Folate metabolic enzymes and transporters

Folate metabolic enzymes and transporters constitute a critical biochemical network responsible for the uptake and processing of folates, which are essential cofactors for one-carbon transfer reactions [1]. This pathway is fundamental for the de novo synthesis of purines and thymidylate, playing a vital role in DNA replication, repair, and methylation [2]. Key components include transporters like the Reduced Folate Carrier (RFC/SLC19A1) and Proton-Coupled Folate Transporter (PCFT/SLC46A1), as well as enzymes such as Dihydrofolate Reductase (DHFR) and Thymidylate Synthase (TYMS) [2,3]. In oncology, these proteins are frequently overexpressed to support the high proliferative demands of cancer cells, making them classic targets for "antifolate" chemotherapy [1,4]. Drugs like methotrexate and pemetrexed inhibit these enzymes to induce "thymineless death" and arrest cell proliferation [4]. Beyond cancer, this pathway is targeted in autoimmune diseases like rheumatoid arthritis and is crucial in preventing neural tube defects through proper supplementation [5]. Genetic variations, such as polymorphisms in the MTHFR gene, can significantly impact folate metabolism and drug efficacy [5]. Therapeutic strategies also include the use of folate receptor-targeted agents, such as antibody-drug conjugates, to deliver toxins specifically to malignant cells [3]. [1] https://www.ncbi.nlm.nih.gov/books/NBK507829/ [2] https://pubmed.ncbi.nlm.nih.gov/23613501/ [3] https://pubmed.ncbi.nlm.nih.gov/32810413/ [4] https://www.nature.com/articles/nrc3277 [5] https://medlineplus.gov/genetics/gene/mthfr/

Other names

Folate pathwayOne-carbon metabolism enzymes and transportersFolate transport and metabolism system

Antifolate drugs primarily act by competitively inhibiting key enzymes such as dihydrofolate reductase (DHFR) and thymidylate synthase (TYMS), which depletes the pool of reduced folates and halts the synthesis of thymidine and purine nucleotides [1,4]. This disruption leads to the inhibition of DNA synthesis and repair, ultimately causing cell cycle arrest and apoptosis, a process often termed "thymineless death" [4]. Additionally, some agents target folate transporters (e.g., RFC) for cellular entry or bind to folate receptors (e.g., FOLR1) to deliver cytotoxic payloads [3].