Black raspberry-derived anthocyanins demethylate tumor suppressor genes through the inhibition of DNMT1 and DNMT3B in colon cancer cells.
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.
Medical College of Wisconsin, Division of Hematology and Oncology, Department of Medicine, Milwaukee, Wisconsin 53226, USA. liswang@mcw.edu
Li-Shu
LS
Wang
Chieh-Ti
CT
Kuo
Seung-Ju
SJ
Cho
Claire
C
Seguin
Jibran
J
Siddiqui
Kristen
K
Stoner
Yu-I
YI
Weng
Tim H-M
TH
Huang
Jay
J
Tichelaar
Martha
M
Yearsley
Gary D
GD
Stoner
Yi-Wen
YW
Huang
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000872:Anthocyanins / Q000494:pharmacology*; D018938:Caco-2 Cells / Q000187:drug effects; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism*; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019175:DNA Methylation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005136:Eye Proteins / Q000235:genetics; D016147:Genes, Tumor Suppressor / Q000187:drug effects*; D019942:Genes, p16; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012097:Repressor Proteins / Q000235:genetics; D027824:Rosaceae / Q000737:chemistry*; D000097584:DNA Methyltransferase 3B; D000094742:Secreted Frizzled-Related Proteins
D048868:Adaptor Proteins, Signal Transducing; D000872:Anthocyanins; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D004791:Enzyme Inhibitors; D005136:Eye Proteins; D008565:Membrane Proteins; D012097:Repressor Proteins; D000097584:DNA Methyltransferase 3B; C109618:SFRP2 protein, human; D000094742:Secreted Frizzled-Related Proteins; C118511:SFRP5 protein, human; C485569:WIF1 protein, human; C000619380:DNMT1 protein, human; C000619381:Dnmt1 protein, mouse