Transferred Mitochondria Accumulate Reactive Oxygen Species, Promoting Proliferation

Cancer cells don't act on their own. Their behavior is influenced by neighboring cells, which sometimes help them grow and spread. For instance, immune cells called macrophages patrol the body, engulfing and destroying potential threats. But when they interact with tumors, they can often produce signals that drive the disease. Scientists like U of U Health biochemist Minna Roh-Johnson, PhD, aim to learn how macrophages promote cancer's growth and spread-a first step toward developing treatments that block those dangerous interactions. Researchers in Roh-Johnson's lab have uncovered a surprising way macrophages spur on cancer cells. She and her colleagues noticed that mitochondria-energy-generating structures inside cells-are often transferred from macrophages to tumor cells. While many scientists suspected the extra mitochondria might help fuel cancer cells, Roh-Johnson's team saw something more complicated. Most of the transferred mitochondria couldn't generate any energy at all-but they were surrounded by highly reactive metabolic byproducts called reactive oxygen species, which activated pathways that drive cell growth. Roh-Johnson notes that researchers have begun exploring the possibility of treating illness by delivering healthy mitochondria to damaged cells-suggesting it might one day be possible to manipulate these mitochondrial signals in cancer cells.