A caspase-independent necrotic death is activated by isopeptidase inhibitor G5 in apoptosis-resistant glioblastoma cells

The regulation of necrotic death and its relevance in anti-cancer therapy are largely unknown. Here we have investigated the pro-apoptotic and pro-necrotic activities of two ubiquitin-proteasome system inhibitors (UPSIs): bortezomib and G5. The present study points out that the glioblastoma cell lines U87MG and T98G are useful models to study the susceptibility to apoptosis and necrosis in response to UPSIs. U87MG cells are resistant to apoptosis induced by bortezomib and G5 but susceptible to necrosis induced by G5. On the opposite T98G cells are susceptible to apoptosis induced by both inhibitors but show some resistance to G5-induced necrosis. By comparing the transcriptional profiles of the two cell lines, we have found that the resistance to G5-induced necrosis could arise from differences in glutathione synthesis/utilization and in the microenvironment. In particular collagen IV, which is highly expressed in T98G cells, and fibronectin, whose adhesive function is counteracted by tenascin-C in U87MG cells, can restrain the necrotic response to G5. Collectively, our results provide an initial characterization of the molecular signals governing cell death by necrosis in glioblastoma cell lines.

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Foti C, Florean C, Pezzutto A, Roncaglia P, Tomasella A, Gustincich S, Brancolini C