Cancer cell proteins offer insight into disease progression

Cancer cells circulating in the blood carry newly identified proteins that could be screened to improve prognostic tests and suggest targets for therapies, report researchers from the Duke Cancer Institute, Durham, NC.

Building on current technologies that detect tumor cells circulating in blood, the team was able to characterize these cells in a new way, illuminating how they may escape from the originating tumors and move to other locations in the body.

The circulating tumor components include proteins normally seen when embryonic stem cells begin to specialize and move through the body to develop organs such as the heart, bones, and skin. The discovery may enhance the accuracy of blood tests that detect circulating cancer cells, giving physicians better information to gauge disease response or progression.

"By developing a better blood test based on our findings, we may be able to identify molecular targets for therapy tailored to an individual patient’s cancer," said lead author Andrew J. Armstrong, MD, ScM.

The researchers isolated tumor cells from blood samples of 57 patients, including 41 men with advanced prostate cancer and 16 women with metastatic breast cancer. In the tumor cells of more than 80% of the prostate cancer patients and 75% of those with breast cancer, the researchers detected a group of proteins normally seen during embryonic development, when stem cells begin to assume distinct roles.

Current FDA-approved blood tests that detect circulating tumor cells flag molecules associated with epithelial transitions; however, the researchers found additional markers associated with mesenchymal origins, adding new targets that could be used to enhance the usefulness and sensitivity of the tests.

"Cancer is a hijacking of that normal embryonic stem cell process," Dr. Armstrong said. "It reactivates this silent program that is turned off in adult cells, allowing tumor cells to move throughout the body and become resistant to therapy."

Results of the study were published online in Molecular Cancer Research (July 26, 2011).