Researchers combine nanotubes and antibodies to detect cancer

The researchers, led by Eric Wickstrom, Ph.D., professor of biochemistry and molecular biology at Jefferson Medical College of Thomas Jefferson University in Philadelphia and at the Kimmel Cancer Center at Jefferson, and Balaji Panchapakesan, Ph.D., assistant professor of electrical engineering at the University of Delaware in Newark, present their findings November 17, 2005 at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics in Philadelphia.

The group took advantage of a surge in electrical current in nanotube-antibody networks when cancer cells bind to the antibodies. They placed microscopic carbon nanotubes between electrodes, and then covered them with monoclonal antibodies – so-called guided protein missiles that home in on target protein "antigens" on the surface of cancer cells. The antibodies were specific for insulin-like growth factor 1 receptor (IGF1R), which is commonly found at high levels on cancer cells. They then measured the changes in electrical current through the antibody-nanotube combinations when two different types of breast cancer cells were applied to the devices.

The researchers found that the increase in current through the antibody-nanotube devices was proportional to the number of receptors on the cancer cell surfaces. One type, human BT474 breast cancer cells, which do not respond to estrogen, had moderate IGF1R levels, while the other type, MCF7, which needs estrogen to grow, had high IGF1R levels.

The BT474 cancer cells, which had less IGF1R on their surfaces, caused a three-fold jump in current. The MCF7 cells showed an eight-fold increase. "When cancer cell bind to antibodies, there is a rush of electrons from the nanotube device into the cell," Dr. Panchapakesan explains. "The semiconductor nanotubes become more conductive," says Dr. Wickstrom. "We saw a larger current increase for the MCF7 cells because it correlates with a greater expression of IGF1 receptors." The cells have a surface protein that is recognized by the antibody on the nanotubes. The current spike occurs only if a target cancer cell with the right antibody target binds to the nanotube array.

"The breast cancer cells don't give a spike if there is a non-specific antibody on the nanotube," he says, "and cells without that target don't cause a current jump whatever antibody is on the nanotubes.

"This method could be used for detection and it could be used for recurring circulating tumor cells or micrometastases remaining from the originally treated tumor," Dr. Wickstrom explains.

"The technique could be cost-effective and could diagnose whether cells are cancerous or not in seconds versus hours or days with histology sectioning," says Dr. Panchapakesan. "It will allow for large scale production methods to make thousands of sensors and have microarrays of these to detect the fingerprints of specific kinds of cancer cells."

Drs. Wickstrom and Panchapakesan would like to test the technique on additional breast cancer markers and markers for other kinds of cancers to determine its utility and breadth. In future studies, researchers will add cancer cells to a drop of blood and apply the mixture to the nanotube detector to see how sensitive it is in detecting the cancer cells mixed in with real blood cells and proteins. Another test might involve using the device to try to detect specific types of cancer cells shed in the blood from tumors in animals.

The technique has limitations. "We don't know if we can detect more than one antigen at a time on a single cell," Dr. Wickstrom says. Ultimately, the researchers would like to design an assay that can detect cancer cells circulating in the human bloodstream on a hand-held device no bigger than a cell phone.

Source: Thomas Jefferson University

New platinum-phosphate compounds kill ovarian cancer cells
A new class of compounds called phosphaplatins can effectively kill ovarian, testicular, head and neck cancer cells with potentially less toxicity than conventional drugs, according to a new study published this week in the journal Proceedings of the National Academy of Sciences.
ADHD medications do not cause genetic damage in children
In contrast to recent findings, two of the most common medications used to treat attention deficit hyperactivity disorder (ADHD) do not appear to cause genetic damage in children who take them as prescribed, according to a new study by researchers at the National Institutes of Health (NIH) and Duke University Medical Center.
New imaging technique tracks cancer-killing cells over prolonged period
Coaxing a patient's own cells to hunt down and tackle infected or diseased cells is a promising therapeutic approach for many disorders. But until now, efforts to follow these specially modified cells after their reintroduction to the body have relied on short-term monitoring techniques that don't give a complete picture of the cells' status.
Researchers identify dangerous 'two-faced' protein crucial to breast cancer spread and growth
Two critical properties of cancer cells are their ability to divide without restraint and to spread away from the primary tumor to establish new tumor sites. Now, researchers from the Mayo Clinic campus in Florida have found a protein they say acts as a deadly master switch, both freeing cancer cells from a tumor while ramping up new growth.
Breaking BubR1 mimics genetic shuffle seen in cancer cells
A study of how one protein enzyme, BubR1, helps make sure chromosomes are equally distributed during mitosis might explain how the process of cell division goes so awry in cancer, according to researchers from Fox Chase Cancer Center. Their findings might offer a better understanding of the processes behind cancer-cell survival and drug-resistance.
Tiny sacs released by brain tumor cells carry information that may guide treatment
Microvesicles – tiny membrane-covered sacs – released from glioblastoma cells contain molecules that may provide data that can guide treatment of the deadly brain tumor. In their report in the December 2008 Nature Cell Biology, which is receiving early online release, Massachusetts General Hospital (MGH) researchers describe finding tumor-associated RNA and proteins in membrane microvesicles called exosomes in blood samples from glioblastoma patients. Detailed analysis of exosome contents identified factors that could facilitate a tumor's growth through delivery of genetic information or proteins, or signify its vulnerability to particular medications.
Arsenic linked to cardiovascular disease at EPA-regulated drinking water standards
When mice are exposed to arsenic at federally-approved levels for drinking water, pores in liver blood vessels close, potentially leading to cardiovascular disease, say University of Pittsburgh researchers in the Dec. 1 issue of the Journal of Clinical Investigation, available online Nov. 13. The study, while preliminary, also reveals how an enzyme linked to hypertension and atherosclerosis alters cells, and may call into question current Environmental Protection Agency standards that are based solely on risks for cancer.
'2-headed' antibody poses a double threat to breast cancer cells
A small, antibody-like molecule created by researchers at Fox Chase Cancer Center can successfully attack two separate molecules on the surface of cancer cells at the same time, halting the growth of breast cancer cells in laboratory tests, the researchers say. The molecule, nickname "ALM," might be a means of slowing cancer spread or, as the researchers believe, a guidance system for delivering more aggressive drugs directly to cancer cells. Their findings appear in a recent issue of the British Journal of Cancer.

Researchers combine nanotubes and antibodies to detect cancer

Related stories:

News discussion: