Sharks Attacking Cancer

NEW YORK (Reuters) -- The oceans' most feared predator may well turn out to be the cancer patient's best friend. Investigators at the medical research company, Magainin, based in Plymouth Meeting, Pennsylvania, have isolated a substance in the immune system of sharks that may help stop the spread of cancer in humans.

Magainin has studied 'alternate' immune systems in various species for years, says company chairman Jay Moorin. "We've got a quite diverse library of compounds from animals as varied as the shark, the fish, the rat, the frog, the pig, and of course, man. We know these systems are in existence throughout nature."

But he said nothing compares to their discoveries surrounding the immune system of sharks, which lack the blood-borne immune system common to most other animals.

"It has almost no immune system," Moorin explained, "and yet this animal eats decaying fish. It's constantly getting cut, yet somehow heals itself. We wondered what kind of equipment this animal had to protect itself."

Moorin's team noticed that when sharks sustained skeletal cartilage tears, tissue repair did not result in unrestrained growth of new cartilage cells. Something was preventing such 'cancer-like' responses from occurring.

Research produced answers. "What we discovered were 18 natural steroids," Moorin explained, "which represent a whole new class of pharmaceutical products. They work on different cells to control those cells' ability to proliferate."

One compound in particular, squalamine, shows particular promise. According to Moorin, animal trials demonstrated that squalamine effectively shut down a tumor's ability to connect to and develop its own blood supply. Once tumors are isolated from the nourishment they need, "hopefully, the immune system will then cause the tumor to shrink," Moorin said. "It's a very exciting approach to treating a number of solid-tumor cancers."

This fall, Magainin, in concert with scientists at Johns Hopkins University in Baltimore, will initiate the first human trials involving the use of squalamine in the treatment of breast and brain cancers.

Researchers believe squalamine could represent a powerful new weapon in the anti-cancer arsenal. Moorin says that animal trials have so far shown no adverse side effects to the drug. "We should be able to use squalamine rather freely because it does not add to the overall toxicity of treatment," Moorin explained.

Sharks may not be the only creature helping humans fight disease. As reported last year by Reuters, Magainin scientists have also isolated proteins in frogs, which seem to help fight painful foot infections linked to diabetes.