Influence of chemotherapeutic agents and cytokines on the expression of 5-fluorouracil-associated enzymes in human colon cancer cell lines.
BACKGROUND
Several studies have demonstrated that intratumoral expression of catabolizing and anabolizing enzymes for 5-fluorouracil (5-FU) is important in the response of cancers to 5-FU-based chemotherapy. We investigated the influence of other chemotherapeutic agents or cytokines, which are often administered for enhancing the efficacy of 5-FU, on the tumoral expression of 5-FU-associated enzymes, i.e., dihydropyrimidine dehydrogenase (DPD), thymidylate synthase (TS), orotate phosphoribosyl transferase (OPRT), and thymidine phosphorylase (TP).


METHODS
Human colon cancer cell lines (HT-29, Caco-2, and DLD-1) were incubated with 5-FU and with 5-FU combined with cisplatin, camptothecin, paclitaxel, mitomycin C, interferon, or TNF-related apoptosis-inducing ligand. mRNA expression of 5-FU-associated enzymes was assessed by real-time PCR. Activity of each enzyme and intracellular 5-FU accumulation after incubation with such agents were also evaluated.


RESULTS
Each agent had a synergistic effect on the cytotoxicity of 5-FU. All chemotherapeutic agents other than cytokines induced marked alteration of the mRNA expression profile of 5-FU-associated enzymes; depression of DPD, elevation of TS, and slight suppression of OPRT and TP. In accordance with mRNA expression, enzyme activity of DPD was significantly depressed by such agents. Furthermore, although 5-FU itself increased DPD mRNA expression, a mechanism considered to be related to the acquisition of 5-FU resistance, the addition of cisplatin or camptothecin significantly inhibited the 5-FU-induced elevation of DPD.


CONCLUSIONS
5-FU-associated enzymes in colon cancer cells were greatly influenced by various chemotherapeutic agents; in particular, DPD expression was depressed. These results appear important in planning chemotherapy and also in understanding the development of adverse effects of 5-FU.
Department of Gastroenterology, Graduate School of Comprehensive Human Science, University of Tsukuba, 1-1-1, Tennoudai, Tsukuba 305-8575, Japan.
Kaori
K
Miyazaki
Takeshi
T
Shibahara
Daisuke
D
Sato
Kazuhiko
K
Uchida
Hideo
H
Suzuki
Hirofumi
H
Matsui
Akinori
A
Yanaka
Akira
A
Nakahara
Yasushi
Y
Matsuzaki
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis; D018938:Caco-2 Cells; D002166:Camptothecin / Q000494:pharmacology; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000201:enzymology*; D016207:Cytokines / Q000494:pharmacology*; D042943:Dihydrouracil Dehydrogenase (NADP) / Q000378:metabolism; D005472:Fluorouracil / Q000378:metabolism* / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D007372:Interferons / Q000494:pharmacology; D008024:Ligands; D016685:Mitomycin / Q000494:pharmacology; D009962:Orotate Phosphoribosyltransferase / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D013939:Thymidine Phosphorylase / Q000378:metabolism; D013940:Thymidylate Synthase / Q000378:metabolism
D000964:Antimetabolites, Antineoplastic; D016207:Cytokines; D008024:Ligands; D012333:RNA, Messenger; D016685:Mitomycin; D007372:Interferons; D042943:Dihydrouracil Dehydrogenase (NADP); D013940:Thymidylate Synthase; D009962:Orotate Phosphoribosyltransferase; D013939:Thymidine Phosphorylase; D017239:Paclitaxel; D002945:Cisplatin; D005472:Fluorouracil; D002166:Camptothecin