title: AMPK reverses the mesenchymal phenotype of cancer cells by targeting the Akt-MDM2-Foxo3a signaling axis.
abstract: In cancer cells, the epithelial-mesenchymal transition (EMT) confers the ability to invade basement membranes and metastasize to distant sites, establishing it as an appealing target for therapeutic intervention. Here, we report a novel function of the master metabolic kinase AMPK in suppressing EMT by modulating the Akt-MDM2-Foxo3 signaling axis. This mechanistic link was supported by the effects of siRNA-mediated knockdown and pharmacologic activation of AMPK on epithelial and mesenchymal markers in established breast and prostate cancer cells. Exposure of cells to OSU-53, a novel allosteric AMPK activator, as well as metformin and AICAR, was sufficient to reverse their mesenchymal phenotype. These effects were abrogated by AMPK silencing. Phenotypic changes were mediated by Foxo3a activation, insofar as silencing or overexpressing Foxo3a mimicked the effects of AMPK silencing or OSU-53 treatment on EMT, respectively. Mechanistically, Foxo3a activation led to the transactivation of the E-cadherin gene and repression of genes encoding EMT-inducing transcription factors. OSU-53 activated Foxo3a through two Akt-dependent pathways, one at the level of nuclear localization by blocking Akt- and IKKβ-mediated phosphorylation, and a second at the level of protein stabilization via cytoplasmic sequestration of MDM2, an E3 ligase responsible for Foxo3a degradation. The suppressive effects of OSU-53 on EMT had therapeutic implications illustrated by its ability to block invasive phenotypes in vitro and metastatic properties in vivo. Overall, our work illuminates a mechanism of EMT regulation in cancer cells mediated by AMPK, along with preclinical evidence supporting a tractable therapeutic strategy to reverse mesenchymal phenotypes associated with invasion and metastasis.
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio.
authors.forename: Chih-Chien
authors.initials: CC
authors.lastname: Chou
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio. Institute for Cancer Biology and Drug Discovery, Taipei Medical University, Taipei, Taiwan.
authors.forename: Kuen-Haur
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio.
authors.forename: I-Lu
authors.initials: IL
authors.lastname: Lai
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio.
authors.forename: Dasheng
authors.initials: D
authors.lastname: Wang
authors.affiliation: Center for Biostatistics, Wexner Medical Center and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio.
authors.forename: Xiaokui
authors.initials: X
authors.lastname: Mo
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio.
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Kulp
authors.affiliation: Division of Medical Oncology, Wexner Medical Center and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio. chen.844@osu.edu Charles.Shapiro@osumc.edu.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Shapiro
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio. Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan. chen.844@osu.edu Charles.Shapiro@osumc.edu.
authors.forename: Ching-Shih
authors.initials: CS
authors.lastname: Chen
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics*; D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology; D015820:Cadherins / Q000235:genetics; D045744:Cell Line, Tumor; D004285:Dogs; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics* / Q000502:physiology; D005260:Female; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D008297:Male; D008807:Mice, Inbred BALB C; D010641:Phenotype; D010766:Phosphorylation / Q000235:genetics; D011471:Prostatic Neoplasms / Q000235:genetics / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics*
chemical_list: D015820:Cadherins; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases