title: Schedule-dependent cytotoxicity of 5-fluorouracil and irinotecan in p53 mutant human colon cancer.
abstract: IFL [irinotecan (CPT-11), 5-fluorouracil (5-FU), and folinic acid] is one of the treatments for metastatic colorectal cancer. We evaluated cytotoxic effects of a sequentially administered a combination of 5-FU with CPT-11 in human p53 mutant colon cancer. Sequential combination of 5-FU and CPT-11 in human colon cancer SW480 cells using a WST-8 colorimetric assay was studied. Cytotoxicity and cell cycle distribution for each drug were evaluated using an apoptosis assay and flow cytometry. Potential mechanisms of sequence-dependent cytotoxic effects were investigated using microarrays. Cytotoxicity of 5-FU (10, 100, 1000 microM) combined with subsequent use of CPT-11 (1 microM) was significantly greater than the reverse sequence of CPT-11 followed by 5-FU (p < 0.05). Following 24 hrs treatment with 5-FU (0.1-100 microM), no significant apoptosis was observed. In contrast, apoptosis was significantly induced after 24 hrs treatment with CPT-11 (1 and 10 microM). Flow cytometric analysis showed no significant difference in cell cycle distribution between different drug concentrations. We demonstrated up-regulation of 85 genes and down-regulation of 21 genes correlating with sequence-dependent cytotoxicities of 5-FU and CPT-11. The superiority of 5-FU-CPT-11 sequence was proven for p53 mutant colon cancer, SW480. Treatment with 5-FU followed by CPT-11 administration may be the optimal sequence for IFL treatment of metastatic colon cancers.
authors.affiliation: Department of Gastrointestinal and Pediatric Surgery, Division of Reparative Medicine, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
authors.forename: J
authors.initials: J
authors.lastname: Hiro
authors.forename: S
authors.initials: S
authors.lastname: Yoshiyama
authors.forename: Y
authors.initials: Y
authors.lastname: Toiyama
authors.forename: T
authors.initials: T
authors.lastname: Eguchi
authors.forename: C
authors.initials: C
authors.lastname: Miki
authors.forename: M
authors.initials: M
authors.lastname: Kusunoki
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000235:genetics*; D004334:Drug Administration Schedule; D005472:Fluorouracil / Q000008:administration & dosage* / Q000627:therapeutic use; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D000077146:Irinotecan; D002955:Leucovorin / Q000627:therapeutic use; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D000077146:Irinotecan; D002955:Leucovorin; D005472:Fluorouracil; D002166:Camptothecin