Background:

Etoposide (VP-16) is the first agent recognized as a topoisomerase II inhibitor of anticancer drug with IC50 of 59.2 μM.

The activity of the topoisomerase II enzyme on re-ligation of DNA strands is interrupted by etoposide. A ternary complex with DNA is formed by etoposide, and causes DNA strands to break [1]. The enzyme was more important in cancer cell than healthy cells, because cancer cells divided more rapidly. So etoposide induced apoptosis of the cancer cells [2]. Etoposide exhibited cytotoxic activity against HepG2 and MOLT-3 cancer cells with IC50 of 30.16 μM and 0.051μM [3]. The IC50 values of etoposide against the tumor cell lines of BGC-823, HeLa, and A549 were 43.74 ± 5.13, 209.90 ± 13.42, and 139.54 ± 7.05 μM, respectively [4].

参考文献:
[1]. Pommier Y, Leo E, Zhang H, Marchand C. DNA topoisomerases and their poisoning by anticancer and antibacterial drugs. Chem Biol. 2010 May 28;17(5):421-33.
[2]. Gordaliza M, García PA, del Corral JM, Castro MA, Gómez-Zurita MA. Podophyllotoxin: distribution, sources, applications and new cytotoxic derivatives. Toxicon. 2004 Sep 15;44(4):441-59.
[3]. Pingaew R, Mandi P, Nantasenamat C, Prachayasittikul S, Ruchirawat S, Prachayasittikul V. Design, synthesis and molecular docking studies of novel N-benzenesulfonyl-1,2,3,4-tetrahydroisoquinoline-based triazoles with potential anticancer activity. Eur J Med Chem. 2014 May 6;81C:192-203.
[4]. Xiao L, Zhao W, Li HM, Wan DJ, Li DS, Chen T, Tang YJ. Design and synthesis of the novel DNA topoisomerase II inhibitors: Esterification and amination substituted 4'-demethylepipodophyllotoxin derivates exhibiting anti-tumor activity by activating ATM/ATR signaling pathways. Eur J Med Chem. 2014 Jun 10;80:267-77.