Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

Methotrexate decreases thymidine kinase activity.

M Abonyi1, N Prajda, Y Hata

  • 1Laboratory for Experimental Oncology, Indiana University School of Medicine, Indianapolis 46202-5200.

Biochemical and Biophysical Research Communications
|August 31, 1992
PubMed
Summary

Methotrexate (MTX) cytotoxicity involves more than dihydrofolate reductase inhibition. MTX treatment also decreases thymidine (TdR) kinase activity, a newly identified target, impacting cancer cell proliferation.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Pressure and low temperature effects on the fluorescence emission spectra and lifetimes of the photosynthetic components of cyanobacteria.

Biophysical journal·1992
Same author

Myxozyma neotropica sp. nov. (Candidaceae)--a new yeast species from Costa Rica.

Antonie van Leeuwenhoek·1992
Same author

Action of tiazofurin and 8-Cl-cAMP in human colon and pancreatic cancer cells.

Cancer biochemistry biophysics·1992
Same author

Direct assay method for guanosine 5'-monophosphate reductase activity.

Analytical biochemistry·1992
Same author

Kluyveromyces piceae sp. nov., a new yeast species isolated from the rhizosphere of Picea abies (L.) Karst.

Antonie van Leeuwenhoek·1992
Same author

Rupture of the duodenum with avulsion of the papilla of Vater due to blunt trauma in a child, and review of the literature.

European journal of pediatric surgery : official journal of Austrian Association of Pediatric Surgery ... [et al] = Zeitschrift fur Kinderchirurgie·1992

Area of Science:

  • Biochemistry
  • Pharmacology
  • Oncology

Background:

  • Methotrexate (MTX) is a chemotherapy drug whose cytotoxicity is primarily attributed to dihydrofolate reductase (DHFR) inhibition.
  • DHFR inhibition leads to decreased thymidylate synthase (dTMP synthase) activity, crucial for DNA synthesis.
  • Thymidine (TdR) kinase, a salvage enzyme, can bypass DHFR inhibition by converting TdR to dTMP, potentially limiting MTX efficacy, especially in cancer cells with high TdR kinase activity.

Purpose of the Study:

  • To investigate the hypothesis that MTX treatment may also inhibit or decrease TdR kinase activity.
  • To identify TdR kinase as a potential novel target of MTX action.
  • To elucidate the mechanisms underlying MTX-induced cytotoxicity beyond DHFR inhibition.

Main Methods:

Related Experiment Videos

  • MTX was administered intraperitoneally (i.p.) to rats at various doses and time points.
  • TdR kinase activity was measured in liver, bone marrow, and hepatoma tissues.
  • Cycloheximide, a protein biosynthesis inhibitor, was used to assess enzyme stability and degradation rates.
  • Activities of other nucleic acid biosynthesis enzymes were also quantified.

    • Main Results:

    • MTX treatment dose- and time-dependently decreased TdR kinase activity in liver, bone marrow, and hepatoma.
    • Cycloheximide administration led to a rapid decrease in TdR kinase activity in hepatoma, with a half-life of 3.6 hours.
    • Other purine and pyrimidine synthetic enzymes showed slower declines in activity following cycloheximide treatment.
    • MTX's effect on purine and pyrimidine biosynthesis limits TdR kinase substrates, making it susceptible to protein degradation.

    Conclusions:

    • TdR kinase is a newly identified target of MTX treatment.
    • MTX reduces TdR kinase activity, contributing to its cytotoxic effects.
    • The increased sensitivity of TdR kinase to protein degradation, influenced by MTX-induced purine and pyrimidine depletion, is a key mechanism.