Utilization of a PNA-peptide conjugate to induce a cancer protease-responsive RNAi effect

Abstract

Small interfering RNA (siRNA) is regarded as a promising tool for cancer therapy because of the wide applicability to various cancer-related genes. However, non-specific delivery of siRNA is one of the major causes of adverse effects. To access the issue, here we designed a new siRNA system which turns on RNAi responding to a cancer cell-specific protease, cathepsin B. The system uses a peptide nucleic acid (PNA)-peptide conjugate to provide this protease-responsive activation. The PNA-peptides were found to form hybrids with double-stranded RNAs with complementary protruding regions, which then affected the susceptibility of dsRNA to Dicer. The dsRNA/PNA-peptide hybrids were activated in cancer cells with a high cathepsin B activity to show RNAi.