Monday, May 25, 2009

Chlorotoxin with Nanoparticles Slows Tumor Spread

Chlorotoxin with Nanoparticles Slows Tumor Spread
Increased cell uptake with nanoparticles
Iron oxide nanoparticles conjugated with chlorotoxin—a scorpion venom compound—slowed brain tumor growth by 98%, researchers report. The combination more than doubled the effect of chlorotoxin alone, the researchers found. "The aim of most experimental therapy with nanoparticles right now is to kill cancer cells," said Miqin Zhang, PhD.

Transmission electron microscope images of cells treated with chlorotoxin-enabled nanoparticles (left) and chlorotoxin alone (right). Endosomes in nanoparticle-treated cells are markedly larger than those in chlorotoxin-only cells.
"The aim of most experimental therapy with nanoparticles right now is to kill cancer cells," said Miqin Zhang, PhD, a professor of materials science and engineering at the University of Washington in Seattle and senior author of a paper describing the findings. "But there has been no good way to stop the tumors [from] spreading. Chlorotoxin conjugated with nanoparticles can really effectively stop the spreading."
Chlorotoxin was already known to stop the spread or invasion of brain cancer cells; the compound is in clinical testing as an anticancer agent, Dr. Zhang said. Her group’s innovation, published in the journal Small, was to bind the chlorotoxin to nanoparticles. (Veiseh O, Gunn JW, Kievit FM, et al. Inhibition of tumor-cell invasion with chlorotoxin-bound superparamagnetic nanoparticles. Small. 2009;5(2):256-264.)
"Nanoparticles conjugated with chlorotoxin, when they are uptaken by the tumor cell, take part of the cell membrane with them, and that part of the membrane is associated with the functionality of the cell to migrate," she explained. "So the nanoparticles improve the uptake of the chlorotoxin, and they also disable the functionality of the cells to migrate."
Dr. Zhang said the chlorotoxin-bound nanoparticles can potentially be combined with other modalities, whether chemotherapy, radiation, or some type of DNA- or siRNA-based therapy, to kill cancer cells.
Dr. Zhang said the team plans to conduct animal toxicity and other studies of the chlorotoxin nanoparticles, with the possibility of clinical testing in five to eight years.

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