Fibroblasts, the most abundant cell type in the human body, play crucial roles in biological processes such as inflammation and cancer progression. They originate from the mesoderm or neural-crest-derived ectomesenchyme. Ectomesenchyme-derived fibroblasts contribute to facial formation and do not express HOX genes during development. The expression and role of the HOX genes in adult fibroblasts is not known. We investigated whether the developmental pattern persists into adulthood and under pathological conditions, such as cancer. We collected adult fibroblasts of ectomesenchymal and mesodermal origins from distinct body parts. The isolated fibroblasts were characterised by immunocytochemistry, and their transcriptome was analysed by whole genome profiling. Significant differences were observed between normal fibroblasts from the face (ectomesenchyme) and upper limb (mesoderm), particularly in genes associated with limb development, including HOX genes, e.g., HOXA9 and HOXD9. Notably, the pattern of HOX gene expression remained consistent postnatally, even in fibroblasts from pathological tissues, including inflammatory states and cancer-associated fibroblasts from primary and metastatic tumours. Therefore, the distinctive HOX gene expression pattern can serve as an indicator of the topological origin of fibroblasts. The influence of cell position and HOX gene expression in fibroblasts on disease progression warrants further investigation.

• Keywords
• Cancer-associated fibroblasts, Ectomesenchyme, Expression pattern, Fibroblasts, Homeobox genes, Mesoderm,
• MeSH
• Adult MeSH
• Fibroblasts * metabolism   cytology   MeSH
• Genes, Homeobox * MeSH
• Homeodomain Proteins * genetics   MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Mesoderm * metabolism   cytology   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Homeodomain Proteins * 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.

• Keywords
• collagen type I, extracellular matrix proteins, fibronectin, glioblastoma, pericytes, proteomics,
• MeSH
• Endopeptidases MeSH
• Extracellular Matrix * metabolism   pathology   MeSH
• Fibronectins * metabolism   MeSH
• Glioblastoma pathology   metabolism   MeSH
• Glioma * pathology   metabolism   MeSH
• Collagen Type I metabolism   MeSH
• Humans MeSH
• Membrane Proteins metabolism   MeSH
• Cell Line, Tumor MeSH
• Tumor Microenvironment physiology   MeSH
• Brain Neoplasms * pathology   metabolism   MeSH
• Pericytes * metabolism   pathology   MeSH
• Cell Movement physiology   MeSH
• Serine Endopeptidases metabolism   MeSH
• Gelatinases metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Endopeptidases MeSH
• fibroblast activation protein alpha MeSH Browser
• Fibronectins * MeSH
• Collagen Type I MeSH
• Membrane Proteins MeSH
• Serine Endopeptidases MeSH
• Gelatinases 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.

• Keywords
• 5-ALA, activity-based probes, cathepsin, fluorescence-guided surgery, glioblastoma, mouse models, oncology,
• MeSH
• Spectroscopy, Near-Infrared MeSH
• Cysteine MeSH
• Glioblastoma * diagnostic imaging   metabolism   surgery   MeSH
• Glioma MeSH
• Heterografts MeSH
• Aminolevulinic Acid * chemistry   metabolism   MeSH
• Models, Animal MeSH
• Molecular Probes * metabolism   MeSH
• Brain diagnostic imaging   metabolism   surgery   MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Cell Line, Tumor MeSH
• Peptide Hydrolases * metabolism   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Names of Substances
• Cysteine MeSH
• Aminolevulinic Acid * MeSH
• Molecular Probes * MeSH
• Peptide Hydrolases * MeSH

Cancer-associated fibroblasts (CAFs) are an essential component of the tumour microenvironment. They represent a heterogeneous group of cells that are under the control of cancer cells and can reversely influence the cancer cell population. They affect the cancer cell differentiation status, and the migration and formation of metastases. This is achieved through the production of the extracellular matrix and numerous bioactive factors. IL-6 seems to play the central role in the communication of noncancerous and cancer cells in the tumour. This review outlines the role of exosomes in cancer cells and cancer-associated fibroblasts. Available data on the exosomal cargo, which can significantly intensify interactions in the tumour, are summarised. The role of exosomes as mediators of the dialogue between cancer cells and cancer-associated fibroblasts is discussed together with their therapeutic relevance. The functional unity of the paracrine- and exosome-mediated communication of cancer cells with the tumour microenvironment represented by CAFs is worthy of attention.

• Keywords
• IL-6, cancer ecosystem, cancer microenvironment, cancer-associated fibroblast, exosome,
• MeSH
• Exosomes metabolism   MeSH
• Cancer-Associated Fibroblasts metabolism   MeSH
• Interleukin-6 metabolism   MeSH
• Humans MeSH
• Tumor Microenvironment MeSH
• Neoplasms metabolism   MeSH
• Paracrine Communication MeSH
• Cell Movement MeSH
• Cell Proliferation MeSH
• Gene Expression Regulation, Neoplastic MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• IL6 protein, human MeSH Browser
• Interleukin-6 MeSH