Oncotarget

Research Papers:

Arenobufagin intercalates with DNA leading to G2 cell cycle arrest via ATM/ATR pathway

Li-Juan Deng _, Qun-Long Peng, Long-Hai Wang, Jun Xu, Jun-Shan Liu, Ying-Jie Li, Zhen-Jian Zhuo, Liang-Liang Bai, Li-Ping Hu, Wei-Min Chen, Wen-Cai Ye and Dong-Mei Zhang

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Oncotarget. 2015; 6:34258-34275. https://doi.org/10.18632/oncotarget.5545

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Abstract

Li-Juan Deng1,*, Qun-Long Peng1,*, Long-Hai Wang1, Jun Xu1, Jun-Shan Liu2, Ying-Jie Li1, Zhen-Jian Zhuo1, Liang-Liang Bai1, Li-Ping Hu1, Wei-Min Chen1, Wen-Cai Ye1, Dong-Mei Zhang1

1Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, P.R. China

2School of Traditional Chinese Medicine, Southern Medical University, Guangzhou 510632, P.R. China

*These authors have contributed equally to this work

Correspondence to:

Dong-Mei Zhang, e-mail: [email protected]

Wen-Cai Ye, e-mail: [email protected]

Keywords: arenobufagin, DNA intercalator, DNA damage response, G2 cell cycle arrest

Received: May 26, 2015     Accepted: October 02, 2015     Published: October 13, 2015

ABSTRACT

Arenobufagin, a representative bufadienolide, is the major active component in the traditional Chinese medicine Chan’su. It possesses significant antineoplastic activity in vitro. Although bufadienolide has been found to disrupt the cell cycle, the underlying mechanisms of this disruption are not defined. Here, we reported that arenobufagin blocked the transition from G2 to M phase of cell cycle through inhibiting the activation of CDK1-Cyclin B1 complex; The tumor suppressor p53 contributed to sustaining arrest at the G2 phase of the cell cycle in hepatocellular carcinoma (HCC) cells. Moreover, arenobufagin caused double-strand DNA breaks (DSBs) and triggered the DNA damage response (DDR), partly via the ATM/ATR-Chk1/Chk2-Cdc25C signaling pathway. Importantly, we used a synthetic biotinylated arenobufagin-conjugated chemical probe in live cells to show that arenobufagin accumulated mainly in the nucleus. The microscopic thermodynamic parameters measured using isothermal titration calorimetry (ITC) also demonstrated that arenobufagin directly bound to DNA in vitro. The hypochromicity in the UV-visible absorption spectrum, the significant changes in the circular dichroism (CD) spectrum of DNA, and the distinct quenching in the fluorescence intensity of the ethidium bromide (EB)-DNA system before and after arenobufagin treatment indicated that arenobufagin bound to DNA in vitro by intercalation. Molecular modeling suggested arenobufagin intercalated with DNA via hydrogen bonds between arenobufagin and GT base pairs. Collectively, these data provide novel insights into arenobufagin-induced cell cycle disruption that are valuable for the further discussion and investigation of the use of arenobufagin in clinical anticancer chemotherapy.


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