Abstract
Diffuse intrinsic pontine glioma (DIPG) is a rare and fatal pediatric brain cancer without cure. DIPG has high percentage histone mutation at K27M on histone H3 locus, which is believed to be one of the drivers of the tumorigenesis. Dysregulation of G1/S cell cycle checkpoint is more enriched in the H3.3K27M mutant subgroup. In this study, we reported that palbociclib (PD0332991), a specific and cytostatic inhibitor of CDK4/6, effectively suppress the growth of treatment-naïve patient derived DIPG cells in vitro and in vivo. First, we established patient derived cell lines from treatment-naïve specimens, which all have H3.3K27M mutation. And our DIPG cell lines with H3.3K27M mutation have high CDK4/6 expression. Then, we showed that depletion of CDK4or CDK6inhibits DIPG cells growth and blocks G1/S transition. Furthermore, palbociclib effectively repressed all 8 cell lines self-renewal, proliferation and cell cycle progression from G1 to S phase in vitro. Transcriptome analysis showed that palbociclibnot only blocks G1/S transition, it also blocks other oncogenic targets such as Myc. Finally, palbociclib activity was assayed in vivo against DIPG orthotropic xenografts to demonstrate the high efficiency of blocking tumor growth. Our findings revealed that palbociclib could be the therapy strategy for DIPG, especially for treatment-naïve patients.