Tumor-Penetrating Delivery of siRNA against TNF\u03b1 to Human Vestibular Schwannomas

Yin Ren,Jessica E Sagers,Sangeeta N Bhatia,Konstantina M Stankovic,Lukas D Landegger

doi:10.1038/s41598-017-13032-9

Abstract

Vestibular schwannoma (VS) is the most common tumor of the cerebellopontine angle, and it typically presents with sensorineural hearing loss. The genomic landscape of schwannoma is complex and many of the molecules implicated in VS pathogenesis represent targets not amenable to antibody-based or small molecule therapeutics. Tumor-targeted delivery of small interfering RNA (siRNA) therapeutics provides a direct and effective means to interrogate targets while minimizing off-target effects. To establish a preclinical model for therapeutic inhibition of putative targets in VS, archived tumor specimens, fresh tumor cells derived from patients with sporadic VS, and an established schwannoma cell line were screened. Nanoparticles directed by the tumor-homing peptide iRGD were selectively taken up by primary VS cultures in vitro via interactions with αvβ3/β5 integrins and neuropilin-1 (NRP-1). Cellular uptake was inhibited by a neutralizing antibody against αv integrin in a dose-dependent manner. When applied to primary VS cultures, iRGD-targeted nanoparticles delivered siRNA directed against TNFα in a receptor-specific fashion to potently silence gene expression and protein secretion. Taken together, our results provide a proof of principle for tumor-targeted, nanoparticle-mediated delivery of siRNA to VS and establish a novel platform for the development and pre-clinical screening of molecular therapeutics against VS.

Highlights

To date, the mainstays of therapy for growing Vestibular schwannoma (VS) include surgical resection and stereotactic radiation, as there are currently no FDA-approved systemic medical therapies to treat VS or ameliorate VS-associated SNHL
We began by investigating the ability of nanoparticles consisting of tandem-peptides complexed with small interfering RNA (siRNA) molecules, previously developed in the laboratory to target human epithelial ovarian cancer cells, to target vestibular schwannoma cells
The iRGD peptide consists of the canonical RGD motif which functions as the affinity ligand for αv integrins, and a cryptic C-terminal arginine motif (RGDK), which is unveiled upon proteolytic processing and interacts with NRP-1 to trigger tissue penetration[17,26]

Summary

Introduction

The mainstays of therapy for growing VSs include surgical resection and stereotactic radiation, as there are currently no FDA-approved systemic medical therapies to treat VS or ameliorate VS-associated SNHL. By decorating the surface of nanoparticles with affinity ligands such as tumor-targeting peptides, siRNA therapeutics can be preferentially directed to tumor cells of interest via specific cell surface receptor-ligand interactions This form of synaphic targeting can further improve the micro-distribution of siRNA therapeutics within the tumor by enhancing cellular uptake, retention and subsequent internalization[14]. Subsequent proteolytic cleavage of iRGD unveils the cryptic C-terminal arginine, known as the CendR domain, which activates a trans-tissue transport pathway by binding to neuropilin-1 (NRP-1)[17,18,19] This allows infiltration of macromolecular payloads such as albumin-bound paclitaxel and nanoparticles as the tumor becomes more “leaky”[20,21]. Compared to non-tumor penetrating conventional RGD peptides, iRGD dramatically enhances the accumulation and efficacy of delivered drugs

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