June 16, 2011
Scientists have identified a new way of fighting cancer that limits the growth and spread of a variety of tumors in laboratory animals.
When you get a cut, the area quickly becomes inflamed - swollen, red, and tender as the body's immune system sends white blood cells to fight infection and heal the wound.
The immune system reacts to many cancers in much the same way, says University of California, San Diego researcher Judith Varner.
"The white blood cells rush to the tumor and attempt to heal the 'wound' in a manner that actually never stops," she explains. "And because it doesn't stop, because the cancer doesn't go away, the white blood cells actually help the cancer to grow."
That happens when the immune system cells are 'hijacked' by the tumor in a way that fosters the growth and spread of tumors.
Varner and her colleagues identified a specific enzyme called PI-3 kinase gamma that allows the immune cells to get into the tumor, where it can be compromised.
They figured out how to block PI-3 kinase gamma, using either drugs or genetic methods, in laboratory mice.
"When we treated animals with early tumors, we found that we could stop the stage of tumor at the early stage, and we prevented the invasive stage from developing. And that's only by targeting the inflammation, even without a drug that affects the tumor cell itself," Varner says.
In addition to the mice with breast cancer, the researchers also used this approach on a variety of other cancers in laboratory animals and found it was consistently effective across a range of different kinds of tumors.
"So we were able to inhibit half of all the tumor growth in pancreatic cancer, breast cancer, melanoma, lung cancer. And there's every reason to believe that any other solid tumor cancer would be also responsive."
Varner says suppressing PI-3 kinase gamma might in theory also be effective to reduce the risk of cancer in the first place, in cases where chronic inflammation contributes to tumor formation.
She says human testing of PI-3 kinase gamma inhibitors to battle cancer could begin as soon as a year or so from now.
Judith Varner of the University of California, San Diego and her colleagues report on this new approach to tumors in the journal Cancer Cell.