Targeting c-Myc with a novel Peptide Nuclear Delivery Device

Biologics such as peptides and antibodies are a well-established class of therapeutics. However, their intracellular delivery remains problematic. In particular, methods to efficiently inhibit intra-nuclear targets are lacking. We previously described that Pseudomonas Exotoxin A reaches the nucleoplasm via the endosomes-to-nucleus trafficking pathway. Here, we show that a non-toxic truncated form of PE can be coupled to peptides and efficiently reach the nucleoplasm. It can be used as a Peptide Nuclear Delivery Device (PNDD) to deliver polypeptidic cargos as large as Glutathione-S-transferase (GST) to the nucleus. PNDD1 is a fusion of PNDD to the c-myc inhibitor peptide H1. PNDD1 is able to inhibit c-Myc dependent transcription at nanomolar concentration. In contrast, H1 fused to various cell-penetrating peptides are active only in the micromolar range. PNDD1 attenuates cell proliferation and induces cell death in various tumor cell lines. In particular, several patient-derived Diffuse Large B-Cell Lymphomas cell lines die after exposure to PNDD1, while normal B-cells survive. Altogether, our data indicate that PNDD is a powerful tool to bring active cargo to the nucleus and PNDD1 could be the basis of a new therapy against lymphoma.