In a first, scientists have found that strawberry extracts may help prevent the spread of aggressively growing breast cancer cells and reduce the size of tumours.

Researchers showed that strawberry extract can inhibit the spread of laboratory-grown breast cancer cells, even when they are inoculated in female mice to induce tumours. Past studies have shown that the ingestion of 500 grams of strawberries (between 10 and 15 strawberries) per day offers antioxidant and anti-inflammatory benefits and reduces blood cholesterol levels.

The new study presents promising results on the potential positive effects of the fruit to prevent or treat breast cancer.

"We have shown for the first time that strawberry extract, rich in phenolic compounds, inhibits the proliferation of breast cancer cells in in vitro and in vivo models," Maurizio Battino, from the Marche Polytechnic University in Italy.

The in vitro model used cells from the highly aggressive, invasive A17 tumour cell line, these were treated with different concentrations (between 0.5 and 5 milligram per millilitre) of extract of the Alba variety of strawberry, for periods of 24, 48 and 72 hours. This decreased cell viability (dependent on dosage and time), blocked the cycle leading to cell division and inhibited migration, researchers said.

It was also shown that strawberry extract reduced the expression of several genes involved in the processes of invasion and metastasis, such as Csf1, Mcam, Nr4a3 and Set.

The extract simultaneously stimulated expression of the gene Htatip2, which is thought to suppress metastasis to the lymphatic ganglion in breast cancer patients, researchers said.

The in vivo model used female laboratory mice, which at one month of age were divided into two groups: one was given a standard diet, while the other group was given an enriched diet, 15 per cent of which was strawberry extract. Another month later, all the mice were injected with A17 breast cancer cells.

The tumours were monitored twice weekly by palpation. After five weeks, the tumours were extracted and analysed to evaluate their weight and volume.

"We also saw a significant reduction in the weight and volume of the tumour," Battino said.

"The majority of diseases, including cancer, are complex and involve complex interactions between cellular and molecular systems that determine the development of the disease," he said.

"These results are without a doubt valid for understanding potential effects of strawberries on breast cancer and the molecular mechanisms involved, but they must be complemented with clinical and epidemiological studies to verify whether humans experience the same positive effects as we have observed in mice," Battino said.
The study was published in the journal Scientific Reports.