The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform

Masakazu Fukushima - One of the best experts on this subject based on the ideXlab platform.

  • in vivo evidence for a significant role of Folylpolyglutamate Synthase in combined chemotherapy with oral fluoropyrimidine uft or s 1 and leucovorin
    Oncology Reports, 2011
    Co-Authors: Sayaka Tsukioka, Etsuko Sakamoto, Hiroaki Tsujimoto, Fumio Nakagawa, Hitoshi Saito, Junji Uchida, Mamoru Kiniwa, Masakazu Fukushima
    Abstract:

    : Combined chemotherapy with 5-fluorouracil and leucovorin (LV) has been widely used for the treatment of patients with colorectal cancer. Given that LV effects are attributable to increased levels of reduced folate in cancer cells, we attempted here to show the in vivo role of Folylpolyglutamate synthetase (FPGS), which stabilizes intracellular reduced folate, in the anticancer activities of oral fluoropyrimidines, UFT or S-1, combined with LV. To this end, HCT-15 human colon cancer cells were knocked down for FPGS expression by RNA interference. The cell line stably expressing FPGS shRNA (FPGS shRNA HCT-15) was cloned and transferred subcutaneously into nude mice fed a low-folate diet. FPGS shRNA HCT-15 tumors expressed a significantly lower level of FPGS at protein and mRNA levels than parental HCT-15 cells, and the levels of reduced folate in FPGS shRNA HCT-15 tumors became 57% of those in parent after a single administration of 10 mg/kg of LV. Notably, FPGS downregulation did not affect the tumor growth or sensitivity to fluoropyrimidine. Importantly, we observed that LV given for 14 days failed to enhance the anticancer effects of UFT and S-1 in FPGS shRNA HCT-15. This was in keeping with the results that LV did not increase the ternary complex of TS, FdUMP and reduced folate. In conclusion, the present results provide in vivo evidence that intratumor FPGS plays an important role in the efficacy of oral fluoropyrimidine plus LV therapy for colorectal cancer.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Cancer Research, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    2815 5-Fluorouracil (5-FU) plus leucovorin (LV) is a standard chemotherapy regimen for colorectal cancer. 5-FU exerts its anticancer activity mainly by inhibiting thymidylate Synthase (TS) via the formation of a ternary complex of TS, 5,10-methylenetetrahydrofolate (CH 2 THF) and 5-fluoro-29-deoxyuridine 59-monophosphate (FdUMP), which is the active form of 5-FU. Although LV enhances the antitumor activity of 5-FU by supplying CH 2 THF and stabilizing the ternary complex, the factors that determine the LV-mediated enhancement of the effect 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 in human colon cancer cell lines. 5-FU-based drug S-1 (6.9 mg/kg) and LV (20 mg/kg) were administered orally for 14 consecutive days to nude mice bearing human colon tumor xenografts COL-1 and KM20C. LV significantly enhanced the inhibitory effect of S-1 on COL-1 tumor growth ( P 2 THF and its direct precursor tetrahydrofolate (THF)) in both tumors ( P P P 3 H] folate level after the addition of [ 3 H] LV in cells treated with FPGS siRNA was reduced by 76% compared with cells treated with control siRNA. On the other hand, treatment with GGH siRNA tended to increase the [ 3 H] folate level compared with cells treated with control siRNA. The downregulation of FPGS by siRNA reduced the enhancement of FdUrd -induced cytotoxicity elicited by LV, whereas the downregulation of GGH by siRNA increased cellular sensitivity to FdUrd combined with LV. These results indicate that the expression of FPGS and GGH within tumor cells regulated the effectiveness of LV in enhancing the antitumor activity of 5-FU, by regulating folate levels. These results also suggest that the levels of FPGS and GGH expression in tumors could predict the effectiveness of LV in combination with 5-FU chemotherapy for colorectal cancer.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Biochemical and Biophysical Research Communications, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    Abstract 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.

Etsuko Sakamoto - One of the best experts on this subject based on the ideXlab platform.

  • in vivo evidence for a significant role of Folylpolyglutamate Synthase in combined chemotherapy with oral fluoropyrimidine uft or s 1 and leucovorin
    Oncology Reports, 2011
    Co-Authors: Sayaka Tsukioka, Etsuko Sakamoto, Hiroaki Tsujimoto, Fumio Nakagawa, Hitoshi Saito, Junji Uchida, Mamoru Kiniwa, Masakazu Fukushima
    Abstract:

    : Combined chemotherapy with 5-fluorouracil and leucovorin (LV) has been widely used for the treatment of patients with colorectal cancer. Given that LV effects are attributable to increased levels of reduced folate in cancer cells, we attempted here to show the in vivo role of Folylpolyglutamate synthetase (FPGS), which stabilizes intracellular reduced folate, in the anticancer activities of oral fluoropyrimidines, UFT or S-1, combined with LV. To this end, HCT-15 human colon cancer cells were knocked down for FPGS expression by RNA interference. The cell line stably expressing FPGS shRNA (FPGS shRNA HCT-15) was cloned and transferred subcutaneously into nude mice fed a low-folate diet. FPGS shRNA HCT-15 tumors expressed a significantly lower level of FPGS at protein and mRNA levels than parental HCT-15 cells, and the levels of reduced folate in FPGS shRNA HCT-15 tumors became 57% of those in parent after a single administration of 10 mg/kg of LV. Notably, FPGS downregulation did not affect the tumor growth or sensitivity to fluoropyrimidine. Importantly, we observed that LV given for 14 days failed to enhance the anticancer effects of UFT and S-1 in FPGS shRNA HCT-15. This was in keeping with the results that LV did not increase the ternary complex of TS, FdUMP and reduced folate. In conclusion, the present results provide in vivo evidence that intratumor FPGS plays an important role in the efficacy of oral fluoropyrimidine plus LV therapy for colorectal cancer.

  • Molecular determinants of folate levels after leucovorin administration in colorectal cancer
    Cancer Chemotherapy and Pharmacology, 2010
    Co-Authors: Sotaro Sadahiro, Etsuko Sakamoto, Sayaka Tsukioka, Toshiyuki Suzuki, Yuji Maeda, Akira Tanaka, Kyoji Ogoshi, Akemi Kamijo, Chieko Murayama, Yousuke Fukui
    Abstract:

    Purpose Oral leucovorin (LV) is used with uracil/tegafur (UFT) in the treatment of colorectal cancer (CRC). In order to find the factors related to the efficacy of LV in enhancing the antitumour effect of UFT, we investigated the relationships between the reduced folate levels in the CRC tissue after LV administration and the gene-expression levels of folate-metabolizing enzymes and folate transporters. Methods The subjects were 60 CRC patients, scheduled to undergo surgery. The control group ( n  = 30) did not receive LV. Three groups ( n  = 10 for each) received a single dose of oral LV at 25 mg, 4, 12 or 18 h before surgery (LV 4 h, LV 12 h or LV 18 h groups, respectively). The reduced folate levels in plasma and tissues were measured by high-performance liquid chromatography (HPLC) or a thymidylate Synthase-FdUMP binding assay, respectively. The intratumoral expression levels of 34 genes were quantitatively evaluated with a real-time polymerase chain reaction (RT-PCR) assay. Results The reduced folate levels persisted for a longer period of time in the CRC tissue than in the plasma after LV administration. A multivariate logistic regression analysis revealed that high Folylpolyglutamate Synthase (FPGS) gene expression, low γ-glutamyl hydrolase (GGH) gene expression and low ATP-binding cassette sub-family C, number 1 (ABCC1) gene expression in CRC tissues were predictive factors for a high reduced folate level after LV administration. Conclusions The expression level of FPGS, GGH and ABCC1 in CRC tissues could predict the reduced folate level after LV administration, and these factors may determine the efficacy of LV treatment.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Cancer Research, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    2815 5-Fluorouracil (5-FU) plus leucovorin (LV) is a standard chemotherapy regimen for colorectal cancer. 5-FU exerts its anticancer activity mainly by inhibiting thymidylate Synthase (TS) via the formation of a ternary complex of TS, 5,10-methylenetetrahydrofolate (CH 2 THF) and 5-fluoro-29-deoxyuridine 59-monophosphate (FdUMP), which is the active form of 5-FU. Although LV enhances the antitumor activity of 5-FU by supplying CH 2 THF and stabilizing the ternary complex, the factors that determine the LV-mediated enhancement of the effect 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 in human colon cancer cell lines. 5-FU-based drug S-1 (6.9 mg/kg) and LV (20 mg/kg) were administered orally for 14 consecutive days to nude mice bearing human colon tumor xenografts COL-1 and KM20C. LV significantly enhanced the inhibitory effect of S-1 on COL-1 tumor growth ( P 2 THF and its direct precursor tetrahydrofolate (THF)) in both tumors ( P P P 3 H] folate level after the addition of [ 3 H] LV in cells treated with FPGS siRNA was reduced by 76% compared with cells treated with control siRNA. On the other hand, treatment with GGH siRNA tended to increase the [ 3 H] folate level compared with cells treated with control siRNA. The downregulation of FPGS by siRNA reduced the enhancement of FdUrd -induced cytotoxicity elicited by LV, whereas the downregulation of GGH by siRNA increased cellular sensitivity to FdUrd combined with LV. These results indicate that the expression of FPGS and GGH within tumor cells regulated the effectiveness of LV in enhancing the antitumor activity of 5-FU, by regulating folate levels. These results also suggest that the levels of FPGS and GGH expression in tumors could predict the effectiveness of LV in combination with 5-FU chemotherapy for colorectal cancer.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Biochemical and Biophysical Research Communications, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    Abstract 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.

Sayaka Tsukioka - One of the best experts on this subject based on the ideXlab platform.

  • in vivo evidence for a significant role of Folylpolyglutamate Synthase in combined chemotherapy with oral fluoropyrimidine uft or s 1 and leucovorin
    Oncology Reports, 2011
    Co-Authors: Sayaka Tsukioka, Etsuko Sakamoto, Hiroaki Tsujimoto, Fumio Nakagawa, Hitoshi Saito, Junji Uchida, Mamoru Kiniwa, Masakazu Fukushima
    Abstract:

    : Combined chemotherapy with 5-fluorouracil and leucovorin (LV) has been widely used for the treatment of patients with colorectal cancer. Given that LV effects are attributable to increased levels of reduced folate in cancer cells, we attempted here to show the in vivo role of Folylpolyglutamate synthetase (FPGS), which stabilizes intracellular reduced folate, in the anticancer activities of oral fluoropyrimidines, UFT or S-1, combined with LV. To this end, HCT-15 human colon cancer cells were knocked down for FPGS expression by RNA interference. The cell line stably expressing FPGS shRNA (FPGS shRNA HCT-15) was cloned and transferred subcutaneously into nude mice fed a low-folate diet. FPGS shRNA HCT-15 tumors expressed a significantly lower level of FPGS at protein and mRNA levels than parental HCT-15 cells, and the levels of reduced folate in FPGS shRNA HCT-15 tumors became 57% of those in parent after a single administration of 10 mg/kg of LV. Notably, FPGS downregulation did not affect the tumor growth or sensitivity to fluoropyrimidine. Importantly, we observed that LV given for 14 days failed to enhance the anticancer effects of UFT and S-1 in FPGS shRNA HCT-15. This was in keeping with the results that LV did not increase the ternary complex of TS, FdUMP and reduced folate. In conclusion, the present results provide in vivo evidence that intratumor FPGS plays an important role in the efficacy of oral fluoropyrimidine plus LV therapy for colorectal cancer.

  • Molecular determinants of folate levels after leucovorin administration in colorectal cancer
    Cancer Chemotherapy and Pharmacology, 2010
    Co-Authors: Sotaro Sadahiro, Etsuko Sakamoto, Sayaka Tsukioka, Toshiyuki Suzuki, Yuji Maeda, Akira Tanaka, Kyoji Ogoshi, Akemi Kamijo, Chieko Murayama, Yousuke Fukui
    Abstract:

    Purpose Oral leucovorin (LV) is used with uracil/tegafur (UFT) in the treatment of colorectal cancer (CRC). In order to find the factors related to the efficacy of LV in enhancing the antitumour effect of UFT, we investigated the relationships between the reduced folate levels in the CRC tissue after LV administration and the gene-expression levels of folate-metabolizing enzymes and folate transporters. Methods The subjects were 60 CRC patients, scheduled to undergo surgery. The control group ( n  = 30) did not receive LV. Three groups ( n  = 10 for each) received a single dose of oral LV at 25 mg, 4, 12 or 18 h before surgery (LV 4 h, LV 12 h or LV 18 h groups, respectively). The reduced folate levels in plasma and tissues were measured by high-performance liquid chromatography (HPLC) or a thymidylate Synthase-FdUMP binding assay, respectively. The intratumoral expression levels of 34 genes were quantitatively evaluated with a real-time polymerase chain reaction (RT-PCR) assay. Results The reduced folate levels persisted for a longer period of time in the CRC tissue than in the plasma after LV administration. A multivariate logistic regression analysis revealed that high Folylpolyglutamate Synthase (FPGS) gene expression, low γ-glutamyl hydrolase (GGH) gene expression and low ATP-binding cassette sub-family C, number 1 (ABCC1) gene expression in CRC tissues were predictive factors for a high reduced folate level after LV administration. Conclusions The expression level of FPGS, GGH and ABCC1 in CRC tissues could predict the reduced folate level after LV administration, and these factors may determine the efficacy of LV treatment.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Cancer Research, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    2815 5-Fluorouracil (5-FU) plus leucovorin (LV) is a standard chemotherapy regimen for colorectal cancer. 5-FU exerts its anticancer activity mainly by inhibiting thymidylate Synthase (TS) via the formation of a ternary complex of TS, 5,10-methylenetetrahydrofolate (CH 2 THF) and 5-fluoro-29-deoxyuridine 59-monophosphate (FdUMP), which is the active form of 5-FU. Although LV enhances the antitumor activity of 5-FU by supplying CH 2 THF and stabilizing the ternary complex, the factors that determine the LV-mediated enhancement of the effect 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 in human colon cancer cell lines. 5-FU-based drug S-1 (6.9 mg/kg) and LV (20 mg/kg) were administered orally for 14 consecutive days to nude mice bearing human colon tumor xenografts COL-1 and KM20C. LV significantly enhanced the inhibitory effect of S-1 on COL-1 tumor growth ( P 2 THF and its direct precursor tetrahydrofolate (THF)) in both tumors ( P P P 3 H] folate level after the addition of [ 3 H] LV in cells treated with FPGS siRNA was reduced by 76% compared with cells treated with control siRNA. On the other hand, treatment with GGH siRNA tended to increase the [ 3 H] folate level compared with cells treated with control siRNA. The downregulation of FPGS by siRNA reduced the enhancement of FdUrd -induced cytotoxicity elicited by LV, whereas the downregulation of GGH by siRNA increased cellular sensitivity to FdUrd combined with LV. These results indicate that the expression of FPGS and GGH within tumor cells regulated the effectiveness of LV in enhancing the antitumor activity of 5-FU, by regulating folate levels. These results also suggest that the levels of FPGS and GGH expression in tumors could predict the effectiveness of LV in combination with 5-FU chemotherapy for colorectal cancer.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Biochemical and Biophysical Research Communications, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    Abstract 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.

Hiroaki Tsujimoto - One of the best experts on this subject based on the ideXlab platform.

  • in vivo evidence for a significant role of Folylpolyglutamate Synthase in combined chemotherapy with oral fluoropyrimidine uft or s 1 and leucovorin
    Oncology Reports, 2011
    Co-Authors: Sayaka Tsukioka, Etsuko Sakamoto, Hiroaki Tsujimoto, Fumio Nakagawa, Hitoshi Saito, Junji Uchida, Mamoru Kiniwa, Masakazu Fukushima
    Abstract:

    : Combined chemotherapy with 5-fluorouracil and leucovorin (LV) has been widely used for the treatment of patients with colorectal cancer. Given that LV effects are attributable to increased levels of reduced folate in cancer cells, we attempted here to show the in vivo role of Folylpolyglutamate synthetase (FPGS), which stabilizes intracellular reduced folate, in the anticancer activities of oral fluoropyrimidines, UFT or S-1, combined with LV. To this end, HCT-15 human colon cancer cells were knocked down for FPGS expression by RNA interference. The cell line stably expressing FPGS shRNA (FPGS shRNA HCT-15) was cloned and transferred subcutaneously into nude mice fed a low-folate diet. FPGS shRNA HCT-15 tumors expressed a significantly lower level of FPGS at protein and mRNA levels than parental HCT-15 cells, and the levels of reduced folate in FPGS shRNA HCT-15 tumors became 57% of those in parent after a single administration of 10 mg/kg of LV. Notably, FPGS downregulation did not affect the tumor growth or sensitivity to fluoropyrimidine. Importantly, we observed that LV given for 14 days failed to enhance the anticancer effects of UFT and S-1 in FPGS shRNA HCT-15. This was in keeping with the results that LV did not increase the ternary complex of TS, FdUMP and reduced folate. In conclusion, the present results provide in vivo evidence that intratumor FPGS plays an important role in the efficacy of oral fluoropyrimidine plus LV therapy for colorectal cancer.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Cancer Research, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    2815 5-Fluorouracil (5-FU) plus leucovorin (LV) is a standard chemotherapy regimen for colorectal cancer. 5-FU exerts its anticancer activity mainly by inhibiting thymidylate Synthase (TS) via the formation of a ternary complex of TS, 5,10-methylenetetrahydrofolate (CH 2 THF) and 5-fluoro-29-deoxyuridine 59-monophosphate (FdUMP), which is the active form of 5-FU. Although LV enhances the antitumor activity of 5-FU by supplying CH 2 THF and stabilizing the ternary complex, the factors that determine the LV-mediated enhancement of the effect 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 in human colon cancer cell lines. 5-FU-based drug S-1 (6.9 mg/kg) and LV (20 mg/kg) were administered orally for 14 consecutive days to nude mice bearing human colon tumor xenografts COL-1 and KM20C. LV significantly enhanced the inhibitory effect of S-1 on COL-1 tumor growth ( P 2 THF and its direct precursor tetrahydrofolate (THF)) in both tumors ( P P P 3 H] folate level after the addition of [ 3 H] LV in cells treated with FPGS siRNA was reduced by 76% compared with cells treated with control siRNA. On the other hand, treatment with GGH siRNA tended to increase the [ 3 H] folate level compared with cells treated with control siRNA. The downregulation of FPGS by siRNA reduced the enhancement of FdUrd -induced cytotoxicity elicited by LV, whereas the downregulation of GGH by siRNA increased cellular sensitivity to FdUrd combined with LV. These results indicate that the expression of FPGS and GGH within tumor cells regulated the effectiveness of LV in enhancing the antitumor activity of 5-FU, by regulating folate levels. These results also suggest that the levels of FPGS and GGH expression in tumors could predict the effectiveness of LV in combination with 5-FU chemotherapy for colorectal cancer.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Biochemical and Biophysical Research Communications, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    Abstract 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.

Takashi Kobunai - One of the best experts on this subject based on the ideXlab platform.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Cancer Research, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    2815 5-Fluorouracil (5-FU) plus leucovorin (LV) is a standard chemotherapy regimen for colorectal cancer. 5-FU exerts its anticancer activity mainly by inhibiting thymidylate Synthase (TS) via the formation of a ternary complex of TS, 5,10-methylenetetrahydrofolate (CH 2 THF) and 5-fluoro-29-deoxyuridine 59-monophosphate (FdUMP), which is the active form of 5-FU. Although LV enhances the antitumor activity of 5-FU by supplying CH 2 THF and stabilizing the ternary complex, the factors that determine the LV-mediated enhancement of the effect 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 in human colon cancer cell lines. 5-FU-based drug S-1 (6.9 mg/kg) and LV (20 mg/kg) were administered orally for 14 consecutive days to nude mice bearing human colon tumor xenografts COL-1 and KM20C. LV significantly enhanced the inhibitory effect of S-1 on COL-1 tumor growth ( P 2 THF and its direct precursor tetrahydrofolate (THF)) in both tumors ( P P P 3 H] folate level after the addition of [ 3 H] LV in cells treated with FPGS siRNA was reduced by 76% compared with cells treated with control siRNA. On the other hand, treatment with GGH siRNA tended to increase the [ 3 H] folate level compared with cells treated with control siRNA. The downregulation of FPGS by siRNA reduced the enhancement of FdUrd -induced cytotoxicity elicited by LV, whereas the downregulation of GGH by siRNA increased cellular sensitivity to FdUrd combined with LV. These results indicate that the expression of FPGS and GGH within tumor cells regulated the effectiveness of LV in enhancing the antitumor activity of 5-FU, by regulating folate levels. These results also suggest that the levels of FPGS and GGH expression in tumors could predict the effectiveness of LV in combination with 5-FU chemotherapy for colorectal cancer.

  • Folylpolyglutamate Synthase and γ glutamyl hydrolase regulate leucovorin enhanced 5 fluorouracil anticancer activity
    Biochemical and Biophysical Research Communications, 2008
    Co-Authors: Etsuko Sakamoto, Sayaka Tsukioka, Takashi Kobunai, Hiroaki Tsujimoto, Kazuki Sakamoto, Yoshihiro Okayama, Yoshikazu Sugimoto, Masakazu Fukushima
    Abstract:

    Abstract 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.