A tumor-targeting cRGD-EGFR siRNA conjugate and its anti-tumor effect on glioblastoma in vitro and in vivo

Abstract

The epidermal growth factor receptor (EGFR) is an important anti-tumor target. The development of novel molecular-targeted anti-tumor drugs that can target the interior of tumor cells and specifically silence EGFR expression is valuable and promising. In this work, a promising anti-tumor conjugate comprising methoxy-modified EGFR siRNA and cyclic arginineglycine-aspartic acid (cRGD) peptides, which selectively bind to avb3 integrins, was synthesized and examined. To prepare cRGD-EGFR siRNA (cRGD-siEGFR), cRGD was covalently conjugated to the 5 0 -end of an siRNA sense strand using a thiol-maleimide linker. The cellular uptake and cytotoxicity of cRGD-siEGFR in vitro were tested using an avb3-positive U87MG cell line. In vivo bio-distribution, anti-tumor activity, immunogenicity and toxicity were investigated in a nude mouse tumor model through repeated i.v. administration of cRGD-siEGFR (7 times over a 48 h interval). Analyses of in vitro data showed that cRGD-siEGFR silenced EGFR expression effectively, with high tumor targeting ability. Administration of cRGD-siEGFR to tumor-bearing nude mice led to significant inhibition of tumor growth, obvious reduction of EGFR expression and down-regulation of EGFR mRNA and protein in tumor tissue. Furthermore, serum biochemistry and pathological section evaluation did not indicate any serious toxicity of cRGDsiEGFR in vivo. cRGD-siEGFR is likely a promising candidate with high targeting ability, substantial anti-tumor effects and low toxicity in vitro and in vivo.

Glut3 Addiction Is a Druggable Vulnerability for a Molecularly Defined Subpopulation of Glioblastoma

“…Aside from cilengitide, there are a number of αvβ3-targeted strategies in development for GBM, including GLPG0187, a small molecule antagonist of multiple integrins including αvβ3, αvβ5, αvβ6, and α5β1 (Cirkel et al, 2016), as well as approaches that use RGD peptides for αvβ3-targeted delivery of radionuclides (Jin et al, 2017), siRNA (He et al, 2017), and chemotherapy-loaded nanoparticles or nanogels (Chen et al, 2017; Fang et al, 2017). Considering that Glut3 addiction is also a feature of GBM cancer stem cells (Flavahan et al, 2013), targeting this phenotype with an αvβ3 antagonist has the potential to eradicate the most aggressive and drug resistant subpopulation within the tumor.…”

Reverting the molecular fingerprint of tumor dormancy as a therapeutic strategy for glioblastoma

“…In another recent study, a methoxy-modified EGFR siRNA was conjugated to cyclic arginine-glycine-aspartic acid peptide, which binds to avb3 integrins expressed on U-87 MG glioblastoma cells. Cyclic arginine-glycine-aspartic acid-siEGFR conjugate demonstrated high tumor targeting abilities, which facilitated effective reduction of EGFR mRNA levels in the tumor tissues and significant inhibition of U-87 MG tumor growth (56). Another commonly used strategy for nanocarrier-directed siRNA delivery, in addition to encapsulation and conjugation, is electrostatic complexation.…”

Efficacy of Concanavalin-A conjugated nanotransfersomal gel of apigenin for enhanced targeted delivery of UV induced skin malignant melanoma

“…The supernatant liquid left after centrifugation was analyzed spectrophotometrically for myeloperoxidase levels. A comparison of exposed tissue samples readings was done with the control group in order to correlate the results with the release profile of myeloperoxidase levels and their inhibition by the prepared formulations [44].…”