Escin-induced DNA damage promotes escin-induced apoptosis in human colorectal cancer cells via p62 regulation of the ATM/γH2AX pathway

Zhong WANG1, Qiang CHEN1, Bin LI2, Jia-ming XIE1, Xiao-dong YANG1, Kui ZHAO1, Yong WU1, Zhen-yu YE1, Zheng-rong CHEN1, Zheng-hong QIN3, Chun-gen XING1
1 Department of General Surgery, Second Affiliated Hospital of Soochow University, Suzhou 215007, China
2 Department of General Surgery, the First People’s Hospital of Wu Jiang, Suzhou 215200, China
3 Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, College of Pharmaceutical Science, Soochow University, Suzhou 215123, China
Correspondence to: Zheng-hong QIN:, Chun-gen XING:,
DOI: 10.1038/aps.2017.192
Received: 13 September 2017
Accepted: 29 December 2017
Advance online: 31 May 2018


Escin, a triterpene saponin isolated from horse chestnut seed, has been used to treat encephaledema, tissue swelling and chronic venous insufficiency. Recent studies show that escin induces cell cycle arrest, tumor proliferation inhibition and tumor cell apoptosis. But the relationship between escin-induced DNA damage and cell apoptosis in tumor cells remains unclear. In this study, we investigated whether and how escin-induced DNA damage contributed to escin-induced apoptosis in human colorectal cancer cells. Escin (5–80 μg/mL) dose-dependently inhibited the cell viability and colony formation in HCT116 and HCT8 cells. Escin treatment induced DNA damage, leading to p-ATM and γH2AX upregulation. Meanwhile, escin treatment increased the expression of p62, an adaptor protein, which played a crucial role in controlling cell survival and tumorigenesis, and had a protective effect against escin-induced DNA damage: knockdown of p62 apparently enhanced escin-induced DNA damage, whereas overexpression of p62 reduced escin-induced DNA damage. In addition, escin treatment induced concentration- and time-dependent apoptosis. Similarly, knockdown of p62 significantly increased escin-induced apoptosis in vitro and produced an escin-like antitumor effect in vivo. Overexpression of p62 decreased the rate of apoptosis. Further studies revealed that the functions of p62 in escin-induced DNA damage were associated with escin-induced apoptosis, and p62 knockdown combined with the ATM inhibitor KU55933 augmented escin-induced DNA damage and further increased escin-induced apoptosis. In conclusion, our results demonstrate that p62 regulates ATM/γH2AX pathway-mediated escin-induced DNA damage and apoptosis.
Keywords: escin p62 DNA damage ATM/γH2AX pathway; apoptosis colorectal cancer; HCT116 cells; HCT8 cells

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