Therapeutics targeting CD90-integrin-AMPK-CD133 signal axis in liver cancer

Abstract

// Wei-Ching Chen 1, 2 , Yung-Sheng Chang 1, 2 , Hui-Ping Hsu 3 , Meng-Chi Yen 1 , Hau-Lun Huang 1, 2 , Chien-Yu Cho 1, 2 , Chih-Yang Wang 1, 2 , Tzu-Yang Weng 1, 2 , Po-Ting Lai 4 , Ching-Shih Chen 4 , Yih-Jyh Lin 3 , Ming-Derg Lai 1, 2, 5 1 Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan 2 Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan 3 Department of Surgery, College of Medicine, National Cheng Kung University, Tainan, Taiwan 4 Division of Medicinal Chemistry, College of Pharmacy, The Ohio State University, Columbus, OH, USA 5 Center for Infectious Diseases and Signaling Research, College of Medicine, National Cheng Kung University, Tainan, Taiwan Correspondence to: Ming-Derg Lai, e-mail: [e-mail] Yih-Jyh Lin, e-mail: [e-mail] Keywords: cancer stem cell marker, integrin, AMPK, mTOR, OSU-CG5 Abbreviations: HCC, hepatocellular carcinoma; HGF, hepatocyte growth factor; TGF-β-1, transforming growth factor-β-1; CSC, cancer stem cell Received: June 09, 2015      Accepted: October 12, 2015      Published: October 22, 2015 ABSTRACT CD90 is used as a marker for cancer stem cell in liver cancer. We aimed to study the mechanism by which CD90 promoted liver cancer progression and identify the new therapeutic targets on CD90 signal pathway. Ectopic expression of CD90 in liver cancer cell lines enhanced anchorage-independent growth and tumor progression. Furthermore, CD90 promoted sphere formation in vitro and upregulated the expression of the cancer stem cell marker CD133. The CD133 expression was higher in CD45-CD90+ cells in liver cancer specimen. The natural carcinogenic molecules TGF-β-1, HGF, and hepatitis B surface antigen increased the expression of CD90 and CD133. Inhibition of CD90 by either shRNA or antibody attenuated the induction of CD133 and anchorage-independent growth. Lentiviral delivery of CD133 shRNA abolished the tumorigenicity induced by CD90. Ectopic expression of CD90 induced mTOR phosphorylation and AMPK dephosphorylation. Mutation of integrin binding-RLD domain in CD90 attenuated the induction of CD133 and anchorage-independent growth. Similar results were observed after silencing β3 integrin. Signaling analyses revealed that AMPK/mTOR and β3 integrin were required for the induction of CD133 and tumor formation by CD90. Importantly, the energy restriction mimetic agent OSU-CG5 reduced the CD90 population in fresh liver tumor sample and repressed the tumor growth. In contrast, sorafenib did not decrease the CD90+ population. In conclusion, the signal axis of CD90-integrin-mTOR/AMPK-CD133 is critical for promoting liver carcinogenesis. Molecules inhibiting the signal axis, including OSU-CG5 and other inhibitors, may serve as potential novel cancer therapeutic targets in liver cancer.