Applying RNA interference to cancer treatments

[jjhunter]

A neat bit of engineering in this press release from MIT today, One-two punch knocks out aggressive tumors.

To improve Doxil’s effectiveness, Hammond’s team wanted to combine it with another type of therapy known as RNA interference (RNAi), which uses very short strands of RNA to block the expression of specific genes inside a living cell.

The researchers used a technique called layer-by-layer assembly to coat the Doxil particles with one layer of siRNA mixed with a positively charged polymer that helps to stabilize the RNA. This layer contains up to 3,500 siRNA molecules, each targeted to block a gene that allows cancer cells to pump the drug molecules out of the cells.

One of the major challenges that researchers have faced in developing RNAi as a cancer treatment is getting the particles to survive in the bloodstream long enough to reach their intended targets. To overcome this, the MIT particles include an outer coating of hyaluronic acid. These molecules absorb water, allowing the nanoparticles to flow through blood vessels undisturbed, Hammond says.

“This stealth layer becomes a cushion of water surrounding the nanoparticle, which allows it to go through the bloodstream as if it were water,” Hammond says. “That makes it circulate much more effectively.”

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n.b. for more info on RNA interference, see this NIH factsheet.