Researchers at The Scripps Research Institute (TSRI) and the University of Wisconsin-Madison recently reported that a specific prodrug with antitumor potential can be effective in eliminating prostate cancer cells. The study was published in the journal Proceedings of the National Academy of Sciences (PNAS) and is entitled “Leinamycin E1 acting as an anticancer prodrug activated by reactive oxygen species”. Part of the research conducted at TSRI focuses on the development of natural products of bacterial origin into potential therapies. Some of these products are antitumor antibiotics produced by Streptomyces bacterium species that have the ability to repress cancer multiplication and cell growth. One such antitumor antibiotic is leinamycin (LNM). LNM biosynthesis has been manipulated resulting in a recombinant strain that generates a LNM biosynthetic intermediate – leinamycin E1 (LNM E1). LNM E1 was developed as a “prodrug”, a medication that is converted through a metabolic process into an active therapy within the body. LNM can undergo reductive activation in the presence of cellular thiols, leading to antitumor activity. In the study, researchers tested whether LNM could also undergo oxidative activation by cellular reactive oxygen species (ROS). ROS are naturally occurring molecules that result from oxygen metabolism. They play an important role in cell signaling and, when present in high levels for instance in stress conditions, can induce significant damage to cell structures and trigger apoptosis (programmed cell death). Cancer cells are known to be under high oxidative stress and to have higher ROS levels compared to normal healthy cells. The team therefore proposed that ROS could be used to target cancer cells. Researchers found that L