Nanoparticles may assist circulating tumor cell detection

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Tiny gold particles can help doctors detect circulating tumor cells in the blood of patients with head and neck cancer and other cancers, according to research published online Feb. 11 in Cancer Research.

The gold particles, which are embedded with dyes allowing their detection by surface-enhanced raman spectroscopy (SERS), could enhance this technique's specificity by reducing the number of false positives.

Researchers at Emory University and Georgia Institute of Technology (Georgia Tech), both in Atlanta, showed that polymer-coated and dye-studded gold particles, directly linked to a growth factor peptide rather than an antibody, can detect circulating tumor cells in the blood of patients with head and neck cancer.

“The key technological advance here is our finding that polymer-coated gold nanoparticles that are conjugated with low molecular weight peptides such as EGF [epithelial growth factor] are much less sticky than particles conjugated to whole antibodies,” said Shuming Nie, PhD, a professor in the department of biomedical engineering at Georgia Tech and Emory. “This effect has led to a major improvement in discriminating tumor cells from non-tumor cells in the blood.”

The particles are linked to EGF, whose counterpart EGFR (epithelial growth factor receptor) is over-produced on the surfaces of several types of tumor cells.

Upon laser illumination, the particles display a sharp fingerprint-like pattern that is specific to the dye, because the gold enhances the signal coming from the dyes, according to the researchers, who suggested that several types of nanoparticles could be combined to gain more information about the growth characteristics of the tumor cells. In addition, they noted that measuring circulating tumor cell levels may be sensitive enough to distinguish patients with localized disease from those with metastatic disease.

“Nanoparticles could be instrumental in modifying the process so that circulating tumor cells can be detected without separating the tumor cells from normal blood cells,” Nie said. “We’ve demonstrated that one tumor cell out of approximately one to ten million normal cells can be detected this way.”

In collaboration with oncologists at Winship Cancer Institute in Atlanta, researchers used nanoparticles to test for circulating tumor cells in blood samples from 19 patients with head and neck cancer. Of these patients, 17 had positive signals for circulating tumor cells in their blood. The two with low signals were verified to have no circulating cells by a different technique.

“Although the results have not been compared or validated with current circulating tumor cell detection methods, our ‘one-tube’ SERS technology could be faster and lower in costs than other detection methods,” said Dong Moon Shin, MD, professor of hematology and oncology and otolaryngology, associate director of academic development for Winship and director of Winship’s chemoprevention program. “We need to validate this pilot study by continuing with larger groups of patients and comparing with other tests.”