GSK-3 Inhibition Is Cytotoxic in Glioma Stem Cells through Centrosome Destabilization and Enhances the Effect of Radiotherapy in Orthotopic Models

Structure-Based Discovery Targeting GSK-3α Reveals Potent Nanomolar Selective 4-Phenyl-1H-benzofuro[3,2-b]pyrazolo[4,3-e]pyridine Inhibitor with Promising Glioblastoma and CNS-Active Potential in Cellular Models

Glycogen synthase kinase-3 (GSK-3) is linked with multiple CNS conditions, including glioblastoma (GBM). Compared to the GSK-3β isoform, structure-based inhibitor design targeting GSK-3α is limited. Virtual screening was employed to identify GSK-3α inhibitors with CNS-active potential. Using a GSK-3α homology model, an optimized protocol with three-dimensional (3D)-pharmacophore filtering and Glide-SP docking was used to screen the ZINC20 biogenic subset. From 14 compounds selected for binding assay validation, three novel hit compounds were identified, with 1 (4-phenyl-1H-benzofuro[3,2-b]pyrazolo[4,3-e]pyridine scaffold) exhibiting nanomolar activity against GSK-3α/β (IC50s ∼ 0.26 μM). Selectivity profiling (12 homologous kinases) revealed selectivity for GSK-3α/β and protein kinase A (PKA). Compound 1 was more potent against three GBM cell lines (cell viability IC50s = 3-6 μM at 72 h) compared to benchmark GSK-3 inhibitor, 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8), and nontoxic to human astrocytes. It demonstrated CNS-active potential in an all-human in vitro blood-brain barrier GBM model, good in vitro metabolic stability, excellent predicted oral bioavailability and represents a promising lead compound for development.

Pharmacological Modulation of the Cytosolic Oscillator Affects Glioblastoma Cell Biology

The circadian system is a conserved time-keeping machinery that regulates a wide range of processes such as sleep/wake, feeding/fasting, and activity/rest cycles to coordinate behavior and physiology. Circadian disruption can be a contributing factor in the development of metabolic diseases, inflammatory disorders, and higher risk of cancer. Glioblastoma (GBM) is a highly aggressive grade 4 brain tumor that is resistant to conventional therapies and has a poor prognosis after diagnosis, with a median survival of only 12-15 months. GBM cells kept in culture were shown to contain a functional circadian oscillator. In seeking more efficient therapies with lower side effects, we evaluated the pharmacological modulation of the circadian clock by targeting the cytosolic kinases glycogen synthase kinase-3 (GSK-3) and casein kinase 1 ε/δ (CK1ε/δ) with specific inhibitors (CHIR99021 and PF670462, respectively), the cryptochrome protein stabilizer (KL001), or circadian disruption after Per2 knockdown expression in GBM-derived cells. CHIR99021-treated cells had a significant effect on cell viability, clock protein expression, migration, and cell cycle distribution. Moreover, cultures exhibited higher levels of reactive oxygen species and alterations in lipid droplet content after GSK-3 inhibition compared to control cells. The combined treatment of CHIR99021 with temozolomide was found to improve the effect on cell viability compared to temozolomide therapy alone. Per2 disruption affected both GBM migration and cell cycle progression. Overall, our results suggest that pharmacological modulation or molecular clock disruption severely affects GBM cell biology.

New insights into the role of GSK-3β in the brain: from neurodegenerative disease to tumorigenesis

Glycogen synthase kinase 3 (GSK-3) is a serine/threonine kinase widely expressed in various tissues and organs. Unlike other kinases, GSK-3 is active under resting conditions and is inactivated upon stimulation. In mammals, GSK-3 includes GSK-3 α and GSK-3β isoforms encoded by two homologous genes, namely, GSK3A and GSK3B. GSK-3β is essential for the control of glucose metabolism, signal transduction, and tissue homeostasis. As more than 100 known proteins have been identified as GSK-3β substrates, it is sometimes referred to as a moonlighting kinase. Previous studies have elucidated the regulation modes of GSK-3β. GSK-3β is involved in almost all aspects of brain functions, such as neuronal morphology, synapse formation, neuroinflammation, and neurological disorders. Recently, several comparatively specific small molecules have facilitated the chemical manipulation of this enzyme within cellular systems, leading to the discovery of novel inhibitors for GSK-3β. Despite these advancements, the therapeutic significance of GSK-3β as a drug target is still complicated by uncertainties surrounding the potential of inhibitors to stimulate tumorigenesis. This review provides a comprehensive overview of the intricate mechanisms of this enzyme and evaluates the existing evidence regarding the therapeutic potential of GSK-3β in brain diseases, including Alzheimer's disease, Parkinson's disease, mood disorders, and glioblastoma.

New Strategies in Diagnosis and Treatments for Brain Tumors

In general, cancer is one of the most frequent causes of death [...].