title: Protein phosphatase 2A inhibition and subsequent cytoskeleton reorganization contributes to cell migration caused by microcystin-LR in human laryngeal epithelial cells (Hep-2).
abstract: The major toxic mechanism of Microcystin-LR is inhibition of the activity of protein phosphatase 2A (PP2A), resulting in a series of cytotoxic effects. Our previous studies have demonstrated that microcystin-LR (MCLR) induced very different molecular effects in normal cells and the tumor cell line SMMC7721. To further explore the MCLR toxicity mechanism in tumor cells, human laryngeal epithelial cells (Hep-2) was examined in this study. Western blot, immunofluorescence, immunoprecipitation, and transwell migration assay were used to detect the effects of MCLR on PP2A activity, PP2A substrates, cytoskeleton, and cell migration. The results showed that the protein level of PP2A subunits and the posttranslational modification of the catalytic subunit were altered and that the binding of the AC core enzyme as well as the binding of PP2A/C and α4, was also affected. As PP2A substrates, the phosphorylation of MAPK pathway members, p38, ERK1/2, and the cytoskeleton-associated proteins, Hsp27, VASP, Tau, and Ezrin were increased. Furthermore, MCLR induced reorganization of the cytoskeleton and promoted cell migration. Taken together, direct covalent binding to PP2A/C, alteration of the protein levels and posttranslational modification, as well as the binding of subunits, are the main pattern for the effects of MCLR on PP2A in Hep-2. A dose-dependent change in p-Tau and p-Ezrin due to PP2A inhibition may contribute to the changes in the cytoskeleton and be related to the cell migration in Hep-2. Our data provide a comprehensive exposition of the MCLR mechanism on tumor cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 890-903, 2017.
authors.affiliation: Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Beilei
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Jinghui
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Pu
authors.initials: P
authors.lastname: Huang
authors.affiliation: Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Kailun
authors.initials: K
authors.lastname: Xu
authors.affiliation: Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Hanying
authors.initials: H
authors.lastname: Wang
authors.affiliation: Zhejiang Center for Disease Control and Prevention, Hangzhou, 310051, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Biosystem Engineering, College of Biosystem Engineering and Food Science, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Zonglou
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Xu
mesh_terms: D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D008387:Marine Toxins; D052998:Microcystins / Q000633:toxicity*; D008840:Microfilament Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D054648:Protein Phosphatase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D016875:tau Proteins / Q000378:metabolism; D000098662:Vasodilator-Stimulated Phosphoprotein; D000099149:Ezrin
chemical_list: D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D055551:HSP27 Heat-Shock Proteins; D008387:Marine Toxins; D052998:Microcystins; D008840:Microfilament Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D010750:Phosphoproteins; D054648:Protein Phosphatase 2; D048051:p38 Mitogen-Activated Protein Kinases; D016875:tau Proteins; D000098662:Vasodilator-Stimulated Phosphoprotein; D000099149:Ezrin; C057862:cyanoginosin LR
keywords: PP2A; cytoskeleton; microcystin; migration