Folylpolyglutamate synthase and γ-glutamyl hydrolase regulate leucovorin-enhanced 5-fluorouracil anticancer activity

Etsuko Sakamoto, Sayaka Tsukioka, Shinji Oie, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Toshinori Oka, Masakazu Fukushima, Tatsuzo Oka

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Although 5-fluorouracil (5-FU) plus leucovorin (LV) is a standard chemotherapy regimen for colorectal cancer, the factors that determine the LV-mediated enhancement of the antitumor activity of 5-FU have remained unknown. We investigated the roles of folylpolyglutamate synthase (FPGS) and γ-glutamyl hydrolase (GGH), which are the main enzymes involved in folate metabolism, in the effect of LV. LV enhanced the anticancer activity of 5-FU and the level of reduced folate in human colon cancer cells. Small-interfering RNA (siRNA) transfected into DLD-1 cells to downregulate FPGS reduced the basal level of reduced folate, the folate level after LV treatment, and the enhancement of 5-fluoro-2′-deoxyuridine (FdUrd)-induced cytotoxicity elicited by LV. By contrast, the downregulation of GGH by siRNA increased cellular sensitivity to FdUrd combined with LV. These results suggest that FPGS and GGH expression levels in tumors are determinants of the efficacy of LV in enhancing the antitumor activity of 5-FU.

Original languageEnglish
Pages (from-to)801-807
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number4
Publication statusPublished - 2008 Jan 25
Externally publishedYes


  • 5-FU
  • 5-Fluorouracil
  • FPGS
  • Folylpolyglutamate synthase
  • GGH
  • LV
  • Leucovorin
  • γ-Glutamyl hydrolase

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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