Camptothecin

Camptothecin is a cytotoxic quinoline alkaloid which inhibits the DNA enzyme topoisomerase I (topo I) with an IC50 and IC70 of 50 nM and 0. 225 μM for breast cancer cell line MDA-MB-231. Camptothecin was isolated from the bark and stem of Camptotheca acuminata, a tree native in China. Two CPT analogues have been approved and are used in cancer chemotherapytoday, topotecan and irinotecan. Breast and lung cancer cell lines were treated with camptothecin and sodium butyrate (NaB) or suberoylanilide hydroxamic acid on the day of, the day before, or the day after camptothecin addition. Depending on the time of addition, NaB-treated cells displayed a spectrum of responses from protection to sensitization, indicating the critical nature of timing in the use of HDIs. The IC80 (72-hour assay) dose of 100 nM camptothecin could be lowered to 15 nM camptothecin while maintaining or surpassing cell killing of the single agent if combined with an HDI added 24 to 48 hours after camptothecin. ^[1][2]

• [1] http://en.wikipedia.org/wiki/Camptothecin ;
• [2] http://www.rxlist.com/hycamtin-capsules-drug.htm ;