Methotrexate inhibits?

What does methotrexate inhibit?

Methotrexate inhibits dihydrofolate reductase (DHFR), the enzyme that regenerates tetrahydrofolate needed for DNA synthesis in rapidly dividing cells. This blocks folate-dependent production of nucleotides. [1]

Why does inhibiting DHFR slow cell growth?

By inhibiting DHFR, methotrexate reduces tetrahydrofolate availability, which in turn impairs the formation of DNA building blocks (purines and thymidylate). Cells that rely on active DNA replication are most affected. [1]

Is methotrexate’s effect only about DHFR?

Methotrexate’s best-known mechanism is DHFR inhibition. It can also increase intracellular levels of other folate forms that further disrupt folate-dependent metabolic pathways, reinforcing the anti-proliferative effect. [1]

How that links to its clinical uses

Because the drug interferes with folate-dependent DNA synthesis, it helps treat conditions where slowing cell proliferation matters, including some cancers and inflammatory autoimmune diseases (like rheumatoid arthritis and psoriasis). [1]

Source
1. Drugs.com – Methotrexate: Uses, Dosage, Side Effects & Mechanism of Action