Aptamer-Functionalized Nanoparticles Mediate PD-L1 siRNA Delivery for Effective Gene Silencing in Triple-Negative Breast Cancer Cells

Abstract

Small interfering RNA (siRNA) therapies require effective delivery vehicles capable of carrying the siRNA cargo into target cells. To achieve tumor-targeting, a drug delivery system would have to incorporate ligands that specifically bind to receptors expressed on cancer cells to function as portals via receptor-mediated endocytosis. Cell-targeting and internalizing aptamers are the most suitable ligands for functionalization of drug-loaded nanocarriers. Here, we designed a novel aptamer-based platform for the active delivery of siRNA targeting programmed cell death-ligand 1 (PD-L1) to triple-negative breast cancer (TNBC) cells. The generated nanovectors consist of PLGA-based polymeric nanoparticles, which were loaded with PD-L1 siRNA and conjugated on their surface with a new RNA aptamer, specific for TNBC and resistant to nucleases. In vitro results demonstrated that these aptamer-conjugated nanoparticles promote siRNA uptake specifically into TNBC MDA-MB-231 and BT-549 target cells, along with its endosomal release, without recognizing non-TNBC BT-474 breast cancer cells. Their efficiency resulted in an almost complete suppression of PD-L1 expression as early as 90 min of cell treatment. This research provides a rational strategy for optimizing siRNA delivery systems for TNBC treatments.

Nanomedicine-Based Drug-Targeting in Breast Cancer: Pharmacokinetics, Clinical Progress, and Challenges

“…In vitro studies show that NPs enhance siRNA uptake specifically into TNBC MDA-MB-231 and BT-549 target cells, leading to endosomal release and suppression of PD-L1 expression within 90 min. Overall, targeting PD-L1 in TNBC cells was achieved . Thus, the above results provide an effective siRNA-delivery system for TNBC treatment.…”

Aptamer-Based Strategies to Boost Immunotherapy in TNBC

“…Recently, poly(lactic-co-glycolic)-block-PEG (PLGA-b-PEG)-based nanoparticles have been loaded with anti-PD-L1 siRNA and decorated with a 2′F-Py RNA aptamer able to bind and internalize specifically into TNBC cells [ 70 , 71 ]. The resulting aptamer-conjugated nanovectors, upon 90 min incubation on TNBC cells, efficiently delivered siRNA into target cells, which was competent to cause an almost complete suppression of PD-L1 expression [ 72 ]. Notably, aptamer-decorated nanocarriers offer the possibility to link different ligands to the surface of the NPs, thus increasing the specificity of targeting, and to encapsulate in the NPs multiple therapeutics, thus allowing for efficacious combined therapies.…”

“…Notably, aptamer-decorated nanocarriers offer the possibility to link different ligands to the surface of the NPs, thus increasing the specificity of targeting, and to encapsulate in the NPs multiple therapeutics, thus allowing for efficacious combined therapies. For example, the concomitant administration of cisplatin [ 40 ] and siPD-L1 [ 72 ] by the PLGA polymeric nanoparticles, which we equipped with TNBC aptamers, may not only promote a reduction in toxic side effects but also counteract the reported negative effect of cisplatin administration on the enrichment of PD-L1+ immune evasive TNBC cells [ 73 ]. In this regard, Kim et al prepared a multifunctional nanosystem having two DNA aptamers conjugated on the external surface of liposomes and two different therapeutics inside nanovectors for synergistic chemoimmunotherapy in TNBC [ 74 ].…”

Aptamers Targeting the PD-1/PD-L1 Axis: A Perspective

“…Using B16 melanoma and MC38 colon cancer models, a 4-fold reduction of tumor growth was obtained, and a higher mice survival rate was correlated with an increase by 2- and 3-fold, respectively, of CD4 + /CD8 + T cells. Camorani et al prepared a PLGA-PEG-COOH NP encapsulating PD-L1 siRNA that was further modified by peptide coupling with an aptamer (TN145) SELEXed against TNBC MDA-MB-231 and BT-549 cells . The proposed aptamer was found to be highly resistant to nucleases.…”

“…Camorani et al prepared a PLGA-PEG-COOH NP encapsulating PD-L1 siRNA that was further modified by peptide coupling with an aptamer (TN145) SELEXed against TNBC MDA-MB-231 and BT-549 cells. 71 The proposed aptamer was found to be highly resistant to nucleases. A fluorescein-labeled siRNA was used to track the construct (100−110 nm size) in cells to confirm the selectivity of the aptamer for TNBC and the easier internalization, followed by localization in endosomes (Lysotracker) and subsequent siRNA release.…”