Effects of non-digestible carbohydrates on the growth of estrogen-dependent human breast cancer (MCF-7) tumors implanted in ovariectomized athymic mice

Non-digestible carbohydrates (NDC(4)) have been used as a low-calorie sweetener and prebiotics that stimulate the growth of certain intestinal bacteria that support healthy colon conditions. In this study, we examined the dietary effect of commercially available NDCs on estrogen receptor positive (ER+) human breast cancer. We conducted a feeding study of fructooligosaccharides (FOSs), Fibersol 2 (F2; digestion resistant maltodextrin), Hi-Maize (HM; high amylose cornstarch), and Frutafit (FF; a range of powdered inulins) (5% in diet, w/w) to evaluate their effects on the growth of ER(+) human breast cancer (MCF-7) tumors in the presence of 17β-estradiol (E(2)) using an athymic xenograft model. F2, HM, and FOSs supplementation significantly reduced E(2)-stimulated MCF-7 tumor growth by inhibiting cellular proliferation (Ki-67) and increasing apoptosis (M30) in tumors. F2, HM, and FOSs treatments also lowered serum E(2) level and reduced uterine weight compared to the control diet. NDCs treatments downregulated relative mRNA expression of the E(2)-responsive gene markers pS2, bcl2, bcl-xL, and cyclin D1 in MCF-7 tumors. In conclusion, the NDC intake may have a protective effect against ER(+) tumors by inhibiting cellular proliferation and increasing apoptosis.