ABSTRACT
BACKGROUND: Glioblastoma (GBM) is a highly aggressive tumor with unmet therapeutic needs, which can be explained by extensive intra-tumoral heterogeneity and plasticity. In this study, we aimed to investigate the specific metabolic features of Glioblastoma stem cells (GSC), a rare tumor subpopulation involved in tumor growth and therapy resistance. METHODS: We conducted comprehensive analyses of primary patient-derived GBM cultures and GSC-enriched cultures of human GBM cell lines using state-of-the-art molecular, metabolic and phenotypic studies. RESULTS: We showed that GSC-enriched cultures display distinct glycolytic profiles compared with differentiated tumor cells. Further analysis revealed that GSC relies on pyruvate carboxylase activity for survival and self-renewal capacity. Interestingly, inhibition of pyruvate carboxylase led to GSC death, particularly when the glutamine pool was low, and increased differentiation. Finally, while GSC displayed resistance to the chemotherapy drug etoposide, genetic or pharmacological inhibition of pyruvate carboxylase restored etoposide sensitivity in GSC, both in vitro and in orthotopic murine models. CONCLUSION: Our findings demonstrate the critical role of pyruvate carboxylase in GSC metabolism, survival and escape to etoposide. They also highlight pyruvate carboxylase as a therapeutic target to overcome therapy resistance in GBM.
ABSTRACT
Centriolar satellites are multiprotein aggregates that orbit the centrosome and govern centrosome homeostasis and primary cilia formation. In contrast to the scaffold PCM1, which nucleates centriolar satellites and has been linked to microtubule dynamics, autophagy, and intracellular trafficking, the functions of its interactant CEP131 beyond ciliogenesis remain unclear. Using a knockout strategy in a non-ciliary T-cell line, we report that, although dispensable for centriolar satellite assembly, CEP131 participates in optimal tubulin glycylation and polyglutamylation, and microtubule regrowth. Our unsupervised label-free proteomic analysis by quantitative mass spectrometry further uncovered mitochondrial and apoptotic signatures. CEP131-deficient cells showed an elongated mitochondrial network. Upon cell death inducers targeting mitochondria, knockout cells displayed delayed cytochrome c release from mitochondria, subsequent caspase activation, and apoptosis. This mitochondrial permeabilization defect was intrinsic, and replicable in vitro with isolated organelles. These findings extend CEP131 functions to life-and-death decisions and propose ways to interfere with mitochondrial apoptosis.
