GLOBAL CHALLENGES

Attacking Cancer from Within

Michael Steinhart | Date: 04-07-10 | Comments

Researchers have developed a technique, using nano-robots, that delivers genetic therapy agents directly into cancerous tumors.

Diseases like cancer spread when abnormal cells divide and multiply quickly. One potential intervention is to introduce genetic material that, very simply put, instructs these cells to stop reproducing.

An RNA inhibitor entering a cell.

The process is called RNA interference (RNAi), or gene silencing, and researchers have been studying it for about 12 years. Back in 2004, doctors used RNAi to block faulty instructions sent by unhealthy genes inside eye cells, with the goal of stopping macular degeneration.

The potential of this therapy to help stop cancerous tumors from growing has always been apparent, but scientists were stymied by the delivery mechanism: How can doctors make sure the RNAi is targeting only the diseased cells?

Different labs have been working on the problem, and last week, researchers in California found that RNAi can be introduced into tumor cells successfully via nano-bots. Here, specially constructed polymer robots, equipped with chemical sensors, carry the RNAi molecules. The unique environment of a cancerous cell triggers the chemical sensor, causing the robot to break down and release small interfering RNA strands, or siRNA.

According to the researchers, post-trial results showed that the melanomas showed both the presence of the RNA and a reduction in tumor gene expression. Here�s an excerpt from the journal article on Nature.com:

"Tumour biopsies from melanoma patients obtained after treatment show the presence of intracellularly localized nanoparticles in amounts that correlate with dose levels of the nanoparticles administered (this is, to our knowledge, a first for systemically delivered nanoparticles of any kind). � Together, these data demonstrate that siRNA administered systemically to a human can produce a specific gene inhibition (reduction in mRNA and protein) by an RNAi mechanism of action."

In other words, the therapy seems to be working. It�s too early to say that these tumors are shrinking, however, but the results do look promising. In fact, portions of the California study will be presented to the American Society of Clinical Oncology this summer.

Experts say that this kind of nano-bot-delivered RNAi therapy can yield positive outcomes in many different scenarios, as RNAi works to disable genetic behavior, not specific diseases. Thus, RNAi may be a practical intervention for viruses like smallpox and SARS, in addition to diseases of cellular degeneration.

Sci-fi writer Joe Clifford Faust imagined a future where nano-bots were first introduced to the public as the primary ingredient in laundry detergent. What other practical applications can you think of for nano-technology?