Topoisomerase I inhibitor 5 is an efficient inhibitor of topoisomerase I, with an IC50 value. It effectively disrupts DNA and inhibits the activity of topoisomerase I. Moreover, it can induce apoptosis in MCF-7 cells and arrest the cell cycle at the G1 phase. Topoisomerase I inhibitor 5 also exhibits potency in reversing P-gp-mediated resistance to Adriamycin [1].

Topoisomerase I inhibitor 5 (compound 14) (0-50 μM; 48 hours) exhibits antiproliferation activity against cancer cell lines and lower cytotoxicity in normal cells [1]. Topoisomerase I inhibitor 5 (2-8 μM; 24 hours) induces MCF-7 cell cycle arrest at the G1 phase [1]. Topoisomerase I inhibitor 5 (2-8 μM; 48 hours) increases the apoptotic rate of MCF-7/ADR and MCF-7 cells [1]. Topoisomerase I inhibitor 5 (1.5-6 μM; 24 hours) increases the expression degree of cleaved-caspase-3 and cleaved-PARP in MCF-7; down-regulates the level of anti-apoptotic protein, up-regulates the levels of pro-apoptotic proteins in MCF-7/ADR [1]. Topoisomerase I inhibitor 5 (0.1 μM; 24 hours) induces cell apoptosis by promoting the accumulation of ROS in MCF-7/ADR cell [1]. Topoisomerase I inhibitor 5 (10 μg/ml; 24 hours) increases the accumulation of the ADR and Rh123 in MCF-7/ADR cells [1]. Topoisomerase I inhibitor 5 (5, 10 and 20 μM; 24 hours) reduces the expression degree of P-gp by 14.95% and 18.10% in MCF-7/ADR cells at 10 and 20 μM [1]. Cell Proliferation Assay Cell Line: A549, HepG-2, MCF-7, MDA-MB-231, MCF-7/ADR and LO2 cells [1] Concentration: 0-50 μM Incubation Time: 48 hours Result: Exhibited antiproliferation activity against cancer cell lines, with IC 50 s of 2.39 ± 0.23 μM, 4.88 ± 0.29 μM, 1.32 ± 0.14 μM, 7.64 ± 0.35 μM and 2.42 ± 0.14 μM in A549, HepG-2, MCF-7, MDA-MB-231, MCF-7/ADR, respectively; and has lower cytotoxicity in LO2 cells with IC 50 of 36.52 ± 2.36 μM. Cell Cycle Analysis Cell Line: MCF-7 [1] Concentration: 2, 4 and 8 μM Incubation Time: 24 hours Result: Induced MCF-7 cell cycle arrest at the G1 phase. Apoptosis Analysis Cell Line: MCF-7 and MCF-7/ADR cells [1] Concentration: 2, 4 and 8 μM Incubation Time: 48 hours Result: Induced apoptosis in a dose-dependent manner in MCF-7 cells, and increased the apoptotic rate of the cells from 2.8% to 15.2% in MCF-7/ADR. Western Blot Analysis Cell Line: MCF-7 [1] Concentration: 1.5, 3 and 6 μM in MCF-7; 5, 10, and 20 μM in MCF-7/ADR Incubation Time: 24 hours Result: Increased the expression degree of cleaved-caspase-3 and cleaved-PARP in MCF-7; down-regulated the level of anti-apoptotic protein bcl-2, up-regulated the levels of pro-apoptotic proteins bax and bad in MCF-7/ADR.

Topoisomerase I inhibitor 5 (1 mg/kg and 10 mg/kg; IV; every two days, for 21 days) decreases the tumor growth significantly [1]. Animal Model: Bal b/c nude mice (injected with 106 MCF-7 cells in the left flank for 7 days) [1] Dosage: 1 mg/kg and 10 mg/kg Administration: IV; every two days, for 21 days Result: Decreased the tumor growth significantly and the tumor inhibition ratio reached to 32.4% at 1 mg/kg and 7.2% at 10 mg/kg.