Peptide-oligonucleotide conjugates (POCs) represent one of the increasingly successful albeit costly approaches to increasing the cellular uptake, tissue delivery, bioavailability, and, thus, overall efficiency of therapeutic nucleic acids, such as, antisense oligonucleotides and small interfering RNAs. This review puts the subject of chemical synthesis of POCs into the wider context of therapeutic oligonucleotides and the problem of nucleic acid drug delivery, cell-penetrating peptide structural types, the mechanisms of their intracellular transport, and the ways of application, which include the formation of non-covalent complexes with oligonucleotides (peptide additives) or covalent conjugation. The main strategies for the synthesis of POCs are viewed in detail, which are conceptually divided into (a) the stepwise solid-phase synthesis approach and (b) post-synthetic conjugation either in solution or on the solid phase, especially by means of various click chemistries. The relative advantages and disadvantages of both strategies are discussed and compared.

A template-assisted assembly approach to a C₂₄ fullerene-like double-stranded DNA polyhedral shell is proposed. The assembly employed a supramolecular oligonucleotide dendrimer as a 3D template that was obtained via the hybridization of siRNA strands and a single-stranded DNA oligonucleotide joined to three- or four-way branched junctions. A four-way branched oligonucleotide building block (a starlet) was designed for the assembly of the shell composed of three identical self-complementary DNA single strands and a single RNA strand for hybridization to the DNA oligonucleotides of the template. To prevent premature auto-hybridization of the self-complementary oligonucleotides in the starlet, a photolabile protecting group was introduced via the N³-substituted thymidine phosphoramidite. Cleavable linkers such as a disulfide linkage, RNase A sensitive triribonucleotides, and di- and trideoxynucleotides were incorporated into the starlet and template at specific points to guide the post-assembly disconnection of the shell from the template, and enzymatic disassembly of the template and the shell in biological media. At the same time, siRNA strands were modified with 2′-OMe ribonucleotides and phosphorothioate groups in certain positions to stabilize toward enzymatic digestion. We report herein a solid-phase synthesis of branched oligodeoxy and oligoribonucleotide building blocks for the DNA/RNA dendritic template and the branched DNA starlet for a template-assisted construction of a C₂₄ fullerene-like DNA shell after initial molecular modeling, followed by the assembly of the shell around the DNA-coated RNA dendritic template, and visualization of the resulting nanostructure by transmission electron microscopy.

Molecular heterogeneity of malignant tumours remains a central challenge in oncology. Although neoplasms of distinct histogenesis share core oncogenic properties, the signaling networks sustaining these phenotypes are tumour-specific, highlighting the need for regulatory-level therapeutics adaptable to distinct molecular contexts. Oncogenic microRNAs (miRNAs), among which miR-21, miR-17, and miR-155 are broadly overexpressed in epithelial, lymphoid, and glial-neuronal neoplasms, represent attractive targets in this regard. MiRNA inhibition by antisense oligonucleotides has emerged as a promising therapeutic strategy, and mesyl (methanesulfonyl) phosphoramidate oligonucleotides (µ-ASOs) represent a next-generation class of anti-miRNA agents with superior nuclease resistance and biological activity. Here, we report a systematic screening of 22 tumour cell lines of diverse histogenesis for sensitivity to paired combinations of µ-ASOs targeting miR-21, miR-17, and miR-155. Epithelial-derived lines showed the highest responsiveness, while lymphoid-derived lines were the least sensitive. The efficacy of specific µ-ASO pairs was found to be cell type-specific: combinations containing miR-21-targeting µ-ASO were most effective in epithelial lines, whereas the miR-17/miR-155-targeting pair showed superior activity in neuroglial models. Cellular responsiveness was driven by the extent of miRNA suppression, with no correlation detected for delivery efficiency or basal miRNA levels. The obtained results provide a basis for tumour type-specific selection of µ-ASO combinations for clinical translation.

Molecular heterogeneity of malignant tumours remains a central challenge in oncology. Although neoplasms of distinct histogenesis share core oncogenic properties, the signalling networks sustaining these phenotypes are tumour-specific, highlighting the need for regulatory-level therapeutics adaptable to distinct molecular contexts. Oncogenic microRNAs (miRNAs), among which miR-21, miR-17, and miR-155 are broadly overexpressed in epithelial, lymphoid, and glial-neuronal neoplasms, represent attractive targets for therapeutic intervention. MiRNA inhibition by antisense oligonucleotides has emerged as a promising therapeutic strategy, and mesyl (methanesulfonyl) phosphoramidate oligonucleotides (µ-AMOs) represent a next-generation class of anti-miRNA agents with superior nuclease resistance and biological activity. Here, we report a systematic screening of 23 tumour cell lines of diverse histogenesis for sensitivity to paired combinations of µ-AMOs targeting miR-21, miR-17, and miR-155. Epithelial-derived lines exhibited the highest responsiveness, while lymphoid cell lines demonstrated the lowest sensitivity. The efficacy of specific µ-AMO pairs was found to be cell type-specific: combinations containing miR-21-targeting µ-AMO were most effective in epithelial lines, whereas the miR-17/miR-155-targeting pair showed superior activity in neuroglial models. Cellular responsiveness was driven by the extent of miRNA suppression, with no correlation detected for delivery efficiency or basal miRNA levels. The obtained results provide a basis for tumour-type-specific selection of µ-AMO combinations for clinical translation.