Detecting breast cancer with a simple blood test is the goal of scientists at the Houston Methodist Research Institute.
In collaboration with a New York University Cancer Institute Colleague, the researchers found that a certain protein can accurately predict the presence of early stage breast cancer tissue in mice and in a small population of human patients.
"We link the catalytic activity of [blood protein created by] carboxypeptidase N to tumor progression in clinical samples from breast cancer patients and a breast cancer animal model," biomedical engineer Tony Hu, Ph.D. said in a statement. "Our results indicate that circulating peptides generated by CPN can serve as clear signatures of early disease onset and progression."
CPN is an enzyme that modifies proteins after the proteins are first created. Past studies have only shown the enzyme is more active in lung cancer patients. The present report in Clinical Chemistry is the first to show CPN isn't merely more active in breast cancer patients, but there's more of it, according to researchers.
In the study, Hu's group first determined the presence of breast cancer tissue in mice and humans, characterized each sample's stage of development, and looked at how much CPN was being expressed. Blood samples were also taken from each individual.
The researchers then compared the stages of breast cancer tissue development in diagnosed patients to the presence of CPN-created peptides in their blood. They found all six peptides were at detectably higher levels, as early as breast cancer's first pathologic stage.
The researchers also found that CPN peptides were at detectably higher levels in the blood of mice, compared to controls, just two weeks after the introduction of breast cancer tissue.
However, CPN activity dropped significantly over time in mice over the eight week study period, suggesting the blood test as currently configured may not work as well in detecting later stages of breast cancer.
The technology being developed by Hu's group combines nanotechnology and advanced mass spectrometry to separate and detect extremely low levels of small proteins (peptides) created by CPN.
These peptides are believed to originate in or near cancerous cells, eventually making their way into the bloodstream, allowing for them to be detected in a blood sample.
The technology may not be available for years. Hu, who leads the project, said more extensive clinical tests are needed. Those tests are slated to being in early 2014
There are currently no inexpensive laboratory tests for the early detection of breast cancer, providing the impetus for researchers around the world to invent them, according to a press release.
"What we are trying to create is a non-invasive test that profiles what's going on at a tissue site without having to do a biopsy or costly imaging," Hu said in a statement. "We think this could be better for patients and -- if we are successful -- a lot cheaper than the technology that exists."
