Multivalent comb-type aptamer–siRNA conjugates for efficient and selective intracellular delivery

Abstract

In this study, a simple and efficient strategy for selective intracellular delivery of RNA therapeutics into target cancer cells was designed using direct complementary base pairing between chemically conjugated multimeric antisense strands and aptamer-incorporating sense strands.

Multivalent Aptamer–RNA Conjugates for Simple and Efficient Delivery of Doxorubicin/siRNA into Multidrug‐Resistant Cells

“…To determine whether multivalent Apt–siRNA efficiently delivered Dox into MDR cells, Dox uptake efficiency in wild‐type and MDR MCF‐7 cells was determined by confocal microscopy (Figure ). We previously found that MUC1‐overexpressing MCF‐7 cells, but not other cell lines, specifically take up multivalent Apt–siRNA, with higher uptake efficiency than that for monovalent Apt–siRNA because of cluster effect . This superior uptake efficiency of multivalent Apt‐siRNA might be attributed to increased binding affinity to cell surface or enhanced endocytosis efficiency because of cluster effect .…”

“…Crosslinked Apt–siRNA with reducible linkages (multivalent Apt–siRNA) was developed by annealing multimeric antisense siRNA with an aptamer–sense siRNA hybrid. According to our previous study, the length of multivalent Apt–siRNA conjugates was assessed about 137 nm by transmission electron microscopy (TEM) analysis after labeling with gold nanoparticles . Considering the length of monovalent Apt–siRNA and intermolecular linker (6 and 1.3 nm, respectively), ≈18 aptamer units might be incorporated in a multivalent Apt–siRNA.…”

“…Here, Dox was delivered using multivalent Apt– BCL2 siRNA, which served as a chemotherapeutic drug delivery vehicle as well as an anticancer agent to facilitate cell death synergistically with Dox. Previously, we observed that silencing effects of target gene expression and following biological activities like apoptotic cell death using multivalent Apt– GFP siRNA and Apt– BCL2 siRNAs, respectively . BCL2 downregulation sensitizes cancer cells to chemotherapeutic agents .…”

Chemical modifications of nucleic acid drugs and their delivery systems for gene‐based therapy

“…Multivalent comb‐type MUC1 aptamer–siRNA (Comb‐Apt‐siRNA, Figure B) was also developed for selective and efficient intracellular delivery to malignant adenocarcinomas (such as MCF‐7 and A549 cells) via mucin 1 (MUC1) receptor‐mediated endocytosis . Comb‐Apt‐siRNA was designed to form multiple aptamer‐modified siRNA duplexes between MUC1 aptamer‐conjugated sense strand RNA and linear multimeric antisense RNA strand, which was formed by conjugation of 3ʹ and 5ʹ terminal thiol modified RNA with dithio‐bismaleimide (DTME) crosslinker through thiol‐maleimide reaction …”

Smart functional nucleic acid chimeras: Enabling tissue specific RNA targeting therapy

“…46,47 In regard to this theory, Yoo et al reported a rod-shaped comb-type aptamer-siRNA chimera. 48 In this study, a mucin 1 (MUC1) targeting DNA aptamer was conjugated to the siRNA. MUC1 is a cell surface associated protein, highly over-expressed in malignant adenocarcinomas.…”