Glioblastomas are aggressive brain tumors for which effective therapy is still lacking, resulting in dismal survival rates. These tumors display significant phenotypic plasticity, harboring diverse cell populations ranging from tumor core cells to dispersed, highly invasive cells. Neuron navigator 3 (NAV3), a microtubule-associated protein affecting microtubule growth and dynamics, is downregulated in various cancers, including glioblastoma, and has thus been considered a tumor suppressor. In this study, we challenge this designation and unveil distinct expression patterns of NAV3 across different invasion phenotypes. Using glioblastoma cell lines and patient-derived glioma stem-like cell cultures, we disclose an upregulation of NAV3 in invading glioblastoma cells, contrasting with its lower expression in cells residing in tumor spheroid cores. Furthermore, we establish an association between low and high NAV3 expression and the amoeboid and mesenchymal invasive phenotype, respectively, and demonstrate that overexpression of NAV3 directly stimulates glioblastoma invasive behavior in both 2D and 3D environments. Consistently, we observed increased NAV3 expression in cells migrating along blood vessels in mouse xenografts. Overall, our results shed light on the role of NAV3 in glioblastoma invasion, providing insights into this lethal aspect of glioblastoma behavior.

• Klíčová slova
• NAV3, amoeboid, glioblastoma, invasion, mesenchymal,
• MeSH
• fenotyp * MeSH
• glioblastom * patologie   genetika   metabolismus   MeSH
• invazivní růst nádoru * genetika   MeSH
• lidé MeSH
• membránové proteiny MeSH
• mikrotubuly metabolismus   MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádory mozku * patologie   genetika   metabolismus   MeSH
• pohyb buněk genetika   fyziologie   MeSH
• proteiny nervové tkáně metabolismus   genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• membránové proteiny MeSH
• NAV3 protein, human MeSH Prohlížeč
• proteiny nervové tkáně MeSH

Gliomagenesis induces profound changes in the composition of the extracellular matrix (ECM) of the brain. In this study, we identified a cellular population responsible for the increased deposition of collagen I and fibronectin in glioblastoma. Elevated levels of the fibrillar proteins collagen I and fibronectin were associated with the expression of fibroblast activation protein (FAP), which is predominantly found in pericyte-like cells in glioblastoma. FAP+ pericyte-like cells were present in regions rich in collagen I and fibronectin in biopsy material and produced substantially more collagen I and fibronectin in vitro compared to other cell types found in the GBM microenvironment. Using mass spectrometry, we demonstrated that 3D matrices produced by FAP+ pericyte-like cells are rich in collagen I and fibronectin and contain several basement membrane proteins. This expression pattern differed markedly from glioma cells. Finally, we have shown that ECM produced by FAP+ pericyte-like cells enhances the migration of glioma cells including glioma stem-like cells, promotes their adhesion, and activates focal adhesion kinase (FAK) signaling. Taken together, our findings establish FAP+ pericyte-like cells as crucial producers of a complex ECM rich in collagen I and fibronectin, facilitating the dissemination of glioma cells through FAK activation.

• Klíčová slova
• collagen type I, extracellular matrix proteins, fibronectin, glioblastoma, pericytes, proteomics,
• MeSH
• endopeptidasy MeSH
• extracelulární matrix * metabolismus   patologie   MeSH
• fibronektiny * metabolismus   MeSH
• glioblastom patologie   metabolismus   MeSH
• gliom * patologie   metabolismus   MeSH
• kolagen typu I metabolismus   MeSH
• lidé MeSH
• membránové proteiny metabolismus   MeSH
• nádorové buněčné linie MeSH
• nádorové mikroprostředí fyziologie   MeSH
• nádory mozku * patologie   metabolismus   MeSH
• pericyty * metabolismus   patologie   MeSH
• pohyb buněk fyziologie   MeSH
• serinové endopeptidasy metabolismus   MeSH
• želatinasy metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• endopeptidasy MeSH
• fibroblast activation protein alpha MeSH Prohlížeč
• fibronektiny * MeSH
• kolagen typu I MeSH
• membránové proteiny MeSH
• serinové endopeptidasy MeSH
• želatinasy MeSH

OBJECTIVE: The highly infiltrative growth of glioblastoma (GBM) makes distinction between the tumor and normal brain tissue challenging. Therefore, fluorescence-guided surgery is often used to improve visual identification of radiological tumor margins. The aim of this study was to evaluate the ability of recently developed molecularly targeted near-infrared (NIR) protease-activated probes to visualize GBM tissue and to compare the most promising candidate with the gold standard, 5-aminolevulinic acid (5-ALA). METHODS: Single-substrate probes 6QC-ICG and 6QC-Cy5 (cysteine cathepsin cleavable), double-substrate probes AG2-FNIR and AG2-Cy5 (cysteine cathepsin and caspase 3 cleavable), and 5-ALA were administered intravenously to mice with orthotopic tumors. Activation of the probes was also evaluated in cell cultures in vitro and in biopsy material from patients with GBM ex vivo. The tumor to normal brain tissue fluorescence ratio (TNR) was quantified in brain sections using preclinical and clinical visualization platforms, and in tissue homogenates and cell suspensions using spectrofluorimetry. Subcellular localization of the fluorophores was visualized by confocal microscopy. RESULTS: In vitro, the single-substrate probe 6QC-ICG was cleaved in glioma cells and macrophages, and the resulting fluorophore accumulated intracellularly. In experimental GBMs, both single- and double-substrate probes visualized tumor tissue, while in healthy brain tissue the signal was minimal. TNR was highest for 6QC-ICG and AG2-FNIR, but the signal intensity was higher for 6QC-ICG. Using xenograft and syngeneic mouse models, as well as human GBM biopsy material ex vivo, the authors confirmed the ability of 6QC-ICG to specifically visualize the glioma tissue using preclinical and clinical visualization platforms. Finally, a comparison with 5-ALA in animals coadministered with both compounds revealed a higher TNR for 6QC-ICG in experimental GBMs. CONCLUSIONS: The cysteine cathepsin-cleavable probe 6QC-ICG is activated by glioma cells and tumor-associated macrophages, leading to a high contrast between tumor and nontumorous brain tissue that is superior to that of the current standard, 5-ALA. In addition to a well-defined mechanism of action, protease-activated probes that use NIR fluorophores (e.g., indocyanine green) have the advantage of low absorption and scattering of the NIR light and lower tissue autofluorescence. These results suggest that 6QC-ICG has the potential to become the targeted agent in intraoperative detection of GBM tissue using fluorescence imaging.

• Klíčová slova
• 5-ALA, activity-based probes, cathepsin, fluorescence-guided surgery, glioblastoma, mouse models, oncology,
• MeSH
• blízká infračervená spektroskopie MeSH
• cystein MeSH
• glioblastom * diagnostické zobrazování   metabolismus   chirurgie   MeSH
• gliom MeSH
• heterografty MeSH
• kyselina aminolevulová * chemie   metabolismus   MeSH
• modely u zvířat MeSH
• molekulární sondy * metabolismus   MeSH
• mozek diagnostické zobrazování   metabolismus   chirurgie   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• proteasy * metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• cystein MeSH
• kyselina aminolevulová * MeSH
• molekulární sondy * MeSH
• proteasy * MeSH

Glioblastoma (GBM) is the most frequently occurring primary malignant brain tumor of astrocytic origin. To change poor prognosis, it is necessary to deeply understand the molecular mechanisms of gliomagenesis and identify new potential biomarkers and therapeutic targets. PIWI-interacting RNAs (piRNAs) help in maintaining genome stability, and their deregulation has already been observed in many tumors. Recent studies suggest that these molecules could also play an important role in the glioma biology. To determine GBM-associated piRNAs, we performed small RNA sequencing analysis in the discovery set of 19 GBM and 11 non-tumor brain samples followed by TaqMan qRT-PCR analyses in the independent set of 77 GBM and 23 non-tumor patients. Obtained data were subsequently bioinformatically analyzed. Small RNA sequencing revealed 58 significantly deregulated piRNA molecules in GBM samples in comparison with non-tumor brain tissues. Deregulation of piR-1849, piR-9491, piR-12487, and piR-12488 was successfully confirmed in the independent groups of patients and controls (all p < 0.0001), and piR-9491 and piR-12488 reduced GBM cells' ability to form colonies in vitro. In addition, piR-23231 was significantly associated with the overall survival of the GBM patients treated with Stupp regimen (p = 0.007). Our results suggest that piRNAs could be a novel promising diagnostic and prognostic biomarker in GBM potentially playing important roles in gliomagenesis.

• Klíčová slova
• PIWI-interacting RNA, diagnosis, glioblastoma, piRNA, prognosis,
• Publikační typ
• časopisecké články MeSH

The proline-specific serine protease fibroblast activation protein (FAP) can participate in the progression of malignant tumors and represents a potential diagnostic and therapeutic target. Recently, we demonstrated an increased expression of FAP in glioblastomas, particularly those of the mesenchymal subtype. Factors controlling FAP expression in glioblastomas are unknown, but evidence suggests that transforming growth factor beta (TGFbeta) can trigger mesenchymal changes in these tumors. Here, we investigated whether TGFbeta promotes FAP expression in transformed and stromal cells constituting the glioblastoma microenvironment. We found that both FAP and TGFbeta-1 are upregulated in glioblastomas and display a significant positive correlation. We detected TGFbeta-1 immunopositivity broadly in glioblastoma tissues, including tumor parenchyma regions in the immediate vicinity of FAP-immunopositive perivascular stromal cells. Wedemonstrate for the first time that TGFbeta-1 induces expression of FAP in non-stem glioma cells, pericytes, and glioblastoma-derived endothelial and FAP+ mesenchymal cells, but not in glioma stem-like cells. In glioma cells, this effect is mediated by the TGFbeta type I receptor and canonical Smad signaling and involves activation of FAP gene transcription. We further present evidence of FAP regulation by TGFbeta-1 secreted by glioma cells. Our results provide insight into the previously unrecognized regulation of FAP expression by autocrine and paracrine TGFbeta-1 signaling in a broad spectrum of cell types present in the glioblastoma microenvironment.

• Klíčová slova
• Smad2, fibroblast activation protein, glioblastoma, regulation of expression, seprase, signaling, transforming growth factor beta, tumor microenvironment,
• MeSH
• endopeptidasy genetika   metabolismus   MeSH
• fluorescenční protilátková technika MeSH
• fosforylace MeSH
• glioblastom etiologie   metabolismus   patologie   MeSH
• imunohistochemie MeSH
• kultivované buňky MeSH
• lidé MeSH
• membránové proteiny genetika   metabolismus   MeSH
• nádorové buněčné linie MeSH
• nádorové mikroprostředí účinky léků   genetika   MeSH
• regulace genové exprese u nádorů * účinky léků   MeSH
• transformující růstový faktor beta1 metabolismus   farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• endopeptidasy MeSH
• fibroblast activation protein alpha MeSH Prohlížeč
• membránové proteiny MeSH
• TGFB1 protein, human MeSH Prohlížeč
• transformující růstový faktor beta1 MeSH