In a new study in Nature Medicine, researchers at the Peter MacCallum Cancer Centre in Australia and their collaborators have found that breast cancer cells metastasize to bone in part by deactivating an immune system response meant to prevent the spread of the disease, says Reuters' Tan Ee Lyn. Using mouse models and by analyzing tissue samples from breast cancer patients, the team found that the IRF7 gene — which controls the production of the immune protein interferon — is turned off in patients whose cancer has metastasized. "Usually when breast cancer cells leave the breast and travel in the bloodstream and into bone marrow, the release of interferons by IRF7 will cause the immune system to recognize those cells and eliminate them," lead author Belinda Parker tells Lyn. "But by losing IRF7, it prevents the stimulation of immune responses and allows those cells to hide from being recognised (and later spread)."
But the researchers also hope that their discovery will allow them to find a way to turn the gene back on. They tried inserting the gene into the cancer cells so they can't turn it off and found that the immune pathways responded and didn't allow the cancer to spread, Lyn says. They also tried treating mice with breast cancer with interferon, which also prevented bone metastases from forming. "Parker said they will study how best to use these two methods on patients in the next few years and plan to have a clinical trial in two to three years," Lyn adds.