Small Molecule Therapeutics SC-60, a Dimer-Based Sorafenib Derivative, Shows a Better Anti–Hepatocellular Carcinoma Effect than Sorafenib in a Preclinical Hepatocellular Carcinoma Model Wei-Tien Tai 1,2 , Chung-Wai Shiau 3 , Yong-Shi Li 1,2 , Yao-Li Chen 4 , Pei-Yi Chu 5 , Jui-Wen Huang 6 , Cheng-Yi Hsu 3 , Yi-Chieh Hsu 3 , Pei-Jer Chen 1 , and Kuen-Feng Chen 1,2 Abstract Sorafenib is the first approved targeted therapeutic reagent for hepatocellular carcinoma. Here, we report that SC-60, a dimer-based sorafenib derivative, overcomes the resistance of sorafenib and shows a better anti-hepatocellular carcinoma effect in vitro and in vivo. SC-60 substantially increased SH2 domain- containing phosphatase 1 (SHP-1) phosphatase activity in hepatocellular carcinoma cells and purified SHP- 1 proteins, suggesting that SC-60 affects SHP-1 directly. Molecular docking and truncated mutants of SHP- 1 further confirmed that SC-60 interferes with the inhibitory N-SH2 domain to relieve the closed catalytic protein tyrosine phosphatase domain of SHP-1. Deletion of N-SH2 domain (dN1) or point mutation (D61A) of SHP-1 abolished the effect of SC-60 on SHP-1, p-STAT3, and apoptosis. Importantly, SC-60 exhibited significant survival benefits compared with sorafenib in a hepatocellular carcinoma orthotopic model via targeting the SHP-1/STAT3–related signaling pathway. In summary, dimer derivative of sorafenib, SC-60, is a SHP-1 agonist and may be a potent reagent for hepatocellular carcinoma–targeted therapy. Mol Cancer Ther; 13(1); 27–36. Ó2013 AACR. Introduction Sorafenib (Nexavar) acts as a tyrosine kinase inhibitor (TKI) against the VEGF receptor (VEGFR) family and Raf-1 (1). According to the survival benefit in several large phase III studies, sorafenib has been proved in renal cell carcinoma and hepatocellular carcinoma since 2006 (2–5). Moreover, sorafenib also displayed a signif- icant clinical benefit for patients with sporadic medul- lary thyroid cancer (6). However, the low rate of tumor remission and the high cost of treatment prompt us to discover more effective and cheaper therapeutic agents than sorafenib for the treatment of hepatocellular car- cinoma. Previously, we have designed a series of sor- afenib derivatives and validated the potency of these derivatives as STAT3 inhibitors independent of kinase inhibition (7, 8). We found that SC-60, a dimer-based structure modified from sorafenib, shows a significant anti–hepatocellular carcinoma effect in vitro and in vivo. Notably, SC-60 increases the activity of SH2 domain- containing phosphatase 1 (SHP-1) directly, suggesting that SC-60 inhibits tumor proliferation via dephosphor- ylation of STAT3. SC-60 further overcomes the resis- tance of sorafenib in sorafenib-resistant hepatocellular carcinoma cells and shows significant survival benefits compared with sorafenib in a preclinical hepatocellular carcinoma model. STAT3 plays a critical role in the transcriptional regulation of genes that are involved in cell proliferation and survival, and regulates expression of numerous apoptosis-related proteins including Bcl-2, Bcl-xL, Mcl-1, survivin, and cyclin D1 (9, 10). Notably, STAT3 signaling is downregulated by protein tyrosine phos- phatases, such as the SH2 domain-containing tyrosine phosphatase family (SHP-1 and SHP-2), and protein tyrosine phosphatase 1B (PTP-1B; refs. 11–16). These phosphatases reduce STAT3 activation directly by dephosphorylation of STAT3 (17–20). SHP-1, a negative regulator of phospho-STAT3, is involved in many hematopoietic signaling processes, but little is known about its role in carcinogenesis. SHP-1 (PTPN6) consists of two SH2 domains at the N-terminus and one catalytic PTP domain at the C-terminus. On the basis of the crystal structure of SHP-1, the N-SH2 domain blocks Authors' Affiliations: 1 Department of Medical Research; 2 National Center of Excellence for Clinical Trial and Research, National Taiwan University Hospital; 3 Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei; 4 Department of Surgery, Changhua Christian Hospital, Changhua; 5 Department of Pathology, St. Martin De Porres Hospital, Chiayi; and 6 Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute, Hsin-Chu, Taiwan Note: Supplementary data for this article are available at Molecular Cancer Therapeutics Online (http://mct.aacrjournals.org/). W.-T. Tai and C.-W. Shiau contributed equally to this work. Corresponding Author: Kuen-Feng Chen, Department of Medical Research, National Taiwan University Hospital, 7, Chung-Shan South Road, Taipei 10016, Taiwan, Republic of China. Phone: 886-223-123- 456, ext. 63548; Fax: 886-223-225-329; E-mail: kfchen1970@ntu.edu.tw doi: 10.1158/1535-7163.MCT-13-0595 Ó2013 American Association for Cancer Research. Molecular Cancer Therapeutics www.aacrjournals.org 27 Downloaded from http://aacrjournals.org/mct/article-pdf/13/1/27/2327780/27.pdf by guest on 18 June 2022