Scientists Disable Cancer’s Ability to Spread Using Tiny Gold Rods


Cancer is most deadly when it spreads, but a new study found a way to halt that proliferation — by disabling cancer’s movement capacity.

The novel approach, which uses heated-up nanoparticles to obliterate movement-enabling protrusions on a cancer cell, is akin to breaking the cell’s legs, suggests the study from researchers at the Georgia Institute of Technology.

Death of a cancer cell. Credit: Susan Arnold [Public domain]/Wikimedia Commons
While the study is preliminary, the new technique showed that the nanotechnology, using tiny gold rods that were zapped by a laser to heat up and essentially saw off the cells’ legs, was able to stop the process of metastasis, or spreading, of cancerous cells in a laboratory culture. That’s significant because few, if any, treatment options exist to halt metastasis.

“If cancer stays in a tumor in one place, you can get to it, and it’s not so likely to kill the patient, but when it spreads around the body, that’s what really makes it deadly,” said lead researcher Mostafa El-Sayed, Julius Brown Chair and Regents Professor at Georgia Tech’s School of Chemistry and Biochemistry.

The other good news is that the rod-and-laser approach spared healthy tissue and surrounding body cells.

“The method appears to be very effective as a locally administered treatment that also protects the body from cancer’s spread away from the treated tumors, and it is also very mild, so it can be applied many times over if needed,” El-Sayed said.

Cancer’s Intricate Moves

Our body’s cells normally create two types of protrusions, called filopodia and lamellipodia, that enable movement through healthy tissue. However, when cancer is present, the mechanisms that create the protrusions get revved up, basically giving malignant cancer cells a vehicle by which to move.

“All these lamellipodia and filopodia give the cancer cells legs,” said Yue Wu, a graduate student in bioanalytical chemistry. “The metastasis requires those protrusions, so the cells can travel.”

For the study, the research team was able to introduce the tiny gold rods directly near the cancer cells. Because the nanorods are coated in particular molecules, they can attach to a key protein known an integrin.

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“The targeted nanorods tied up the integrin and blocked its functions, so it could not keep guiding the cytoskeleton to overproduce lamellipodia and filopodia,” said Yan Tang, a postdoctoral assistant in Computational Biology.

Because cancer cells create specific types of integrin, the rods can find an exact match.

“There are certain, specific integrins that are overproduced in cancerous cells,” said Moustafa Ali, one of the study’s first authors. “And you don’t find them so much in healthy cells.”

Once the rods were in place, the researchers zapped them with a laser, bringing the movement of cancer cells to an abrupt end.

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“The light was not absorbed by the cells, but the gold nanorods absorbed it, and as a result, they heated up and partially melted cancer cells they are connected with, mangling lamellipodia and filopodia,” Ali said. “It didn’t kill all the cells, not in this experiment. If we killed them, we would not have been able to observe whether we stopped them from migrating or not.”

With their successful findings in hand, the researchers envision a method of treating multiple kinds of cancer, including breast and skin cancers.

The study appears in the Proceedings of the National Academy of Sciences of the United States of America.