Connecting The Dots to Kill Cancer

Cornell dots, or C dots, named after the university where they were invented, are a specialized type of nanoparticle that have been kicking around around more than a dozen years. Fluorescent silica particles, as small as 5 nanometers in diameter, C dots were originally designed to be used as diagnostic tools. They clung to cancer cells and lit up, showing a surgeon where the tumor cells are. 

Now, a team of scientists has managed to tweak the tiny glowing machines into killers.

By administering C dots in large doses and with the cancerous tumors in a state of nutrient deprivation, scientists can trigger a type of cell death called ferroptosis.

“If you had to design a nanoparticle for killing cancer, this would be exactly the way you would do it,” said Ulrich Wiesner, the Spencer T. Olin Professor of Engineering at Cornell. “The particle is well tolerated in normally healthy tissue, but as soon as you have a tumor, and under very specific conditions, these particles become killers.”

What happens is that peptide-coated nanoparticles absorb iron from your system on their way to finding the tumors. But instead of just giving a light show, the iron-laden C dots are programmed to penetrate the cancer cells. That act triggers ferroptosis, a necrotic form of cell death involving the rupture of the cell's plasma membrane.

The scientists hadn't set out to build a better cancer-fighting bazooka, however.

“The original purpose for studying the dots in cells was to see how well larger concentrations would be tolerated without altering cellular function,” said Michael Overholtzer, cell biologist at Memorial Sloan Kettering Cancer Center. “While high concentrations were well-tolerated under normal conditions, we wanted to also know how cancer cells under stress might respond.”

The team was startled to discover that in 1 to 2 days after the cancer cells were exposed to the dots, there was, as Wiesner described it, a “wave of destruction” throughout the entire cell culture.

Wiesner sees the next gen C dots as not only a new and efficient cancer killer, but a sea change for the entire nanotechnology industry.

“We’ve found another tool that people have not thought about at all so far,” he said. “This has changed our way of thinking about nanoparticles and what they could potentially do.”

The team is now focused upon mixing and matching their nanoparticles with other conventional therapies for a given type of tumor, and tailoring the particles to specific cancers.

They have published their research in Nature Nanotechnology.