Gossypol Interferes with Both Type I and Type II Topoisomerase Activities Without Generating Strand Breaks

Abstract

A considerable number of agents with chemotherapeutic potentials reported over the past years were shown to interfere with the reactions of DNA topoisomerases, the essential enzymes that regulate conformational changes in DNA topology. Gossypol, a naturally occurring bioactive phytochemical is a chemopreventive agent against various types of cancer cell growth with a reported activity on mammalian topoisomerase II. The compounds targeting topoisomerases vary in their mode of action; class I compounds act by stabilizing covalent topoisomerase-DNA complexes resulting in DNA strand breaks while class II compounds interfere with the catalytic function of topoisomerases without generating strand breaks. In this study, we report Gossypol as the interfering agent with type I topoisomerases as well. We also carried out an extensive set of assays to analyze the type of interference manifested by Gossypol on DNA topoisomerases. Our results strongly suggest that Gossypol is a potential class II inhibitor as it blocked DNA topoisomerase reactions with no consequently formed strand breaks.

Structural modification of ellipticine derivatives with alkyl groups of varying length is influential on their effects on human DNA topoisomerase II: a combined experimental and computational study

“…Given that vast majority of compounds, covering a number of ellipticine derivatives effective on tumor cells were reported to exert their effects through interfering with topoisomerase II reactions we screened the activities of the derivatives against DNA topoisomerase II reactions (Senarisoy et al 2013;Ashley and Osheroff 2014;Miller et al 2012;McClendon and Osheroff 2007). We therefore employed decatenatiation, intercalation, and cleavage assays.…”

“…Decatenation assay is specific for topoisomerase II activity. It is based on the detection of kinetoplast DNA, the mitochondrial DNA of Crithidia fasciculata found as a catenated network of DNA rings (Senarisoy et al 2013). All of the derivatives, Z-1, Z-2, Z-5, and Z-6, inhibited decatenation activity of topoisomerase II at 0.2 mM concentration.…”

“…DNA cleavage assays contained 10 nM negatively supercoiled pBR322 DNA and 150 nM human topoisomerase II of either alfa or beta isoforms in a final volume of 20 µL of 10 mM Tris-HCl, pH 7.9, 5 mM MgCl 2 , 100 mM KCl, 0.1 mM EDTA, and 2.5% (v/v) glycerol (Senarisoy et al 2013;Vann et al 2016a). Mixtures were incubated for 6 min at 37°C.…”

“…DNA topoisomerases play fundamental roles in overcoming topological problems of DNA by introducing transient breaks in the duplex during replication, transcription, recombination, and chromosomal segregation (Wang 1971). Given that the inherent functions of topoisomerases are crucial for genomic integrity, the interfere with these enzymes or generating enzyme-mediated DNA damage is an effective strategy in development of chemotherapeutic agents (Coban et al 2008;Gul et al 2009;Senarisoy et al 2013;Ashley and Osheroff 2014;Ketron and Osheroff 2014;Zupkó et al 2014;Vann et al 2016aVann et al , 2016bDelgado et al 2018).…”

Multiple Topoisomerase I (TopoI), Topoisomerase II (TopoII) and Tyrosyl-DNA Phosphodiesterase (TDP) inhibitors in the development of anticancer drugs

“…Gossypol (GSP), 5 (Chart 1) is a natural polyphenol isolated from cotton plant, Gossypium (Malvaceae). In 2013, Senarisoy M. et al, (Senarisoy et al, 2013) reported that 5 is able to inhibit both TopoI and TopoII enzymes, and in particular this compound belongs to the class of the catalytic inhibitors.…”