KU-0060648 inhibits hepatocellular carcinoma cells through DNA-PKcs-dependent and DNA-PKcs-independent mechanisms
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Min-Bin Chen1,*, Zhen-Tao Zhou2,*, Lan Yang3,*, Mu-Xin Wei4, Min Tang1, Ting-Yan Ruan5, Jun-Ying Xu5, Xiao-zhong Zhou2, Gang Chen6, Pei-Hua Lu5
1Department of Oncology, Kunshan First People’s Hospital Affiliated to Jiangsu University, Kunshan 215300, China
2Department of Orthopedics, the Second Affiliated Hospital of Soochow University, Suzhou 215000, China
3Department of Breast Surgery, the Third Affiliated Hospital of Soochow University, Changzhou 213003, China
4Department of Traditional Chinese Medicine, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
5Department of Medical Oncology, Wuxi People’s Hospital Affiliated to Nanjing Medical University, Wuxi 214023, China
6Department of Neurosurgery, the First Affiliated Hospital of Soochow University, Suzhou 215006, China
*These authors have contributed equally to this work
Pei-Hua Lu, e-mail: firstname.lastname@example.org
Xiao-zhong Zhou, e-mail: email@example.com
Gang Chen, e-mail: firstname.lastname@example.org
Keywords: hepatocellular carcinoma (HCC), DNA-PKcs, KU-0060648, PI3K-AKT-mTOR signaling, miRNA
Received: October 22, 2015 Accepted: February 05, 2016 Published: February 26, 2016
Here we tested anti-tumor activity of KU-0060648 in preclinical hepatocellular carcinoma (HCC) models. Our results demonstrated that KU-0060648 was anti-proliferative and pro-apoptotic in established (HepG2, Huh-7 and KYN-2 lines) and primary human HCC cells, but was non-cytotoxic to non-cancerous HL-7702 hepatocytes. DNA-PKcs (DNA-activated protein kinase catalytic subunit) is an important but not exclusive target of KU-0060648. DNA-PKcs knockdown or dominant negative mutation inhibited HCC cell proliferation. On the other hand, overexpression of wild-type DNA-PKcs enhanced HepG2 cell proliferation. Importantly, KU-0060648 was still cytotoxic to DNA-PKcs-silenced or -mutated HepG2 cells, although its activity in these cells was relatively weak. Further studies showed that KU-0060648 inhibited PI3K-AKT-mTOR activation, independent of DNA-PKcs. Introduction of constitutively-active AKT1 (CA-AKT1) restored AKT-mTOR activation after KU-0060648 treatment in HepG2 cells, and alleviated subsequent cytotoxicity. In vivo, intraperitoneal (i.p.) injection of KU-0060648 significantly inhibited HepG2 xenograft growth in nude mice. AKT-mTOR activation was also inhibited in xenografted tumors. Finally, we showed that DNA-PKcs expression was significantly upregulated in human HCC tissues. Yet miRNA-101, an anti-DNA-PKcs miRNA, was downregulated. Over-expression of miR-101 in HepG2 cells inhibited DNA-PKcs expression and cell proliferation. Together, these results indicate that KU-0060648 inhibits HCC cells through DNA-PKcs-dependent and -independent mechanisms.
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