A bee sting can be painful, but its venomous payload might hold promise for a beneficial purpose—fighting cancer.

Researchers at Washington University in St. Louis have used an ingredient of bee venom called melittin to shrink or slow the growth of tumors in mice. Melittin's anti-tumor potential has been known for years, but it hasn't been used as a drug because it also attacks healthy cells, including vital red blood cells.

Now the researchers have found a way, using the burgeoning field of nanotechnology, to pinpoint tumors for attack by melittin while largely shielding healthy cells. They do this by attaching the bee-venom ingredient to nanoparticles, which are ultra-tiny, synthetically manufactured spheres. The resultant product, called nanobees, are injected into the blood stream where they circulate until they reach and attack cancerous tumors. The approach also has the potential to avoid some of the toxic side effects seen in older cancer therapies like chemotherapy.

Nanobees showed promise in a study published this summer in the Journal of Clinical Investigation. The study found that nanobees halted tumor growth or shrank tumors in mice with breast and skin cancers, and reduced precancerous lesions. The experiments showed minimal toxicity to healthy cells from the treatment.

"In effect, we've got something that does what a bee does except it's a synthetic particle. It's got a stinger and injector to insert the toxin into a cell," says Samuel Wickline, a professor at Washington University's medical school.