GSK3 Inhibitors Regulate MYCN mRNA Levels and Reduce Neuroblastoma Cell Viability through Multiple Mechanisms, Including p53 and Wnt Signaling

Abstract

Neuroblastoma is an embryonal tumor accounting for approximately 15% of childhood cancer deaths. There exists a clinical need to identify novel therapeutic targets, particularly for treatment-resistant forms of neuroblastoma. Therefore, we investigated the role of the neuronal master regulator GSK3 in controlling neuroblastoma cell fate. We identified novel GSK3-mediated regulation of MYC (c-MYC and MYCN) mRNA levels, which may have implications for numerous MYC-driven cancers. In addition, we showed that certain GSK3 inhibitors induced large-scale cell death in neuroblastoma cells, primarily through activating apoptosis. mRNA-seq of GSK3 inhibitor-treated cells was performed and subsequent pathway analysis revealed that multiple signaling pathways contributed to the loss of neuroblastoma cell viability. The contribution of two of the signaling pathways highlighted by the mRNA-seq analysis was functionally validated. Inhibition of the p53 tumor suppressor partly rescued the cell death phenotype, whereas activation of canonical Wnt signaling contributed to the loss of viability, in a p53-independent manner. Two GSK3 inhibitors (BIO-acetoxime and LiCl) and one small-molecule Wnt agonist (Wnt Agonist 1) demonstrated therapeutic potential for neuroblastoma treatment. These inhibitors reduced the viability of numerous neuroblastoma cell lines, even those derived from high-risk MYCN-amplified metastatic tumors, for which effective therapeutics are currently lacking. Furthermore, although LiCl was lethal to neuroblastoma cells, it did not reduce the viability of differentiated neurons. Taken together our data suggest that these small molecules may hold potential as effective therapeutic agents for the treatment of neuroblastoma and other MYC-driven cancers. Mol Cancer Ther; 13(2); 454-67. Ó2013 AACR.

Integrated High Throughput Analysis Identifies GSK3 as a Crucial Determinant of p53-Mediated Apoptosis in Lung Cancer Cells

“…4G). Given that Wnt signalling has been shown to confer the apoptotic effect of some GSK3 inhibitor in cancer cells [45], these results indicated that GSK3 inhibition is synthetic lethal with p53 re-activation, possibly through its effect on the action of Wnt signalling.…”

“…Therefore, it is hard to identify the factor conferring the synthetic lethal effect of GSK3 inhibition and p53 re-activation based on our current findings. Additionally, Wnt signalling has been shown to be important for the apoptotic effect of some GSK3 inhibitor in cancer cells [45], since GSK3 is a key kinase repressing Wnt signalling pathway through mediating β-catenin phosphorylation and subsequent degradation [44]. In present study, we found that the transcriptional activity of β-catenin induced by SB216763 was much lower than those induced by other inhibitors, although the transcriptional activity of β-catenin was enhanced by all these four inhibitors (Fig.…”

LncRNA HANR Promotes Tumorigenesis and Increase of Chemoresistance in Hepatocellular Carcinoma

“…For example, GSK3β and Wnt/Axin2 coordinately regulate β-catenin-TCF to control tumor proliferation and metastasis in breast cancer [34]. Wnt pathway is reported as downstream target of GSK3β in controlling neuroblastoma growth [35]. In addition, although not investigated for cancer, GSK3β directly induces the expression of Bax1 in an ischemic injury model [36].…”

Measuring Transcription Rate Changes via Time-Course 4-Thiouridine Pulse-Labelling Improves Transcriptional Target Identification

“…The RNA extraction, DNA digestion, quality control, sequencing and bioinformatics were performed as previously described on an Illumina GA IIx [19]. The aligned data are publically available in ArrayExpress under the accession number E-MTAB-2691.…”