miR-603 targeted hexokinase-2 to inhibit the malignancy of ovarian cancer cells

The Warburg effect, characterized by energy production through a high rate of aerobic glycolysis, is a metabolic hallmark of cancer cells. We previously found that ginsenoside 20(S)-Rg3 upregulated miR-603 and impaired the malignancy of ovarian cancer cells by inhibiting the Warburg effect. However, the precise functional role of miR603 in ovarian cancer progression remains poorly defined. Here, we report that the level of miR-603 in ovarian cancer tissues is significantly lower than that in para-tumor tissues. Overexpression of miR-603 in ovarian cancer cells inhibits the Warburg effect as evidenced by a decrease in glucose consumption, lactate production and hexokinase-2 (HK2) expression, reduces cell proliferation in vitro, and weakens their migration and invasion. Further, miR-603 directly targets HK2 as indicated in a luciferase reporter assay. In contrast to agomiR-NC, agomiR-603 treatment significantly inhibits tumor growth in vivo and the Warburg effect, which is illustrated by a decreased uptake of F-18-FDG in subcutaneous xenografts and HK2 downregulation. Finally, miR-603 is negatively regulated by DNMT3A-mediated DNA methylation in the promoter region of its precursor gene, suggesting that 20(S)-Rg3 antagonizes DNMT3A-mediated DNA methylation to impair growth, migration and invasion of ovarian cancer cells. In conclusion, miR-603 is a tumor suppressor targeting HK2 in ovarian cancer and its low level may result from DNMT3A-mediated methylation.