Improved diagnostic techniques for prostate cancer, the most common
cancer among American men, have led to a threefold increase in the rate
of diagnosis since 1988. But that presents physicians with a dilemma: Many
of these early cancers are relatively benign and do not warrant aggressive
intervention. How is the physician to tell which cancers will go on to
develop life-threatening metastases?
Harvard researchers may have found a way. In the December issue of Nature
Medicine, a research team led by Lere Bao, instructor in surgery at
Children's Hospital, Boston, reports the identification and genetic description
of a telltale molecule: thymosin B15, a protein involved in cell motility.
The researchers found that, in an animal model, the protein gears up the
cancer cell's ability to move around the body, which is part of the progression
of metastasis. They also note that thymosin B15 is not expressed in normal
or benign human prostate cells but appears at high levels in human prostate
cancers with high metastatic potential.
Apparently, the protein helps the cancer cell break free of its attachments
to neighboring cells and surrounding tissue, allowing it to course through
the body and form secondary tumors elsewhere.
Other authors are Massimo Loda and Robert Stewart, Beth Israel Deaconess
Medical Center; Paul A. Janmey, Brigham and Women's Hospital; and Bela
Anand-Apte and Bruce R. Zetter, Children's Hospital.