A Double-Negative Feedback Interaction between MicroRNA-29b and DNMT3A/3B Contributes to Ovarian Cancer Progression.
BACKGROUND
Epigenetic abnormalities are increasingly observed in multiple malignancies, including epithelial ovarian cancer (EOC), and their effects can be significantly counteracted by tumor-suppressor microRNAs, namely epi-miRNAs. Here, we investigated the role of miR-29b, a well-established epi-miRNA, in the DNA methylation regulation of EOC cells.


METHODS
The correlation between miR-29b and DNMT3A/3B expression was evaluated by RT-qPCR, western blotting and immunohistochemical analysis. The functional roles of miR-29b and DNMT3A/3B were tested by anti-miRs and microRNA precursors. A luciferase reporter assay was employed to detect the direct binding of miR-29b to DNMT3A/3B 3' UTRs. Co-IP was utilized for investigating Id-1 binding activity.


RESULTS
miR-29b was negatively correlated with DNMT3A/3B expression at the cellular/histological levels. miR-29b silencing was correlated with increased DNMT3A/3B levels, whereasmiR-29b over-expression caused DNMT3A/3B down-regulation. Luciferase reporter assays confirmed that the miR-29b-mediated downregulation of DNMT3A/3Boccurred through the direct targeting of theirmRNAs'3'-UTRs,whereasBGS assays found that DNMT3A/3B knockdown increased miR-29b expression via CpG island promoter hypomethylation, thus suggesting a crucial crosstalk betweenmiR-29b and DNMT3A/3B via a double-negative feedback loop. Co-IP assay confirmed direct binding between DNMT3A and Id-1.


CONCLUSIONS
Taken together, our study sheds light on a novel epigenetic circuitry regulating EOC progression and may provide novel options for miR-29b-based epi-therapeutic approaches for future EOC treatment.
Department of Obstetrics and Gynecology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an Jiaotong University, Xi'an, China.
Yue
Y
Teng
Xiaohang
X
Zuo
Meng
M
Hou
Yan
Y
Zhang
Chen
C
Li
Wenjuan
W
Luo
Xu
X
Li
D001483:Base Sequence; D000077216:Carcinoma, Ovarian Epithelial; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D019175:DNA Methylation / Q000235:genetics; D000090205:DNA Methyltransferase 3A; D018450:Disease Progression; D025461:Feedback, Physiological; D005260:Female; D006801:Humans; D051798:Inhibitor of Differentiation Protein 1 / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009375:Neoplasms, Glandular and Epithelial / Q000235:genetics / Q000473:pathology; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology*; D000097584:DNA Methyltransferase 3B
D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D051798:Inhibitor of Differentiation Protein 1; D035683:MicroRNAs; D000097584:DNA Methyltransferase 3B; C000717967:DNMT3A protein, human; C497453:ID1 protein, human; C532045:MIRN29a microRNA, human