Their study is the latest in a line of studies to be published on the health benefits of this fruit, originally native to the Middle East.
Much of the recent focus has been on heart health properties but already by 2001, the Technion-Israel Institute of Technology had reported that pomegranate seed oil triggered apoptosis in breast cancer cells.
University of Wisconsin researchers have also shown that the antioxidant-rich pomegranate is effective against tumours in mouse skin.
In the new trial, a team from the same institute found that an extract of the fruit had a dose-dependant effect on human prostate cancer cells cultured in laboratory dishes.
Dr Hasan Mukhtar and his colleagues note in yesterday's Proceedings of the National Academy of Sciences Early Edition that pomegranates are high in polyphenolic compounds, making its juice higher in antioxidant activity than red wine and green tea.
In further tests, the scientists used 24 mice that had been injected with prostate cancer cells from humans and developed malignancies. A control group received normal drinking water, while animals in second and third groups had their drinking water supplemented with 0.1 per cent and 0.2 per cent pomegranate extract respectively.
The doses were designed to be similar to those that a human might get from drinking juice of the fruit on a daily basis.
The study showed that mice receiving the higher concentration of pomegranate extract had significant slowing of their cancer progression and a decrease in the levels of prostate-specific antigen (PSA), a marker used to indicate the presence of prostate cancer in humans.
The animals that received only water had tumours that grew much faster than those in the animals treated with pomegranate extract.
"Our study - while early - adds to growing evidence that pomegranates contain very powerful agents against cancer, particularly prostate cancer," said lead author Dr Hasan Mukhtar, professor of dermatology in the UW Medical School.
"There is good reason now to test this fruit in humans - both for cancer prevention and for treatment," he added.
Prostate cancer is the second most common cancer in men after lung cancer, and accounted for 15 per cent of cancers in men in the European Union during 2004 and 238,000 new cases, according to the International Agency for Research on Cancer (IARC).
Although the fruit needs to be assessed for its potential to prevent cancer in humans, recent figures from retailers in the UK suggest that pomegranate juice is already becoming popular.
The UK's leading retailer Tesco said recently that sales of pomegranate juice are up 300 per cent since the start of the year, and it is now selling close to 500,000 litres per week.