October 27th, 2009

Did you know that an (ugly) rodent called the naked mole rat is teaching us a lot about cancer prevention?

Reports the New York Times:

They live in underground colonies with a queen, her harem of favorite males, soldiers to defend the tunnel system and workers to keep excavating in search of food. But despite having the social structure of an ants’ nest or beehive, naked mole rats are mammals about the size of a mouse. And among their many peculiarities are features that could, if understood, be of great relevance to human health and longevity.

Their life span is of extraordinary length for a rodent. Mice live a couple of years but mole rats can reach the venerable age of 28. The long life is probably a consequence of their protected existence. Mice have a short life span because they have many predators. Better to breed fast and young than prepare for an old age none will never live to see. Gray squirrels, on the other hand, have fewer enemies and can live for more than 20 years.

…

Mice are very prone to cancer; in some strains, 90 percent of them die of tumors. People have stronger defenses against cancer, as is necessary for a long-lived animal: the disease accounts for 23 percent of human mortality. But the mole rat has taken its anticancer defenses even further: it seems not to get the disease at all. “These animals have never been observed to develop any spontaneous neoplasms,” Vera Gorbunova and colleagues said in an article in the current Proceedings of the National Academy of Sciences.

Dr. Gorbunova, who works at the University of Rochester, has taken a first step toward understanding the genetic basis of the mole rat’s surprising immunity to cancer. She and her colleagues have found that the rats’ cells have a double system for inhibiting irregular proliferation, compared with the single system in human cells.

Normal human cells grown in a lab dish show behavior known as contact inhibition. Once the cells come in contact with one another, they form a single layer and stop dividing. Cancer cells, however, have thrown off that restraint and keep proliferating, forming one layer on top of another.

Dr. Gorbunova has found that both mole rat and human cells have the same system of contact inhibition, mediated in both species by a gene known as p27. But mole rats, in addition, have an early acting version of the same system and presumably use the p27 system just as a backup.

Find out more at the NYT.