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A Rapid Screening Workflow to Identify Potential Combination Therapy for GBM using Patient-Derived Glioma Stem Cells
Published on: March 28, 2021
G-quadruplex stabilizer CX-5461 effectively combines with radiotherapy to target α-thalassemia/mental retardation
Sharvari Dharmaiah1,2, Prit Benny Malgulwar1, William E Johnson1
1Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Background:
Inactivation of α-thalassemia/mental retardation X-linked (ATRX) represents a defining molecular feature in large subsets of malignant glioma. ATRX deficiency gives rise to abnormal G-quadruplex (G4) DNA secondary structures, enhancing replication stress and genomic instability. Building on earlier work, we evaluated the extent to which pharmacological G4 stabilization selectively enhances DNA damage and cell death in ATRX-deficient preclinical glioma models.
Methods:
Using the G4 stabilizer CX-5461, we treated patient-derived glioma stem cells (GSCs) in vitro and GSC flank and intracranial murine xenografts in vivo to evaluate efficacy as both a single agent and in combination with ionizing radiation (IR), the latter a central element of current treatment standards.
Results:
CX-5461 promoted dose-sensitive lethality in ATRX-deficient GSCs relative to ATRX-intact controls. Mechanistic studies revealed that CX-5461 disrupted histone variant H3.3 deposition, enhanced replication stress and DNA damage, activated p53-independent apoptosis, and induced G2/M arrest to a greater extent in ATRX-deficient GSCs than in ATRX-intact counterparts. These data were corroborated in vivo, where CX-5461/IR treatment profoundly delayed tumor growth and prolonged survival in mice bearing ATRX-deficient flank xenografts. Histopathological analyses revealed decreased proliferation, increased apoptosis, and significant G4 induction, replication stress, and DNA damage in CX-5461-treated tumors, both alone and in combination with IR. Finally, despite suboptimal blood-brain-barrier penetration, systemic CX-5461 treatment induced tangible pharmacodynamic effects in ATRX-deficient intracranial GSC models.
Conclusions:
In totality, our work substantively demonstrates efficacy and defines mechanisms of action for G4 stabilization as a novel therapeutic strategy targeting ATRX-deficient malignant glioma, laying the groundwork for clinical translation.
Insights
Pharmacological G-quadruplex (G4) stabilization with CX-5461 selectively kills ATRX-deficient glioma cells by inducing DNA damage. This approach shows promise for treating malignant glioma with ATRX inactivation.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Malignant glioma often features alpha-thalassemia/mental retardation X-linked (ATRX) inactivation.
- ATRX deficiency promotes G-quadruplex (G4) DNA structures, increasing replication stress and genomic instability.
Purpose of the Study:
- To evaluate pharmacological G4 stabilization for selectively targeting ATRX-deficient glioma models.
- To assess the efficacy of CX-5461 alone and with ionizing radiation (IR).
Main Methods:
- Treated patient-derived glioma stem cells (GSCs) in vitro and in vivo xenografts with CX-5461.
- Evaluated CX-5461 in combination with IR in preclinical models.
- Assessed G4 stabilization, replication stress, DNA damage, and apoptosis.
Main Results:
- CX-5461 induced dose-sensitive cell death in ATRX-deficient GSCs.
- CX-5461 disrupted H3.3 deposition, enhanced replication stress, and triggered p53-independent apoptosis.
- Combination therapy with IR significantly delayed tumor growth and prolonged survival in vivo.
Conclusions:
- G4 stabilization is a viable therapeutic strategy for ATRX-deficient malignant glioma.
- The study defines mechanisms of action, supporting clinical translation.
- CX-5461 demonstrated pharmacodynamic effects even with limited blood-brain-barrier penetration.
