Teixeira 2013 Thesis Universidade Federal do Rio de Janeiro - Brazil
|Teixeira CAA (2013) Mechanisms of antitumoral effects of direct electric current: an in vitro study in lung adenocarcinoma. Thesis Universidade Federal do Rio de Janeiro - Brazil 345pp.|
Abstract: Electrochemical Therapy (ETT) consists of treatment of solid tumors with low-intensity direct electric currents (CE), a therapeutic approach with several successful clinical reports worldwide. However, this technique lacks characterization of its molecular and biochemical mechanisms of action. The aim of the present work was to study the effects of CE treatment on biochemical and morphological features of the A549 human lung cancer cell line. A549 cells were treated using an in vitro model that allows the treatment of cells with the anodic flow (FA) generated by CE. In order to verify the acute and late FA damage, the cells were analyzed immediately and after progressive times of post-treatment. Cell viability was assessed by MTT and trypan blue dye exclusion methods. Apoptosis was investigated by caspase-3 activity and mitochondrial transmembrane potential dissipation using a colorimetric assay and flow cytometry with rhodamine-123, respectively. Cell morphology was analyzed by optical and transmission electron microscopy and lipid droplets were studied by morphometric analysis and X-ray qualitative elemental microanalysis of the thin sections. Mitochondrial respiratory function was studied by cellular oxygen consumption determination using high resolution respirometry. A549 cell viability decreased immediately after treatment in a dose-dependent manner. Additionally, a significant drop in cell viability was observed between 18 and 24 h after treatment, which was accompanied by an increase in both caspase-3 activity and number of cells with reduced mitochondrial transmembrane potential. Immediately after treatment, highresolution respirometry and transmission electron microscopy revealed marked functional impairment and ultrastructural damage of cellular mitochondria. Conversely, 24 h after treatment, the cells presented enhanced respiratory capacity and significantly increased non-mitochondrial oxygen consumption, despite a wellpreserved mitochondrial ultrastructure. In addition, these cells presented an increased number of lipid bodies, rich in unsaturated lipids, which can be related to an augment ix of fatty acids or eicosanoid storage 24 h after CE treatment. Our data show that AF produces remarkable late effects, independent from continuous contact with CE or its electrolysis products, including caspase-3-related apoptosis, alterations in cellular oxygen metabolism and lipid content. These mechanisms are described here in A549 lung cancer cells for the first time and are possibly involved with antitumoral effects of ETT.
• Keywords: Electrochemical Therapy, A549 Human Lung Cancer, Direct Electric Current, Mitochondria, Apoptosis, Oxidative Phosphorylation, Lipid Bodies
Labels: MiParea: Respiration Pathology: Cancer
Organism: Human Tissue;cell: Lung;gill, Other cell lines