title: Influence of captopril on the cellular uptake and toxic potential of microcystin-LR in non-hepatic adhesive cell lines.
abstract: Microcystin-LR (MC-LR) is a toxin produced by various cyanobacterial strains. Its cytotoxicity is due to inhibition of the protein phosphatases PP1 and PP2A, resulting in hyperphosphorylation of a number of functional and cytoskeletal proteins. To penetrate through the plasma membrane, MC-LR needs specific transporters such the organic anion-transporting polypeptides (OATP) that are highly expressed on the hepatocytes. Hence, our goal was to investigate the role of the membrane transport proteins for the cytotoxic effect of MC-LR on adhesive cell lines different from hepatocytes. We have used three cell lines--A549 (human lung carcinoma), SK-Hep-1 (human liver adenocarcinoma), FL (human amniotic normal cells), and two inhibitors of the OATP (cyclosporine A and captopril). To examine the cytotoxic effect of MC-LR we applied MTT and Neutral Red assays. In addition, a fluorescent staining of the mitochondria by JC-1 was performed. A dose-dependent cytotoxic effect was observed for the three cell lines, as this effect was most pronounced in A549. No cytotoxicity was detected when the captopril was added 2 h before treatment of the cells with MC-LR. Addition of captopril to the cells 2 h after treatment with MC-LR leads to enhancement of the cytotoxic effect. Reduced mitochondrial membrane potential after treatment with MC-LR was detected in the three cell lines, compared to untreated control cells. Results from the NR-cytotoxicity assay indicated that MC-LR does not affect the lysosomes. Captopril is an effective inhibitor of both OATP influx membrane transport proteins and the P-gp efflux pumps involved in the transport of MC-LR. It protects the cells from toxic effects of the cyanotoxin MC-LR.
authors.affiliation: Faculty of Biology, Plovdiv University, Plovdiv, Bulgaria.
authors.forename: Ivanka
authors.initials: I
authors.lastname: Teneva
authors.affiliation: Department of Clinical Science and Education, Karolinska Institutet, Södersjukhuset (KI SÖS), S1, Sjukhusbacken 10, 118 83, Stockholm, Sweden. Electronic address: dorota.klaczkowska@ki.se.
authors.forename: Dorota
authors.initials: D
authors.lastname: Klaczkowska
authors.affiliation: Faculty of Biology, Plovdiv University, Plovdiv, Bulgaria.
authors.forename: Tsvetelina
authors.initials: T
authors.lastname: Batsalova
authors.affiliation: Faculty of Biology, Plovdiv University, Plovdiv, Bulgaria.
authors.forename: Zhivka
authors.initials: Z
authors.lastname: Kostova
authors.affiliation: Faculty of Biology, Plovdiv University, Plovdiv, Bulgaria.
authors.forename: Balik
authors.initials: B
authors.lastname: Dzhambazov
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism; D000650:Amnion / Q000166:cytology / Q000378:metabolism; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000493:pharmacokinetics*; D002216:Captopril / Q000493:pharmacokinetics*; D002448:Cell Adhesion; D002460:Cell Line; D004347:Drug Interactions; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism; D008387:Marine Toxins; D026901:Membrane Transport Proteins / Q000378:metabolism; D052998:Microcystins / Q000493:pharmacokinetics*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D008387:Marine Toxins; D026901:Membrane Transport Proteins; D052998:Microcystins; D002216:Captopril; C057862:cyanoginosin LR
keywords: Captopril; Cyanobacteria; Cytotoxicity; Membrane transport proteins; Microcystin-LR; OATP