1. 3,6-Dihydroxyflavone regulates microRNA-34a through DNA methylation.
- Author
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Peng X, Chang H, Chen J, Zhang Q, Yu X, and Mi M
- Subjects
- Animals, Breast Neoplasms genetics, Breast Neoplasms metabolism, Breast Neoplasms pathology, Cell Line, Tumor, Cell Transformation, Neoplastic genetics, Cell Transformation, Neoplastic metabolism, DNA (Cytosine-5-)-Methyltransferase 1 genetics, Female, Humans, Mice, Mixed Function Oxygenases genetics, Promoter Regions, Genetic, Proto-Oncogene Proteins genetics, RNA Interference, RNA, Small Interfering genetics, Rats, DNA Methylation, Flavonoids pharmacology, Gene Expression Regulation, Neoplastic drug effects, MicroRNAs genetics
- Abstract
Background: Breast cancer is the common cancer in China. In previous study, we determined that 3,6-dihydroxyflavone (3,6-DHF) increases miR-34a significantly in breast carcinogenesis, but the mechanism remains unclear., Methods: We used qRT-PCR to analyze miR-34a and ten-eleven translocation (TET)1, TET2, TET3 levels in breast cancer cells. With a cellular breast carcinogenesis model and an experimental model of carcinogenesis in rats, TET1 levels were evaluated by western blot analysis and immunofluorescence. TET1 and 5hmC (5-hydroxymethylcytosine) levels were evaluated by immunofluorescence in nude mouse xenografts of MDA-MB-231 cells. Chromatin immunoprecipitation(ChIP) assayed for TET1 on the TET1 promoter, and dot blot analysis of DNA 5hmC was performed in MDA-MB-231 cells. We evaluated the mechanism of 3,6-DHF on the expression of tumor suppressor miR-34a by transfecting them with DNA methyltransferase (DNMT)1 plasmid and TET1 siRNA in breast cancer cells. Methylation-specific PCR detected methylation of the miR-34a promoter., Results: First, we found that 3,6-DHF promotes the expression of TET1 during carcinogen-induced breast carcinogenesis in MCF10A cells and in rats. 3,6-DHF also increased TET1 and 5hmC levels in MDA-MB-231 cells. Further study indicated that TET1 siRNA and pcDNA3/Myc-DNMT1 inhibited the 3,6-DHF reactivation effect on expression of miR-34a in breast cancer cells. Methylation-specific PCR assays indicated that TET1 siRNA and pcDNA3/Myc-DNMT1 inhibit the effect of 3,6-DHF on the demethylation of the miR-34a promoter., Conclusions: Our study showed that 3,6-DHF effectively increases TET1 expression by inhibiting DNMT1 and DNA hypermethylation, and consequently up-regulates miR-34a in breast carcinogenesis.
- Published
- 2017
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