Prostate cancer biomarker may predict patient outcomes
A cell-surface protein called CD151 may serve as a biomarker that accurately predicts which patients with prostate cancer are likely to experience metastasis or recurrence.
Prostate cancer is the second leading cause of cancer-related deaths among men in North America. Some prostate cancer spreads slowly and does not lead to serious symptoms, but in other patients, the cancer metastasizes and is fatal. The identification of a biomarker that predicts which patients should be followed through surveillance and which patients should be treated aggressively would have a dramatic impact on prostate cancer morbidity and mortality.
CD151 is a transmembrane protein that is normally associated with integrin, a protein that is involved in cellular adhesion to surrounding tissues. In prostate cancer cell lines, CD151 is free from integrin and appears to regulate tumor cell migration.
"It was a big surprise that some of this CD151 protein was now free of that partner and it turns out that it only occurs when a cancer is formed," said Andries Zijlstra, PhD, assistant professor at Vanderbilt University School of Medicine in Nashville, Tennessee. "What's so novel about this discovery is we're not talking about changing protein expression, which is what we traditionally see. We're talking about a protein that changes its molecular state and detection of that molecular state is an indication of disease progression."
Tissue samples from 137 patients treated for prostate cancer over the past 12 years were examined in a study published in Cancer Research (doi: 10.1158/0008-5472.CAN-13-0275). Patients who tested positive for CD151free had recurrence and spread of prostate cancer an average of 10 years earlier than patients who had no detectable CD151free.
Multivariate analysis identified CD151free as an independent predictor of survival. The detection of CD151free could be used to stratify survival among patients with elevated prostate-specific antigen.
Preliminary work in other solid tumors suggests that this may be a universal mechanism important for cancer progression.
"It is increasingly clear that a molecular switch in cell migration corresponds to patient outcome in solid tumors," said Zijlstra. "Consequently, the detection of that switch can assist in determining whether a patient is going to develop aggressive cancer or if the disease will remain benign. That information ultimately determines the type of care given to a cancer patient."
The group is working on development of an antibody test for use in clinical settings.