Lung cancer inhibitory activity of dietary berries and berry polyphenolics

Abstract

BACKGROUND: Blueberry (BB) and black raspberry (BRB) have been shown to be chemopreventive against estrogen-mediated breast cancer in pre-clinical studies. However, therapeutic efficacy of these berries against lung cancer is not known. METHODS: In this study we investigated i) relative efficacy of individual anthocyanidins vs. respective anthocyanins, ii) relative antiproliferative activity of mixture of anthocyanidins compared to individual anthocyanidins, iii) antitumor activity of dietary BB, iv) Tumor inhibitory activity of diet supplemented with BB, alone and in combination with BRB, against lung tumor xenograft using nude mice, and finally, v) the efficacy of select polyphenolics present in BB and BRB against lung tumor xenograft. RESULTS: Our findings indicated that individual anthocyanidins (aglycones) were significantly more potent (2-3 fold lower IC50) in inhibiting the non-small-cell lung cancer (NSCLC) cell growth vs. respective anthocyanins (glycones). Further, anthocyanidins mixture at equimolar concentrations exhibited synergistic antiproliferative activity vs. individual anthocyanidins. When tested against NSCLC (A549 and H1299) cells in nude mice, dietary BB (7.5, w/w) showed >40 reduction in tumor volume against H1299 xenografts. The maximal growth inhibition occurred with 5 BB dose, with no additional protection occurring at a higher dose (7.5). However, somewhat lower protection was found when the BB diet initiated prior to tumor cell inoculation. The mixture of BB (5, w/w) and BRB (2.5) resulted in higher inhibition of tumor growth vs. BB alone (71 vs 42). Likewise, a combination of delphinidin (bioactive of BB) and punicalagins (a bioactive of BRB, which gets converted to ellagic acid in vivo) showed higher tumor growth inhibition compared to delphinidin. CONCLUSIONS: The therapeutic effects of the berries and berry polyphenolics observed against lung cancer in this study are highly encouraging. Further investigation into the mechanism of action of the combinations of the berry bioactives will be valuable for clinical use of this potent natural product against lung cancer.