Valproic Acid Inhibits Proliferation and Reduces Invasiveness in Glioma Stem Cells Through Wnt/β Catenin Signalling Activation

Abstract

Glioblastoma is the most common malignant brain tumour in adults. The failure of current therapies can be ascribed to glioma stem cells (GSCs), which can rapidly repopulate the tumour following the initial treatment. The study of histone deacetylase inhibitors, such as valproic acid (VPA), is becoming an attractive field in cancer research. However, the exact mechanisms underlying its anti-cancer effect remain to be elucidated due to its pleiotropic effects on several cell-signalling pathways. Ingenuity Pathway Analysis (IPA) bioinformatics analysis was performed on genome-wide data regarding GSCs methylome to identify the signalling pathways mainly affected by methylation changes induced by VPA. Real time PCR and luciferase reporter assay were used to better investigate VPA effects on Wnt/β-catenin signalling pathway. VPA effect on GSC proliferation was evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) and Trypan blue assays. Finally, VPA impact on GSC motility was demonstrated by Boyden chamber assay and further confirmed evaluating the expression levels or localisation, through western blot or immunofluorescence, of Twist1, Snail1, E-Cadherin and N-Cadherin. The bioinformatics analyses performed on GSCs methylome highlighted that Wnt/β-catenin signalling was affected by the methylation changes induced by VPA, which could influence its activation status. In particular, we pointed out a general activation of this pathway after VPA exposure, which was accompanied by an inhibitory potential on GSCs proliferation. Finally, we also proved VPA’s ability to inhibit GSCs invasion through Snail1 and Twist1 downregulation and E-Cadherin relocalisation. VPA treatment may represent a new, interesting therapeutic approach to affect GSC proliferation and motility, but further investigations are certainly needed.

Specific Expression of a New Bruton Tyrosine Kinase Isoform (p65BTK) in the Glioblastoma Gemistocytic Histotype

“…The GSC lines (GBM2, G144, G166, GBM04) were isolated from patients affected by glioblastoma and characterized for their stemness properties from a genetic and molecular point of view (Baronchelli et al, 2013). All the GSC lines were already expanded in vitro as stable cell lines and used as powerful model for studying their biology and testing drug susceptibility, furthermore their cytogenomic and epigenomic profiles were well characterized (Riva et al, 2014, 2018; Cilibrasi et al, 2017). GSC were cultured in adherent culture condition using 10 mg/ml laminin (Invitrogen) in a proliferation permissive medium composed by DMEM F-12 and Neurobasal 1:1 (Invitrogen), B-27 supplement without vitamin A (Invitrogen), 2 mM L-glutamine, 10 ng/ml recombinant human bFGF and 20 ng/ml recombinant human EGF (Miltenyi Biotec), 20 UI/ml penicillin and 20 g/ml streptomycin (Euroclone; complete medium).…”

Surprising Anticancer Activities of Psychiatric Medications: Old Drugs Offer New Hope for Patients With Brain Cancer

“…Rampazzo et al (Rampazzo et al, 2013) found that Wnt/β-catenin mediated the reprogramming of GBM cells toward a neuronal-like fate. Intriguingly, a recent study demonstrated that VPA can affect the canonical Wnt/β-catenin pathway (Riva et al, 2018), a highly conserved signaling pathway that has been thought to play pivotal roles in stem cell self-renewal and embryogenesis modulation (Nusse et al, 2008; van Amerongen and Nusse, 2009; Riva et al, 2018) and whose aberrant activation has been identified in a range of cancers (Duchartre et al, 2016; Zhan et al, 2017), including GBM (Zhang et al, 2012). Impairment of the canonical Wnt signaling pathway is observed frequently in patients with GBM (Zhang et al, 2012) and is associated closely with GBM development, invasiveness, and progression (Gong and Huang, 2012; Kahlert et al, 2012; Kierulf-Vieira et al, 2016).…”

Differential Expression of Multiple Disease-Related Protein Groups Induced by Valproic Acid in Human SH-SY5Y Neuroblastoma Cells

“…VPA is an inhibitor of histone deacetylases (HDACs) and has pleiotropic effects on many biological processes such as cancer cell growth arrest, proliferation, differentiation, invasion, apoptosis, immune system, and neuroprotection [ 32 , 33 , 34 , 35 , 36 , 37 ]. Several studies indicate that HDAC inhibitors may be promising therapeutic agents for neurodegenerative diseases [ 38 , 39 ].…”