Size Matters: Arginine-Derived Peptides Targeting the PSMA Receptor Can Efficiently Complex but Not Transfect siRNA

Christopher N Cultrara; Sunil Shah; Gina Antuono; Claudia J Heller; Jorge A Ramos; Uri Samuni; Jenny Zilberberg; David Sabatino

doi:10.1016/j.omtn.2019.10.013

Size Matters: Arginine-Derived Peptides Targeting the PSMA Receptor Can Efficiently Complex but Not Transfect siRNA

Mol Ther Nucleic Acids. 2019 Dec 6:18:863-870. doi: 10.1016/j.omtn.2019.10.013. Epub 2019 Oct 23.

Authors

Christopher N Cultrara¹, Sunil Shah¹, Gina Antuono¹, Claudia J Heller¹, Jorge A Ramos², Uri Samuni², Jenny Zilberberg³, David Sabatino⁴

Affiliations

¹ Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Avenue, South Orange, NJ 07079, USA.
² Department of Chemistry and Biochemistry, Queens College, City University of New York, Flushing, NY 11367, USA; PhD Programs in Biochemistry and Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA.
³ Center for Discovery and Innovation, Hackensack University Medical Center, 340 Kingsland Street, Building 102, Nutley, NJ 07110, USA.
⁴ Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Avenue, South Orange, NJ 07079, USA. Electronic address: david.sabatino@shu.edu.

Abstract

Oligoarginine sequences conjugated to a short cancer-targeting peptide (CTP) selective for the prostate-specific membrane antigen (PSMA) receptor was developed for selective small interfering RNA (siRNA) delivery to a human metastatic/castration-resistant prostate cancer (PCa) cell line, which expresses PSMA on the surface. The PSMA-R_n (n = 6 and 9) peptides were synthesized by solid-phase peptide synthesis, characterized by liquid chromatography-mass spectrometry (LC-MS) and condensed with glucose-regulated protein (GRP)-silencing siRNAs. Native gels showed formation of stable CTP:siRNA ionic complexes. Furthermore, siRNA release was effected by heparin competition, supporting the peptides' capabilities to act as condensing and releasing agents. However, dynamic light scattering (DLS) and transmission electron microscopy (TEM) studies revealed large anionic complexes that were prone to aggregation and limited cell uptake for RNAi activity. Taken together, these data support the notion that the development of efficient peptide-based siRNA delivery systems is in part contingent on the formulation of discrete nanoparticles that can effectively condense and release siRNA in cells.