title: Relationship between doxorubicin cell sensitivity, drug-induced DNA double-strand breaks, glutathione content and P-glycoprotein in mammalian tumor cells.
abstract: We have measured the cytotoxic effect of 1 h exposure to doxorubicin (DOX) on a panel of tumor cell lines. Cellular effects were measured by monolayer colony-forming assay and a colorimetric cytotoxicity assay. As parameters of chemosensitivity we used two different end-points: the dose of DOX that reduces to 50% the number of colonies (ID50) and the dose of DOX that reduces the final optical density to 50% of the control value (IC50). There was a significant correlation between both chemosensitivity indices (r = 0.886, p = 0.0034). DOX-induced DNA double-strand breaks (dsb) were evaluated using pulsed-field gel electrophoresis (PFGE) and compared with cellular effects, P-glycoprotein expression (P-170) and intracellular glutathione (GSH) levels. Our results showed a relationship between the slope of DNA dsb dose-response curves and the percentage of cells that express P-170 (r = -0.957, p = 0.0002). Our study also detects a positive relationship between cellular chemosensitivity parameters and GSH content [ID50 versus GSH (r = 0.794, p = 0.0186), IC50 versus GSH (r = 0.790, p = 0.0198)] in our panel of cell lines.
authors.affiliation: Departamento de Radiología Medicina Física, Universidad de Granada, Spain.
authors.forename: M T
authors.initials: MT
authors.lastname: Valenzuela
authors.forename: M I
authors.initials: MI
authors.lastname: Núñez
authors.forename: M
authors.initials: M
authors.lastname: Villalobos
authors.forename: E
authors.initials: E
authors.lastname: Siles
authors.forename: N
authors.initials: N
authors.lastname: Olea
authors.forename: V
authors.initials: V
authors.lastname: Pedraza
authors.forename: T J
authors.initials: TJ
authors.lastname: McMillan
authors.forename: J M
authors.initials: JM
authors.lastname: Ruíz de Almodóvar
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis*; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D002470:Cell Survival / Q000187:drug effects; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects*; D004249:DNA Damage; D004273:DNA, Neoplasm / Q000096:biosynthesis / Q000187:drug effects*; D004317:Doxorubicin / Q000633:toxicity*; D004591:Electrophoresis, Polyacrylamide Gel; D005978:Glutathione / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D014411:Neoplastic Stem Cells; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D004273:DNA, Neoplasm; D004317:Doxorubicin; D004247:DNA; D005978:Glutathione