3,6-Dihydroxyflavone regulates microRNA-34a through DNA methylation.

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.

• Authors: Xiaoli Peng, Hui Chang, Junli Chen, Qianyong Zhang, Xiaoping Yu, Mantian Mi
• Journal: BMC cancer (BMC Cancer) Vol. 17 Issue 1 Pg. 619 (Sep 05 2017) ISSN: 1471-2407 [Electronic] England
• PMID: 28870206 (Publication Type: Journal Article)

Chemical References

• 3,6-dihydroxyflavone
• Flavonoids
• MIRN34 microRNA, human
• MicroRNAs
• Proto-Oncogene Proteins
• RNA, Small Interfering
• Mixed Function Oxygenases
• TET1 protein, human
• DNA (Cytosine-5-)-Methyltransferase 1
• DNMT1 protein, human

Topics

• Animals
• Breast Neoplasms (genetics, metabolism, pathology)
• Cell Line, Tumor
• Cell Transformation, Neoplastic (genetics, metabolism)
• DNA (Cytosine-5-)-Methyltransferase 1 (genetics)
• DNA Methylation
• Female
• Flavonoids (pharmacology)
• Gene Expression Regulation, Neoplastic (drug effects)
• Humans
• Mice
• MicroRNAs (genetics)
• Mixed Function Oxygenases (genetics)
• Promoter Regions, Genetic
• Proto-Oncogene Proteins (genetics)
• RNA Interference
• RNA, Small Interfering (genetics)
• Rats