Proteins seen to shut down cancer cells SAN ANTONIO, July 9 (UPI) -- Protein interactions outside breast cancer cells can send signals to permanently stop them proliferating, suggesting possible treatments, U.S. researchers say. The goal of such treatments would be to make that "dormant state" permanent, scientists at the University of Texas Health Science Center in San Antonio said. "Because this protein cascade is outside the cells, it is likely amenable to therapeutic manipulation," biochemist Yuzuru Shiio, said. I hope our study will ultimately lead to a therapeutic strategy to reprogram cancer cells to a state of permanent dormancy. Shiio, the study's lead author, cautioned that the finding was observed in cell cultures and is still far from a human cancer therapy. In chemotherapy treatments, to goal is to cause cancer cells to either die or permanently stop proliferation. The latter phenomenon is called senescence and is poorly understood, Shiio said. In chemotherapeutic experiments on cell cultures, the cancer cells were seen to release protein factors that stop proliferation, and the researchers found a protein called IGFBP3 (insulin-like growth factor binding protein 3) is a key player in cancer senescence. The research has been published in the Proceedings of the National Academy of Sciences.