Clam Cancer Spreads Along Eastern Seaboard
MELISSA BLOCK, HOST:
The expression happy as a clam doesn't always apply to real clans. It turns out clams and other shellfish can get diseases, including cancer. And researchers studying cancer in soft shell clams think it can spread from one to the next in a very unusual way. NPR's Richard Harris reports.
RICHARD HARRIS, BYLINE: The first surprise in this story is that soft shell clams can actually get leukemia, a cancer of the blood.
STEPHEN GOFF: But the fact is they have a circulatory system, and they can get leukemia.
HARRIS: Stephen Goff, a Howard Hughes investigator at Columbia University, says this poses no risk to people who eat clams, like the soft shell clams that are harvested along the Eastern Seaboard.
GOFF: I love them. They're what you get as fried claims and steamers - very popular in New England.
HARRIS: But Goff's relationship with clams has just changed dramatically. He usually studies viruses that cause cancer in mice, and he was contacted by a scientist studying leukemia in soft shell clams.
GOFF: She was curious to know whether there might be a virus involved.
HARRIS: And did you find a virus?
GOFF: So we didn't.
HARRIS: Goff and his colleagues don't think a virus is actually spreading the disease. Instead, what he discovered came as a big surprise. The clam cancers all shared a very similar genetic fingerprint - one distinct from the sick clams themselves. So he concludes that clones of this rogue cell are responsible for spreading cancer from one clam to the next.
GOFF: We know the cells can survive in seawater quite long, and we can only guess that they would be picked up somehow by another healthy clam. We do know that these are filter feeders. They filter enormous volumes of seawater. So maybe they just pick up one cell. If it's an aggressive tumor with the capability, it can somehow transmit the leukemia to it.
HARRIS: There are only two other cancers known to be spread by cells like this. One is devastating populations of Tasmanian devils, meat-eating marsupials in Australia. Another is spread sexually in dogs. Goff thinks this might be the third example. It opens up a host of questions about how diseases might spread through the marine environment, and it might have implications for human health as well.
GOFF: Learning how these cells are evolving, learning how they manage to spread, will be very interesting. I think it could inform our understanding of how metastasis occurs.
MICHAEL LESSER: It's very clear that something unusual is going on here.
HARRIS: Michael Lesser is a marine biologist at the University of New Hampshire, and he's fascinated by the paper that Goff and his colleagues just published in the journal Cell. But he says this isn't an open and shut case. Nobody has yet done the critical lab experiment to show that this cell-based transmission actually occurs.
LESSER: There's a lot of steps from just feeding on the cells in the environment that have to occur in the clam as well in order for this to be a definitive or a realized mechanism for transmission.
HARRIS: Lesser says no question, people who study these clams are eager to jump on it and see whether they can prove this is actually happening. Stephen Goff says however this turns out, it's surprises like this that can really move science forward.
GOFF: I'm a big fan of the idea that when something really intriguing comes along, it's great to follow your lead and see where this is going to take you.
HARRIS: His next step is to look for signs of spreading cancer cells in other shellfish, like cockles and mussels. Richard Harris, NPR News. Transcript provided by NPR, Copyright NPR.