Methotrexate Antitumor Activity

Methotrexate-7-Hydrazide and Divinyl Ether—Maleic Anhydride Conjugate Antitumor Activity in Mice... 

Pignatello R, et al. Effect of liposomal delivery on in vitro antitumor activity of lipophilic conjugates of methotrexate with lipoamino acids. Drug Deliv 2003 10 95. 

It possessed cytotoxicity for six cell lines (IC50 l 100pg/mL) and antitumor effects on human nasopharyngeal cancer (CNE2, SUNE-1) and human liver cancer (BEL-7402) in nude mice. Recently artesunate has been analyzed for its antitumor activity against 55 cell lines.It was most active against leukemia and colon cancer cell lines. It is notable that no CEM leukemia sublines, which are resistant to either doxorubicin, vincristine, methotrexate, or hydroxyurea, showed cross resistance to artesunate. 

Rosowski, A., Eorsch, R. A., Freisheim, J. H., Moran, R. G., Wick, M. Methotrexate analogues. 19. Replacement of the glutamate side chain in classical antifolates by L-homocysteic acid and L-cysteic acid effect on enzyme inhibition and antitumor activity. J. Med. Chem. 1984,27, 600-604. 

Another enzyme for which X-ray diffraction studies have aided in an analysis of the mode of action is the enzyme dihydrofolate reductase. This catalyzes the reduction of 7,8-dihydrofolate to 5,6,7,8-tetrahydrofolate, an essential coenzyme used in the synthesis of thymidylate, inosinate, and methionine. The antitumor agent methotrexate is a powerful inhibitor of dihydrofolate reductase, causing, on binding, a cellular deficiency of thymidylate (the cause of its antitumor activity). The crystal structures of the enzyme from two bacterial sources—Escherichia coli and Lactobacillus casei—and from chicken liver have been studied (88-90). Both the E. coli and L casei enzymes have been studied as complexes with methotrexate bound at the active site, and, in the case of the . casei enzyme, the cofactor, NADPH, was also present. 

Colleoni M, Rocca A et al. (2002) Low-dose oral methotrexate and cyclophosphamide in metastatic breast cancer antitumor activity and correlation with vascular endothelial growth factor levels. Ann Oncol 13(1) 73-80... 

J. Chen, L. Huang, H. Ijsa, C. Lu, M. Fang, Q. Zhang, X. Luo, Methotrexate-loaded PEGylated chitosan nanoparticles Synthesis, characterization, and in vitro and in vivo antitumoral activity. Mol. Pharm. 11 (2013) 2213-2223. 

Malik et al. (1999) conjugated cisplatin, a potent anticancer drug, to PAMAM dendrimers and observed increased solubility, decreased systemic toxicity, and EPR effect to target tumors when administered intravenously. Targeting methotrexate to epithelial cancers using PAMAM-folic acid system also showed increased antitumor activity (Kukowska-Latallo et al. 2005) compared to free drug after intravenous administration. 

Based on these data various conjugates with antitumor agents (daunomycin, methotrexate, GnRH antagonist ), boron compounds or radionuclides were prepared. Antitumor activity of Ac-[D-Trp D-Cpa ,... 

Folate in the human organism is converted to tetrahydrofolate (THF or FH4) by a reductive process. The reduction reaction is a stepwise one folate to dihydrofolate, then to THF. A single enzyme, dihydrofolate reductase, catalyzes both steps. The reaction is inhibited by folate analogues and the antitumor agents methotrexate and aminopterin (Figure 6.3). Because THF is required for DNA biosynthesis (Chapter 10) and tumors have a very high level of DNA biosynthetic activity, even modest decreases in THF availability will inhibit tumor growth. 

Dihydrofolate reductase activates folate to tetrahydrofolate with dihydrofolate as an intermediate. Methotrexate, an antitumor agent, inhibits this enzyme. The 5-methyl group is first oxidized to the formaldehyde level, then to the formate level, then to C02. Three steps require three molecules of NAD or an equivalent, for a total of 3 x 3 = 9 ATP molecules. 

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