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

方法：八株 TNBC 细胞系用 Camptothecin (0.1-5 µM) 处理 72 h，使用 PrestoBlue 检测细胞活力。
结果：Camptothecin 抑制 MCF7、HCC1428、HCC1419、HCC202、MDA453、MDA231、Sum149、BT549 细胞活力，IC50 值分别为 0.089/0.448/0.067/0.481/0.058/0.040/0.065/0.056 µM。[1]
方法：肺癌细胞 H1299 和 H460 用 Camptothecin (0.5-5 µM) 处理 16 h，使用 wound-healing assay 检测细胞迁移情况。
结果：Camptothecin 抑制 H1299 和 H460 细胞迁移，但没有剂量依赖性作用。[2]

方法：为检测体内抗肿瘤活性，将 Camptothecin (0.15-1.2 mg/kg) 和 doxorubicin (0.25-2 mg/kg) 静脉注射给携带三阴性乳腺癌肿瘤 MDA-MB-231 的 athymic nu/n 小鼠，每两天一次，给药四次。
结果：观察到肿瘤生长的剂量依赖性减少，在 0.5 mg/kg DOX + 0.3 mg/kg CPT 下减少 40.8% ，在 1.5 mg/kg DOX + 0.9 mg/kg CPT 下减少 93%。最高的测试剂量 (2 mg/kg DOX + 1.2 mg/kg CPT) 在第 44 天完全停止了肿瘤的生长。[3]
方法：为研究对肥胖的作用，将 Camptothecin (1 mg/kg，0.1% Tween 80) 口服给药给肥胖小鼠，每天一次，持续三天。
结果：口服 Camptothecin 可增加饮食诱导肥胖 (DIO) 小鼠和遗传 ob/ob 小鼠的循环 GDF15 水平。与 GDF15 的厌食作用一致，Camptothecin 抑制食物摄入，从而降低肥胖小鼠的体重、血糖和肝脏脂肪含量。[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)