Chemoprevention of esophageal cancer with black raspberries, their component anthocyanins, and a major anthocyanin metabolite, protocatechuic acid
Menée sur des rats exposés à un agent cancérigène (la N-nitrosométhylbenzylamine), cette étude évalue l'effet chimiopréventif d'un extrait de framboise noire (Rubus occidentalis) riche en anthocyanines et de leur métabolite principal, l'acide protocatéchuique, sur la carcinogenèse de l'œsophage
Diets containing either freeze-dried black raspberries (BRB) or their polyphenolic anthocyanins (AC) have been shown to inhibit the development of N-nitrosomethylbenzylamine (NMBA)-induced esophageal cancer in rats. The present study was conducted to determine if PCA, a major microbial metabolite of BRB AC, also prevents NMBA-induced esophageal cancer in rats. F344 rats were injected with NMBA three times a week for five weeks and then fed control or experimental diets containing 6.1% BRB, an AC-rich fraction derived from BRB, or PCA. Animals were exsanguinated at weeks 15, 25, & 35 to quantify the development of preneoplastic lesions and tumors in the esophagus, and to relate this to the expression of inflammatory biomarkers. At weeks 15 & 25, all experimental diets were equally effective in reducing NMBA-induced esophageal tumorigenesis, as well as in reducing the expression of Pentraxin-3 (PTX3), a cytokine produced by peripheral blood mononuclear cells in response to IL-1β and TNF-α. All experimental diets were also active at reducing tumorigenesis at week 35; however, the BRB diet was significantly more effective than the AC & PCA diets. Further, all experimental diets inhibited inflammation in the esophagus via reducing biomarker (COX-2, iNOS, p-NF-κB, sEH) and cytokine (PTX3) expression. Overall, our data suggest that BRB, their component AC and PCA inhibit NMBA-induced esophageal tumorigenesis, at least in part, by their inhibitory effects on genes associated with inflammation.