Comparing the Variants of Iron Oxide Nanoparticle-Mediated Delivery of miRNA34a for Efficiency in Silencing of PD-L1 Genes in Cancer Cells

Abstract

The blocking of programmed death-ligand 1 (PD-L1) in tumor cells represents a powerful strategy in cancer immunotherapy. Using viral vectors to deliver the cargo for inactivating the PD-L1 gene could be associated with host cell genotoxicity and concomitant immune attack. To develop an alternative safe gene delivery method, we designed a unique combination for miRNA34a delivery using a transgene carrier in the form of iron oxide magnetic nanoparticles (IONPs) via magnetofection to downregulate PD-L1 expression in cancer cells. We synthesized IONPs of multiple shapes (IONRs (iron oxide nanorods), IONSs (iron oxide nanospheres), and ITOHs (iron oxide truncated octahedrons)), surface-functionalized with polyethyleneimine (PEI) using the ligand exchange method, as gene delivery systems. Under the guidance of an external magnetic field, PEI@IONPs loaded with plasmid DNA (DNA/PEI@IONPs) encoding GFP showed high transfection efficiency at different weight ratios and time points in A549 and MDA-MB-231 cells. Additionally, the DNA/PEI@IONPs with miRNA34a inserts under a static magnetic field resulted in significant knockdown of the PD-L1 gene, as demonstrated via immunoblotting of the PD-L1 protein. Among the three shapes of IONPs, IONRs showed the highest PD-L1 knockdown efficiency. The genetic expression of miRNA34a was also studied using qPCR and it showed high expression of miRNA in cells treated with PEI@IONRs. Flow cytometry and a live/dead assay confirmed apoptosis after transfection with miRNA34a. To conclude, in this paper, a promising transgene carrier with low cost, negligible cytotoxicity, and high transfection efficiency has been successfully established for miRNA gene delivery in the context of cancer immunotherapy.

Immunotherapy Study on Non-small-Cell Lung Cancer (NSCLC) Combined with Cytotoxic T Cells and miRNA34a

“…The decrease in MHC-I expression could be attributed to the interaction between the Jurkat T cells and A549 cells during coculture, which might involve the release of soluble factors or cell-to-cell contact-mediated signaling that further downregulates MHC-I expression . The decreased PD-L1 expression on A549 cells after transfection with miRNA34a boosts the immune activity of cytotoxic T cells to recognize cancer cells and suppress their activity . For these reasons, we observed a higher suppression in the MHC-I expression when the cells were cocultured with active Jurkat T cells than those with inactive Jurkat T cells.…”

“…A visible difference in the apoptosis activity of A549 cells transfected with miRNA34a is seen in the coculture system between active and inactive Jurkat T cells. MiRNA34a functions as a tumor suppressor by targeting a wide range of genes involved in cell survival, proliferation, and antiapoptotic pathways . MiRNA34a indirectly modulates the expression of various antiapoptotic proteins, including B-cell lymphoma 2 (Bcl-2), myeloid cell leukemia sequence 1 (MCL-1), and survivin .…”

“…The use of IONRs as a gene delivery agent has previously been successfully established as safe, minimizing cytotoxicity concerns associated with other transfection reagents. 21 Immunotherapy has emerged as a promising approach in the treatment of various cancers, including NSCLC. It is a prevalent type of lung cancer with limited treatment options, and innovative strategies are continuously being explored to improve patient outcomes.…”

“…Additionally, to enhance the delivery of miRNA34a into cancer cells, IONRs have been utilized as a magnetofection agent. The use of IONRs as a gene delivery agent has previously been successfully established as safe, minimizing cytotoxicity concerns associated with other transfection reagents …”

MicroRNA-nanoparticles against cancer: Opportunities and challenges for personalized medicine

“… 109 More recently, the miR-34a delivery using a transgene carrier in the form of iron oxide magnetic nanoparticles (IONPs) via magnetofection has been effective to downregulate the programmed death-ligand 1 (PD-L1) gene in both non-small-cell lung carcinoma and TNBC cells. 110 …”