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 IC50s 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.
甲氨蝶呤（Methotrexate）是一种抗叶酸类抗代谢药，有效抑制二氢叶酸还原酶（DHFR）活性，IC50约为7nM[1]。叶酸对于嘌呤和嘧啶碱的生物合成至关重要，因此甲氨蝶呤会干扰DNA复制和细胞增殖所需的嘌呤和嘧啶合成[2]。甲氨蝶呤还会抑制腺苷脱氨酶（ADA），导致细胞外腺嘌呤核苷酸水平升高[3]。甲氨蝶呤具有抗癌、抗风湿、抗炎和免疫调节活性[4]。
在体外，甲氨蝶呤（5μg/ml）对各种癌细胞系的IC50范围很广，从6.05±0.81nM 到>1,000nM， Saos-2和MCF-7细胞对甲氨蝶呤的耐药性最强，AGS和 HCT-116细胞对甲氨蝶呤高度敏感，IC50分别为6.05±0.81nM和13.56±3.76nM。NCI-H23和A549细胞对甲氨蝶呤表现出相似的敏感性[5]。甲氨蝶呤（3ng/ml-1μg/ml）测量U-2OS细胞系的耐药程度，发现该细胞耐药性与胞内DHFR水平的增加有关[6]。
在体内，甲氨蝶呤（2-50mg/kg; s.c.）治疗关节炎DBA/1J小鼠后，剂量依赖性地降低了疾病活动性和平均爪体积，增加了平均体重百分比[7]。甲氨蝶呤（2 mg/kg;i.p.）治疗大鼠关节炎，具有显著的抗关节炎作用，并且预防了血液毒性的发生[8]。