Abstract LB-008: Intracellular delivery of SOCS3 suppresses hepatocelluar carcinoma progression

Abstract

Abstract Background Practical methods to deliver proteins systemically in animals have been hampered by poor tissue penetration and inefficient cytoplasmic localization of internalized proteins. Therefore, we have developed novel cell-penetrating peptides (CPPs), named advanced macromolecule transduction domains (aMTDs), to deliver therapeutically active macromolecule including proteins systemically in vivo. The suppressor of cytokine signaling 3 (SOCS3) is negative feedback regulator of JAK/STAT signaling that plays a key role in inflammation, fibrosis and carcinogenesis in the liver. Furthermore, hypermethylation of CpG islands in the SOCS3 promoter is correlated with its transcriptional silencing in some cancers, including hepatocellular carcinoma (HCC). Objective The present study utilized aMTD sequences to develop improved cell-permeable (iCP-) SOCS3 as a protein-based biotherapeutics against HCC. Methods Cell permeable SOCS3 proteins, with and without a 12-amino acid aMTD sequence, were expressed at high yields in E. coli. The proteins also contained a solubilization domain (SD) to enhance the solubility of the recombinant proteins in physiological buffers. Results iCP-SOCS3 fused to aMTD/SD suppressed cancer cell phenotypes (e.g., 84% inhibition of proliferation, arrested cell cycle progression, 86% inhibition of migration/invasion), apoptotic loss of cell viability (40 ~ 80% in HCC cell lines: Hep3B2.1-7, HepG2, Huh7 and SK-Hep1) and changes in apoptosis biomarker expression (e.g., Bcl-2 and cleaved caspase-3). In contrast, iCP-SOCS3 did not affect proliferation and apoptosis of non-cancer cells (Chang). In addition, iCP-SOCS3 also significantly suppressed the tumor growth (70% inhibition in Hep3B2.1-7; 67% inhibition in HepG2, respectively) in human-mouse xenograft models. The anti-tumor activity of iCP-SOCS3 was accompanied by changes in the expression of biomarkers linked to SOCS3 signaling including cyclin E, p21, Bax and VEGF. Furthermore, iCP-SOCS3 suppressed tumor growth equivalently to Cisplatin®, a well-established cytotoxic agent, but without observed toxicity or adverse effects. These results suggest that iCP-SOCS3 inhibits the growth of HCC tumor cells and tumor xenografts. Conclusions These results provide further evidence that SOCS3 can function as a tumor suppressor and intracellular delivery of iCP-SOCS3 may provide a novel protein therapy against HCC. Citation Format: Seulmee Shin, Kuysook Lee, Yunseo Hwang, Youngsil Choi, Daewoong Jo. Intracellular delivery of SOCS3 suppresses hepatocelluar carcinoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-008.