A Double-Negative Feedback Interaction between MicroRNA-29b and DNMT3A/3B Contributes to Ovarian Cancer Progression.

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. 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. 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. 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.

Teng Y ，Zuo X ，Hou M ，Zhang Y ，Li C ，Luo W ，Li X ... -  《-》

MicroRNA-29B (mir-29b) regulates the Warburg effect in ovarian cancer by targeting AKT2 and AKT3.

Teng Y ，Zhang Y ，Qu K ，Yang X ，Fu J ，Chen W ，Li X ... -  《Oncotarget》

Deregulation between miR-29b/c and DNMT3A is associated with epigenetic silencing of the CDH1 gene, affecting cell migration and invasion in gastric cancer.

Cui H ，Wang L ，Gong P ，Zhao C ，Zhang S ，Zhang K ，Zhou R ，Zhao Z ，Fan H ... -  《PLoS One》

Mir-29b Regulates Oxidative Stress by Targeting SIRT1 in Ovarian Cancer Cells.

Metabolic abnormalities are frequently observed in multiple malignancies including epithelial ovarian cancer (EOC), among which imbalance between generation and elimination of reactive oxygen species (ROS) plays a critical role in EOC onset and progression. Here we investigated the role of miR-29b, a well-established tumor-suppressor miRNA in metabolic regulation of EOC cells. cell viability and apoptosis in miR-29b inhibited and over-expressed EOC cells were evaluated by CCK8 and Annexin V-FITC/PI assays. Change in miR-29b was detected in EOC cells incubated in H2O2 culture by q-PCR. Relative ROS levels were also detected in different EOC cultures, including modified miR-29b and SIRT1 levels as well as H2O2 incubation. A luciferase reporter assay was employed to detect the direct binding of miR-29b to SIRT1 3' UTR. Changes in cell viability and ROS levels were assessed in SIRT1-knocked down EOC cells. miR-29b expression correlates with decreased EOC cell viability and increased apoptosis. H2O2 downregulated miR-29b in a time and dose-dependent manner. miR-29b expression negatively correlated with ROS levels, whereas SIRT1 significantly stimulated ROS formation. Luciferase reporter assays confirmed miR-29b downregulation of SIRT1by directly targeting its mRNA 3'-UTR. SIRT1 silencing rescues cell viability of H2O2 treated cells. Also, SIRT1 inhibition blocked cell apoptosis induced by H2O2 as well as reduced intracellular ROS levels. Together, our findings indicated that the miR-29b/SIRT1 axis has a protective effect against H2O2-induced damage of cell viability and oxidative stress and may provide novel options for miR-29b-based therapeutic approaches for EOC treatment.

Hou M ，Zuo X ，Li C ，Zhang Y ，Teng Y ... -  《-》

Double-negative feedback interaction between DNA methyltransferase 3A and microRNA-145 in the Warburg effect of ovarian cancer cells.

Ovarian cancer is the most lethal gynecological malignancy because of its poor prognosis. The Warburg effect is one of the key mechanisms mediating cancer progression. Molecules targeting the Warburg effect are therefore of significant therapeutic value for the treatment of cancers. Many microRNAs (miR) are dysregulated in cancers, and aberrant miR expression patterns have been suggested to correlate with the Warburg effect in cancer cells. In our study, we found that miR-145 negatively correlated with DNA methyltransferase (DNMT)3A expression at cellular/histological levels. miR-145 inhibited the Warburg effect by targeting HK2. Luciferase reporter assays confirmed that miR-145-mediated downregulation of DNMT3A occurred through direct targeting of its mRNA 3'-UTRs, whereas methylation-specific PCR (MSP) assays found that knockdown of DNMT3A increased mRNA level of miR-145 and decreased methylation levels of promoter regions in the miR-145 precursor gene, thus suggesting a crucial crosstalk between miR-145 and DNMT3A by a double-negative feedback loop. DNMT3A promoted the Warburg effect through miR-145. Coimmunoprecipitation assays confirmed no direct binding between DNMT3A and HK2. In conclusion, a feedback loop between miR-145 and DNMT3A is a potent signature for the Warburg effect in ovarian cancer, promising a potential target for improved anticancer treatment.

Zhang S ，Pei M ，Li Z ，Li H ，Liu Y ，Li J ... -  《-》