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.