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

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.

• Keywords
• Smad2, fibroblast activation protein, glioblastoma, regulation of expression, seprase, signaling, transforming growth factor beta, tumor microenvironment,
• MeSH
• Endopeptidases genetics   metabolism   MeSH
• Fluorescent Antibody Technique MeSH
• Phosphorylation MeSH
• Glioblastoma etiology   metabolism   pathology   MeSH
• Immunohistochemistry MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Membrane Proteins genetics   metabolism   MeSH
• Cell Line, Tumor MeSH
• Tumor Microenvironment drug effects   genetics   MeSH
• Gene Expression Regulation, Neoplastic * drug effects   MeSH
• Transforming Growth Factor beta1 metabolism   pharmacology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Endopeptidases MeSH
• fibroblast activation protein alpha MeSH Browser
• Membrane Proteins MeSH
• TGFB1 protein, human MeSH Browser
• Transforming Growth Factor beta1 MeSH

Interleukin-6 (IL-6) is a cytokine with multifaceted effects playing a remarkable role in the initiation of the immune response. The increased level of this cytokine in the elderly seems to be associated with the chronic inflammatory setting of the microenvironment in aged individuals. IL-6 also represents one of the main signals in communication between cancer cells and their non-malignant neighbours within the tumour niche. IL-6 also participates in the development of a premetastatic niche and in the adjustment of the metabolism in terminal-stage patients suffering from a malignant disease. IL-6 is a fundamental factor of the cytokine storm in patients with severe COVID-19, where it is responsible for the fatal outcome of the disease. A better understanding of the role of IL-6 under physiological as well as pathological conditions and the preparation of new strategies for the therapeutic control of the IL-6 axis may help to manage the problems associated with the elderly, cancer, and serious viral infections.

• Keywords
• COVID-19, IL-6, ageing, cancer ecosystem, cancer-associated fibroblasts, cytokine, cytokine storm, tumour microenvironment,
• MeSH
• COVID-19 MeSH
• Interleukin-6 genetics   metabolism   MeSH
• Coronavirus Infections metabolism   pathology   MeSH
• Humans MeSH
• Neoplasms metabolism   pathology   MeSH
• Pandemics MeSH
• Signal Transduction MeSH
• Aging metabolism   pathology   MeSH
• Pneumonia, Viral metabolism   pathology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Interleukin-6 MeSH