OSU research finds trout are better models for cancer research than mice

[Spiel]

OSU research finds trout are better models for cancer research than mice

 

 

Monday July 20, 2009

Chris Spitzer / The Oregonian

 

 

George Bailey helped build the world-class trout research facility at Oregon State University, and recently retired after his team completed a sensitive study of the carcinogen DBP. Doug Beghtel/The Oregonian

 

A rainbow trout can inspire and inform. It can lead a young fisherman to a life-long career studying human health. It can reveal the risks of carcinogens, and help develop treatments to prevent cancer. It can become the centerpiece of a world-class research facility that may reshape how government agencies regulate environmental toxins.

 

George Bailey knows all this and has plenty of fish stories. As a professor, he spent three decades studying disease with trout in his aquatic laboratory at Oregon State University.

 

From outside, the building sits on a dusty lot just outside of Corvallis and doesn't look like much. Walk inside, and you'll find a bustling laboratory. The air is cool and the fishy smell is surprisingly slight. Eggs and fry swirl in large glass cylinders off to one side. Once they're big enough, the fish will graduate to the hundred gallon tanks that pack the huge central room, which covers a third of an acre. There is constant activity as the dozen staff members prepare cheesy fish food and systematically check the tanks.

 

"What we have here is the only facility of its kind anywhere in the world," says Bailey, 68. "Completely unique."

 

He officially retired six years ago, but continued to work at half pay to complete the capstone of his career, the most accurate study of the chemical DBP, an environmental carcinogen. The results, published in May, were surprising.

 

"It was known to be a powerful agent," Bailey says, "but there wasn't much information."

 

By using trout, Bailey measured risk of DBP at low exposures, and found reducing exposure by half meant less than half as much cancer. The Environmental Protection Agency calculates a proportionate risk level from high exposure data. In essence, the EPA guesses conservatively to compensate for lack of data.

 

But Bailey's fish gave him low exposure data so he could pinpoint the risk. And for DBP, Bailey found that the EPA would overestimate the cancer risk by a factor of 1,000.

 

David Williams, director of the Superfund Research Center at OSU, thinks the research could have a big impact. "A lot of people are going to sit up and take notice, because this is by far the best cancer data set in the world."

 

Tiny amounts of DBP exist naturally in soil. But it's also concentrated in cigarette and coal smoke.

 

It might seem odd that you can learn about people from trout, but in both animals, DBP causes stomach and liver cancer by attacking and damaging DNA, tiny strings of molecules that contain cell-building information. People are good at repairing DNA, but trout have more difficulty. Like a canary in a coal mine, fish tend to get sick before people.

 

Rats and mice are canaries, too. Bailey points to two advantages of rainbow trout.

 

First, when trout are fed a healthy diet and treated well, they have an inherently lower cancer rate. Only one in a thousand trout would get stomach cancer, compared with the rat rate of one in 20. That's why trouts' cancer risk to DBP can be measured at low levels.

 

Then there's the matter of money for research. "We can do it at roughly 5 percent of the cost of doing the rodent study," Bailey says.

 

Since each carcinogen acts differently, the results of Bailey's study applies only to DBP. Some chemicals might generate a cancer response that is proportional to the exposure, in which case the EPA's method would accurately determine risk.

 

Bailey's OSU group is not proposing any specific regulations, but knows their finding should sharpen risk assessment. "We're not sure what the EPA will make of these results," Bailey says.

 

Bailey's past trout studies have also led to effective treatments. Aflatoxin is a carcinogen present on foods like grains and nuts. In the United States, aflatoxin levels are carefully checked, but in developing areas, like parts of China, the levels are so high that one in 10 men dies of liver cancer by age 45. In an OSU study with trout a decade ago, scientists discovered chlorophyllin, a derivative of the stuff that makes plants green, renders aflatoxin harmless. "It should work in all species, including humans," Bailey discovered, and went on to develop a small green chlorophyllin pill effective in human trials.

 

"We can reduce the cancer rate in those people for pennies a day, affecting millions of human lives, and this was discovered because of the rainbow trout," Bailey says.

 

OSU's trout expertise may even help make animal studies obsolete. As scientists learn more about the basic biology of cancer, rodents and fish can be replaced by experiments that don't require any animals. Animal rights organizations, such as the Humane Society, say the government should prioritize ending all animal research as alternative methods can be developed.

 

Bailey was first drawn to trout science by his passion for fishing in Berkeley in the 1960s, where he finished his doctoral work in less than four years. The trout followed him through positions in British Columbia and New Zealand before he landed at OSU in 1979, where he eventually took the reins of the program from Russ Sinnhuber, a pioneer in using trout to study human health.

 

The trout facility is not Bailey's only legacy. He helped bring the Linus Pauling Institute to OSU from Palo Alto, Calif., in 1996, and recruited the current director. LPI does groundbreaking research in the link between disease and diet.

 

Fish scientists have pretty big shoes to fill with Bailey's departure. As his OSU colleague Williams puts it, "He planted a lot of seeds, and was able to make them grow."

 

Now that the DBP study is complete, Bailey has decided to spend more time enjoying retirement, though he occasionally consults for OSU. He spends many of his days at his home in central Oregon, where he rebuilds old pickups with his grandkids, picks the banjo, and, yes, fishes a little now and then.

 

 

-- Chris Spitzer has a Ph.D. from the University of Washington in theoretical particle physics and is an intern at The Oregonian through the American Association for the Advancement of Science: 503-221-8272; [email protected]