Enhanced intracellular delivery and multi-target gene silencing triggered by tripodal RNA structures

Background The development of gene interfering RNA (iRNA) molecules such as small interfering RNAs (siRNAs) and antagomirs provides promising therapeutic modalities for targeting specific mRNAs and microRNAs (miRNAs) involved in disease mechanisms. Therapeutic iRNA strategy against cancer or hypermutable viruses prefers targeting multiple genes simultaneously to achieve synergistic inhibition and to prevent resistance. Methods In the present study, we report chemically synthesized, multi-target gene interfering RNA structures based upon branched, tripodal interfering RNAs (termed T-tiRNAs). Results The T-tiRNAs could simultaneously inhibit up to three different mRNAs or miRNAs by harboring three siRNA or antagomir units. Moreover, when complexed with cationic delivery vehicles, T-tiRNAs showed enhanced gene interfering activity over conventional siRNAs or antagomirs as a result of increased intracellular delivery. Conclusions The data obtained in the present study provide an example of synthetic multi-functional RNA structures that enable multiple gene interference in mammalian cells, which could become powerful tools for an efficient combinatorial iRNA strategy. Copyright (C) 2012 John Wiley & Sons, Ltd.