Siramesine -- a drug molecule developed by Lundbeck A/S to treat anxiety but discontinued due to unsatisfying trials -- was first shown to inhibit the growth of cultured cancer cells as well as that of solid tumors in mice by Danish scientists.

Researchers at the University of Helsinki, led by Paavo Kinnunen, are studying how the drug may promote apoptosis -- programmed cell death by which organisms deal with defective cells. Cancer cells survive by avoiding apoptosis.

The researchers find the production of phosphatidic acid acts as a signaling molecule for cells promoting cellular growth which can help prevent apoptosis. Siramesine may slow production of phosphatidic acid and so promote apotosis.

"The key finding of our study was that siramesine avidly and specifically binds to phosphatidic acid," Dr. Mikko Parry of University of Helsinki says in a statement. "Importantly, this is the first time it's shown that a lipid second messenger can act as a drug target: It is a totally new mechanism of action and constitutes a novel paradigm for developing new, more effective anti-cancer drugs."