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Cancer Killing Nanoparticles

Cancer Killing Nanoparticles

Researcher’s giver cancer-killing nanoparticles new ways of getting to the site of tumor…

A team of researchers at the California Institute of Technology (Caltech) have found a way to deliver cancer-killing nanoparticles directly to the site of a tumor, where they effectively work to turn off cancer proteins.

The technique of ‘interfering’ with the development of caner proteins, known as RNA interference (RNAi), earned Andrew Fire and Craig Mello the 2006 Nobel Prize in Physiology or Medicine. And ever since the discovery of RNAi, scientists have been working to find more efficient ways of administering the technique.

Now, the team of Caltech researchers led by Mark Davis, has successfully found a way to deliver such particles into patients with the skin cancer melanoma.

The team developed the technique after noticing that a key gene called RRM2 was needed for cancer cells to multiply.

siRNAs Targeting Cancer Proteins

siRNAs Targeting Cancer Proteins

The researchers created the particles from two polymers, a protein that binds to receptors on the surface of cancer cells, and pieces of small-interfering RNA, or siRNA, designed to stop the RRM2 gene from being translated into protein.

The siRNA works by sticking to the messenger RNA (mRNA) and telling it to stop at a specific spot. When the components are mixed together in water, they assemble into particles about 70 nanometers in diameter. These particles are too big to pass through the walls of healthy blood vessels, but are small enough to pass through the damaged ‘leaky’ blood vessels that supply a tumor.

“It sneaks in, evades the immune system, delivers the siRNA, and the disassembled components exit out,” Davis says.

Once absorbed into the tumor the nanoparticles fall apart, the siRNA binds to cells, and the remaining parts of the nanoparticles are so tiny, they simply pass out of the body in urine.

The discovery of the new delivery method has massive potential. Davis explained that:

“In principle, that means every protein now is 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 become available.”

The phase 1 clinical trial was conducted only to test the safety of the new delivery technique, and not test the effectiveness of the treatment. While the results did show that at least one patient showed reduced levels of the protein after treatments, the main achievement was delivering the tiny amounts of siRNA precisely to the tumor.

“The more we put in, the more ends up where they are supposed to be,” Davis said.

This means that researchers will need more data from clinical trials to ensure that such therapies are safe to use in people. But Davis says that his study means there is now direct evidence that nanoparticles and RNAi can be used to attack harmful genes in humans — and not just in the test tube.

The results were published in the March 21 advance online edition of the journal Nature.

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