title: Sensitivity to microcystins: a comparative study in human cell lines with and without multidrug resistance phenotype.
abstract: Multidrug resistance (MDR) is an obstacle in cancer treatment. An understanding of how tumoral cells react to oxidants can help us elucidate the cellular mechanism involved in resistance. Microcystins are cyanobacteria hepatotoxins known to generate oxidative stress. The aim of this study was to compare the sensitivity to microcystins of human tumoral cell lines with (Lucena) and without (K562) MDR phenotype. Endpoints analyzed were effective microcystins concentration to 50% of exposed cells (EC50), antioxidant enzyme activity, lipid peroxidation, DNA damage, reactive oxygen species (ROS) concentration, and tubulin content. Lucena were more resistant and showed lower DNA damage than K562 cells (P<0.05). Although microcystins did not alter catalase activity, a higher mean value was observed in Lucena than in K562 cells. Lucena cells also showed lower ROS concentration and higher tubulin content. The higher metabolism associated with the MDR phenotype should increase ROS concentration and make for an improved antioxidant defense against the toxic effects of microcystins.
authors.affiliation: Departamento de Ciências Fisiológicas, Fundação Universidade Federal do Rio Grande (FURG), Rio Grande 96201-900, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: de Souza Votto
authors.forename: Viviane Plasse
authors.initials: VP
authors.lastname: Renon
authors.forename: João Sarkis
authors.initials: JS
authors.lastname: Yunes
authors.forename: Vivian Mary
authors.initials: VM
authors.lastname: Rumjanek
authors.forename: Márcia Alves
authors.initials: MA
authors.lastname: Marques Capella
authors.forename: Vivaldo Moura
authors.initials: VM
authors.lastname: Neto
authors.forename: Marta
authors.initials: M
authors.lastname: Sampaio de Freitas
authors.forename: Laura
authors.initials: L
authors.lastname: Alicia Geracitano
authors.forename: José María
authors.initials: JM
authors.lastname: Monserrat
authors.forename: Gilma Santos
authors.initials: GS
authors.lastname: Trindade
mesh_terms: D045744:Cell Line, Tumor; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D006801:Humans; D020014:K562 Cells; D053858:Metabolic Networks and Pathways; D052998:Microcystins / Q000494:pharmacology*; D016877:Oxidants / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism
chemical_list: D052998:Microcystins; D016877:Oxidants; D017382:Reactive Oxygen Species; D014404:Tubulin