Technologies that mediate targeted delivery of small interfering RNAs (siRNAs) are needed to improve their therapeutic efficacy and safety. Therefore, we have developed aptamer-siRNA chimeric RNAs capable of cell type–specific binding and delivery of functional siRNAs into cells. The aptamer portion of the chimeras mediates binding to PSMA, a cell-surface receptor overexpressed in prostate cancer cells and tumor vascular endothelium, whereas the siRNA portion targets the expression of survival genes. When applied to cells expressing PSMA, these RNAs are internalized and processed by Dicer, resulting in depletion of the siRNA target proteins and cell death. In contrast, the chimeras do not bind to or function in cells that do not express PSMA. These reagents also specifically inhibit tumor growth and mediate tumor regression in a xenograft model of prostate cancer. These studies demonstrate an approach for targeted delivery of siRNAs with numerous potential applications, including cancer therapeutics.
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We thank John Madden and Johannes Vieweg for useful discussions and Mariano Garcia-Blanco and Joseph R. Nevins for useful reagents. B.A.S., E.G., R.E.R., Y.W., K.D.V. and P.H.G. are supported by the National Institutes of Health (NIH). E.R.A. is supported by a postdoctoral training grant from Susan G. Komen Breast Cancer Foundation. J.O.M. is supported by an NIH postdoctoral training grant (5T32CA00911-28). This work was supported by NIH grants 2P01GM059299 and 1U54CA119313 to B.A.S.
The authors declare no competing financial interests.
Cell-type specific expression of PSMA. (PDF 540 kb)
Relative affinity measurements of A10 and A10 aptamer-siRNA chimeras. (PDF 1048 kb)
Gene silencing mediated by functional siRNAs against Polo-like kinase 1 (Plk1) and Bcl2. (PDF 784 kb)
siRNA-mediated silencing of Dicer. (PDF 552 kb)
Aptamer-siRNA chimeras do not trigger an interferon response. (PDF 607 kb)
Individual tumor curves demonstrating effect of RNA chimeras on growth of LNCaP-derived tumors in mice. (PDF 1083 kb)
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McNamara, J., Andrechek, E., Wang, Y. et al. Cell type–specific delivery of siRNAs with aptamer-siRNA chimeras. Nat Biotechnol 24, 1005–1015 (2006). https://doi.org/10.1038/nbt1223
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