title: Cytotoxic effects of pemetrexed in gastric cancer cells.
abstract: Pemetrexed is a newly developed multitargeted antifolate with promising clinical activity in many solid tumors including gastric cancer. The aim of the present study was to evaluate the cytotoxicity of pemetrexed and its mode of interaction with cisplatin in gastric cancer cell lines, and to identify genes associated with sensitivity to pemetrexed. The cytotoxic activity of pemetrexed was assessed by tetrazolium-based colorimetric assay (MTT assay) and the interaction between pemetrexed and cisplatin was evaluated by the isobologram method. Western immunoblotting and real time RT-PCR analysis of thymidylate synthase (TS), folylpoly-gamma-glutamate synthetase (FPGS) and reduced folate carrier (RFC1) were performed in order to determine whether sensitivity to pemetrexed would be predictable by protein or mRNA expression levels. Pemetrexed was more cytotoxic than 5-fluorouracil, with IC50 between 17 and 310 nM in most of the gastric cancer cell lines examined and the pemetrexed/cisplatin combination resulted in additive or synergistic interaction. The protein expressions of TS, FPGS, and RFC1 were significantly associated with IC50 for 5-fluorouracil, but no such association was found for pemetrexed chemosensitivity. The mRNA expressions of RFC1, FPGS and other target and resistance related genes revealed no significant association with pemetrexed sensitivity. In conclusion, pemetrexed is active against gastric cancer cell lines and the pemetrexed/cisplatin combination showed a synergistic or additive interaction, supporting its clinical use in gastric cancer. Drug sensitivity toward pemetrexed could not be predicted by the expressions of TS, RFC1, or FPGS and we suggest that it is determined by interactions between multiple genes.
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, 28, Yongon-Dong, Chongno-Gu, Seoul.
authors.forename: Jee Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Keun-Wook
authors.initials: KW
authors.lastname: Lee
authors.forename: Yeonjoo
authors.initials: Y
authors.lastname: Jung
authors.forename: Tai Young
authors.initials: TY
authors.lastname: Kim
authors.forename: Hye Seon
authors.initials: HS
authors.lastname: Ham
authors.forename: Hyun-Soon
authors.initials: HS
authors.lastname: Jong
authors.forename: Kyung Hae
authors.initials: KH
authors.lastname: Jung
authors.forename: Seock-Ah
authors.initials: SA
authors.lastname: Im
authors.forename: Tae-You
authors.initials: TY
authors.lastname: Kim
authors.forename: Noe Kyeong
authors.initials: NK
authors.lastname: Kim
authors.forename: Yung-Jue
authors.initials: YJ
authors.lastname: Bang
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D015153:Blotting, Western; D016923:Cell Death; D004249:DNA Damage; D004260:DNA Repair; D019008:Drug Resistance, Neoplasm; D005786:Gene Expression Regulation / Q000187:drug effects*; D005971:Glutamates / Q000494:pharmacology*; D006147:Guanine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006801:Humans; D026901:Membrane Transport Proteins / Q000096:biosynthesis / Q000502:physiology; D000068437:Pemetrexed; D010453:Peptide Synthases / Q000096:biosynthesis / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics / Q000473:pathology*; D013940:Thymidylate Synthase / Q000096:biosynthesis / Q000502:physiology; D014407:Tumor Cells, Cultured
chemical_list: D000964:Antimetabolites, Antineoplastic; D005971:Glutamates; D026901:Membrane Transport Proteins; C120043:SLC19A2 protein, human; D000068437:Pemetrexed; D006147:Guanine; D013940:Thymidylate Synthase; D010453:Peptide Synthases; C023103:folylpolyglutamate synthetase