title: Oxidative stress, cell cycle arrest and differentiation contribute toward the antiproliferative action of BSO and calcitriol on Caco-2 cells.
abstract: The prognosis and incidence of colon cancer are linked to vitamin D3 serum levels. To evaluate the effects of D,L-buthionine-S,R-sulfoximine (BSO), 1,25(OH)2D3 and their combination on intestinal Caco-2 cell growth, to elucidate the possible cellular mechanisms involved in their antiproliferative action, and to determine whether BSO acts as a sensitizer to 1,25(OH)2D3 treatment, enabling minimization of the toxic effects caused by high doses of the steroid. Human colon cancer Caco-2 cells were treated with 1,25(OH)2D3, BSO, both, or vehicle. Cell proliferation was evaluated by crystal violet staining. Cell cycle and mitochondrial membrane potential were measured by flow cytometry. Total glutathione, catalase, superoxide dismutase, superoxide anion levels, and alkaline phosphatase activities were analyzed by spectrophotometry. DNA fragmentation was evaluated using the terminal dUTP nick end labeling assay. BSO and 1,25(OH)2D3 inhibited Caco-2 cell growth, an effect that was higher with the combined treatment. The antiproliferative effect produced by the combination could be protected by ascorbic acid. BSO plus 1,25(OH)2D3 induced cell cycle arrest and suppressed cell division. Total glutathione decreased and superoxide anion increased with BSO and BSO plus 1,25(OH)2D3. Catalase activity increased with the combined treatment. Mitochondrial membrane potential and alkaline phosphatase activity were altered by 1,25(OH)2D3 alone or plus BSO. The percentage of terminal dUTP nick end labeling-positive cells was increased. BSO increases the antiproliferative effect of 1,25(OH)2D3 on Caco-2 cells through induction of oxidative stress, which occurs simultaneously with DNA breakage. The antioxidant system can partially compensate the damage induced by BSO plus 1,25(OH)2D3. Cell differentiation induction is also involved in the response to the combined treatment.
authors.affiliation: aDr Fernando Cañas Lab, Biochemistry and Molecular Biology, School of Medicine, National Research Institute of Health Science (INICSA), National Research Council of Science and Technology (CONICET), National University of Córdoba (UNC) bClinical Biochemistry, Investigation Center of Clinical Biochemistry and Immunology (CIBICI-CONICET), Chemistry Faculty, UNC, Córdoba, Argentina.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Liaudat
authors.forename: Luciana P
authors.initials: LP
authors.lastname: Bohl
authors.forename: Nori G
authors.initials: NG
authors.lastname: Tolosa de Talamoni
authors.forename: Belkys
authors.initials: B
authors.lastname: Maletto
authors.forename: María C
authors.initials: MC
authors.lastname: Pistoresi-Palencia
authors.forename: Gabriela
authors.initials: G
authors.lastname: Picotto
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D019328:Buthionine Sulfoximine / Q000494:pharmacology*; D018938:Caco-2 Cells; D002117:Calcitriol / Q000494:pharmacology*; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D053938:DNA Fragmentation / Q000187:drug effects; D004357:Drug Synergism; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*
chemical_list: D000970:Antineoplastic Agents; D019328:Buthionine Sulfoximine; D000469:Alkaline Phosphatase; D002117:Calcitriol