Gold Nanoparticles Show Potential For Noninvasive Cancer Treatment

The researchers are a father and son, working together on oppositecoasts. Their study findings are reported in the on-line edition of thejournal Cancer Letters, found at Sciencedirect.com (quicksearch:El-Sayed nanoparticles).

"In an earlier study we showed how gold nanoparticles could bebound to malignant cells, making cancer detection easier. Now we haveexamined how the particles' ability to absorb light helps kill thosecancer cells," said principal author Ivan El-Sayed, MD, assistantprofessor of otolaryngology at UCSF Medical Center.

Ivan conducted the study with his father, Mostafa El-Sayed,PhD, director of the Laser Dynamics Laboratory and chemistry professorat Georgia Tech.

Many cancer cells have a protein, known as epidermal growth factorreceptor (EGFR), all over their surface, while healthy cells typicallydo not express the protein as strongly. By conjugating, or binding, thegold nanoparticles to an antibody for EGFR, suitably named anti-EGFR,the researchers were able to get the nanoparticles to specificallyattach themselves to the cancer cells.

In the new study, the researchers incubated two oral squamous carcinomacell lines and one benign epithelial cell line with anti-EFGRconjugated gold nanoparticles and then exposed them to continuousvisible argon laser. "The malignant cells required less than half thelaser energy to be killed than the benign cells," said Ivan. "Inaddition, we observed no photothermal destruction of any type of cellin the absence of gold nanoparticles at these low laser powers."

"We now have the potential to design an 'all in one' activeagent that can be used to noninvasively find the cancer and then killit," Ivan said. "This holds great promise for a number of types ofcancer."

"There is the real potential to design instrumentation to allownoninvasive detection and treatment of the particles in living humans,"Mostafa said. "The particles can be used to create multiple designeragents targeted toward specific cancers. Much work still needs to bedone, but at some point, we hope to be able to inject these compoundsinto patients with cancer in a search-and-destroy mission. Findingcancers not apparent to the eye will help physicians detect cancersearlier. Exposing the cells to the correct amount of light would thencause destruction of the cancer cells only and leave the healthy cellsalone."

The technique isn't toxic to human cells. "Gold nanoparticleshave been used in humans for 50 years," Ivan said. "For example, in thepast, a radioactive form of colloidal gold has been used to search forcancerous lymph nodes."

"Our technique is very simple and inexpensive--only a few centsworth of gold can yield results. We think it holds great promise toreduce the time, effort, and expense in cancer research, detection, andtherapy in humans and under the microscope," he added.

Ivan, who sees many patients with oral cancers, hopes that inthe not-too-distant future his research will pay off for his patients."Our best chance to save lives is to catch cancer and treat it early.Our work with gold nanoparticles may result in a valuable tool infighting not only oral cancers, but also a number of other types,including stomach, colon and skin cancers."

The research was supported by a grant from the ChemicalScience, Geoscience and Biosciences Division of the U.S. Department ofEnergy.

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