Identification of proteases associated with glioblastoma and their modulation by interferon-gamma signaling

Glioblastoma is a lethal primary brain tumor that is therapeutically challenging due to its rapid progression. Interferon-gamma (IFN-γ) signaling is altered in glioblastoma. Moreover, proteolytic enzymes, known as proteases, have been linked to the invasive growth of cancerous cells. In this study, we aimed to identify a glioblastoma-associated protease group and to determine its potential connection with IFN-γ signaling. Using cancer expression databases, we analyzed the differential expression of 35 proteases in glioblastoma and healthy brain tissue, and the relevance of their deregulation to patient survival. We also explored correlations between IFN-γ signaling element expression and upregulated proteases in glioblastoma. Additionally, we analyzed the effect of IFN-γ on the levels of these 35 proteases using a protein microarray and found that cathepsin L (CTSL) was upregulated by IFN-γ. Then, we analyzed the modulation of CTSL by IFN-γ in glioblastoma cells using dot blot, western blot, and immunofluorescence assays. We identified 11 proteases (cathepsin B, Z, C, S (CTSB, CTSZ, CTSC, CTSS), matrix metalloproteinase 2, 7, 9 (MMP2, MMP7, MMP9), a disintegrin and metalloproteinase 9 (ADAM9), urokinase-type plasminogen activator (PLAU), presenilin 1 (PSEN1), and CTSL that were upregulated in glioblastoma tissue compared to healthy brain tissue. The expression of specific elements of the IFN-γ pathway correlated with the expression of some of these proteases in glioblastoma samples. Moreover, IFN-γ affected the intracellular and extracellular levels of proteases (four were upregulated and six were downregulated) in glioblastoma-derived cells. Hence, IFN-γ signaling may play a role in glioblastoma by regulating the expression of some proteases. The CTSL protease was upregulated by IFN-γ and was associated with poor glioblastoma prognoses. Thus, we revealed a protease profile (ADAM9, CTSB, MMP7, CTSC, CTSL, MMP9, and PLAU) associated with glioblastoma progression and further demonstrated that CTSL is regulated by IFN-γ in glioblastoma cells. These results establish a link between IFN-γ signaling and protease regulation in glioblastoma.