The impact of 5-formyltetrahydrofolate on the anti-tumor activity of pralatrexate, as compared to methotrexate, in HeLa cells in vitro

Michele Visentin, Ersin Selcuk Unal, I. David Goldman

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Purpose: To investigate the impact of 5-formyltetrahydrofolate on the activities of pralatrexate, as compared to methotrexate (MTX), in vitro. Methods: Cells were exposed to (6S)5-formyltetrahydrofolate (5-formylTHF) for 24 h, before or after a 6-h exposure to antifolates following which the cellular accumulation and activities of the drugs were evaluated in HeLa cells. Results: A 24-h delay between a 6-h exposure to antifolates and a subsequent 24-h exposure to 4 μM 5-formylTHF sustained the full activities of both antifolates. A 72-h interval was required between a single exposure of up to 4 μM 5-formylTHF and subsequent exposure to drugs to sustain activities of the antifolates. When cells were incubated with 4 μM 5-formylTHF for 24 h weekly, for 4 weeks, there was no significant increase in the IC50 for pralatrexate, but the MTX IC50 increased 2.5-fold as compared to cells growing continuously in 25 nM 5-formylTHF. This cyclical exposure to 5-formylTHF increased the cell folate pool by 16 %, had no significant effect on the intracellular pralatrexate level, but decreased intracellular MTX by 15 %. An extracellular concentration of MTX 50-fold higher than that of pralatrexate was required to achieve an intracellular level, and growth inhibition, comparable to that of pralatrexate. Conclusions: Cyclical exposures to 5-formylTHF at levels in excess of what is achieved in most clinical "rescue" regimens do not affect pralatrexate accumulation nor antitumor activity in HeLa cells, in contrast to MTX. An important element in preserving pralatrexate activity is achieving a sufficient interval between exposure to 5-formylTHF and the next dose of antifolate.

Original languageEnglish (US)
Pages (from-to)1055-1062
Number of pages8
JournalCancer Chemotherapy and Pharmacology
Volume73
Issue number5
DOIs
StatePublished - 2014

Fingerprint

Leucovorin
HeLa Cells
Methotrexate
Tumors
Folic Acid Antagonists
Neoplasms
Inhibitory Concentration 50
In Vitro Techniques
10-propargyl-10-deazaaminopterin
Folic Acid
Pharmaceutical Preparations

Keywords

  • (6S)5-formyltetrahydrofolate
  • 5- Formyltetrahydrofolate
  • Folylpolyglutamate synthetase
  • Leucovorin
  • Methotrexate
  • Pralatrexate
  • Reduced folate carrier
  • Rescue

ASJC Scopus subject areas

  • Cancer Research
  • Oncology
  • Pharmacology
  • Pharmacology (medical)
  • Toxicology

Cite this

The impact of 5-formyltetrahydrofolate on the anti-tumor activity of pralatrexate, as compared to methotrexate, in HeLa cells in vitro. / Visentin, Michele; Unal, Ersin Selcuk; Goldman, I. David.

In: Cancer Chemotherapy and Pharmacology, Vol. 73, No. 5, 2014, p. 1055-1062.

Research output: Contribution to journalArticle

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abstract = "Purpose: To investigate the impact of 5-formyltetrahydrofolate on the activities of pralatrexate, as compared to methotrexate (MTX), in vitro. Methods: Cells were exposed to (6S)5-formyltetrahydrofolate (5-formylTHF) for 24 h, before or after a 6-h exposure to antifolates following which the cellular accumulation and activities of the drugs were evaluated in HeLa cells. Results: A 24-h delay between a 6-h exposure to antifolates and a subsequent 24-h exposure to 4 μM 5-formylTHF sustained the full activities of both antifolates. A 72-h interval was required between a single exposure of up to 4 μM 5-formylTHF and subsequent exposure to drugs to sustain activities of the antifolates. When cells were incubated with 4 μM 5-formylTHF for 24 h weekly, for 4 weeks, there was no significant increase in the IC50 for pralatrexate, but the MTX IC50 increased 2.5-fold as compared to cells growing continuously in 25 nM 5-formylTHF. This cyclical exposure to 5-formylTHF increased the cell folate pool by 16 {\%}, had no significant effect on the intracellular pralatrexate level, but decreased intracellular MTX by 15 {\%}. An extracellular concentration of MTX 50-fold higher than that of pralatrexate was required to achieve an intracellular level, and growth inhibition, comparable to that of pralatrexate. Conclusions: Cyclical exposures to 5-formylTHF at levels in excess of what is achieved in most clinical {"}rescue{"} regimens do not affect pralatrexate accumulation nor antitumor activity in HeLa cells, in contrast to MTX. An important element in preserving pralatrexate activity is achieving a sufficient interval between exposure to 5-formylTHF and the next dose of antifolate.",
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T1 - The impact of 5-formyltetrahydrofolate on the anti-tumor activity of pralatrexate, as compared to methotrexate, in HeLa cells in vitro

AU - Visentin, Michele

AU - Unal, Ersin Selcuk

AU - Goldman, I. David

PY - 2014

Y1 - 2014

N2 - Purpose: To investigate the impact of 5-formyltetrahydrofolate on the activities of pralatrexate, as compared to methotrexate (MTX), in vitro. Methods: Cells were exposed to (6S)5-formyltetrahydrofolate (5-formylTHF) for 24 h, before or after a 6-h exposure to antifolates following which the cellular accumulation and activities of the drugs were evaluated in HeLa cells. Results: A 24-h delay between a 6-h exposure to antifolates and a subsequent 24-h exposure to 4 μM 5-formylTHF sustained the full activities of both antifolates. A 72-h interval was required between a single exposure of up to 4 μM 5-formylTHF and subsequent exposure to drugs to sustain activities of the antifolates. When cells were incubated with 4 μM 5-formylTHF for 24 h weekly, for 4 weeks, there was no significant increase in the IC50 for pralatrexate, but the MTX IC50 increased 2.5-fold as compared to cells growing continuously in 25 nM 5-formylTHF. This cyclical exposure to 5-formylTHF increased the cell folate pool by 16 %, had no significant effect on the intracellular pralatrexate level, but decreased intracellular MTX by 15 %. An extracellular concentration of MTX 50-fold higher than that of pralatrexate was required to achieve an intracellular level, and growth inhibition, comparable to that of pralatrexate. Conclusions: Cyclical exposures to 5-formylTHF at levels in excess of what is achieved in most clinical "rescue" regimens do not affect pralatrexate accumulation nor antitumor activity in HeLa cells, in contrast to MTX. An important element in preserving pralatrexate activity is achieving a sufficient interval between exposure to 5-formylTHF and the next dose of antifolate.

AB - Purpose: To investigate the impact of 5-formyltetrahydrofolate on the activities of pralatrexate, as compared to methotrexate (MTX), in vitro. Methods: Cells were exposed to (6S)5-formyltetrahydrofolate (5-formylTHF) for 24 h, before or after a 6-h exposure to antifolates following which the cellular accumulation and activities of the drugs were evaluated in HeLa cells. Results: A 24-h delay between a 6-h exposure to antifolates and a subsequent 24-h exposure to 4 μM 5-formylTHF sustained the full activities of both antifolates. A 72-h interval was required between a single exposure of up to 4 μM 5-formylTHF and subsequent exposure to drugs to sustain activities of the antifolates. When cells were incubated with 4 μM 5-formylTHF for 24 h weekly, for 4 weeks, there was no significant increase in the IC50 for pralatrexate, but the MTX IC50 increased 2.5-fold as compared to cells growing continuously in 25 nM 5-formylTHF. This cyclical exposure to 5-formylTHF increased the cell folate pool by 16 %, had no significant effect on the intracellular pralatrexate level, but decreased intracellular MTX by 15 %. An extracellular concentration of MTX 50-fold higher than that of pralatrexate was required to achieve an intracellular level, and growth inhibition, comparable to that of pralatrexate. Conclusions: Cyclical exposures to 5-formylTHF at levels in excess of what is achieved in most clinical "rescue" regimens do not affect pralatrexate accumulation nor antitumor activity in HeLa cells, in contrast to MTX. An important element in preserving pralatrexate activity is achieving a sufficient interval between exposure to 5-formylTHF and the next dose of antifolate.

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KW - Pralatrexate

KW - Reduced folate carrier

KW - Rescue

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