Caltech Research Uses Nanotech To Attack Cancer

Pasadena - A team of Caltech researchers and clinicians today said they have developed a way to turn off an important cancer gene by shooting a nanoparticle into the bloodstream, it was reported.

One UCLA doctor says the new technique allows doctors to use nanoparticle drugs or modified human genomes to target cancerous RNA that, until now, was too small, too concealed or too fragile to be targeted.

Writing in today's issue of the science journal Nature, the team reported that injecting particles known as double-stranded small interfering RNA interference, or siRNAi, into the bloodstream can send proportionate numbers of nanoparticles in targeted tumor cells.

This opens the door to "game-changing" therapeutics that attack cancer and other diseases at the genetic level, said Caltech chemical engineering professor Mark Davis, the research team's leader. "RNAi is a new way to stop the production of proteins."

The new tool can attack vulnerable areas of a protein that are hidden within its three-dimensional folds, making it difficult for doctors to reach them. RNA interference targets the messenger RNA, or mRNA, that encodes the information that confuses regular cells and makes them cancerous.

"In principle," Davis said. "that means every protein is now druggable, because its inhibition is accomplished by destroying the mRNA. And we can go after mRNAs in a very designed way, given all the genomic data that are, and will be, available."

"These nanoparticles are able to take the siRNAs to the targeted site within the body," Davis said. Once they reach their targets in this case, the cancer cells within tumors -- the nanoparticles -- enter the cells and release the siRNAs.

"It's the first time anyone has found an RNA fragment from a patient's cell showing the mRNA was cut at exactly the right base via the RNAi mechanism," Davis said. "It proves that the RNAi mechanism can happen using siRNA in a human."

"There are many cancer targets that can be efficiently blocked in the laboratory using siRNA, but blocking them in the clinic has been elusive," said UCLA associate professor of medicine Antoni Ribas.

"This is because many of these targets are not amenable to be blocked by traditionally designed anti-cancer drugs. This (new) research provides the first evidence that what works in the lab could help patients in the future by the specific delivery of siRNA using targeted nanoparticles," Ribas said. "We can start thinking about targeting the untargetable."