Primary Tumors Drive Cancer Growth

Ivanhoe Newswire
Tuesday, June 17, 2008; 4:15 AM

(Ivanhoe Newswire) Researchers discovered a new clue to help them understand how and why cancers spread in the body.

The scientists from the Massachusetts Institute of Technology studied primary tumors from human breast cancers that appeared to mobilize bone marrow cells. The tumors then fed inactive cancer cells elsewhere in the body. It's usually these metastases that cause death.  One key to the process seems to be a substance called osteopontin, which is found in high levels in breast cancer patients.
"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."
The researchers injected mice with instigating human breast cancer tumor cells as well as indolent colon cancer cells. The indolent cells grew, but only when the instigating tumor cells were present. Osteopontin was involved but it doesn't act alone. They go on to report that there is a possibility the indolent cells may somehow be recruiting the instigating cells using bone marrow.

"The ability of instigating tumors to foster the growth of a human colon tumor surgical specimen underscores the powers of systemic instigation," wrote the researchers. "In the longer term, identification of additional tumor-derived factors that perturb the host systemic environment in one way or another may allow one to predict the effects that a given primary tumor has on the outgrowth of indolent cancer cells that have disseminated to distant sites."

SOURCE: Cell, June 13, 2008

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