Myxobacterial tubulysins are promising chemotherapeutics inhibiting microtubule polymerization, however, high unspecific toxicity so far prevents their application in therapy. For selective cancer cell targeting, here the coupling of a synthetic cytolysin to the hY1-receptor preferring peptide [F(7),P(34)]-neuropeptide Y (NPY) using a labile disulfide linker is described. Since hY1-receptors are overexpressed in breast tumors and internalize rapidly, this system has high potential as peptide-drug shuttle system. Molecular characterization of the cytolysin-[F(7),P(34)]-NPY bioconjugate revealed potent receptor activation and receptor-selective internalization, while viability studies verified toxicity. Triple SILAC studies comparing free cytolysin with the bioconjugate demonstrated an intracellular mechanism of action regardless of the delivery pathway. Treatments resulted in a regulation of proteins implemented in cell cycle arrest confirming the tubulysin-like effect of the cytolysin. Thus, the cytolysin-peptide bioconjugate fused by a cleavable linker enables a receptor-specific delivery as well as a potent intracellular drug-release with high cytotoxic activity.
Keywords: Breast cancer; Cytolysin; Neuropeptide Y; Peptide–drug conjugate; Quantitative proteomics; SILAC.
Copyright © 2015. Published by Elsevier B.V.