title: AMPK Inhibits the Stimulatory Effects of TGF-β on Smad2/3 Activity, Cell Migration, and Epithelial-to-Mesenchymal Transition.
abstract: AMP-activated protein kinase (AMPK), an important downstream effector of the tumor suppressor liver kinase 1 (LKB1) and pharmacologic target of metformin, is well known to exert a preventive and inhibitory effect on tumorigenesis; however, its role in cancer progression and metastasis has not been well characterized. The present study investigates the potential roles of AMPK in inhibiting cancer-cell migration and epithelial-to-mesenchymal transition (EMT) by regulating the canonical transforming growth factor β (TGF-β) signaling pathway, an important promoting factor for cancer progression. Our results showed that activation of AMPK by metformin inhibited TGF-β-induced Smad2/3 phosphorylation in cancer cells in a dose-dependent manner. The effect of metformin is dependent on the presence of LKB1. A similar effect was obtained by expressing a constitutive active mutant of AMPKα1 subunit, whereas the expression of a dominant negative mutant of AMPKα1 or ablation of AMPKα subunits greatly enhanced TGF-β stimulation of Smad2/3 phosphorylation. As a consequence, expression of genes downstream of Smad2/3, including plasminogen activator inhibitor-1, fibronectin, and connective tissue growth factor, was suppressed by metformin in a LKB1-dependent fashion. In addition, metformin blocked TGF-β-induced inteleukin-6 expression through both LKB1-dependent and -independent mechanisms. Our results also indicate that activation of LKB1/AMPK inhibits TGF-β-stimulated cancer cell migration. Finally, TGF-β induction of EMT was inhibited by phenformin and enhanced by knockdown of LKB1 expression with shRNA. Together, our data suggest that AMPK could be a drug target for controlling cancer progression and metastasis.
authors.affiliation: Graduate Program of Clinical Medicine, School of Basic Medical Sciences (H.L, N.-S.L., H.H., Y.Y., Z.L.), Research Institute of Digestive Diseases, and Department of Gastroenterology, the First Affiliated Hospital (L.L., D.H., N.L.); Nanchang University, Nanchang, Jiangxi and Graduate Program in Biological Sciences, Northeastern University (S.S.) and Department of Biochemistry, Boston University School of Medicine (H.L., H.H., Y.Y. Z.L.), Boston, Massachusetts.
authors.forename: Hui
authors.initials: H
authors.lastname: Lin
authors.affiliation: Graduate Program of Clinical Medicine, School of Basic Medical Sciences (H.L, N.-S.L., H.H., Y.Y., Z.L.), Research Institute of Digestive Diseases, and Department of Gastroenterology, the First Affiliated Hospital (L.L., D.H., N.L.); Nanchang University, Nanchang, Jiangxi and Graduate Program in Biological Sciences, Northeastern University (S.S.) and Department of Biochemistry, Boston University School of Medicine (H.L., H.H., Y.Y. Z.L.), Boston, Massachusetts.
authors.forename: Nianshuang
authors.initials: N
authors.lastname: Li
authors.affiliation: Graduate Program of Clinical Medicine, School of Basic Medical Sciences (H.L, N.-S.L., H.H., Y.Y., Z.L.), Research Institute of Digestive Diseases, and Department of Gastroenterology, the First Affiliated Hospital (L.L., D.H., N.L.); Nanchang University, Nanchang, Jiangxi and Graduate Program in Biological Sciences, Northeastern University (S.S.) and Department of Biochemistry, Boston University School of Medicine (H.L., H.H., Y.Y. Z.L.), Boston, Massachusetts.
authors.forename: Huan
authors.initials: H
authors.lastname: He
authors.affiliation: Graduate Program of Clinical Medicine, School of Basic Medical Sciences (H.L, N.-S.L., H.H., Y.Y., Z.L.), Research Institute of Digestive Diseases, and Department of Gastroenterology, the First Affiliated Hospital (L.L., D.H., N.L.); Nanchang University, Nanchang, Jiangxi and Graduate Program in Biological Sciences, Northeastern University (S.S.) and Department of Biochemistry, Boston University School of Medicine (H.L., H.H., Y.Y. Z.L.), Boston, Massachusetts.
authors.forename: Ying
authors.initials: Y
authors.lastname: Ying
authors.affiliation: Graduate Program of Clinical Medicine, School of Basic Medical Sciences (H.L, N.-S.L., H.H., Y.Y., Z.L.), Research Institute of Digestive Diseases, and Department of Gastroenterology, the First Affiliated Hospital (L.L., D.H., N.L.); Nanchang University, Nanchang, Jiangxi and Graduate Program in Biological Sciences, Northeastern University (S.S.) and Department of Biochemistry, Boston University School of Medicine (H.L., H.H., Y.Y. Z.L.), Boston, Massachusetts.
authors.forename: Shashank
authors.initials: S
authors.lastname: Sunkara
authors.affiliation: Graduate Program of Clinical Medicine, School of Basic Medical Sciences (H.L, N.-S.L., H.H., Y.Y., Z.L.), Research Institute of Digestive Diseases, and Department of Gastroenterology, the First Affiliated Hospital (L.L., D.H., N.L.); Nanchang University, Nanchang, Jiangxi and Graduate Program in Biological Sciences, Northeastern University (S.S.) and Department of Biochemistry, Boston University School of Medicine (H.L., H.H., Y.Y. Z.L.), Boston, Massachusetts.
authors.forename: Lingyu
authors.initials: L
authors.lastname: Luo
authors.affiliation: Graduate Program of Clinical Medicine, School of Basic Medical Sciences (H.L, N.-S.L., H.H., Y.Y., Z.L.), Research Institute of Digestive Diseases, and Department of Gastroenterology, the First Affiliated Hospital (L.L., D.H., N.L.); Nanchang University, Nanchang, Jiangxi and Graduate Program in Biological Sciences, Northeastern University (S.S.) and Department of Biochemistry, Boston University School of Medicine (H.L., H.H., Y.Y. Z.L.), Boston, Massachusetts.
authors.forename: Nonghua
authors.initials: N
authors.lastname: Lv
authors.affiliation: Graduate Program of Clinical Medicine, School of Basic Medical Sciences (H.L, N.-S.L., H.H., Y.Y., Z.L.), Research Institute of Digestive Diseases, and Department of Gastroenterology, the First Affiliated Hospital (L.L., D.H., N.L.); Nanchang University, Nanchang, Jiangxi and Graduate Program in Biological Sciences, Northeastern University (S.S.) and Department of Biochemistry, Boston University School of Medicine (H.L., H.H., Y.Y. Z.L.), Boston, Massachusetts zluo@bu.edu hdq0515@163.com.
authors.forename: Deqiang
authors.initials: D
authors.lastname: Huang
authors.affiliation: Graduate Program of Clinical Medicine, School of Basic Medical Sciences (H.L, N.-S.L., H.H., Y.Y., Z.L.), Research Institute of Digestive Diseases, and Department of Gastroenterology, the First Affiliated Hospital (L.L., D.H., N.L.); Nanchang University, Nanchang, Jiangxi and Graduate Program in Biological Sciences, Northeastern University (S.S.) and Department of Biochemistry, Boston University School of Medicine (H.L., H.H., Y.Y. Z.L.), Boston, Massachusetts zluo@bu.edu hdq0515@163.com.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Luo
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D051899:Smad2 Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051900:Smad3 Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; D055372:AMP-Activated Protein Kinases