An aptamer-siRNA chimera silences the eukaryotic elongation factor 2 gene and induces apoptosis in cancers expressing av beta 3 integrin

Small interfering RNAs (siRNAs) silence gene expression by triggering the sequence-specific degradation of mRNAs, but the targeted delivery of such reagents remains challenging and a significant obstacle to therapeutic applications. One promising approach is the use of RNA aptamers that bind tumor-associated antigens to achieve the delivery of siRNAs to tumor cells displaying specific antigens. Wholly RNA-based constructs are advantageous because they are inexpensive to synthesize and their immunogenicity is low. We therefore joined an aptamer-recognizing alpha V and integrin beta 3 (av beta 3) integrin to a siRNA that targets eukaryotic elongation factor 2 and achieved for the first time the targeted delivery of a siRNA to tumor cells expressing av beta3 integrin, causing the inhibition of cell proliferation and the induction of apoptosis specifically in tumor cells. The impact of our results on the development of therapeutic aptamer-siRNA constructs is discussed.