Chemical structure of camptothecin.
Western blot analysis of extracts from MCF7 cells, untreated (-) or treated with Camptothecin (6 hr) at the indicated concentrations, using Phospho-p53 (Ser15) Antibody #9284 (upper), p53 (1C12) Mouse mAb #2524 (middle), and β-Actin (D6A8) Rabbit mAb #8457 (lower).
Camptothecin is supplied as a lyophilized powder. For a 10 mM stock, reconstitute the 10 mg in 2.87 ml DMSO. Working concentrations and length of treatment can vary depending on the desired effect, but it is typically used at 1-10 µM for 1-24 hr.
Store lyophilized or in solution at -20ºC, desiccated. In lyophilized form, the chemical is stable for 24 months. Once in solution, use within 3 months to prevent loss of potency. Aliquot to avoid multiple freeze/thaw cycles.
Camptothecin is a cytotoxic plant alkaloid originally isolated from C. acuminate that inhibits DNA and RNA synthesis in mammalian cells and is an effective anti-tumor agent (1). Research studies indicate that camptothecin inhibits topoisomerase I with an IC50 of 679 nM (2). Camptothecin binds and stabilizes topoisomerase I–DNA cleavage complexes, which leads to DNA strand breaks (1,3,4). The resultant DNA damage can induce cell cycle arrest in many cancer cell lines (5,6). Inactivation of the tumor suppressor protein p53 can increase the cytotoxicity of camptothecin (6).
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