The highly lethal brain cancer glioblastoma undergoes dynamic changes in molecular profile and cellular phenotype throughout tumor core establishment and in primary-to-recurrent tumor progression. These dynamic changes allow glioblastoma tumors to escape from multimodal therapies, resulting in patient lethality. Here, we identified the emergence of dependence on NEK2-mediated EZH2 signaling, specifically in therapy-resistant tumor core-located glioblastoma cells. In patient-derived glioblastoma core models, NEK2 was required for in vivo tumor initiation, propagation, and radio-resistance. Mechanistically, in glioblastoma core cells, NEK2 binds with EZH2 to prevent its proteasome-mediated degradation in a kinase-dependent manner. Clinically, NEK2 expression is elevated in recurrent tumors after therapeutic failure as opposed to their matched primary untreated cases, and its high expression is indicative of worse prognosis. For therapeutic development, we designed a novel NEK2 kinase inhibitor CMP3a, which effectively attenuated growth of murine glioblastoma models and exhibited a synergistic effect with radiation therapy. Collectively, the emerging NEK2-EZH2 signaling axis is critical in glioblastoma, particularly within the tumor core, and the small molecule inhibitor CMP3a for NEK2 is a potential novel therapeutic agent for glioblastoma.
Glioblastoma (GBM) is a lethal brain tumor that contains cancer stem cells that are bestowed with tumor initiating and treatment resistant properties. Patient-derived glioma stem-like cells (GSCs) that resemble the clinically relevant MES subtype harbor more aggressive and therapy resistant properties. Here we report that exposure of GSCs to ionizing radiation (IR) provokes inter-cellular signals from therapy-induced senescent non-stem cancer cells to stimulate compensatory growth in cancer stem cells resulting in persistent transcriptomic and phenotypic shift toward a more MES subtype. This IR-induced gain of MES features in GSCs is accompanied by conversion of CD133+ stem cell populations to CD133- /CD109+ cells. In both de novo and IR-induced MES GSCs, CD109+, but not CD109- populations are highly tumorigenic and multipotent in vivo. Inhibition of CD109 attenuates clonogenicity and radioresistance in MES GSCs GBM. Clinically, CD109 expression is significantly associated with the MES GBMs and poorer prognosis of GBM patients. Taken together, our data imply that radiation of GSCs induces direct transformation of cancer stem cells to the MES subtype accompanied by a loss of the widely adopted stem cell marker CD133 and a gain of a novel, tumor propagating, and clinically relevant MES stem cell marker, CD109.
Citation Format: Mutsuko Minata, Ichiro Nakano, Sunghak Kim, Marat PavliuKov, Jia Wang, Svetlana Komarova, Jun Wang. Crosstalk between stem and non-stem cells in glioblastoma promotes radioresistance in a CD109-dependent manner. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2518.
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