Emodin triggers DNA double-strand breaks by stabilizing topoisomerase II-DNA cleavage complexes and by inhibiting ATP hydrolysis of topoisomerase II.
Emodin, an anthraquinone derived from a plant and fungi, has been reported to possess potential genotoxicity, but the mechanism is not entirely clear. Here, we report that emodin causes DNA double-strand breaks (DSBs) through stabilization of topoisomerase (Topo) II-DNA cleavage complexes and inhibition of ATP hydrolysis. In our study, emodin did not induce mutagenecity in the salmonella mutation assay but caused genotoxicity in the thymidine kinase gene mutation assay and in the micronucleus test. Moreover, emodin induced DNA DSBs demonstrated by induction of comet tails, the expression of phosphorylated histone H2AX, and phosphorylation of ataxia telangiectasia mutated. Our studies also revealed that emodin exerted strong inhibitory activity against Topo II in the supercoiled pBR322 relaxation assay and in Topo II-mediated kinetoplast DNA decatenation, similar to the previous report. We also showed that the inhibitory effect of emodin on Topo II was because of its ability to stabilize Topo II-DNA complexes and to inhibit the ATP hydrolysis of Topo II. Furthermore, emodin was found to trigger DNA DSBs in a Topo II-dependent manner using the Topo II catalytic inhibitor aclarubicin and in Topo II-deficient mitoxantrone-resistant variant HL-60/MX2 cells. Together, these results suggest that in emodin-induced DNA DSBs and genotoxicity, stabilization of Topo II-DNA cleavage complexes and inhibition of ATP hydrolysis play an important role.
Li
Yan
Y
Center for Drug Safety Evaluation and Research, State Key Laboratory of New Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China.
Luan
Yang
Y
Qi
Xinming
X
Li
Ming
M
Gong
Likun
L
Xue
Xiang
X
Wu
Xiongfei
X
Wu
Yuanfeng
Y
Chen
Min
M
Xing
Guozhen
G
Yao
Jun
J
Ren
Jin
J
D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors* / Q000378:metabolism; D045744:Cell Line, Tumor; D020552:Comet Assay; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004642:Emodin / Q000633:toxicity*; D006801:Humans; D006868:Hydrolysis; D015162:Micronucleus Tests; D009153:Mutagens / Q000633:toxicity*; D009154:Mutation / Q000187:drug effects; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D059005:Topoisomerase II Inhibitors / Q000633:toxicity*
D009153:Mutagens; D059005:Topoisomerase II Inhibitors; D000255:Adenosine Triphosphate; D013937:Thymidine Kinase; D004250:DNA Topoisomerases, Type II; D004642:Emodin