Olanzapine inhibits the proliferation and induces the differentiation of glioma stem-like cells through modulating the Wnt signaling pathway in vitro.

OBJECTIVE: Olanzapine, a D2/5-HT2 antagonist, is often used as an atypical antipsychotic drug in clinical. Previous research has found its new pharmacological influence on enhancing the differentiation of neural stem cells (NSCs) to oligodendrocyte-like cells (ODLCs). Glioblastomas are associated with poor prognoses owing to the glioma stem-like cells (GSLCs), which have a great many of similarities with adult NSCs. Hence, in this article, we aim to study the effects and associated mechanisms of olanzapine on GSLCs derived from human U87MG glioblastoma cell lines.

MATERIALS AND METHODS: The methyl thiazolyl tetrazolium (MTT) colorimetric assay was conducted to investigate the effects of olanzapine on cell viability of GSLCs. Flow cytometric analysis was applied to study the cell cycle dynamics of GSLCs and Cell Counting Kit-8 (CCK-8) was used to further investigate the proliferation of GSLCs after treated with olanzapine or dimethyl sulfoxide (DMSO) for 48 h. Cell differentiation assay was carried out to study the differentiation of GSLCs and then Image-Pro Plus image analysis was used to measure the protrusion length of the differentiated cells. Furthermore, the confocal [Ca2+]c measurement was conducted to observe the influence of olanzapine on the opening function of Ca2+ channel. After the application of olanzapine for 48 h, RT-PCR was conducted to measure mRNA levels of calcium-sensing receptor (CaSR) and stromal interaction molecule 1 (STIM1), and Western blotting analysis was carried out to examine the expression of myelin basic protein (MBP), glial fibrillary acidic protein (GFAP), CaSR protein, STIM1 protein and β-catenin protein.

RESULTS: Our results demonstrated that olanzapine inhibited the proliferation of GSLCs by arresting cell cycle in G0/G1 phase and facilitated the differentiation of such cells to ODLCs. After treated with olanzapine for 48 h, cells were very sensitive to 100 mM K+ stimulation, with increased spontaneous calcium wave. We also found olanzapine increased the protein expression of MBP and GFAP. In addition, the mRNA transcription and protein expression of CaSR and STIM1 were enhanced after treated with olanzapine for 48h, while the protein expression of β-catenin was suppressed.

CONCLUSIONS: Our results suggest that olanzapine modulates the Wnt signaling pathway through activating the Ca2+ pathway and restraining the β-catenin pathway, leading to the differentiation of GSLCs to ODLCs. It provides exciting prospects that olanzapine might be a new novel chemotherapeutic modality targeting GSLCs for the treatment of glioblastomas.