IF GARY MEADOWS is right, popping Prozac will do more for you than relieve depression. Meadows’s preliminary data suggest that fluoxetine, the generic form of Prozac, inhibits the growth of melanoma tumors in mice.
The Prozac project began about two years ago in collaboration with neurophysiologist Tanja Obradovic, then at Washington State University. Obradovic and Meadows, who is Dorothy O. Kennedy distinguished professor and director of WSU’s Cancer Prevention and Research Center in Spokane, knew that melanoma cells not only make the neurotransmitter serotonin, but also have receptors for it. A receptor is a site on a cell that binds with substances such as hormones or neurotransmitters.
Serotonin, like other neurotransmitters, is also used by the nervous system to move information from one nerve cell to another. Once the information has been moved, the sending nerve cell reclaims the serotonin from the space between the two cells and recycles it. Prozac’s antidepressant function is due to its ability to prolong the time serotonin spends in the space between the nerve cells.
Meadows and Obradovic wondered whether serotonin would have any effect on melanoma cells, and their tests showed it to be highly toxic. But serotonin can’t be used to treat melanomas in live animals, because it would cause a generalized overstimulation of the entire body’s nervous system, says Meadows.
Since Obradovic knew that both melanoma cells and fat cells have receptors for fluoxetine, they next treated both mouse and human melanoma cells with it. In both cases, fluoxetine inhibited cell growth at a dose low enough for use in live animals and humans.
Testing the drug in mice indicated that not only does fluoxetine kill melanoma cells in live animals, but it also prevents some of the weight loss that usually is seen in animals with melanoma tumors.
Currently the lab is looking at the effect of combining fluoxetine with various chemotherapeutic drugs now in use, says Meadows. He hopes that human clinical trials will soon follow.
If the approach works, it should provide melanoma patients with treatment that not only helps stop the growth of their cancer, but also helps relieve the depression that often accompanies the disease.