bims-limsir 2024-02-25 papers

Alzheimers Dement. 2024 Feb 20.

Silencing Apoe with divalent-siRNAs improves amyloid burden and activates immune response pathways in Alzheimer's disease.

Chantal M Ferguson, Samuel Hildebrand, Bruno M D C Godinho, Julianna Buchwald, Dimas Echeverria, Andrew Coles, Anastasia Grigorenko, Lorenc Vangjeli, Jacquelyn Sousa, Nicholas McHugh, Matthew Hassler, Francesco Santarelli, Michael T Heneka, Evgeny Rogaev, Anastasia Khvorova.

INTRODUCTION: The most significant genetic risk factor for late-onset Alzheimer's disease (AD) is APOE4, with evidence for gain- and loss-of-function mechanisms. A clinical need remains for therapeutically relevant tools that potently modulate APOE expression.
METHODS: We optimized small interfering RNAs (di-siRNA, GalNAc) to potently silence brain or liver Apoe and evaluated the impact of each pool of Apoe on pathology.
RESULTS: In adult 5xFAD mice, siRNAs targeting CNS Apoe efficiently silenced Apoe expression and reduced amyloid burden without affecting systemic cholesterol, confirming that potent silencing of brain Apoe is sufficient to slow disease progression. Mechanistically, silencing Apoe reduced APOE-rich amyloid cores and activated immune system responses.
DISCUSSION: These results establish siRNA-based modulation of Apoe as a viable therapeutic approach, highlight immune activation as a key pathway affected by Apoe modulation, and provide the technology to further evaluate the impact of APOE silencing on neurodegeneration.

Keywords: Alzheimer's Disease; Apoe; RNAi; neurodegeneration; oligonucleotide therapeutics; siRNA

DOI: https://doi.org/10.1002/alz.13703

Molecules. 2024 Feb 08. pii: 786. [Epub ahead of print]29(4):

Cholesterol Conjugates of Small Interfering RNA: Linkers and Patterns of Modification.

Ivan V Chernikov, Ul'yana A Ponomareva, Mariya I Meschaninova, Irina K Bachkova, Valentin V Vlassov, Marina A Zenkova, Elena L Chernolovskaya.

Cholesterol siRNA conjugates attract attention because they allow the delivery of siRNA into cells without the use of transfection agents. In this study, we compared the efficacy and duration of silencing induced by cholesterol conjugates of selectively and totally modified siRNAs and their heteroduplexes of the same sequence and explored the impact of linker length between the 3' end of the sense strand of siRNA and cholesterol on the silencing activity of "light" and "heavy" modified siRNAs. All 3'-cholesterol conjugates were equally active under transfection, but the conjugate with a C3 linker was less active than those with longer linkers (C8 and C15) in a carrier-free mode. At the same time, they were significantly inferior in activity to the 5'-cholesterol conjugate. Shortening the sense strand carrying cholesterol by two nucleotides from the 3'-end did not have a significant effect on the activity of the conjugate. Replacing the antisense strand or both strands with fully modified ones had a significant effect on silencing as well as improving the duration in transfection-mediated and carrier-free modes. A significant 78% suppression of MDR1 gene expression in KB-8-5 xenograft tumors developed in mice promises an advantage from the use of fully modified siRNA cholesterol conjugates in combination chemotherapy.

Keywords: MDR1 gene; chemical modifications; cholesterol conjugate; duration of silencing; nuclease resistance; siRNA

DOI: https://doi.org/10.3390/molecules29040786

Nat Commun. 2024 Feb 21. 15(1): 1581

Structural optimization of siRNA conjugates for albumin binding achieves effective MCL1-directed cancer therapy.

The high potential of siRNAs to silence oncogenic drivers remains largely untapped due to the challenges of tumor cell delivery. Here, divalent lipid-conjugated siRNAs are optimized for in situ binding to albumin to improve pharmacokinetics and tumor delivery. Systematic variation of the siRNA conjugate structure reveals that the location of the linker branching site dictates tendency toward albumin association versus self-assembly, while the lipid hydrophobicity and reversibility of albumin binding also contribute to siRNA intracellular delivery. The lead structure increases tumor siRNA accumulation 12-fold in orthotopic triple negative breast cancer (TNBC) tumors over the parent siRNA. This structure achieves approximately 80% silencing of the anti-apoptotic oncogene MCL1 and yields better survival outcomes in three TNBC models than an MCL-1 small molecule inhibitor. These studies provide new structure-function insights on siRNA-lipid conjugate structures that are intravenously injected, associate in situ with serum albumin, and improve pharmacokinetics and tumor treatment efficacy.

DOI: https://doi.org/10.1038/s41467-024-45609-0