trans-kingdom RNAi

Some time ago I gave an introductional presentation to some of my collegues about the use of RNA interference to knockdown or silence genes. Back then the use of RNAi to knockdown certain genes was problematic since a solid way of delivering the RNAi to mammalian cells was not at hand. However since then alot of progress has been made...

Exciting progress has been made by Xiang and co-workers, non pathogenic Escherichia coli was engineered to produce short hairpin RNA (shRNA) targeting a mammalian gene, this to induce trans-kingdom RNAi in vitro and in vivo. The engineered E. coli strain induced, upon oral or intravenous administration, significant gene silencing in the intestinal epithelium and in human colon cancer xenografts in mice. "These results provide an example of trans-kingdom RNAi in higher organisms and suggest the potential of bacteria-mediated RNAi for functional genomics, therapeutic target validation and development of clinically compatible RNAi-based therapies".

Xiang, S., Fruehauf, J. & Li, C.J. Short hairpin RNA-expressing bacteria elicit RNA interference in mammals. Nat Biotechnol (2006).

and a great (short) review about the use of in vivo siRNA:
Xie, F.Y., Woodle, M.C. & Lu, P.Y. Harnessing in vivo siRNA delivery for drug discovery and therapeutic development. Drug Discov Today 11, 67-73 (2006).