Sea squirt may hold key to melanoma fight

University of South Florida chemist Bill Baker, who spends much of his time diving in the frigid waters of Antarctica retrieving tunicates, blob-like marine animals, has isolated a compound in tunicate biochemistry that may fight melanoma, a type of skin cancer rising at alarming rates. “Tunicates have proven to be an important source of bioactive natural products,” said Baker, who experimented with the tunicate Synioicum adareanum, retrieved from the shallow waters around Anvers Island. “We isolated a natural product in the species and sent it to the National Cancer Institute for testing against 60 different cancer cell lines. NCI conclude the compounded inhibited melanoma, a form of skin cancer that is rising in prevalence.”

Tunicates, also called “sea squirts,” spend most of their time attached to rocks. Built like barrels, tunicates are vertebrates with firm, flexible bodies. They feed off plankton through an oral siphon.

Baker and colleagues Jim McClintock and Charles Amsler, from the University of Alabama at Birmingham, named the compound Palmerolide A after the area from which they took the tunicates near Antarctica. Back in the USF lab, graduate student Thushara Diyabalanage isolated the chemical and obtained the structure of the compound before sending it off to the NCI labs. There, Palmerolide A showed little to no effect against cancer cell lines such as breast cancer, prostate cancer and others, but its effect on melanoma cells was nothing less than spectacular, said Baker.

“It inhibited melanoma by three orders of magnitude,” explained Baker, who is hopeful the compound can be tested in laboratory animals, humans, and finally make it to the market as an effective anti-melanoma drug.

The NCI maintains a databank of cancer cell lines and researchers regularly submit compounds for testing and NCI responded to Baker’s test by referring Palmerolide A to the NCI’s Biological Evaluation Committee for animal testing because of its huge impact on melanoma cells.

According to the H. Lee Moffitt Cancer Center library ( of cancer information, melanoma is the most serious form of skin cancer usually caused by sun exposure. Its prevalence has risen by 1200 percent over the last 70 years. People living for more than 10 years in the “Sunbelt” of the U.S. are at particular risk. Risk factors also include a family history of melanoma.

From University of South Florida

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