siRNA molecules that enhance the silencing efficiency of target genes and their applications
A gene-targeting and silencing technology, applied in DNA/RNA fragments, medical preparations containing active ingredients, genetic engineering, etc., can solve the problems of low potency, complicated preparation process and high preparation cost of siRNA molecule delivery system
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Embodiment 1
[0056] Embodiment 1, siRNA preparation:
[0057] The present invention refers to the methods provided by Elbashir and Reynolds et al. (Elbashir SM, et al.Methods.2002; 26:199-213. and Reynolds A, et al.Nature Biotechnology. 2004; 22:326-330), designed and synthesized Multiple candidate siRNA molecular sequences. Blast comparative analysis shows that the siRNA sequence designed in the present invention has no homology with other genes other than the target gene.
[0058] The target genes selected for the preparation of siRNA in the present invention are Vascular Endothelial Growth Factor Receptor 2 (VEGFR2), Phosphoinositide 3-Kinase Catalytic Beta Polypeptide (PIK3CB), and epidermal Growth factor receptor (Epidermal Growth Factor Receptor, EGFR). These cytokines are closely related to cell growth and survival. VEGFR2 is expressed at a high level on the surface of neovascular endothelial cells, and angiogenesis runs through the whole process of malignant tumors, affecting tu...
Embodiment 2
[0062] Example 2, modifying the stability of the siRNA molecular structure to increase its gene silencing activity:
[0063] siRNA molecules have nucleic acid-like structural properties. When used as drug molecules in the body, they will be degraded by nucleoside enzymes in body fluids and cells. The stability modification of each base of siRNA nucleotides can effectively prevent nucleosides in the body. Enzymatic degradation prolongs the action time in vivo. However, the modification of nucleotides may reduce the gene silencing activity of the entire siRNA molecule, increase the clinical dosage, and produce new adverse reactions, which is not conducive to clinical transformation. The modification rule found in the present invention has the following characteristics: 1) In the double strand, except for the 3' terminal base of the positive sense strand, the 2'-OH position on the pentose sugar structure in all nucleotides is replaced by 2'-fluoro (2' -F) or 2'-methoxy (2'-OMe) ...
Embodiment 3
[0064] Example 3, tissue targeting molecules modify siRNA molecules to increase their gene silencing activity:
[0065]siRNA molecules have the structural characteristics of nucleic acid molecules. Even if the structure is modified by the above-mentioned modification method, it cannot actively enter the cell to exert gene silencing activity. It must be assisted by a drug carrier to enter through receptor-mediated or cell membrane fusion. biological activity in cells. The present invention provides tissue-targeting structural molecules to modify siRNA molecules at one or both ends of the sense strand, which can enhance the gene silencing efficiency of the siRNA molecular structure, and has the following properties: 1) biRGD-siRNA can target a high level of integrin αvβ3 receptor The expressed neovascular endothelial cell membrane and part of the tumor cell membrane endocytose the siRNA carried into the cell through a receptor-mediated manner, thereby exerting the gene silencing...
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