Abstract 7235: Exosome-mediated delivery of siRNA against NRF2 for treatment of lung cancer
Authors: Kandimalla Raghuram , Wallen Margaret , Jeyabalan Jeyaprakash , Moholkar Disha N. , Spencer Wendy , Gupta Ramesh C. , Aqil Farrukh 
Published: March 2024

Abstract
Nuclear factor erythroid 2-related factor 2 (NRF2) activation is the third most common genetic event in lung adenocarcinomas (25%), primarily induced by loss of function mutations in its master regulator, KEAP1. NRF2 is a key modulator of tumor growth and metabolic reprogramming, resulting in resistance to traditional chemotherapeutics. Due to its role in modulating oxidative stress, sustained NRF2 overexpression promotes disease progression, particularly in lung cancer. This study demonstrates the effective knockdown of NRF2 expression by small interfering RNA (siRNA) delivered via a nanoplatform based on bovine colostrum exosomes to lung cancer cells, both in vitro and in vivo, resulting in inhibition of proliferation and disease progression. Bovine colostrum is an abundant source of exosomes. Here we present a novel exosome-polyethyleneimine matrix (EPM) to deliver therapeutic siRNA targeting NRF2 expression (siNRF2). Specific delivery of the EPM to tumors was further enhanced via folic acid (FA) functionalization, targeting folate receptors highly expressed on lung tumor cells. Exosomes were isolated from standardized colostrum powder through rehydration and differential centrifugation, and characterized by size, polydispersity index (pdi) and surface charge by Zetasizer, and the presence of surface protein markers by Western blot. siNRF2 was loaded onto the EPM, and the resultant EPM-siNRF2 complex was harvested by PEG precipitation. Entrapment efficiency was determined using 5’-32P-labeled siRNA as a tracer. The gene knockdown efficiency of EPM-siNRF2 was assessed in lung cancer (A549) cells by Western blot and the therapeutic effect of target knockdown in vitro was confirmed by analyzing the corresponding modulation in downstream targets of NRF2. The anti-tumor effect was then evaluated using both subcutaneous and orthotropic lung tumor models in immunocompromised mice. The EPM exhibited high entrapment efficiency (&gt;90%) of siNRF2 (up to 20 μg) and protected entrapped siRNA from enzymatic degradation upon exposure to RNases. EPM-siNRF2 dose dependently decreased NRF2 expression in A549 lung cancer cells. When formulated with FA-functionalized exosomes, EPM-siNRF2 inhibited subcutaneous and orthotropic lung tumors in mice by over 57% (p&lt;0.01) and 84% (p&lt;0.001), respectively. Mice treated with FA-EPM-siNRF2 showed decreased levels of NRF2 in tumor tissue, but not in the adjacent lung, indicating FA-mediated targeted delivery.
This bovine colostrum exosome based EPM technology showcases high efficiency in gene knockdown and lung tumor inhibition, providing a promising nanoplatform for delivering nucleic acid therapeutics to the tumor site.
Funding: Supported from the NIH grant R44 CA-221487, 3P Biotechnology Contract and, in part, Agnes Brown Duggan Endowment.
Keywords: Bovine colostrum, Exosomes, NRF2, siRNA, Lung cancer.
Citation Format: Raghuram Kandimalla, Margaret Wallen, Jeyaprakash Jeyabalan, Disha N. Moholkar, Wendy Spencer, Ramesh C. Gupta, Farrukh Aqil. Exosome-mediated delivery of siRNA against NRF2 for treatment of lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7235.