Page 183 - Haematologica April 2020

EZH2 inhibition synergies with CDK9 inhibition
EZH2i reversed the upregulation of H3K27me3 evoked byCDKI-73andcausesasynergisticeffectinDLBCL
It has been reported that down-regulation of H3K27me3 expression by EZH2i has marked anti-tumor potency in
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EZH2 mutant (mut) DLBCL preclinical models.14 Therefore, CDKI-73 improved H3K27me3 expression, which may attenuate its anti-tumor activity against DLBCL . This inspired us to explore whether EZH2i could
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Figure 2. CDKI-73 induces H3K27me3 via CDK9 inhibition. (A) Mass Spectrometry assay (MS). Graphical illustration of MS process (left) and normalized CDKI- 73/DMSO ration of 36 loci (right). H3K27me3 is labeled in the red circle. (B) Methylation level of histone in Pfeiffer and SU-DHL-4 cells after treated with CDKI- 73/Flavopiridol for 24 hours (h). (C) Summary of ChIP-seq H3K27me3 peaks in the CDKI-73 (red) and control (blue) samples. “0bp” in X-axis indicates the H3K27me3 peak center. (D) The relative mRNA levels of H3K27me3 target genes GATA4, CDKN2A, HOXC8, and TNFRSF21 in Pfeiffer when cells were treated with CDKI- 73/Flavopiridol for 6 h. The influence of CDK9i (E) CDK4/6 inhibitor (F) and CDK9 (G) CDK1, CDK2, CDK4, CDK7 knock-down (H) on the protein level of H3K27me3. (I) The relative mRNA levels of GATA4, CDKN2A, HOXC8, and TNFRSF21 in CDK9 depletion Karpas-422 cells. C: CDKI-73; SNS: SNS-032; AT: AT-7519; Dina: Dinaciclib; PD: PD0332991. All data are representative of at least three independent experiments. ***P<0.001, **P<0.01, *P<0.05 compared with the control group.
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