Decitabine regulates the expression and mechanism of miR-1301-3p in breast cancer cells through DNA methylation
OBJECTIVE To explore the DNA methylation status of miR-1301-3p induced by decitabine(DAC)to eluci-date the regulatory mechanism of lowered expression of miR-1301-3p in breast cancer.METHODS Bioinformatic software was utilized for predicting the methylation island of miR-1301-3p promoter region.And methylation-specific polymerase chain reaction(PCR)(MSP)was employed for detecting the methylation level of miR-1301-3p promoter region.The effects of DAC on the methylation and expression of miR-1301-3p promoter were detected by MSP and quantitative real-time PCR(qRT-PCR).sh-DNMT3B was transfected into breast cancer cells.The effect of DNMT3B on the expression of miR-1301-3p was detected by qRT-PCR.The effects of sh-DNMT3B and miR-1301-3p inhibitor on the proliferation of breast cancer cells were detected by methylthiazolyldiphenyl tetrazolium(MTT)assay.RESULTS There were methylation islands in promoter region of miR-1301-3p.The methylation level of promoter region of miR-1301-3p in breast cancer cells was higher than that in normal breast epi-thelial cells.After DAC treatment of MDA-MB-231 and MCF7 for 48 h,methylation level in promoter region of miR-1301-3p declined markedly in breast cancer cells and the expression of miR-1301-3p gene was significantly up-regulated.Silencing DNMT3B could promote the expression of miR-1301-3p and arrest the proliferation of breast cancer cells.Co-transfection of miR-1301-3p inhibitor and sh-DNMT3B reversed the inhibitory effect of sh-DNMT3B on the proliferation of breast cancer cells.CONCLUSION The hypermethylation of miR-1301-3p site leads to a down-regulation of miR-1301-3p in breast cancer cells.DAC may lower the methylation level of miR-1301-3p promoter region and activate its expression by blunting the expression of DNMT3B,thus suppressing the proliferation of breast cancer cells.
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