Chicken Antibodies Guide Cancer-Killing Nanotubes

A recent paper described a novel hi-tech mechanism for tracking and destroying cancer cells. The method is based on a highly specific chicken antibody (immunoglobulin Y, or IgY) directed at the cancer cell surface HER2 (human epidermal growth factor receptor 2) protein covalently bound to single-walled nanotubes.

The nanotubes (SWNTs) exhibit two unique optical properties that make them useful for this application. When exposed to laser light at a wavelength of 785 nanometers, a strong Raman signal is given off that can be detected with a special Raman microscope. Exposure to laser light at 808 nanometers (near infrared or NIR) causes the SWNTs to heat up, which results in thermal destruction of living tissue in the near vicinity.

Investigators at the [U.S.] National Institute of Standards and Technology (Gaithersburg, MD, USA) worked with two types of cancer cells growing in tissue culture. Both HER2-expressing SK-BR-3 cells and HER2-negative MCF-7 cells were treated with the IgY-SWNTs and then exposed to different wavelengths of laser light.

Results published in the October 2, 2009, issue of the journal BMC Cancer revealed that the anti-HER2 IgY guided the nanotubes to those cells expressing HER2. Thus, the Raman signal collected at single-cell level from the SWNT-treated SK-BR-3 cells was significantly greater than that from the MCF-7 cells. Exposure to NIR irradiation selectively destroyed the SWNT-targeted breast cancer cells without harming receptor-free cells. Significantly, cell death was effectuated without the need of internalization of SWNTs by the cancer cells.

The authors concluded that, "The complex can be potentially used for both detection and selective photothermal ablation of receptor-positive breast cancer cells without the need of internalization by the cells. Thus, the unique intrinsic properties of SWNTs combined with high specificity and sensitivity of IgY antibodies can lead to new strategies for cancer detection and therapy."

Related Links:
[U.S.] National Institute of Standards and Technology