Scorpion venom stings cancer

While the sting of most scorpions is nonlethal to humans, it's not usually considered health-enhancing either. But the venom could actually prove lifesaving.

Dr. James M. Olson and colleagues at the Fred Hutchinson Cancer Research Center in Seattle attached the peptide chlorotoxin to Cy5.5, a fluorescent molecule that emits near-infrared light. Chlorotoxin, a component of scorpion venom, preferentially binds to cancer cells (Cancer Res 2007;67:6882-6888).

The probe lit up malignant gliomas, medulloblastomas, prostate cancer, intestinal cancer, and sarcomas. Brain tumors as small as 1 mm in diameter and as few as 200 metastatic prostate cancer cells were visualized.

The unique contrast agent shows promise for imaging melanoma and skin, esophageal, cervical, lung, and colon cancers. It binds to cancer cells within minutes after injection, but its signal can be detected for 14 days. Iron oxide-based nanoparticles coated with chlorotoxin imaging are being developed for use with MR.