Epigenetic Mechanisms Underlying the Therapeutic Effects of Temozolomide in Glioma

Temozolomide remains the standard chemotherapeutic for glioblastoma multiforme, the most aggressive primary brain tumor. Traditionally, temozolomide has long been understood as a DNA alkylating agent that triggers cell death through O^6-methylguanine formation and subsequent mismatch repair-mediated apoptosis. However, emerging research has uncovered that temozolomide also functions as a dual epigenetic regulator. Beyond DNA methylation, temozolomide can modulate histone methylation patterns both through direct chemical modifications and indirect effects on histone-modifying enzyme activity. These mechanisms fundamentally reorganize chromatin architectures and alter gene expression programs within cancer cells. The combined genotoxic and epigenetic actions of temozolomide not only contribute to its anti-tumor effectiveness but also drive adaptive mechanisms of cancer cell resistance and recurrence. Understanding temozolomide’s capacity for epigenetic reprogramming and its impact on tumor microenvironment dynamics provides crucial insights for developing more effective treatment strategies. This knowledge supports the rationale for combination therapies that integrate temozolomide with epigenetic inhibitors, targeted enzyme modulators, or bioactive natural compounds alongside radiation therapy, potentially leading to significantly improved clinical outcomes for glioma patients.