|
Protein-cleaving enzymes called proteases are important for normal cell development, but their presence in unhealthy cells can promote tumor growth and spread. Proteases are "major contributors to cancer's morbid effects," says
Suresh Mohla, Ph.D., chief of the Tumor Biology and Metastasis Branch in NCI's Division of Cancer Biology. Many researchers have studied protease inhibitors as a means to block bone metastasis, but maspin is one of the few to live up to hopeful expectations.
In the Wayne State University study, tumor cells engineered to make maspin did not form invasive tumors in human bone fragments implanted in mice. In striking contrast, cells that did not create maspin formed large tumors that destroyed all bone tissue in the mice. While the exact mechanism by which maspin stops bone metastasis is not yet clear, maspin is known to be a potent inhibitor of rokinase-type plasminogen activator, or uPA, a protease that leads
to bone deterioration and invasive tumor growth.
"Maspin presents an exciting therapeutic potential for treatment and prevention of metastases" in cancers that invade the bone, such as tumors of the breast and prostate, explains NCI's Mohla. He points out, however, that significant challenges remain in translating these mouse studies into human use. For example, implanting maspin-producing cells into rodents is much less complex than devising a method to target all prostate tumor cells throughout a patient's body to produce the metastasis suppressor.
|
