Their work adds to earlier evidence showing the cancer-fighting potential of a number of different flavonoids, including apigenin.
And taken together, these studies could help explain why fruit and vegetable consumption has been associated with lower risk of prostate and other cancers in epidemiological studies.
For the new study, Dr Sanjay Gupta, an assistant professor in urology at Case Western Reserve University, and colleagues orally fed doses of 20mcg and 50mcg apigenin to mice daily two weeks before implanting a prostate tumour and then continued to feed the compound for eight weeks.
In a second protocol, apigenin was fed to mice two weeks after tumour implantation.
The first protocol mimicked prevention regimens, while the second followed therapeutic regimens for cancer.
Writing in the October online issue of the Federation of American Societies for Experimental Biology journal (doi:10.1096/fj.05-3740fje), the researchers say the apigenin slowed tumour growth in both cases and did not appear to cause any adverse side effects such as weight gain or changes in diet. These are common in patients who undergo chemotherapy treatments.
Apigenin also resulted in a decrease in levels of IGF-1 (insulin-like growth factor), which are associated with higher risk of breast, prostate, colorectal and lung cancers.
In addition, the researchers report a significant increase in IGFBP-3 (insulin-like growth factor binding protein) levels, associated with a decreased risk for these same cancers.
The effect impacts the survival of prostate cancer by triggering cell self-destruction.
"Apigenin may prove useful in the prevention and therapy of prostate cancer by shutting off the IGF signalling that leads to prostate cancer cell growth and/or development," Gupta said.
Apigenin is found in a variety of foods including apples, beans, broccoli, celery, cherries, grapes, leeks, onions, parsley and tomatoes, as well as plant-derived beverages like tea and wine.
The authors noted that it has already been shown to lower inflammation and oxidative stress, "and exerts growth inhibitory effects on cancer cells".
However, the mechanisms underlying these effects had not been well understood.
"This study presents the first evidence that the in vitro and in vivo growth inhibitory effects of apigenin involve modulation of IGF-axis signalling in prostate cancer," the authors write.
The next step for Gupta's team will be to evaluate apigenin action on other molecular pathways involved in prostate cancer.
The disease is a key target for research as it is the second most common cancer in men after lung cancer. It 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).