Topotecan hydrochloride (NSC609699) is an antineoplastic agent used to treat ovarian cancer.

Topo I (MCF-7 Luc cells):13 nM, Topo I (DU-145 Luc cells):2 nM

Topotecan induces effective anti-leukemic activity in a severe combined immunodeficient (SCID) mouse model of poor-prognosis acute lymphoblastic leukemia (ALL). Its administration significantly prolongs the disease-free survival in SCID mice challenged with a lethal dose of human leukemia cells at systemic drug exposure levels. Glioblastomas preferentially express TNF-related apoptosis-inducing ligand receptor 2 (TRAIL R2), and Topotecan treatment notably upregulates this expression. Furthermore, when DU-145 Luc cells are subcutaneously implanted and treated with Topotecan, significant tumor growth inhibition and regression are observed via caudal vein injection and bioluminescent imaging.

In radiation-resistant human B-lineage acute lymphoblastic leukemia cells, Topotecan stabilizes topoisomerase I/DNA cleavable complexes, inducing rapid apoptosis regardless of high bcl-2 protein expression, and inhibits clonal growth of the cells in a dose-dependent manner. Topotecan exhibits augmented drug activity against DU-145 Luc and MCF-7 Luc cells. During DNA replication, its cytotoxic action is mediated by stabilizing the covalent complex between topoisomerase I and DNA, preventing religation of the enzyme-linked single-strand DNA breaks.

Topotecan is dissolved in sterile water to a stock concentration of 1 mg/mL, diluted to 6 μg/mL in cultured medium and then serially diluted 1:4 in opaque, white tissue culture-treated microplates to a final volume of 0.1 mL/well. MCF-7 Luc and DU-145 Luc cells are resuspended in 3×104 cells/mL in DMEM with high glucose containing 10% FBS and 0.5 mg/mL Geneticin; 100 μL of cells are added in each well. Plates are incubated for 4 days at 37 °C in 95% humidity/5% CO2. After incubation, 0.05 mL of 0.1 M HEPES buffer (pH 7.9) containing 50 μg/mL D-luciferin is added to each well. After incubation at room temperature for 10 minutes, the culture microplate is measured in a microplate luminometer and a molecular light imager. Results obtained with the microplate luminometer are calculated using no inhibition control wells without exogenous drug and maximum inhibition control wells containing ATP inhibitor. Results for the molecular light imager are similarly calculated using values obtained with a 5 minutes luminescent imager. (Only for Reference)