Tadpole Study Shows 'Destructive Oxygen Molecules' Could Help Cancer Recovery

A study of tadpoles suggests that destructive molecules linked to ageing and cancer could play an important role in healing.

Scientists investigating how tadpoles regrow severed tails found an unexpected link to oxygen molecules normally considered highly harmful to health.

Without the molecules, known as reactive oxygen species (ROS), the tails would not regenerate.

Reactive oxygen molecules damage DNA and cell membranes and are associated with heart disease, cancer, and ageing.

Millions of people take antioxidant supplements to combat their effects. Health advice also encourages people to increase their consumption of antioxidant-rich fruits and vegetables.

But the new research suggests that ROS may have a previously unknown beneficial role in the healing process.

A number of animals, especially amphibians such as frogs and salamanders, have regenerative powers not shared by mammals.

If a tadpole loses its tail, it will grow a new one within a week.

Scientists know that regeneration of body parts involves a genetic pathway called Wnt, but many aspects of it remain a mystery.

Unravelling the secrets of tadpole regeneration could on one day lead to new healing treatments.

Researchers at the University of Manchester found that several metabolic genes were activated during tail regeneration in tadpoles. They included those involved in the production of ROS, in particular the powerfully destructive molecule hydrogen peroxide.

A marked increase in hydrogen peroxide levels occurred after tadpole tails were docked which remained throughout the regeneration process.

Lead scientist Professor Enrique Amaya, whose findings appear in the journal Nature Cell Biology, said: "When we decreased ROS levels, tissue growth and regeneration failed to occur.

"Our research suggests that ROS are essential to initiate and sustain the regeneration response. We also found that ROS production is essential to activate Wnt signalling, which has been implicated in essentially every studied regeneration system, including those found in humans. It was also striking that our study showed that antioxidants had such a negative impact on tissue regrowth, as we are often told that antioxidants should be beneficial to health."

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The study follows controversial claims by Dr James Watson, co-discoverer of the structure of DNA, that antioxidants may be harmful to people with late-stage cancer.

Writing in the journal Open Biology, he said reactive oxygen species help clear dysfunctional and dangerous cells from the body. Antioxidants may hinder cancer recovery by blocking their effect, he argued.

Professor Amaya added: "It's very interesting that two papers suggesting that antioxidants may not always be beneficial have been published recently.

"Our findings and those of others are leading to a reversal in our thinking about the relative beneficial versus harmful effects that oxidants and antioxidants may have on human health, and indeed that oxidants, such as ROS, may play some important beneficial roles in healing and regeneration."

The team at the University of Manchester's Healing Foundation Centre now plans to study the role of ROS in healing and regeneration more closely.

Manipulating reactive oxygen species may improve the body's ability to heal and regenerate itself, the scientists believe.

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