Protein transduction exploits the ability of some
cell-penetrating
peptide (CPP) sequences to enhance the uptake of proteins and other macromolecules by mammalian cells. Previously developed hydrophobic CPPs, named membrane translocating sequence (MTS), membrane translocating motif (MTM) and
macromolecule transduction domain (MTD), are able to deliver biologically active proteins into a variety of cells and tissues. Various cargo proteins fused to these CPPs have been used to test the functional and / or therapeutic
efficacy of
protein transduction. For example, recombinant proteins consisting of
suppressor of
cytokine signaling 3
protein (CP-SOCS3) fused to the
fibroblast growth factor (FGF) 4-derived MTM were developed to inhibit
inflammation and
apoptosis. However, CP-SOCS3 fusion proteins expressed in
bacteria were hard to purify in soluble form. To address these critical limitations, CPP sequences called advanced MTDs (aMTD) have been developed in this art. This is accomplished by (i) analyzing previous developed hydrophobic CPP sequences to identify specific
critical factors (CFs) that affect
intracellular delivery potential and (ii) constructing artificial aMTD sequences satisfied for each critical factor. In addition, solubilization domains (SDs) have been incorporated into the aMTD-fused SOCS3 recombinant proteins to enhance
solubility with corresponding increases in
protein yield and
cell- / tissue-permeability. These recombinant SOCS3 proteins fused to aMTD / SD having much higher
solubility / yield and
cell- / tissue-permeability have been named as improved cell-permeable SOCS3 (iCP-SOCS3) proteins. Previously developed CP-SOCS3 proteins fused to MTM were only tested or used as anti-inflammatory agents to treat
acute liver injury. In the present art, iCP-SOCS3 proteins have been tested for use as anti-
cancer agents in the treatment of
hepatocellular carcinoma. Since SOCS3 is frequently deleted in and loss of SOCS3 in hepatocytes promotes resistance to
apoptosis and proliferation, we reasoned that iCP-SOCS3 could be used as a protein-based
intracellular replacement therapy for the treatment of
hepatocellular carcinoma. The results support this reasoning: treatment of
hepatocellular carcinoma cells with iCP-SOCS3 results in reduced
cancer cell viability, enhanced
apoptosis and loss of
cell migration / invasion potential. Furthermore, iCP-SOCS3 inhibits the growth of hepatocellular
carcinoma in a subcutaneous xenografts model. In the present invention with iCP-SOCS3 fused to an empirically determined combination of newly developed aMTD and customized SD,
macromolecule intracellular transduction technology (MITT) enabled by the advanced MTD may provide
novel protein therapy against hepatocellular
carcinoma.