Aims
The Warburg effect is one of the main metabolic features for cancers, with long non-coding RNA (lncRNA) being involved as a class of crucial regulators. Our previous studies have shown that ginsenoside 20(S)-Rg3, an active saponin monomer extracted from red ginseng, inhibits the Warburg effect in ovarian cancer cells. However, the detailed lncRNA regulatory network modulated by 20(S)-Rg3 to prevent the Warburg effect in ovarian cancer cells has not been explored.
Background/aims
The Warburg effect is one of the main metabolic features for cancers, with long non-coding RNA (lncRNA) being involved as a class of crucial regulators. Our previous studies have shown that ginsenoside 20(S)-Rg3, an active saponin monomer extracted from red ginseng, inhibits the Warburg effect in ovarian cancer cells. However, the detailed lncRNA regulatory network modulated by 20(S)-Rg3 to prevent the Warburg effect in ovarian cancer cells has not been explored.
Conclusion
Our study revealed that 20(S)-Rg3 blocked the competitive inhibition of H19 on miR-324-5p, which enhanced the suppression of miR-324-5p on PKM2 and therefore inhibited the Warburg effect and repressed tumorigenesis. In a word, 20(S)-Rg3 inhibited the Warburg effect in ovarian cancer cells via H19/miR-324-5p/PKM2 pathway.
Methods
High-throughput sequencing was used to screen out the differentially expressed lncRNAs between 20(S)-Rg3-treated and non-treated SKOV3 cells. The levels of lncRNA H19 and miR-324-5p were manipulated in SKOV3 and A2780, and the glucose consumption, lactate production and PKM2 protein level were detected. Dual-luciferase reporter assay and RIP were utilized to verify the direct binding of H19 to miR-324-5p and miR-324-5p to PKM2. Cell proliferation was examined by CCK8 and colony formation assay. Nude mice subcutaneous xenograft tumor models were established to evaluate the impact of miR-324-5p on tumor growth in vivo.
Results
20(S)-Rg3 downregulated 67 lncRNAs, and H19 was one of the most decreased lncRNAs. Suppression of H19 by siRNA transfection reduced glucose consumption, lactate production and PKM2 expression in ovarian cancer cells, while H19 overexpression in 20(S)-Rg3-treated ovarian cancer cells enhanced glucose consumption, lactate production and PKM2 expression. Dual-luciferase reporter assay and RIP results showed that H19 directly bound to miR-324-5p. Dual-luciferase reporter assay showed that miR-324-5p directly targeted PKM2, and miR-324-5p negatively regulated glucose consumption and lactate production in ovarian cancer cells. miR-324-5p overexpression inhibited cell proliferation in vitro and in vivo.