Black Raspberries Protectively Regulate Methylation of Wnt Pathway Genes in Precancerous Colon Tissue
CANCER PREVENTION RESEARCH
Authors: Wang, Li-Shu; Kuo, Chieh-Ti; Huang, Tim H. -M.; Yearsley, Martha; Oshima, Kiyoko; Stoner, Gary D.; Yu, Jianhua; Lechner, John F.; Huang, Yi-Wen
Abstract
Ulcerative colitis is frequently an intermediate step to colon cancer. The interleukin-10 knockout mouse is a genetic model of this progression. We report that knockout mice fed 5% black raspberries (BRB) had significantly less colonic ulceration as compared with knockout mice that consumed the control diet. Dysfunction of the Wnt signaling pathway is a key event in ulcerative colitis-associated colon carcinogenesis. Therefore, we investigated the effects of BRBs on the Wnt pathway and found that the BRB-fed knockout mice exhibited a significantly lower level of beta-catenin nuclear translocation. We followed-up this observation by evaluating the effect of BRBs on selected Wnt pathway antagonists. The mRNA expression levels of wif1, sox17, and qki were diminished in the knockout mice, whereas they were expressed at normal levels in knockout mice that were fed BRBs. The lower mRNA expression of these genes in the colon from the knockout mice correlated with hypermethylation of their promoter regions; BRBs decreased their promoter methylation and increased mRNA expression of these genes. This hypomethylation was associated with elevated protein expression of key proteins/enzymes that augment methylation, for example, dnmt3b, hdac1, hdac2, and mbd2 in the knockout mice; in addition, BRBs decreased the protein expression of these proteins/enzymes. The knockout mouse model recapitulates what occurs in human ulcerative colitis. Promoter methylation of CDH1 and SFRP1 was significantly higher in human ulcerative colitis tissues compared with their adjacent normal tissues. In conclusion, our results suggest that BRBs inhibit colonic ulceration and, ultimately, colon cancer partly through inhibiting aberrant epigenetic events that dysregulate Wnt signaling. (C) 2013 AACR.
miR-590-3p promotes colon cancer cell proliferation via Wnt/beta-catenin signaling pathway by inhibiting WIF1 and DKK1
EUROPEAN REVIEW FOR MEDICAL AND PHARMACOLOGICAL SCIENCES
Authors: Feng, Z. -Y.; Xu, X. -H.; Cen, D. -Z.; Luo, C. -Y.; Wu, S. -B.
Abstract
OBJECTIVE: Colon cancer is one of the most common and deadly types of gastrointestinal tumor. Despite progressive treatments, the patient prognosis has not been improved effectively. MATERIALS AND METHODS: Expression of miRNA and mRNA were tested by Realtime PCR. Cell cycle was detected by flow cytometry. Cell viability was evaluated by MTT assay. Cell spheroid formation was determined by colony assay. Wnt signaling pathway activity was evaluated by TOP/FOP ratio. Protein expression was tested using Western blot. beta-catenin binding ability was detected by ChIP assay. miRNA target gene was confirmed by luciferase assay. RESULTS: miR-590-3p was found to be over-expressed in both glioma tissues and cell lines. miR-590-3p is upregulated in colon cancer cells and tissues compared to non-tumorigenic colon cells and normal colon tissues. miR-590-3p positively regulated cell proliferation, spheroid formation, and cell cycle in LS174T cells. Conversely, inhibition of miR-590-3p reduced these effects. We confirmed that WIF1 and DKK1 are targets of miR-590-3p. Overexpression of miR-5903p promoted TOP flash luciferase activity, enhanced nuclear beta-catenin levels and increased target genes expression of Wnt signaling pathway. The results indicated that miR-590-3p activates the Wnt/beta-catenin signaling pathway. CONCLUSIONS: We demonstrate that miR590-3p regulates colon cancer progression via WIF1 and DKK1, which suggests that miR-5903p may be a promising candidate for therapeutic applications in colon cancer treatment.