TY - JOUR
T1 - Effects of 5-methyltetrahydrofolate on the activity of fluoropyrimidines against human leukemia (CCRF-CEM) cells
AU - Mini, Enrico
AU - Mazzei, Teresita
AU - Coronnello, Marcella
AU - Criscuoli, Luciana
AU - Gualtieri, Monica
AU - Periti, Piero
AU - Bertino, Joseph R.
N1 - Funding Information:
Council, Special Project “Oncotogy”, Contract No. 85.02245.44 and by a grant of the Italian Association for Cancer Research. t To whom reprint requests should be sent at the following address: Dipartimento di Farmacologia Preclinica e Clinica, Universita degli Studi. Viale Morgagni 65, 50134 Firenze, Italy. $ American Cancer Society Professor of Medicine and Pharmacology. 11A bbreviations used: FUra, 5-fluorouracil; FdUrd, S-fluoro-2’-deoxyuridine; FUTP, 5-fluorouridine 5’-triphosphate; FdUTP, 5-fluoro-2’-deoxyuridine 5’-triphosphate; FdUMP, 5-fluoro-2’-deoxyuridine; 5,10-CH,-H,PteGlu, 5,10-methylenetetrahydrofolate; LV, leucovorin, 5-formyltetrahydrofolate; dThd, thymidine; Hyp, hypoxanthine; 5-CH,-H,PteGlu, 5_methyltetrahydrofolate; PRPP, phosphoribosylpyrophosphate.
Funding Information:
* Supported by a grant of the Italian National Research
PY - 1987/9/15
Y1 - 1987/9/15
N2 - The growth inhibitory effects of 5-fluorouracil (FUra) or 5-fluoro-2'-deoxyuridine (FdUrd) combined with 5-methyltetrahydrofolate (5-CH3-H4PteGlu) were determined, as a function of time, dose, and sequence of exposure, on human T-Iymphoblast leukemia cells, CCRF-CEM. Synergistic inhibitory effects on cell growth were obtained when exponentially growing CCRF-CEM cells were exposed to 5-CH3-H4PteGlu (1-100 μM) for 4 hr and to FUra (250 μM) or FdUrd (0.5 μM) during the last 2 hr. Synergism was dependent on 5-CH3-H4PteGlu dose (100 > 10 > 1 μM) and did not occur at 0.1 μM. No clear dependence of synergism on sequence was observed with FUra and 5-CH3-H4PteGlu combinations (5-CH3-H4PteGlu → FUra, 5-CH3-H4PteGlu + FUra, or FUra → 5-CH3- H4PteGlu). With 5-CH3-H4PteGlu and FdUrd combinations, synergism was dependent on sequence of exposure (5-CH3-H4 PteGlu + FdUrd, 5-CH3-H4PteGlu → FdUrd were synergistic, but FdUrd → 5-CH3-H4 PteGlu was not). Thymidine (0.1 μM), added after drug treatment, substantially rescued CCRF-CEM cells from 5-CH3-H4PteGlu → FUra cytotoxicity. L-methionine (1500 mg/I) completely protected CCRF-CEM cells from enhanced cytotoxicity of the combination, 5-CH3-H4PteGlu-FdUrd. The results are consistent with the hypothesis that the mechanism by which 5-CH3-H4PteGlu potentiates fluoropyrimidine cytotoxicity is the enhancement of complex formation between thymidylate synthase and 5-fluorodeoxyuridylate, as a consequence of an increase of intracellular levels of 5,10-methylenetetrahydrofolate generated from 5-CH3-H4PteGlu. Also, enhanced stability of the complex in the presence of high levels of this folate coenzyme may contribute to the synergism observed. These data provide a rationale basis for further trials of folate coenzymes and fluoropyrimidine combinations in the clinic.
AB - The growth inhibitory effects of 5-fluorouracil (FUra) or 5-fluoro-2'-deoxyuridine (FdUrd) combined with 5-methyltetrahydrofolate (5-CH3-H4PteGlu) were determined, as a function of time, dose, and sequence of exposure, on human T-Iymphoblast leukemia cells, CCRF-CEM. Synergistic inhibitory effects on cell growth were obtained when exponentially growing CCRF-CEM cells were exposed to 5-CH3-H4PteGlu (1-100 μM) for 4 hr and to FUra (250 μM) or FdUrd (0.5 μM) during the last 2 hr. Synergism was dependent on 5-CH3-H4PteGlu dose (100 > 10 > 1 μM) and did not occur at 0.1 μM. No clear dependence of synergism on sequence was observed with FUra and 5-CH3-H4PteGlu combinations (5-CH3-H4PteGlu → FUra, 5-CH3-H4PteGlu + FUra, or FUra → 5-CH3- H4PteGlu). With 5-CH3-H4PteGlu and FdUrd combinations, synergism was dependent on sequence of exposure (5-CH3-H4 PteGlu + FdUrd, 5-CH3-H4PteGlu → FdUrd were synergistic, but FdUrd → 5-CH3-H4 PteGlu was not). Thymidine (0.1 μM), added after drug treatment, substantially rescued CCRF-CEM cells from 5-CH3-H4PteGlu → FUra cytotoxicity. L-methionine (1500 mg/I) completely protected CCRF-CEM cells from enhanced cytotoxicity of the combination, 5-CH3-H4PteGlu-FdUrd. The results are consistent with the hypothesis that the mechanism by which 5-CH3-H4PteGlu potentiates fluoropyrimidine cytotoxicity is the enhancement of complex formation between thymidylate synthase and 5-fluorodeoxyuridylate, as a consequence of an increase of intracellular levels of 5,10-methylenetetrahydrofolate generated from 5-CH3-H4PteGlu. Also, enhanced stability of the complex in the presence of high levels of this folate coenzyme may contribute to the synergism observed. These data provide a rationale basis for further trials of folate coenzymes and fluoropyrimidine combinations in the clinic.
UR - https://www.scopus.com/pages/publications/0023230165
UR - https://www.scopus.com/pages/publications/0023230165#tab=citedBy
U2 - 10.1016/0006-2952(87)90201-2
DO - 10.1016/0006-2952(87)90201-2
M3 - Article
C2 - 2958010
AN - SCOPUS:0023230165
SN - 0006-2952
VL - 36
SP - 2905
EP - 2911
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 18
ER -