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This is the VOA Special English Science Report.

A new study suggests that a protein that protects animals from cancer early in life may later cause extreme aging. The protein is called p-fifty-three.

Scientists say p-fifty-three also helps prevent cancer in humans. It probably does this by halting growth or killing damaged cells that might develop into tumors. However, recent research on mice also shows that increased activity by the protein ages the animals later in life. It stops the natural renewal of their tissue and organs. The study also showed that p-fifty-three caused other effects of aging.

Too much p53?

Scientists at the Baylor College of Medicine in Houston, Texas, reported their work in the publication "Nature." Lawrence Donehower led a team that studied normal mice. The team also studied mice that were accidentally created with unusually large amounts of p-fifty-three in their cells.

The scientists observed that the mice with extra p-fifty-three aged sooner than normal. Their bones became weak. Their muscles and organs became smaller. They lost weight. They lost some of their hair. However, these mice did not develop cancerous tumors. By comparison, forty-five percent of the normal animals developed tumors. Still, the normal mice lived an average twenty percent longer than the ones with extra p-fifty-three.

"Nature" magazine published the comments of two independent experts about the results of the Baylor team research.

The experts said the study may mean that aging may be a product of the body's natural protection against cancer. The study has special importance for scientists trying to develop medicines to treat the effects of aging. The research raises the question if such treatments that suppress the p-fifty-three gene could make a person more likely to get cancer.

The study results also may be important for young cancer patients treated with chemotherapy. These chemical treatments help suppress tumors. They do this by attacking some of the genetic material in the body's cells. However, the process may increase the activity of the p-fifty-three protein. This might threaten recovered cancer patients with aging sooner than normal. These young people might develop age-related health problems before their time.

This VOA Special English Science Report was written by Jerilyn Watson.