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Cartilage of Sharks Could Yield Anti-Cancer Protein

Associated Press

Fresno State University researchers are studying shark cartilage in hopes of isolating a protein that could fight cancer.

The research is based on a theory that a protein in cartilage might be able to block the growth of capillaries, tiny blood vessels that tumors need to thrive but which are basically absent from cartilage.

The Fresno State team was able to extract a chunk of cartilage that was four inches long, one inch wide and about one-eighth of an inch thick from a cow shoulder blade obtained from a slaughterhouse.

But they decided that shark would be a better source of cartilage in large quantities because they have the rubbery substance in place of bones.

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An expedition to a shark-fishing tournament last year at Moss Landing produced enough cartilage to give the research a boost.

Three Ice Chests Full

“We got about three ice chests full,” said Robert Ewy, a master’s candidate. “We didn’t have time to clean all the cartilage off, they were coming so fast.”

The next steps in the study involved cleaning the cartilage, freezing it, shredding it, chemically treating it to release proteins and screening minute amounts to test their ability to inhibit the capillaries. That is the current stage of research.

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“What we believe is that the tumors secrete a protein which promotes the growth of capillaries,” said Dr. K. P. Wong, a biochemist and dean of the university’s school of natural sciences.

The goal of the study is to locate a protein inhibitor that “has the ability to basically digest that protein, chopping it into pieces before it can do its job.”

The inhibitor could act at various points to interfere with a tumor, Ewy said. It could inhibit a protein called angiogenin that tumors emit to attract capillaries; it could bind the capillary cells; or it could bind enzymes that break down cell structure.

But researchers have to isolate the protein before they can venture an accurate guess of what it does.

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A Harvard University team working with tumors has isolated angiogenin, which will help scientists understand how they develop.

Trying to Stop Tumors

The Fresno State project approaches the problem from the opposite direction, trying to stop tumors.

The study is an outgrowth of an eye doctor’s research in which cartilage placed between a tumor and the nearest capillaries in a rabbit’s eye seemed to force the capillaries to detour around the implant.

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As expected, researchers are having difficulty isolating cartilage samples containing an inhibitor because the substance they seek would be present in minute amounts.


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