: 197] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/18/2015] [Indexed: 12/18/2022]
Abstract
The oxidative pentose phosphate pathway (PPP) contributes to tumor growth, but the precise contribution of 6-phosphogluconate dehydrogenase (6PGD), the third enzyme in this pathway, to tumorigenesis remains unclear. We found that suppression of 6PGD decreased lipogenesis and RNA biosynthesis and elevated ROS levels in cancer cells, attenuating cell proliferation and tumor growth. 6PGD-mediated production of ribulose-5-phosphate (Ru-5-P) inhibits AMPK activation by disrupting the active LKB1 complex, thereby activating acetyl-CoA carboxylase 1 and lipogenesis. Ru-5-P and NADPH are thought to be precursors in RNA biosynthesis and lipogenesis, respectively; thus, our findings provide an additional link between oxidative PPP and lipogenesis through Ru-5-P-dependent inhibition of LKB1-AMPK signaling. Moreover, we identified and developed 6PGD inhibitors, Physcion and its derivative S3, that effectively inhibited 6PGD, cancer cell proliferation and tumor growth in nude mice xenografts without obvious toxicity, suggesting that 6PGD could be an anticancer target.
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Affiliation(s)
- Ruiting Lin
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Shannon Elf
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Changliang Shan
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Hee-Bum Kang
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Quanjiang Ji
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA
| | - Lu Zhou
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA
| | - Taro Hitosugi
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Liang Zhang
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA
| | - Shuai Zhang
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Jae Ho Seo
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Jianxin Xie
- Cell Signaling Technology, Inc. (CST), Danvers, Massachusetts 01923, USA
| | - Meghan Tucker
- Cell Signaling Technology, Inc. (CST), Danvers, Massachusetts 01923, USA
| | - Ting-Lei Gu
- Cell Signaling Technology, Inc. (CST), Danvers, Massachusetts 01923, USA
| | - Jessica Sudderth
- Children's Research Institute, UT Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Lei Jiang
- Children's Research Institute, UT Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Matthew Mitsche
- Eugene McDermott Center for Human Growth and Development, UT Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Ralph J DeBerardinis
- Children's Research Institute, UT Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Shaoxiong Wu
- Department of Chemistry, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Yuancheng Li
- Department of Radiology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Hui Mao
- Department of Radiology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Peng R Chen
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Dongsheng Wang
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Georgia Zhuo Chen
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Selwyn J Hurwitz
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Sagar Lonial
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Martha L Arellano
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Hanna J Khoury
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Fadlo R Khuri
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Benjamin H Lee
- Novartis Institutes for BioMedical Research, Cambridge, Massachusetts 02139, USA
| | - Qunying Lei
- School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Daniel J Brat
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Titus J Boggon
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Chuan He
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA
| | - Sumin Kang
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Jun Fan
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Jing Chen
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Andrade-Vieira R, Goguen D, Bentley HA, Bowen CV, Marignani PA. Pre-clinical study of drug combinations that reduce breast cancer burden due to aberrant mTOR and metabolism promoted by LKB1 loss. Oncotarget 2014; 5:12738-52. [PMID: 25436981 PMCID: PMC4350354 DOI: 10.18632/oncotarget.2818] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 11/24/2014] [Indexed: 02/07/2023] Open
Abstract
Cancer therapies that simultaneously target activated mammalian target of rapamycin (mTOR) and cell metabolism are urgently needed. The goal of our study was to identify therapies that effectively inhibited both mTOR activity and cancer cell metabolism in primary tumors in vivo. Using our mouse model of spontaneous breast cancer promoted by loss of LKB1 expression in an ErbB2 activated model; referred to as LKB1-/-NIC mice, we evaluated the effect of novel therapies in vivo on primary tumors. Treatment of LKB1-/-NIC mice with AZD8055 and 2-DG mono-therapies significantly reduced mammary gland tumorigenesis by inhibiting mTOR pathways and glycolytic metabolism; however simultaneous inhibition of these pathways with AZD8055/2-DG combination was significantly more effective at reducing tumor volume and burden. At the molecular level, combination treatment inhibited mTORC1/mTORC2 activity, selectively inhibited mitochondria function and blocked MAPK pro-survival signaling responsible for the ERK-p90RSK feedback loop. Our findings suggest that loss of LKB1 expression be considered a marker for metabolic dysfunction given its role in regulating AMPK and mTOR function. Finally, the outcome of our pre-clinical study confirms therapies that simultaneously target mTORC1/mTORC2 and glycolytic metabolism in cancer produce the best therapeutic outcome for the treatment of patients harboring metabolically active HER2 positive breast cancers.
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Affiliation(s)
- Rafaela Andrade-Vieira
- Department of Biochemistry and Molecular Biology, Dalhousie University, Faculty of Medicine, Halifax, Nova Scotia Canada
| | - Donna Goguen
- Department of Biochemistry and Molecular Biology, Dalhousie University, Faculty of Medicine, Halifax, Nova Scotia Canada
| | - Heidi A. Bentley
- Department of Biochemistry and Molecular Biology, Dalhousie University, Faculty of Medicine, Halifax, Nova Scotia Canada
| | | | - Paola A. Marignani
- Department of Biochemistry and Molecular Biology, Dalhousie University, Faculty of Medicine, Halifax, Nova Scotia Canada
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Veleva-Rotse BO, Smart JL, Baas AF, Edmonds B, Zhao ZM, Brown A, Klug LR, Hansen K, Reilly G, Gardner AP, Subbiah K, Gaucher EA, Clevers H, Barnes AP. STRAD pseudokinases regulate axogenesis and LKB1 stability. Neural Dev 2014; 9:5. [PMID: 24594058 PMCID: PMC4016016 DOI: 10.1186/1749-8104-9-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Accepted: 02/18/2014] [Indexed: 11/12/2022] Open
Abstract
Background Neuronal polarization is an essential step of morphogenesis and connectivity in the developing brain. The serine/threonine kinase LKB1 is a key regulator of cell polarity, metabolism, tumorigenesis, and is required for axon formation. It is allosterically regulated by two related and evolutionarily conserved pseudokinases, STe20-Related ADapters (STRADs) α and β. The roles of STRADα and STRADβ in the developing nervous system are not fully defined, nor is it known whether they serve distinct functions. Results We find that STRADα is highly spliced and appears to be the primal STRAD paralog. We report that each STRAD is sufficient for axogenesis and promoting cell survival in the developing cortex. We also reveal a reciprocal protein-stabilizing relationship in vivo between LKB1 and STRADα, whereby STRADα specifically maintains LKB1 protein levels via cytoplasmic compartmentalization. Conclusions We demonstrate a novel role for STRADβ in axogenesis and also show for the first time in vivo that STRADα, but not STRADβ, is responsible for LKB1 protein stability.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Anthony P Barnes
- Department of Pediatrics-Doernbecher, Children's Hospital, Portland, OR 97239, USA.
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9
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Andrade-Vieira R, Han JH, Marignani PA. Omega-3 polyunsaturated fatty acid promotes the inhibition of glycolytic enzymes and mTOR signaling by regulating the tumor suppressor LKB1. Cancer Biol Ther 2013; 14:1050-8. [PMID: 24025358 DOI: 10.4161/cbt.26206] [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: 12/18/2022] Open
Abstract
The omega-3 polyunsaturated fatty acids (ω3PUFAs) are a class of lipids biologically effective for the treatment of inflammatory disorders, cardiovascular disease and cancer. Patients consuming a high dietary intake of ω3PUFAs have shown a low incidence of metabolic disorders, including cancer. Although the effects of ω3PUFAs intake was shown to be involved in the prevention and treatment of these diseases, the underlying molecular mechanisms involved are not well understood. Here, we show that ω3PUFA, docosahexaenoic acid (DHA) enhanced the tumor suppressor function of LKB1. We observed that when LKB1 expressing cells are treated with DHA, there is an increase in LKB1 activity leading to phosphorylation of AMPK and inhibition of mTOR signaling. Abrogation of LKB1 in MCF-7 cells by siRNA reversed this phenotype. Furthermore, cellular metabolism was altered and ATP levels were reduced in response to DHA treatment, which was further attenuated in cells expressing LKB1. More importantly, in mammary epithelial cells expressing LKB1, the rate of glycolysis was decreased as a result of diminished expression of glycolytic enzymes. Functionally, these events lead to a decrease in the migration potential of these cells. Overall, our discovery shows for the first time that LKB1 function is enhanced in response to ω3PUFA treatment, thereby resulting in the regulation of cell metabolism.
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Affiliation(s)
- Rafaela Andrade-Vieira
- Department of Biochemistry and Molecular Biology; Faculty of Medicine; Dalhousie University; Halifax, NS Canada
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Zhang H, Photiou A, Grothey A, Stebbing J, Giamas G. The role of pseudokinases in cancer. Cell Signal 2012; 24:1173-84. [PMID: 22330072 DOI: 10.1016/j.cellsig.2012.01.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 01/27/2012] [Indexed: 01/12/2023]
Abstract
Kinases play a critical role in regulating many cellular functions including development, differentiation and proliferation. To date, over 518 proteins with kinase activity, comprising ~2-3% of total cellular proteins, have been identified from within the human kinome. Interestingly, approximately 10% of kinases are categorised as pseudokinases since they lack one or more conserved catalytic residues within their kinase domain and were originally thought to have no enzymatic activity. Recently, there has been strong evidence to suggest that some pseudokinsases can not only function as scaffold proteins, but may also possess kinase activity leading to modulation of cell signalling pathways. Altered activity of these pseudokinases can result in impaired cellular function, particularly in malignancies. In this review we are discussing recent evidence that apart from a scaffolding role, pseudokinases also orchestrate cellular processes as active kinases per se in signalling pathways of malignant cells.
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Affiliation(s)
- Hua Zhang
- Department of Cancer and Surgery, Imperial College, Hammersmith Hospital Campus, Du Cane Road, London, W12 ONN, UK
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11
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Abstract
Initially identified as the Caenorhabditis elegans PAR-4 homologue, the serine threonine kinase LKB1 is conserved throughout evolution and ubiquitously expressed. In humans, LKB1 is causally linked to the Peutz-Jeghers syndrome and is one of the most commonly mutated genes in several cancers like lung and cervical carcinomas. These observations have led to classify LKB1 as tumour suppressor gene. Although, considerable dark zones remain, an impressive leap in the understanding of LKB1 functions has been done during the last decade. Role of LKB1 as a major actor of the AMPK/mTOR pathway connecting cellular metabolism, cell growth and tumorigenesis has been extensively studied probably to the detriment of other functions of equal importance. This review will discuss about LKB1 activity regulation, its effectors and clues on their involvement in cell polarity.
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12
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Smith CD, Compton RA, Bowler JS, Kemp JT, Sudweeks SN, Thomson DM, Winder WW. Characterization of the liver kinase B1-mouse protein-25 -Ste-20-related adaptor protein complex in adult mouse skeletal muscle. J Appl Physiol (1985) 2011; 111:1622-8. [PMID: 21903876 DOI: 10.1152/japplphysiol.00160.2011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In liver, the AMP-activated protein kinase kinase (AMPKK) complex was identified as the association of liver kinase B1 (LKB1), mouse protein 25 (MO25α/β), and Ste-20-related adaptor protein (STRADα/β); however, this complex has yet to be characterized in skeletal muscle. We demonstrate the expression of the LKB1-MO25-STRAD complex in skeletal muscle, confirm the absence of mRNA splice variants, and report the relative mRNA expression levels of these proteins in control and muscle-specific LKB1 knockout (LKB1(-/-)) mouse muscle. LKB1 detection in untreated control and LKB1(-/-) muscle lysates revealed two protein bands (50 and 60 kDa), although only the heavier band was diminished in LKB1(-/-) samples [55 ± 2.5 and 13 ± 1.5 arbitrary units (AU) in control and LKB1(-/-), respectively, P < 0.01], suggesting that LKB1 is not represented at 50 kDa, as previously cited. The 60-kDa LKB1 band was further confirmed following purification using polyethylene glycol (43 ± 5 and 8.4 ± 4 AU in control and LKB1(-/-), respectively, P < 0.01) and ion-exchange fast protein liquid chromatography. Mass spectrometry confirmed LKB1 protein detection in the 60-kDa protein band, while none was detected in the 50-kDa band. Coimmunoprecipitation assays demonstrated LKB1-MO25-STRAD complex formation. Quantitative PCR revealed significantly reduced LKB1, MO25α, and STRADβ mRNA in LKB1(-/-) muscle. These findings demonstrate that the LKB1-MO25-STRAD complex is the principal AMPKK in skeletal muscle.
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Affiliation(s)
- Cody D Smith
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, Utah, USA
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13
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Abstract
In the past decade, studies of the human tumour suppressor LKB1 have uncovered a novel signalling pathway that links cell metabolism to growth control and cell polarity. LKB1 encodes a serine-threonine kinase that directly phosphorylates and activates AMPK, a central metabolic sensor. AMPK regulates lipid, cholesterol and glucose metabolism in specialized metabolic tissues, such as liver, muscle and adipose tissue. This function has made AMPK a key therapeutic target in patients with diabetes. The connection of AMPK with several tumour suppressors suggests that therapeutic manipulation of this pathway using established diabetes drugs warrants further investigation in patients with cancer.
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Affiliation(s)
- David B. Shackelford
- Dulbecco Center for Cancer Research, Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, USA 92037
| | - Reuben J. Shaw
- Dulbecco Center for Cancer Research, Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, USA 92037
- Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, CA, USA 92037
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14
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Nath-Sain S, Marignani PA. LKB1 catalytic activity contributes to estrogen receptor alpha signaling. Mol Biol Cell 2009; 20:2785-95. [PMID: 19369417 DOI: 10.1091/mbc.e08-11-1138] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The tumor suppressor serine-threonine kinase LKB1 is mutated in Peutz-Jeghers syndrome (PJS) and in epithelial cancers, including hormone-sensitive organs such as breast, ovaries, testes, and prostate. Clinical studies in breast cancer patients show low LKB1 expression is related to poor prognosis, whereas in PJS, the risk of breast cancer is similar to the risk from germline mutations in breast cancer (BRCA) 1/BRCA2. In this study, we investigate the role of LKB1 in estrogen receptor alpha (ERalpha) signaling. We demonstrate for the first time that LKB1 binds to ERalpha in the cell nucleus in which it is recruited to the promoter of ERalpha-responsive genes. Furthermore, LKB1 catalytic activity enhances ERalpha transactivation compared with LKB1 catalytically deficient mutants. The significance of our discovery is that we demonstrate for the first time a novel functional link between LKB1 and ERalpha. Our discovery places LKB1 in a coactivator role for ERalpha signaling, broadening the scientific scope of this tumor suppressor kinase and laying the groundwork for the use of LKB1 as a target for the development of new therapies against breast cancer.
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Affiliation(s)
- Suchita Nath-Sain
- Faculty of Medicine, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
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Abstract
The LKB1 serine/threonine kinase is a tumour suppressor responsible for the inherited familial cancer disorder Peutz-Jeghers syndrome and is inactivated in a large percentage of human lung cancers. LKB1 acts a master kinase, directly phosphorylating and activating a family of 14 AMPK (AMP-activated protein kinase)-related kinases which control cell metabolism, cell growth and cell polarity. In this issue of the Biochemical Journal, Hardie and colleagues discover an alternative splice form of LKB1 that alters the C-terminus of the protein containing a few known sites of post-translational regulation. Although widely expressed, the short isoform (LKB1(s)) is the sole splice isoform expressed in testes, and its expression peaks at the time of spermatid maturation. Male mice lacking the LKB1(s) isoform have dramatic defects in spermatozoa, resulting in sterility.
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