This topic was of great interest at the seminar for ageing at the conference "Functional genomics and disease" taking place in Oslo, Norway. Thomas Kirkwood is the director of the internationally recognised Institute of Ageing and Health (IAH).

Developmentally it has been more important for humans to invest energy in reproduction and not in maintenance or repair of the body over time.

But genetic factors do exist. "Approximately 25 percent of how a person ages is inherited from parents," says Kirkwood. "Stress, environment, nutrition, lifestyle and immunity play an additional role. Great variation between individuals can be seen in organisms such as round worms - and in humans."

Studies of ageing also give insight into the causes of cancer, because cancer and ageing have the same background causes, thinks Vilhelm Bohr, professor at the University of Baltimore in the United States.

"Cancer is more frequent with age. We must understand the causes of ageing to be able to understand why we have cancer," points out Bohr during his presentation at the conference.

Kirkwood's paper was presented at the "Functional genomics and disease" conference - Genetics Conference, Oslo, Norway, University of Oslo and European Science Foundation (ESF).

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Snail was first identified in fruit flies and later in mice based on its essential role in embryogenesis during a developmental transition in which normal cells undergo a similar change in shape. "Snail controls a complex set of cellular functions that cancer cells appropriate by turning on this master regulatory gene," explains Chodosh.

To prove a cause-and-effect, the researchers added Snail back to the original tumor cells in mice and showed that Snail increased the rate of recurrence.

But could Snail expression play a similar role in women with breast cancer? When the Penn team delved into public databases of breast cancer tissue data, separating cases into those with high levels of Snail and those with low levels of Snail, they found that women whose original breast cancers expressed high levels of Snail were twice as likely to experience a recurrence within five years following surgery compared to women whose cancers expressed low levels of Snail.

The magnitude of risk associated with high Snail expression is comparable to standard prognostic factors such as estrogen-receptor status, HER-2/Neu amplification, tumor size and grade, and lymph node status and - after correcting for the effects of these factors - Snail expression was shown to predict a woman's risk of recurrence independent of these factors.

Currently, Chodosh and colleagues are exploring the precise molecular mechanism by which Snail triggers breast cancer recurrence, as well as ways of targeting Snail's signaling pathways as a possible therapeutic approach to prevent recurrence.

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