Engineering target nanomaterials for stable and efficient delivery of siRNA

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI--COLUMBIA AT REQUEST OF AUTHOR.] Lung cancer has the highest cancer-related mortality rate in the United States. The most common form of lung cancer is non-small cell lung cancer (NSCLC) with 80-85% of new diagnoses. Mutations in KRAS is the most prevalent one, and affects over 25% of NSCLC patients, and these patients often fail to respond to conventional treatments including tyrosine kinase inhibitor therapies. Silencing these driver oncogenic mutations provide new opportunities to treat tumor. RNAi technology has the potential to selectively knock down the mutated KRAS gene and thereby increase the susceptibility of the tumor to conventional therapies. In fact, "Silenseed", siG12D, a siRNA-based drug conjugate, showed efficacy in knocking-down the gene in human Phase II clinical trials. However, the integral instability of siRNA restricts the intratumoral administration of the drug. Therefore, there is a need to develop a delivery system for carrying siRNA to tumor without the fear of disintegration. In order to circumvent this problem, our research is focused on engineering nanoparticles, especially based on proteins due to its non-toxic and biodegradable characteristics, and evaluating their ability in vitro to serve as carriers for delivering KRAS siRNA. In this project, we have synthesized a library of protein-based nanoparticles which have demonstrated stable loading of siRNA and efficient knockdown of the KRAS expression in NSCLC cell lines. These nanoparticles are targeted using anti-EGFR antibody to tumor. Additionally, we compared the efficacy of encapsulation versus surface conjugation in siRNA loading to the nanoparticle. In summary, we have synthesized and evaluated a xii total of 10 different protein-based nano-conjugates, and identified two nanoparticles with excellent stability for further in vivo evaluation.