irinotecan brands

Molecular formula: C33H38N4O6

DNA topoisomerase I is a nuclear enzyme that ensures proper DNA topology during replication and transcription. It relieves torsional strain in the DNA double helix during replication and transcription by creating reversible single-strand breaks. Upon administration, irinotecan is converted into its active metabolite, SN-38, by carboxylesterase in the liver and gastrointestinal tract. Irinotecan and SN-38 both inhibit DNA topoisomerase I, acting on the S and G2 phases of the cell cycle. Irinotecan and SN-38 bind to the topoisomerase I-DNA complex and prevent the religation of single-strand breaks. The ternary complex formed by topoisomerase I, DNA, and either irinotecan or SN-38 interferes with the moving replication fork, inducing replication arrest and lethal double-stranded breaks in DNA. Because double-stranded breaks cannot be efficiently repaired by mammalian cells, apoptosis of cancer cells occurs. Irinotecan is a derivative of camptothecin. Camptothecins interact specifically with the enzyme topoisomerase I which relieves torsional strain in DNA by inducing reversible single-strand breaks. Irinotecan and its active metabolite SN-38 bind to the topoisomerase I-DNA complex and prevent religation of these single-strand breaks. Current research suggests that the cytotoxicity of irinotecan is due to double-strand DNA damage produced during DNA synthesis when replication enzymes interact with the ternary complex formed by topoisomerase I, DNA, and either irinotecan or SN-38. Mammalian cells cannot efficiently repair these double-strand breaks.

Source: PubChem (NCBI) · compound 60838