An EZH2-FBP1 Feedback Circuitry Promotes Tumorigenesis in Gluconeogenic Tissues

We report that enhancer of zeste homologue 2 (EZH2) represses the expression of a rate-limiting gluconeogenic enzyme fructose-1, 6 -bisphosphatase 1 (FBP1) to promote tumorigenesis. More intriguingly, FBP1 inhibits EZH2 methyltransferase activity by binding EZH2 at targeted loci and dissembles the polycomb complex, which constitutes a negative feedback loop for EZH2-initiated signalings. We performed ChIP-Seq assays using the EZH2 and H3K27me3 antibody in HCC cells with vector control, FBP1 wild-type (WT) or FBP1 S169A re-expression. FBP1 WT severely reduced EZH2 and H3K27me3 signals. Conversely, FBP1 S169A exhibits much less effects on global or target-specific H3K27me3. In addition, ChIP-Seq assays with the FBP1 uncover a significant overlap between EZH2 and FBP1 binding sites, confirming that FBP1 inhibits EZH2 though physical interactions in the vicinity of chromosomes. Collectively, these studies reveal an unexpected crosstalk between metabolic and epigenetic events, and identify a new mechanistic circuitry highlighting EZH2 inhibitors as liver and kidney cancer therapeutics. We performed ChIP-Seq assays using the EZH2 and H3K27me3 antibody in HCC Hep3B cells with vector control, FBP1 wild-type (WT) or FBP1 S169A re-expression.