Anthocyanin-rich extracts from black raspberries inhibit growth promoting and anti-apoptotic signaling pathways in human bladder carcinoma cell lines

Abstract

Epidemiologic and laboratory data suggest that diets rich in fruits and vegetables are associated with a reduced risk of bladder cancer. It has been proposed that anthocyanin pigments, the most abundant phenolic compounds in fruits and vegetables, contribute to this chemopreventive activity. We examined the effect of black raspberry (BR) phenolics on cell proliferation of two phenotypically diverse human cancer cell lines isolated from patients with different stages and grades of transitional cell carcinoma. Anthocyanins were extracted from lyophilized black raspberry and the amounts and composition determined by pH differential spectrophotometric analysis and high pressure liquid chromatography with photo diode array and mass spectrometry detectors. Extraction with 70% acetone followed by partitioning with chloroform yielded 120 mg cyanidin 3-glucoside equivalents/100 g BR powder, whereas yield after extraction with warm acidified water (50 °C, 0.26 M formic acid) was 25% less. The anthocyanin profile was cyanidin-3-rutinoside (56%), cyanidin-3-glucoside/ cyanidin-3-xylosrutinoside (30-33%) and cyanidin-3-sambubioside (10-13%). Initial studies with poorly differentiated bladder cancer cell lines show that 48h exposure to 200 µg anthocyanin equivalents/ml media inhibits growth by 63%. AKT and ERK signaling pathways participate in aberrant cell proliferation and migration. J82 cells were exposed to the BR anthocyanin-rich fraction and activated or phosphorylated AKT and ERK were assessed. Exposure of these cells to BR anthocyanin-rich fraction was associated with decreased phosphorylation of AKT (P- 473Ser) and ERK without alteration in total AKT and ERK levels. These data suggest that the BR anthocyanin-rich fraction can modulate key signaling pathways associated with cellular proliferation.