Primary tumors can encourage the growth of stray cancer cells lurking elsewhere in the body that otherwise may not have amounted to much, according to a new study in the June 13 issue of the journal Cell, a publication of Cell Press. As people age, most may have such indolent cancer cells given the sheer number of cells in the body, although their rarity makes them impossible to detect, the researchers said.
The primary tumors under study, which were derived from human breast cancers, seem to "instigate" the growth of other cancers by mobilizing bone marrow cells, which then feed the secondary tumors' growth, they report.
One key to the process is the secretion of a substance known as osteopontin by the instigating tumor, a finding that may have therapeutic implications. Indeed, the researchers noted that osteopontin is present at elevated levels in women with metastatic breast cancer, supporting the notion that the new findings may hold clinical significance.
" If metastases depend on stimulation by primary tumors, interception of the signal through neutralizing antibodies" might block cancer spread, said Robert Weinberg of the Massachusetts Institute of Technology. "That's still speculative, but it's an interesting idea to ponder," he added, noting that treatments today don't specifically target metastases, which are responsible for the vast majority of cancer deaths.
The researchers noted that while the effects of the tumor microenvironment has been much studied, much less was known about how the systemic environment in the body contributes to tumor growth. Several earlier reports had shown that assorted bone marrow-derived cells can be incorporated to various extents into the supportive framework, or stroma, of tumors. However, it wasn't clear whether tumors actively recruit stromal cells by directly perturbing other cell reservoirs, such as the bone marrow, or whether tumors are just passive recipients of stromal
|Contact: Cathleen Genova|