Protein Kinase C Alpha-Responsive Gene Carrier For Cancer-Specific Transgene Expression And Cancer Therapy

The presence of intracellular signal transduction and its abnormal activities in many cancers has potential for medical and pharmaceutical applications. We recently developed a protein kinase C alpha (PKC alpha)-responsive gene carrier for cancerspecific gene delivery. Here, we demonstrate an in-depth analysis of cellular signal-responsive gene carrier and the impact of its selective transgene expression in response to malfunctioning intracellular signaling in cancer cells. We prepared a novel gene carrier consisting of a linear polyethylenimine (LPEI) main chain grafted to a cationic PKC alpha-specific substrate (FKKQGSFAKKK-NH2). The LPEI-peptide conjugate formed a nanosized polyplex with pDNA and mediated efficient cellular uptake and endosomal escape. This polyplex also led to successful transgene expression which responded to the target PKC alpha in various cancer cells and exhibited a 10-100-fold higher efficiency compared to the control group. In xenograft tumor models, the LPEI-peptide conjugate promoted transgene expression showing a clear-cut response to PKC alpha. Furthermore, when a plasmid containing a therapeutic gene, human caspase-8 (pcDNA-hcasp8), was used, the LPEIpeptide conjugate had significant cancer-suppressive effects and extended animal survival. Collectively, these results reveal that our method has great potential for cancer-specific gene delivery and therapy.