Thymidylate synthase inhibitors are chemical agents which inhibit the enzyme thymidylate synthase and have potential as an anticancer chemotherapy. [1] This inhibition prevents the methylation of C5 of deoxyuridine monophosphate (dUMP) thereby inhibiting the synthesis of deoxythymidine monophosphate (dTMP). The downstream effect is promotion of cell death because cells would not be able to properly undergo DNA synthesis if they are lacking dTMP, a necessary precursor to dTTP. [2] Five agents were in clinical trials in 2002: raltitrexed, pemetrexed, nolatrexed, ZD9331, and GS7904L. [3]
Examples include
A salvage pathway is a pathway in which a biological product is produced from intermediates in the degradative pathway of its own or a similar substance. The term often refers to nucleotide salvage in particular, in which nucleotides are synthesized from intermediates in their degradative pathway.
Fluorouracil (5-FU), sold under the brand name Adrucil among others, is a chemotherapy medication used to treat cancer. By injection into a vein it is used for colon cancer, esophageal cancer, stomach cancer, pancreatic cancer, breast cancer, and cervical cancer. As a cream it is used for actinic keratosis, basal cell carcinoma, and skin warts.
Thymidine kinase is an enzyme, a phosphotransferase : 2'-deoxythymidine kinase, ATP-thymidine 5'-phosphotransferase, EC 2.7.1.21. It can be found in most living cells. It is present in two forms in mammalian cells, TK1 and TK2. Certain viruses also have genetic information for expression of viral thymidine kinases. Thymidine kinase catalyzes the reaction:
HAT Medium is a selection medium for mammalian cell culture, which relies on the combination of aminopterin, a drug that acts as a powerful folate metabolism inhibitor by inhibiting dihydrofolate reductase, with hypoxanthine and thymidine which are intermediates in DNA synthesis. The trick is that aminopterin blocks DNA de novo synthesis, which is absolutely required for cell division to proceed, but hypoxanthine and thymidine provide cells with the raw material to evade the blockage, provided that they have the right enzymes, which means having functioning copies of the genes that encode them.
Betulinic acid is a naturally occurring pentacyclic triterpenoid which has antiretroviral, antimalarial, and anti-inflammatory properties, as well as a more recently discovered potential as an anticancer agent, by inhibition of topoisomerase. It is found in the bark of several species of plants, principally the white birch from which it gets its name, but also the ber tree, selfheal, the tropical carnivorous plants Triphyophyllum peltatum and Ancistrocladus heyneanus, Diospyros leucomelas, a member of the persimmon family, Tetracera boiviniana, the jambul, flowering quince, rosemary, and Pulsatilla chinensis.
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Thymidylate synthase (TS) is an enzyme that catalyzes the conversion of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate (dTMP). Thymidine is one of the nucleotides in DNA. With inhibition of TS, an imbalance of deoxynucleotides and increased levels of dUMP arise. Both cause DNA damage.
Levomefolic acid (INN) (also known as L-5-MTHF, L-methylfolate and L-5-methyltetrahydrofolate and (6S)-5-methyltetrahydrofolate, and (6S)-5-MTHF) is the primary biologically active form of folate used at the cellular level for DNA reproduction, the cysteine cycle and the regulation of homocysteine. It is also the form found in circulation and transported across membranes into tissues and across the blood–brain barrier. In the cell, L-methylfolate is used in the methylation of homocysteine to form methionine and tetrahydrofolate (THF). THF is the immediate acceptor of one carbon unit for the synthesis of thymidine-DNA, purines (RNA and DNA) and methionine. The un-methylated form, folic acid (vitamin B9), is a synthetic form of folate, and must undergo enzymatic reduction by dihydrofolate reductase (DHFR) to become biologically active.
5,10-Methylenetetrahydrofolate (N5,N10-Methylenetetrahydrofolate; 5,10-CH2-THF) is cofactor in several biochemical reactions. It exists in nature as the diastereoisomer [6R]-5,10-methylene-THF.
In enzymology, a thymidylate synthase (FAD) (EC 2.1.1.148) is an enzyme that catalyzes the chemical reaction
Antifolates are a class of antimetabolite medications that antagonise (that is, block) the actions of folic acid (vitamin B9). Folic acid's primary function in the body is as a cofactor to various methyltransferases involved in serine, methionine, thymidine and purine biosynthesis. Consequently, antifolates inhibit cell division, DNA/RNA synthesis and repair and protein synthesis. Some such as proguanil, pyrimethamine and trimethoprim selectively inhibit folate's actions in microbial organisms such as bacteria, protozoa and fungi. The majority of antifolates work by inhibiting dihydrofolate reductase (DHFR).
Carmofur (INN) or HCFU (1-hexylcarbamoyl-5-fluorouracil) is a pyrimidine analogue used as an antineoplastic agent. It is a derivative of fluorouracil, being a lypophilic-masked analog of 5-FU that can be administered orally.
OSI-7904 is a noncompetitive liposomal thymidylate synthase inhibitor. OSI-7904 is a benzoquinazoline folate analog with antineoplastic activity. As a thymidylate synthase inhibitor, OSI-7904 noncompetitively binds to thymidylate synthase, resulting in inhibition of thymine nucleotide synthesis and DNA replication.
Thymectacin is an anticancer prodrug of brivudine monophosphate. It developed by New Biotics and it has entered in phase I clinical trials for colon cancer.
Thymidylate kinase catalyzes the phosphorylation of thymidine 5'-monophosphate (dTMP) to form thymidine 5'-diphosphate (dTDP) in the presence of ATP and magnesium:
Trifluridine/tipiracil, sold under the brand name Lonsurf, is a fixed-dose combination medication that is used as a third- or fourth-line treatment of metastatic colorectal cancer or gastric cancer, after chemotherapy and targeted therapeutics have failed. It is a combination of two active pharmaceutical ingredients: trifluridine, a nucleoside analog, and tipiracil, a thymidine phosphorylase inhibitor. Tipiracil prevents rapid metabolism of trifluridine, increasing the bioavailability of trifluridine.
Antineoplastic resistance, often used interchangeably with chemotherapy resistance, is the resistance of neoplastic (cancerous) cells, or the ability of cancer cells to survive and grow despite anti-cancer therapies. In some cases, cancers can evolve resistance to multiple drugs, called multiple drug resistance.
ONX-0801 is an experimental drug that has been developed to target ovarian cancer. It is a folate receptor alpha mediated thymidylate synthase inhibitor.
Professor Kenneth Reginald Harrap (1931-2017) was a British oncological biochemist.
Fluorodeoxyuridylate, also known as FdUMP, 5-Fluoro-2'-deoxyuridylate, or 5-Fluoro-2'-deoxyuridine 5'-monophosphate sodium salt, is a molecule formed in vivo from 5-fluorouracil or 5-fluorodeoxyuridin.
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