Methotrexate

Methotrexate is an antifolate antimetabolite that effectively inhibits the activity of dihydrofolate reductase (DHFR), with an IC₅₀ of approximately 7nM ^[1]. Folic acid is essential for the biosynthesis of purine and pyrimidine bases, so methotrexate interferes with the synthesis of purines and pyrimidines required for DNA replication and cell proliferation ^[2]. Methotrexate also inhibits adenosine deaminase (ADA), resulting in increased extracellular adenine nucleotide levels ^[3]. Methotrexate has anticancer, antirheumatic, anti-inflammatory and immunomodulatory activities ^[4].

In vitro, methotrexate (5 μg/ml) has a wide range of IC_50s against various cancer cell lines, from 6.05±0.81 nM to >1,000 nM. Methotrexate resistance in Saos-2 and MCF-7 cells The most potent, AGS and HCT-116 cells are highly sensitive to methotrexate, with IC₅₀ of 6.05±0.81nM and 13.56±3.76nM respectively. NCI-H23 and A549 cells show similar sensitivity to methotrexate ^[5]. Methotrexate (3ng/ml-1μg/ml) measured the degree of drug resistance of the U-2OS cell line and found that the cell resistance was related to the increase in intracellular DHFR levels ^[6].

In vivo, treatment of arthritic DBA/1J mice with methotrexate (2-50 mg/kg; s.c.) dose-dependently reduced disease activity and mean paw volume and increased mean body weight percentage ^[7]. Methotrexate (2 mg/kg; i.p.) treats arthritis in rats and has significant anti-arthritic effects and prevents the occurrence of hematological toxicity ^[8].

References:

[1]Gurdag S, Khandare J, Stapels S, et al. Activity of dendrimer−methotrexate conjugates on methotrexate-sensitive and-resistant cell lines[J]. Bioconjugate chemistry, 2006, 17(2): 275-283.  

[2] Rajagopalan P T R , Zhang Z , Mccourt L ,et al.Interaction of dihydrofolate reductase with methotrexate: Ensemble and single-molecule kinetics[J].Proceedings of the National Academy of Sciences, 2002, 99(21):13481-13486.

[3] Sramek M, Neradil J, Veselska R. Much more than you expected: the non-DHFR-mediated effects of methotrexate[J]. Biochimica et Biophysica Acta (BBA)-General Subjects, 2017, 1861(3): 499-503.

[4] Bedoui Y, Guillot X, Sélambarom J, et al. Methotrexate an old drug with new tricks[J]. International journal of molecular sciences, 2019, 20(20): 5023.

[5] Yoon S A , Choi J R , Kim J O ,et al. Influence of Reduced Folate Carrier and Dihydrofolate Reductase Genes on Methotrexate-Induced Cytotoxicity[J].Cancer Research & Treatment, 2010, 42(3):163-171.

[6]Serra M , Reverter B G , Maurici D ,et al.Analysis of dihydrofolate reductase and reduced folate carrier gene status in relation to methotrexate resistance in osteosarcoma cells.[J].Annals of oncology, 2004.

[7] Singh, Rakesh K.van Haandel, LeonKiptoo, et al . Methotrexate disposition, anti-folate activity and efficacy in the collagen-induced arthritis mouse model[J].European Journal of Pharmacology: An International Journal, 2019, 853.

[8] Banji D , Banji O F , Reddy K , et al. Evaluation of the concomitant use of methotrexate and curcumin on Freund's complete adjuvant-induced arthritis and hematological indices in rats[J]. Indian Journal of Pharmacology, 2011, 43(5):546-550.