Lin T.-Y.Huang C.-P.Au L.-C.Chang Y.-W.CHUNG-YI HULin S.-B.2021-03-152021-03-1520120893-228Xhttps://scholars.lib.ntu.edu.tw/handle/123456789/552721We previously reported that the anticancer activity of a botanical compound 10′(Z),13′(E),15′(E)-heptadecatrienylhydroquinone [HQ17(3)] was attributed to topoisomerase (Topo) IIα poisoning and the induction of oxidative damage. HQ17(3) irreversibly inhibits Topo IIα activity in vitro and is more cytotoxic in leukemia HL-60 cells than in Topo IIα-deficient variant HL-60/MX2 cells, which suggests that Topo IIα is a cellular target of HQ17(3). This study further characterizes the molecular mechanisms of the anticancer activity of HQ17(3). Proteomic analyses indicated that HQ17(3) reacted with Cys-427, Cys-733, and Cys-997 of recombinant Topo IIα in vitro, whereas it reacted with Cys-427 of cellular Topo IIα in Huh7 hepatoma cells. The modification of HQ17(3) inhibited Topo IIα catalytic activity, increased the Topo IIα-DNA cleavage complex, and caused the accumulation of DNA breakage. In Huh7 cells, HQ17(3) treatment caused prompt inhibition of DNA synthesis and consequently induced the expression of DNA damage-related genes DDIT3, GADD45A, and GADD45G. Topo IIα inhibition, apoptosis, and oxidative stress were found to account for cytotoxicity caused by HQ17(3). Pretreatment of Huh7 cells with N-acetylcysteine (NAC) partially attenuated mitochondrial membrane damage, DNA breakage, and caspase activation. However, NAC pretreatment did not diminish HQ17(3)-induced cell death. These results suggest that the anticancer activity of HQ17(3) is attributed significantly to Topo IIα poisoning. The structural feature of HQ17(3) can be used as a model for the design of Topo IIα inhibitors and anticancer drugs. ? 2012 American Chemical Society.[SDGs]SDG3acetylcysteine; antineoplastic agent; caspase; DNA topoisomerase (ATP hydrolysing); growth arrest and DNA damage inducible protein 153; growth arrest and DNA damage inducible protein 45; heptadecatrienylhydroquinone; hydroquinone derivative; unclassified drug; antineoplastic activity; apoptosis; article; cancer cell; cell viability; controlled study; DNA strand breakage; enzyme activation; hepatoma cell; human; human cell; in vitro study; mitochondrial membrane; protein modification; Western blotting; Antigens, Neoplasm; Antineoplastic Agents; Apoptosis; Cell Survival; Cysteine; DNA Breaks; DNA Breaks, Double-Stranded; DNA Topoisomerases, Type II; DNA-Binding Proteins; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Enzyme Inhibitors; Flow Cytometry; Humans; Hydroquinones; Structure-Activity Relationship; Tumor Cells, Culturedjournal article10.1021/tx3002302230887862-s2.0-84869392897