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: Ting-Yu Lin, Cheng-Po Huang, Lo-Chun Au, Ya-Wen Chang, Chung-Yi Hu, Shwu-Bin Lin
• Journal: Chemical research in toxicology (Chem Res Toxicol) Vol. 25 Issue 11 Pg. 2340-51 (Nov 19 2012) ISSN: 1520-5010 [Electronic] United States
• PMID: 23088786 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• 10'(Z),13'(E),15'(E)-heptadecatrienylhydroquinone
• Antigens, Neoplasm
• Antineoplastic Agents
• DNA-Binding Proteins
• Enzyme Inhibitors
• Hydroquinones
• DNA Topoisomerases, Type II
• Cysteine

Topics

• Antigens, Neoplasm (metabolism)
• Antineoplastic Agents (chemistry, isolation & purification, pharmacology)
• Apoptosis (drug effects)
• Cell Survival (drug effects)
• Cysteine (chemistry)
• DNA Breaks (drug effects)
• DNA Breaks, Double-Stranded (drug effects)
• DNA Topoisomerases, Type II (metabolism)
• DNA-Binding Proteins (antagonists & inhibitors, metabolism)
• Dose-Response Relationship, Drug
• Drug Screening Assays, Antitumor
• Enzyme Inhibitors (chemistry, isolation & purification, pharmacology)
• Flow Cytometry
• Humans
• Hydroquinones (chemistry, isolation & purification, pharmacology)
• Structure-Activity Relationship
• Tumor Cells, Cultured