Complexity of proteomes has become intensively investigated. The detection of cathepsins, has relied on using the probes that incorporate reactive electrophilic moieties to modify a cysteine in the active site covalently. We first report on the activity-based probe targeting cathepsins and incorporating a photo inducible benzophenone group for covalent labelling. When tested, this probe selectively and specifically detected cathepsin L making the photo affinity labelling promising for developing selective protease probes.
Despite progress, glioblastoma remains a terminal disease and new therapeutic approaches are urgently needed. Cathepsin L inhibition appeared as a new therapeutic modality, where the mechanism of cathepsinL antiapoptotic activity needs to be resolved. We showed that in U87 GBM cells cathepsin L is present in the nucleus, where regulates the p53 dependent transcription of caspases 3/7. Since p53 is often mutated in GBM, these findings need to be considered at using cathepsin L inhibition for GBM therapy, as such adjuvant therapy may work efficiently only in p53 wt subpopulation of GBM patients.
Resveratrol-a phytoalexin elicits cell cycle arrest, apoptosis and senescence. With U87MG cells and primary glioblastoma cells we demonstrate, that its chronical administration elicits not only cell growth arrest, but limits cell migration and invasion and promoted longlasting morphological changes reminiscent of a mature glial phenotype. In the cells that survived chronic administration of resveratrol, the expression of differentiation markers of mature glial cells and of neurons, was rreversibly increased. These findings support the introduction of resveratrol in GBM chemotherapy.
Cysteine cathepsins play an important role in infiltrative growth of gliomas. Their activity is elevated in invasive GBM cells, in part due to attenuation of their endogenous inhibitors, the cystatins. To investigate this hypothesis in vivo, we established U87-MG xenografts in NOD/SCID-eGFP mice. We confirmed that tumour growth correlated with an elevated enzymatic activity of cathepsins and reversely with the inhibitors stefins. Analysing primary human biopsies, we were first to reveal that significantly elevated StefA mRNA level is highly significant for GBM patients' survival.
CD133 is a marker of glioblastoma (GBM) and normal neural stem cells (nNSC). We aimed to reveal whether the migratory potential and differentiation of stem cells is associated with CD133 expression and cathepsin proteases (Cats). The study confirms CD133 prognostic value for the survival of GBM patients. We demonstrated that nNSCs as well as differentiated malignant GBM cells have higher invasion potential and invade the collagen matrix in a mode different from that of CD133+ GBM stem cells. Results could be utilized for designing new therapeutics based on protease inhibitors.