Black Raspberry-Derived Anthocyanins Demethylate Tumor Suppressor Genes Through the Inhibition of DNMT1 and DNMT3B in Colon Cancer Cells

Abstract

We previously reported that oral administration of black raspberry powder decreased promoter methylation of tumor suppressor genes in tumors from patients with colorectal cancer. The anthocyanins (ACs) in black raspberries are responsible, at least in part, for their cancer-inhibitory effects. In the present study, we asked if ACs are responsible for the demethylation effects observed in colorectal cancers. Three days of treatment of ACs at 0.5, 5, and 25 μg/ml suppressed activity and protein expression of DNMT1 and DNMT3B in HCT116, Caco2 and SW480 cells. Promoters of CDKN2A, and SFRP2, SFRP5, and WIF1, upstream of Wnt pathway, were demethylated by ACs. mRNA expression of some of these genes was increased. mRNA expression of β-catenin and c-Myc, downstream of Wnt pathway, and cell proliferation were decreased; apoptosis was increased. ACs were taken up into HCT116 cells and were differentially localized with DNMT1 and DNMT3B in the same cells visualized using confocal laser scanning microscopy. Although it was reported that DNMT3B is regulated by c-Myc in mouse lymphoma, DNMT3B did not bind with c-Myc in HCT116 cells. In conclusion, our results suggest that ACs are responsible, at least in part, for the demethylation effects of whole black raspberries in colorectal cancers.

Anthocyanins Prevent Colorectal Cancer Development in a Mouse Model

“…Anthocyanins were also able to inhibit cell growth and are an inducer of cell apoptosis in colon cancer cells by modulating DNA damage [22][23][24] , inducing a cell cycle arrest [12,25] or are responsible for demethylation of tumour suppressor genes [26] .…”

The effect of diet on the intestinal epigenome

“…In recent studies with animal models, the same group has confirmed that dietary supplementation with black raspberries inhibits colorectal carcinogenesis by partial reactivation of epigenetically silenced Wnt regulatory genes [84,85]. They have also convincingly demonstrated that the anthocyanins, a group of polyphenols present in large quantities in black raspberries, are at least in part responsible for these effects [86].…”

Whole Plant Foods and Colon Cancer Risk

“…Further evidence from studies with CRC patients suggests that consumption of black raspberries decreases proliferation markers in colon tissue, demethylates tumor suppressor genes and modulates other biomarkers of tumor development in the human colon and rectum 96 and beneficially modulate inflammatory markers such as IL-8 97 and that these effects may be mediated by inhibition of DNA methyltransferase 1 (DNMT1). 98 …”