Chromosomal Instability as a Determinant of Glioblastoma Heterogeneity and Therapeutic Vulnerability

Glioblastoma, the most aggressive and lethal form of brain cancer, is defined by profound genomic instability, with Chromosomal Instability (CIN) playing a central role in driving tumor progression, therapy resistance, and poor prognosis. CIN is characterized by numerical and structural alterations, driven by mechanisms such as mitotic errors, centrosome amplification, spindle assembly checkpoint dysfunction, and defective DNA repair pathways. These aberrations contribute to tumor heterogeneity, leading to the emergence of Glioblastoma Stem Cells (GSCs) with enhanced plasticity, therapy resistance, and metastatic capacity.

Chromothripsis, which frequently involves specific chromosomes and stems from micronuclei rupture, often results in catastrophic chromosomal rearrangement. The immune implications of CIN are also critical, with the Cyclic GMP–AMP Synthase–Stimulator of Interferon Genes (cGAS‐STING) pathway toggling between anti‐tumor immunity and immune evasion. Therapeutic strategies targeting CIN are currently being explored, including inhibitors of centrosomal clustering, DNA damage response pathways, and spindle assembly components, as well as innovative approaches like Chimeric Antigen Receptor T (CAR‐T) cell therapies. Advances in single‐cell sequencing technologies provide transformative insights into CIN‐driven glioblastoma heterogeneity and therapeutic vulnerabilities. Furthermore, novel small-molecule inhibitors are being evaluated to overcome the chemoresistance commonly associated with alkylating agents like Temozolomide .

Key Molecular Drivers and Regulatory Components

The following table summarizes the essential proteins and pathways identified as critical regulators of genomic integrity and mitotic fidelity in glioblastoma pathogenesis:

Recent advances demonstrate that chromosomal aberrations—whether numerical or structural—are not merely random occurrences but serve as significant indicators for cancer prognosis and therapeutic responses. Numerical aberration influences CIN, leading to frequent gains or losses of entire or large chromosomal regions over successive cell generations, such as Chromosomal Arm Aneuploidy (CAA) and polyploidy, which fundamentally alter gene dosage and expression.

Importantly, CIN and aneuploidy are closely related yet mechanistically distinct processes. Aneuploidy refers to an abnormal chromosome number arising from a single chromosome mis‐segregation event, resulting in a stable but imbalanced karyotype. In contrast, CIN represents a dynamic, ongoing process of chromosome mis‐segregation that continuously generates karyotypic diversity. This reciprocal relationship sustains genetic diversity and underlies tumor evolution. Numerical CIN events in glioblastoma produce various sub-clones, typically characterized by the gain or loss of chromosomes 7 or 10 and varying degrees of EGFR amplification, which subsequently hyperactivates downstream signaling axes such as PI3K/AKT and HGF/MET.