Inhibition of DYRK1A destabilizes EGFR and reduces EGFR-dependent glioblastoma growth

Abstract

Glioblastomas (GBMs) are very aggressive tumors that are resistant to conventional chemo-and radiotherapy. New molecular therapeutic strategies are required to effectively eliminate the subpopulation of GBM tumorinitiating cells that are responsible for relapse. Since EGFR is altered in 50% of GBMs, it represents one of the most promising targets; however, EGFR kinase inhibitors have produced poor results in clinical assays, with no clear explanation for the observed resistance. We uncovered a fundamental role for the dual-specificity tyrosine phosphorylation-regulated kinase, DYRK1A, in regulating EGFR in GBMs. We found that DYRK1A was highly expressed in these tumors and that its expression was correlated with that of EGFR. Moreover, DYRK1A inhibition promoted EGFR degradation in primary GBM cell lines and neural progenitor cells, sharply reducing the self-renewal capacity of normal and tumorigenic cells. Most importantly, our data suggest that a subset of GBMs depends on high surface EGFR levels, as DYRK1A inhibition compromised their survival and produced a profound decrease in tumor burden. We propose that the recovery of EGFR stability is a key oncogenic event in a large proportion of gliomas and that pharmacological inhibition of DYRK1A could represent a promising therapeutic intervention for EGFR-dependent GBMs.

Preclinical Test of Dacomitinib, an Irreversible EGFR Inhibitor, Confirms Its Effectiveness for Glioblastoma

“…So far, our results indicate that the effect of dacomitinib is EGFR-dependent as it does not produce a significant inhibition of GBM5, a primary cell line without EGFR amplification and showing low levels of receptor expression (22). To confirm that dacomitinib is effectively targeting EGFR signaling, we investigated the phosphorylation status of the receptor and its downstream targets in the treated tumors.…”

“…Primary cultures GBM3 to 7 were established from those samples and processed and cultured as previously described (22). Primary lines GBM1 and GBM2 were kindly provided by Dr. Rosella Galli (Neural Stem Cell Biology Unit, Division of Regenerative Medicine, Stem Cells and Gene Therapy, San Raffaele Scientific Institute, Milan, Italy).…”

“…For immunoblot analysis, cells or small tissue fragments were collected and processed as previously described (22). Primary and secondary antibodies used are shown in Supplementary Tables S3a and S3b.…”

“…For the intracranial xenografts, animals were perfused with 4% paraformaldehyde (PFA; Merck) and brains were cryoprotected and cut in a cryostat in 20 mmol/L coronal sections. Immunostaining was performed as previously described (22). Tables S3a and S3b.…”

Flexible Analogues of Azaindole DYRK1A Inhibitors Elicit Cytotoxicity in Glioblastoma Cells

“…[1a] Pozo and coworkers recently reported a promising therapeutic intervention by targeting dualspecificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) for epidermal growth factor receptor (EGFR)-dependent glioblastomas. [6] DYRK1A is upregulated in glioblastoma cells. [6] The increased phosphorylation of sprouty2 mediated by DYRK1A blocks EGFR degradation as a result of overexpression of EGFR at the cell surface, and the enhanced EGFR signalling eventually leads to tumour survival.…”