title: Microcystin-LR induces a wide variety of biochemical changes in the A549 human non-small cell lung cancer cell line: Roles for protein phosphatase 2A and its substrates.
abstract: Our previous studies have described the toxic effects of microcystin-LR (MC-LR) in various normal cell lines and human hepatoma SMMC-7721 cells, but the specific effects of MC-LR in other types of cancer cells with respect to protein phosphatase 2A (PP2A) have not been fully elaborated. A549 human lung adenocarcinoma cells have been identified to express organic anion-transporting polypeptides (OATP) involved in cellular uptake of MC-LR, and thus probably make an appropriate in vitro model to assess MC-LR's cytotoxicity. Hence, in our present study, A549 cells were treated with various concentrations of MC-LR for 24 h. The presence of MC-LR in A549 cells was confirmed, and PP2A activity, PP2A substrates, cytoskeleton, apoptosis, and proliferation were subsequently explored. The results showed that 5-10 μM MC-LR inhibited PP2A activity significantly but 0.5-1 μM MC-LR did not change PP2A activity dramatically. The inhibition could result from the hyperphosphorylation of PP2A/C at Tyr307, an elevation in the total PP2A/C expression and the dissociation of α4/PP2A/C complexes. Moreover, MC-LR led to rearrangements of filamentous actin and microtubules, which might be correlated with the hyperphosphorylation of Ezrin, VASP and HSP27 due to PP2A inhibition and mitogen-activated protein kinase (MAPK) activation. However, exposure to MC-LR for 24 h failed to trigger either apoptosis or proliferation, which might be related to PP2A-inhibition-induced hyperphosphorylation of Bcl-2 and Bad and the activation status of Akt. In conclusion, our data indicated that MC-LR induced extensive molecular and cellular alterations in A549 cells through a PP2A-centered pathway, which differed in some respects from our previous study in SMMC-7721 cells. To our knowledge, this is the first report comprehensively demonstrating the effects of MC-LR in A549 cells, and our findings provide insights into the mechanism of MC-LR toxicity in cancer cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1065-1078, 2017.
authors.affiliation: Department III of Clinical Medicine, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China.
authors.forename: Hanying
authors.identifier: http://orcid.org/0000-0002-9216-9342
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department II of Clinical Medicine, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, 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: Beilei
authors.identifier: http://orcid.org/0000-0001-9313-1154
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 environmental and occupational health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of environmental and occupational health, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, China.
authors.forename: Mingluan
authors.initials: M
authors.lastname: Xing
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 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: D000199:Actins / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D008387:Marine Toxins; D052998:Microcystins / Q000494:pharmacology*; D008870:Microtubules / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D054648:Protein Phosphatase 2 / Q000378:metabolism / Q000502:physiology*
chemical_list: D000199:Actins; D055551:HSP27 Heat-Shock Proteins; D008387:Marine Toxins; D052998:Microcystins; D020928:Mitogen-Activated Protein Kinases; D054648:Protein Phosphatase 2; C057862:cyanoginosin LR
keywords: apoptosis; cytoskeleton; microcystin-LR; proliferation; protein phosphatase 2A