The Small Molecule Ephrin Receptor Inhibitor, GLPG1790, Reduces Renewal Capabilities of Cancer Stem Cells, Showing Anti-Tumour Efficacy on Preclinical Glioblastoma Models

Abstract

Therapies against glioblastoma (GBM) show a high percentage of failure associated with the survival of glioma stem cells (GSCs) that repopulate treated tumours. Forced differentiation of GSCs is a promising new approach in cancer treatment. Erythropoietin-producing hepatocellular (Eph) receptors drive tumourigenicity and stemness in GBM. We tested GLPG1790, a first small molecule with inhibition activity versus inhibitor of various Eph receptor kinases, in preclinical GBM models using in vitro and in vivo assays. GLPG1790 rapidly and persistently inhibited Ephrin-A1-mediated phosphorylation of Tyr588 and Ser897, completely blocking EphA2 receptor signalling. Similarly, this compound blocks the ephrin B2-mediated EphA3 and EphB4 tyrosine phosphorylation. This resulted in anti-glioma effects. GLPG1790 down-modulated the expression of mesenchymal markers CD44, Sox2, nestin, octamer-binding transcription factor 3/4 (Oct3/4), Nanog, CD90, and CD105, and up-regulated that of glial fibrillary acidic protein (GFAP) and pro-neural/neuronal markers, βIII tubulin, and neurofilaments. GLPG1790 reduced tumour growth in vivo. These effects were larger compared to radiation therapy (RT; U251 and T98G xenografts) and smaller than those of temozolomide (TMZ; U251 and U87MG cell models). By contrast, GLPG1790 showed effects that were higher than Radiotherapy (RT) and similar to Temozolomide (TMZ) in orthotopic U87MG and CSCs-5 models in terms of disease-free survival (DFS) and overall survival (OS). Further experiments were necessary to study possible interactions with radio- and chemotherapy. GLPG1790 demonstrated anti-tumor effects regulating both the differentiative status of Glioma Initiating Cells (GICs) and the quality of tumor microenvironment, translating into efficacy in aggressive GBM mouse models. Significant common molecular targets to radio and chemo therapy supported the combination use of GLPG1790 in ameliorative antiglioma therapy.

Antitumorigenic Effects of Inhibiting Ephrin Receptor Kinase Signaling by GLPG1790 against Colorectal Cancer Cell Lines In Vitro and In Vivo

“…CRC cells express high levels of different Eph proteins including EphA2, a known marker of poor prognosis in advanced CRC and a potentially critical therapeutic target for the treatment of CRC [7][8][9]. We have recently shown the anticancer proprieties of GLPG1790, a new pan inhibitor of the Eph receptors with a strong efficiency versus EphA2, versus several breast, rhabdomyosarcoma, and glioblastoma cell lines, both in vitro and in vivo [10][11][12]. Since our preliminary in vitro investigation showed the therapeutic potential of GLPG1790 also versus CRC [13], we decided to better characterize the pharmacological action of this drug on CRC by using in vitro and in vivo approaches on p53 wild-type or mutated CRC cell lines.…”

“…e cells were incubated at 37°C and 5% CO 2 , with humidity. Evaluation of cell viability (IC 50 ) and proliferation, wound-healing assays, FACS analysis, and β-galactosidase assays were performed as previously described [12,15].…”

“…Herein, GLPG1790 strongly and persistently increased the phosphorylation/ activation of ERK signaling in HCT116 cells indicating that relationship between RAS and Eph signaling is similar to that of RMS cells. However, the fact that both RMS [40] and CRC [12] cell lines express constitutively activated RAS, which cannot be regulated, suggests that Eph could modulate the ERK activation downstream of Ras. is could also explain why GLPG1790 failed to modulate ERKs in HCT15 cells expressing constitutively active Ras.…”

“…We have recently developed a preclinical, orally bioavailable small molecule named GLPG1790 that is able to inhibit, at nanomolar concentrations, the activity of various Eph receptors, with a particularly strong efficiency versus EphA2 [10]. e molecule to efficiently diminishes the phenotypic transformation of several breast, rhabdomyosarcoma, and glioblastoma cancer cell lines, both in vitro and in vivo [10][11][12], and our recent preliminary data suggest a potential therapeutic role for GLPG1790 also in treating CRC [13]. e present study has investigated the therapeutic efficiency of GLPG1790 against HCT116 and HCT15 CRC cell lines, both expressing a mutated form of KRAS in addition to either a wild-type p53 protein (p53 WT ) or mutated p53 (p53 MT ), respectively [14].…”

“…Silencing p53 with siRNA specific for the protein enhanced the ability of GLPG1790 to induce senescence in HCT15 cells only, while having the opposite effect on HC116, suggesting that the role of p53 varies depending on cellular context. p53 WT and p53 MT , expressed, respectively, by HCT116 and HCT15 [12], are known to promote or diminish, respectively, the activation of senescence in CRC [22,34,35]. is evidence seems to suggest that the mutational status of p53 could affect the ability of GLPG1790 to induce senescence and that the presence of the mutated p53, known to have acquired oncogenic features due to a gain-of-function mutation [36], has a negative effect on the therapeutic efficacy of GLPG1790.…”