Induced Telomere Damage to Treat Telomerase Expressing Therapy-Resistant Pediatric Brain Tumors

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Pediatric brain tumors like DIPG, HGG, and medulloblastoma are leading causes of cancer death in children.
• Current therapies have significant long-term side effects, necessitating novel therapeutic strategies.
• Telomerase and telomeres are crucial in cancer development and present viable therapeutic targets.

Purpose of the Study:

• To investigate the efficacy of 6-thio-2'deoxyguanosine (6-thio-dG), a telomerase substrate analog, in treating pediatric brain tumors.
• To evaluate the molecular mechanisms and therapeutic potential of 6-thio-dG in preclinical models.

Main Methods:

• Treatment of patient-derived stem-like cells from DIPG, HGG, and medulloblastoma with 6-thio-dG.
• Assessment of telomere dysfunction, genomic damage, cell death, and cell cycle arrest.
• In vivo studies using medulloblastoma xenografts and an orthotopic DIPG mouse model to evaluate tumor growth, BBB penetration, and therapeutic effects.

Main Results:

• 6-thio-dG incorporation into telomeres induced telomere dysfunction, genomic damage, and cell death in pediatric brain tumor cells.
• The drug's effects were persistent even after withdrawal and activated ATR/ATM pathways, causing G2-M arrest.
• In vivo, 6-thio-dG delayed tumor growth, increased telomere dysfunction and apoptosis, crossed the blood-brain barrier, and targeted tumor cells.

Conclusions:

• 6-thio-dG demonstrates significant preclinical efficacy against telomerase-positive pediatric brain tumors.
• The drug's ability to induce persistent DNA damage and target tumor cells, including crossing the blood-brain barrier, makes it a promising therapeutic candidate.
• 6-thio-dG represents a novel and potentially effective treatment strategy for therapy-resistant pediatric brain tumors.