Camptothecin (CPT) belongs to the alkaloid group of natural products and is a specific DNA topoisomerase I (Topo I) inhibitor (IC50=679 nM) with specificity. Camptothecin has antitumor activity and induces apoptosis.

Topo I:0.68 μM

METHODS: Eight TNBC cell lines were treated with Camptothecin (0.1-5 µM) for 72 h. Cell viability was measured by PrestoBlue.
RESULTS: Camptothecin inhibited the cell viability of MCF7, HCC1428, HCC1419, HCC202, MDA453, MDA231, Sum149, and BT549 cells, with IC50 values of 0.089/0.448/0.067/0.481/0.058/0.040/0.065/ 0.056 µM.[1].
METHODS: Lung cancer cells H1299 and H460 were treated with Camptothecin (0.5-5 µM) for 16 h. Cell migration was detected by wound-healing assay.
RESULTS: Camptothecin inhibited the migration of H1299 and H460 cells without a dose-dependent effect. [2]

METHODS: To assay antitumor activity in vivo, Camptothecin (0.15-1.2 mg/kg) and doxorubicin (0.25-2 mg/kg) were intravenously injected into athymic nu/n mice bearing triple-negative mammary carcinoma tumors, MDA-MB-231, every two days for four administrations.
RESULTS: A dose-dependent reduction in tumor growth was observed, with a 40.8% reduction at 0.5 mg/kg DOX + 0.3 mg/kg CPT and a 93% reduction at 1.5 mg/kg DOX + 0.9 mg/kg CPT. The highest dose tested (2 mg/kg DOX + 1.2 mg/kg CPT) completely stopped tumor growth on day 44. [3]
METHODS: To study the effects on obesity, Camptothecin (1 mg/kg, 0.1% Tween 80) was administered orally to obese mice once daily for three days.
RESULTS: Oral administration of Camptothecin increased circulating GDF15 levels in diet-induced obese (DIO) mice and genetic ob/ob mice. Consistent with the anorectic effects of GDF15, Camptothecin inhibited food intake, thereby reducing body weight, blood glucose, and liver fat content in obese mice. [4]

Topoisomerase I Cleavable Complex Assay: Topoisomerase I is isolated from calf thymus and is devoid of topoisomerase II. All reactions are carried out in 10 mL volumes of reaction buffer (50 mM Tris-HCl, pH 7.5, 100 mM KCl, 0.5 mM EDTA, and 30 pg/mL BSA) in microtiter plates. Camptothecin is dissolved in DMSO at 10 mg/mL and serially diluted in 96-well microtiter plates to which the 32P end-labeled pBR322 DNA and topoisomerase enzyme are added. The reaction mixture is incubated at room temperature for 30 min and then the reaction stopped by adding 2 mL of a mixture of sodium dodecyl sulfate and proteinase K (1.6% and 0.14 mg/mL final concentrations, respectively). The plates are heated at 50 °C for 30 min, 10 mL of standard stop mixture containing 0.45 N NaOH is added in order to generate single-stranded DNA, and the samples are electrophoresed in 1.5% agarose gels in TBE buffer. Gels are blotted on nitrocellulose paper, dried, and exposed to X-ray film. The units of cleavage are calculated from the autoradiographs and plotted against the log drug concentration. The IC50 values are then obtaine

Tumor cells are plated in 100 μL of medium in 96-well microtiter plates at a density of 1500 to 4000 cells per well and allowed to adhere overnight. Cells are incubated with Camptothecin for 48 hours and then with fresh medium for 48 hours. Camptothecin at each concentration is added in quadruplicate. Following a 4-hour incubation of treated cells with MTT, the reduced dye product is extracted from the cells with 0.2 mL of DMSO followed by 50 μL of Sorensen's buffer. The plates are shaken briefly, and the absorbance at 570 nm is read and quantitated. Curves are fitted to the MTT assay data using a four-parameter logistic equation.(Only for Reference)