title: A cysteine-reactive alkyl hydroquinone modifies topoisomerase IIα, enhances DNA breakage, and induces apoptosis in cancer cells.
abstract: We 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.
authors.affiliation: Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan, Republic of China.
authors.forename: Ting-Yu
authors.initials: TY
authors.lastname: Lin
authors.forename: Cheng-Po
authors.initials: CP
authors.lastname: Huang
authors.forename: Lo-Chun
authors.initials: LC
authors.lastname: Au
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: Chang
authors.forename: Chung-Yi
authors.initials: CY
authors.lastname: Hu
authors.forename: Shwu-Bin
authors.initials: SB
authors.lastname: Lin
mesh_terms: D000951:Antigens, Neoplasm / Q000378:metabolism; D000970:Antineoplastic Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D003545:Cysteine / Q000737:chemistry*; D053960:DNA Breaks / Q000187:drug effects*; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D006873:Hydroquinones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured
chemical_list: C471674:10'(Z),13'(E),15'(E)-heptadecatrienylhydroquinone; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D006873:Hydroquinones; D004250:DNA Topoisomerases, Type II; D003545:Cysteine