UC San Diego

Ionizing radiation is classified as a potent carcinogen and its injury to cells is, to a large extent, due to oxidative damage generated by reactive oxidative species (ROS). The biomolecules most often reported to be damaged by ionizing radiation are lipids and DNA. Dr. Boss has shown that cobinamide, a structural analogue of cobalamin (vitamin B12), binds to superoxide anion in vitro. We now show that in cultured cells cobinamide can work as a possible therapeutic agent for radiation-induced injury. First, in HeLa cells cobinamide improved increased DNA synthesis by an average of 19 percent when given prior to irradiation, and 7 percent when given 24 hours post- irradiation. Secondly, in irradiated MDA MB-231 cells, the doubling rate was 19 percent higher in cobinamide-treated cells than in non-treated cells. And finally, cells treated with cobinamide showed less fragmentation and blebbing following irradiation than non-treated cells. These data suggest that cobinamide might be beneficial in treating the effects of ionizing radiation