Glycogen synthase kinase-3 inhibition in glioblastoma multiforme cells induces apoptosis, cell cycle arrest and changing biomolecular structure

Abstract Glioblastoma multiforme (GBM) is the most malignant and aggressive primary human brain tumors. The regulatory pathways of apoptosis are altered in GBMs, leading to a survival advantage of the tumor cells. Thus, identification of target molecules, which are effective in triggering of the cell death mechanisms in GBM, is an essential strategy for therapeutic purposes. Glycogen synthase kinase-3 (GSK-3) plays an important role in apoptosis, proliferation and cell cycle. This study focused on the effect of GSK-3 inhibitor IX in the GBM cells. Apoptosis induction was determined by Annexin-V assay, multicaspase activity and immunofluorescence analyses. Concentration-dependent effects of GSK-3 inhibitor IX on the cell cycle were also evaluated. Moreover, the effect of GSK inhibitor on the cellular biomolecules was assessed by using ATR-FTIR spectroscopy. Our assay results indicated that GSK-3 inhibitor IX induces apoptosis, resulting in a significant increase in the expression of caspase-3 and caspase-8 proteins. Cell cycle analyses revealed that GSK-3 inhibitor IX leads to dose-dependent G2/M-phase cell cycle arrest. Based on the FTIR data, treatment of GBM cells causes dysregulation in the carbohydrate metabolism and induces apoptotic cell death which was characterized by the spectral alterations in nucleic acids, an increment in the lipid amount with disordering state and compositional changes in the cellular proteins. These findings suggest that GSK-3 inhibitor IX exhibits anti-cancer effects by inducing apoptosis and changing biomolecular structure of membrane lipids, carbohydrates, nucleic acids and proteins, and thus, may be further evaluated as a potential effective candidate agent for the GBM combination therapies.