Abstract 461: Dual-kinase targeted miRNA nanotherapy for the treatment of triple-negative breast cancer
Authors: Kara Goknur , Dundar Pinar Atalay , Kahraman Nermin , Denkbas Emir Baki , Ozpolat Bulent 
Published: March 2024

Abstract
Triple-negative breast cancer (TNBC) represents 20% of breast cancer (BC) patients (51,000 cases/year in the US). It is associated with a highly aggressive course, early metastasis and relapses, and drug-resistant phenotype. About 40% of the patients die within 5 years despite available therapies. If the disease is metastatic, patients survive only 13 months. Since TNBC does not express targetable receptors such as ER, PR, and HER2, and it is a highly heterogeneous cancer with six genetically defined sub-types, currently, there are no common actionable molecular targets and no effective targeted therapies for TNBC. microRNAs (miRNAs) are 18-20 nt long non-coding RNAs and are often dysregulated in cancer cells. Tumor-suppressive miRNAs specifically silence their protooncogenic target genes (mRNAs) by binding specifically to their 3’-UTRs located in their target mRNAs, leading to inhibition of oncogenes that play critical roles in cell proliferation, cell cycle, migration, invasion, angiogenesis, drug resistance, tumor growth, and progression. We have previously demonstrated that Eukaryotic Elongation factor-2 kinase (eEF2K) and AXL are oncogenic kinases, and their higher expression is associated with poor survival in patients with TNBC. However, currently, there is no FDA-approved eEF2K and AXL-targeted therapeutics. To effectively co-target these kinases, we extensively analyzed miRNA databases using miRNA target prediction algorithms and recently, we discovered that miR-329-3p has a specific binding site at both 3’-UTRs of eEF2K and AXL mRNAs. Analyzing the TCGA TNBC database, we found that low expression of miR-329-3p is correlated with shorter overall survival in TNBC patients, and the expression of miR-329-3p is commonly reduced or lost in TNBC patient tumors. Since the successful clinical application of miRNA-based therapeutics requires safe and effective nano-delivery systems, we have developed magnetic iron-oxide-based nanoparticles (MNPs) for the delivery of miR-329-3p. We showed that miR-329-3p significantly suppresses cell proliferation, invasion, and migration by targeting both eEF2K and AXL and their downstream mediators such as SRC/FAK and Cyclin D1 in TNBC cell lines. In vivo systemic treatment with MNPs-miR-329 completely blocks tumor growth in orthotopic MDA-MB-231 and MDA-MB-436 TNBC xenograft models in mice. Analysis of tumors shows remarkable inhibition in eEF2K and AXL expression, and clinically significant downstream targets including SRC, FAK, and Cyclin D1. We also demonstrated that miR-329 nanotherapy induces apoptosis and inhibits intratumoral proliferation in TNBC tumors in mice. Toxicity markers in mouse blood samples show that miR-329 nanotherapy is safe and not toxic to mice. Taken together, our study suggests that miR-329-3p nanotherapy may be used as a novel potential therapeutic approach in TNBC patients.
Citation Format: Goknur Kara, Pinar Atalay Dundar, Nermin Kahraman, Emir Baki Denkbas, Bulent Ozpolat. Dual-kinase targeted miRNA nanotherapy for the treatment of triple-negative breast 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 461.