Podoplanin expression is a prognostic biomarker but may be dispensable for the malignancy of glioblastoma

Abstract

Background. Treatment options of glioblastoma, the most aggressive primary brain tumor with frequent relapses and high mortality, are still very limited, urgently calling for novel therapeutic targets. Expression of the glycoprotein podoplanin correlates with poor prognosis in various cancer entities, including glioblastoma. Furthermore, podoplanin has been associated with tumor cell migration and proliferation in vitro; however, experimental data on its function in gliomagenesis in vivo are still missing. Hence, we have functionally investigated the impact of podoplanin on glioblastoma in a preclinical mouse model to evaluate its potential as a therapeutic target. Methods. Fluorescence activated cell sorting, genome-wide expression analysis, and clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated nuclease 9 (Cas9)-mediated deletion of podoplanin in patient-derived human glioblastoma cells were combined with organotypic brain slice cultures and intracranial injections into mice. Results. We defined a malignant gene signature in tumor cells with high podoplanin expression. The increase and/ or maintenance of high podoplanin expression in serial transplantations and in podoplanin low-sorted glioblastoma cells during outgrowth indicated the association of high podoplanin expression and poor outcome. Unexpectedly, similar rates of proliferation, apoptosis, angiogenesis, and invasion were observed in control and podoplanindeleted tumors. Accordingly, neither tumor growth nor survival was affected upon podoplanin loss. Conclusion. We report that tumor progression occurs independently of podoplanin. Thus, in contrast to previous suggestions, blocking of podoplanin does not represent a promising therapeutic approach. However, as podoplanin is associated with tumor aggressiveness and progression, we propose the cell surface protein as a biomarker for poor prognosis. Key Points 1. High podoplanin expression in glioma cells is part of a malignant gene signature. 2. Glioma cells acquire high podoplanin expression during in vivo tumor growth.

Modeling glioblastoma invasion using human brain organoids and single-cell transcriptomics

“…Patient-derived GBM cell cultures were established as described. 17 Cells were cultured in suspension culture in 75 cm 2 ultra-low attachment flasks in Neurobasal medium (Gibco) supplemented with 2 mM L-glutamine (Life Technologies), 1x B27 (Gibco), 2 µg/mL heparin, 20 ng/mL epidermal growth factor and 20 ng/mL basic fibroblast growth factor (R&D Systems). For passaging, spheroid cultures were dissociated using Accutase (StemCell Technologies) when they had reached diameters of ~100 µm, every 1–3 weeks.…”

Modeling glioblastoma invasion using human brain organoids and single-cell transcriptomics

“…Experiments involving human patient material were performed in accordance with the Declaration of Helsinki and were approved by the ethics committee of the University Cancer Center Frankfurt, project number SNO_01_13. Patient-derived GBM cell cultures were established as described 28 . Cells were cultured in suspension culture in 75 cm 2 ultra-low attachment flasks in Neurobasal medium (Gibco) supplemented with 2 mM L-glutamine (Life Technologies), 1x B27 (Gibco), 2 µg/ml heparin, 20 ng/ml EGF and 20 ng/ml bFGF (R&D Systems).…”

Venous Thromboembolism in Brain Tumors: Risk Factors, Molecular Mechanisms, and Clinical Challenges

“…50 In contrast, a recent study by Eisemann et al suggested that podoplanin is rather a marker of malignancy than directly involved in tumor progression, as deletion of podoplanin in their mouse model did not interfere with tumor growth or survival of mice. 51 The authors concluded, however, that podoplanin might still be used as marker for tumor aggressiveness and also as a target to deliver antineoplastic drugs and as a target for CAR T cell therapy. Moreover, targeting podoplanin might decrease the risk of VTE.…”