Thursday, June 23, 2005

Antibody mediated in vivo delivery of small interfering RNAs via cell-surface receptors - Nature Biotechnology

Antibody mediated in vivo delivery of small interfering RNAs via cell-surface receptors - Nature Biotechnology

Here's a link to an article about use of one of the hot subjects in biotechnology right now: RNA interference, in this case small-interfering RNA in particular (siRNA). Unfortunately most people won't be able to read the whole article, for the publishers restrict access (which is a whole other rant for me) and it is technical writing. For the non-technical among us let me give just a brief background. When a gene is expressed it is copied from the genome DNA into a similar, but distinctly different, molecule called RNA. RNA is generally much smaller than the DNA from which it is copied (transcribed we should say). It is this RNA which is directly translated into proteins that will do that actual work in the cell or outside the cell.

Here's when things get hot with RNA interference. Almost all pharmaceutical treatments work at the most basic level by binding to a protein and keeping it from working normally, effectively stopping the action of that protein. If the protein wasn't there to begin with that would be an alternative way to achieve the same purpose, and possible better. Often the small molecules to inibit a protein don't do a very good job, and may inhibit things they aren't supposed to. RNA interference poses the possibility that we could decrease a protein's expression more specifically than with a small molecule that inhibits that protein's activity.

The problems of RNAi of many at this point though. It is difficult to make work inside the body (in vivo), and the levels required make it orders of magnitude more expensive than most drugs. It's stability is poor, working only transiently. Those methods that do allow for delivery of the siRNA are not very specific. Peopel are working to address all these problems, but RNAi has a long way to go before it reaches mainstream.

What makes this paper with the link so impressive is that the authors figured out a way to target siRNA to a specific tissue (in this case a tumor) that was expressing one of the HIV proteins (a potential therapeutic target). They managed to slow the growth of the tumor (as measured by weight) to ~50% of their controls, very impressiv e in my mind for an initial study. I'll try to keep an eye out for more from their group.

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