title: In vivo 5-fluorouracil-[corrected]induced apoptosis on murine thymocytes: involvement of FAS, Bax and Caspase3.
abstract: Apoptosis is a highly regulated and programmed cell breakdown process characterized by numerous changes. It was reported as the major mechanism of anticancer drug-induced cells death. Unfortunately, many of these drugs are non-specific and cause severe side effects. The effects of 5-fluorouracil (5-FU) on the apoptotic events in normal murine thymus were evaluated using an in vivo model. A single dose of 5-FU (150 mg/kg ip) was injected to CF-1 mice. A multiparametric analysis of thymic weight, cellularity, viability, architectural organization, apoptosis, DNA fragmentation, and the expression of several apoptotic proteins was evaluated in 10 days time-course study post-5-FU dosing. Total organ weights, thymocyte counts, and cell viabilities diminished drastically from the second day. The thymus architecture assessed through electron scanning microscopy revealed deep alterations and the lost of cell-cell contact between the first and the third days. DNA fragmentation and apoptotic indexes (May Grünwald Giemsa staining, double fluorescent dyes, and TdT-mediated dUTP nick-end labeling assay) revealed that cell death was maximal on the second day (three times over control). Furthermore, the pro-apoptotic proteins FAS and Bax were strongly up-regulated during the first 2 days. The aforementioned morphological and biochemical changes were also accompanied within the same period by caspase 3 activation. This study revealed that in vivo apoptosis in normal thymus after 5-FU administration is related to FAS, Bax, and Caspase 3 co-expressions under the current experimental conditions, these findings, therefore, contribute to a new insight into the molecular mechanisms involved during 5-FU administration upon the thymus and the possible events committed in the lymphophenia associated with chemotherapy.
authors.affiliation: Faculty of Medicine, Biochemistry, Northeast National University, Moreno 1240, Corrientes 3400, Argentina.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Aquino Esperanza
authors.forename: Maria V
authors.initials: MV
authors.lastname: Aguirre
authors.forename: Gualberto R
authors.initials: GR
authors.lastname: Aispuru
authors.forename: Carolina N
authors.initials: CN
authors.lastname: Lettieri
authors.forename: Julian A
authors.initials: JA
authors.lastname: Juaristi
authors.forename: Mirta A
authors.initials: MA
authors.lastname: Alvarez
authors.forename: Nora Cristina
authors.initials: NC
authors.lastname: Brandan
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism*; D004249:DNA Damage; D053938:DNA Fragmentation; D005260:Female; D005472:Fluorouracil / Q000494:pharmacology*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D013950:Thymus Gland / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism*
chemical_list: D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D051028:bcl-2-Associated X Protein; D019014:fas Receptor; D053148:Caspase 3; D005472:Fluorouracil