CHICAGO, Sept. 5 (Xinhua) -- A natural plant compound called FR900359 (FR) can exploit a newly identified G alpha q in a cancer of the eye, uveal melanoma, to shut down the overactive signaling that drives uveal melanoma cell growth, researchers at Washington University School of Medicine in St. Louis found.
The solution is pretty simple: rather than turning off parts of the cascade activated by G alpha q, the researchers just wait for G alpha q to release the molecule that keeps it active. If a drug is present that can trap G alpha q in its inactive state, the entire cancer-causing signaling cascade would gradually shut down, one protein at a time.
FR is present in a member of the primrose family of plants.
"This plant compound binds tightly to inactive G alpha q, trapping it in its deactivated state," said senior author Kendall J. Blumer, a professor of cell biology and physiology at the university. "When the cancer-causing form of G alpha q just happens to switch off on its own, FR traps it there."
The study shows that the cancer-causing form of G alpha q doesn't have to be turned off by force. It just turns itself off every now and then on its own. But it then can be locked down with FR. "That's enough to shut down tumor cell growth," added first author Michael D. Onken, an assistant professor of biochemistry and molecular biophysics.
FR not only killed human uveal melanoma cells growing in the lab, it also appeared to revert a subset of those cells back to a state resembling normal pigmented cells of the eye, the study found.
Uveal, or ocular, melanoma arises from the layer of pigmented cells of the eye that includes the iris. Fatal in about half of the patients who develop it, the cancer represents about 3 to 5 percent of all melanoma cases.
The study was published Sept. 4 in the journal Science Signaling.
