title: Therapeutic enhancement of S-1 with CPT-11 through down-regulation of thymidylate synthase in bladder cancer.
abstract: Thymidylate synthase (TS), a target enzyme of 5-fluorouracil (5-FU), is significantly associated with prognosis in various cancers. Recently, it has been reported that S-1, a novel 5-FU-based agent has an effect on bladder cancer. However, in cells with high TS level, S-1 did not have significant effects. Therefore, we examined whether down-regulation of TS enhanced effects of S-1 in them. First, we measured TS level in an aggressive bladder cancer cell line, KU-19-19 by enzyme-linked immunosorbent assay (ELISA) and evaluated its sensitivity to 5-FU using a small interfering RNA (siRNA) for TS. Next, we measured TS mRNA after exposure to various agents. Finally, we evaluated enhancement of cytotoxicity of S-1 by CPT-11 (7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin) which down-regulated TS in in vivo study. The median TS and dihydropyrimidine dehydrogenase (DPD) level was 53.3 ng/mg and 80.3 ng/mg in KU-19-19 cells, respectively. The 5-FU treatment in KU-19-19 cells transfected with siRNA for TS gene (TYMS) inhibited cell growth more significantly than that for nontargeting control. Down-regulation of TS was observed after exposure to SN-38 (7-ethyl-10-hydroxycamptothecin) in a dose-dependent manner. The combination treatment of 5-FU and SN-38 significantly inhibited cell growth, as compared to the single treatment. Meanwhile, in cells transfected with siRNA for TYMS, neither an additive nor a synergistic effect was observed. Also, combined S-1 and CPT-11 dramatically inhibited tumor growth, compared to S-1 or CPT-11 alone in in vivo study. In conclusion, CPT-11 down-regulated TS level and enhanced the effect of S-1. Thus, the combination therapy with S-1 and CPT-11 might be a novel modality for bladder cancer, even with high TS level.
authors.affiliation: Department of Urology, Keio University School of Medicine Tokyo, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ide
authors.forename: Eiji
authors.initials: E
authors.lastname: Kikuchi
authors.forename: Masanori
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Seiya
authors.initials: S
authors.lastname: Hattori
authors.forename: Yota
authors.initials: Y
authors.lastname: Yasumizu
authors.forename: Akira
authors.initials: A
authors.lastname: Miyajima
authors.forename: Mototsugu
authors.initials: M
authors.lastname: Oya
mesh_terms: D000818:Animals; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000633:toxicity; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004338:Drug Combinations; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D004357:Drug Synergism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D000077146:Irinotecan; D051379:Mice; D008819:Mice, Nude; D010094:Oxonic Acid / Q000008:administration & dosage / Q000494:pharmacology* / Q000633:toxicity; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D005641:Tegafur / Q000008:administration & dosage / Q000494:pharmacology* / Q000633:toxicity; D013940:Thymidylate Synthase / Q000235:genetics* / Q000378:metabolism; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000235:genetics*; D023041:Xenograft Model Antitumor Assays
chemical_list: D004338:Drug Combinations; D034741:RNA, Small Interfering; C079198:S 1 (combination); D005641:Tegafur; D010094:Oxonic Acid; D000077146:Irinotecan; D013940:Thymidylate Synthase; D002166:Camptothecin
keywords: 5-Fluorouracil; S-1; irinotecan; thymidylate synthase; urothelial carcinoma