Mammalian target of rapamycin complex 1 activation sensitizes human glioma cells to hypoxia-induced cell death

Thiepold, Anna-Luisa; Lorenz, Nadja I.; Foltyn, Martha; Engel, Anna L; Divé, Iris; Urban, H.; Heller, Sonja; Bruns, Ines; Hofmann, Ute; Dröse, Stefan; Harter, Patrick N.; Mittelbronn, Michel; Steinbach, Joachim P.; Ronellenfitsch, Michael

doi:10.1093/brain/awx196

Cited by 36 publications

(78 citation statements)

References 55 publications

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“…Glucose and lactate concentrations were measured in cell-free supernatants with a biochemistry analyzer Hitachy 917 (Roche). For the analysis of oxygen consumption, cultured cells were overlaid with paraffin oil and oxygen concentrations were measured every 15 min utilizing a fluorescence-based assay with a sensor at the bottom of each well (Oxodish, PreSens), as previously described (27).…”

Section: Measurement Of Glucose Lactate and Atp Concentrationsmentioning

confidence: 99%

“…Glucose and oxygen concentrations are two decisive determinants in cerebral ischemic lesions. Therefore, the present study first employed an established paradigm (26)(27)(28) of severe hypoxia with 0.1% oxygen, varied glucose concentrations and complete glutamine deprivation. cell death was measured by flow cytometry [fluorescence-activated cell sorting (FAcS)] as a percentage of PI-positive cells (for exemplary PI FAcS plots please see Fig.…”

Section: Inhibition Of Glycolysis and Activation Of Ampk Protects Svgmentioning

confidence: 99%

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AMPK activation protects astrocytes from hypoxia‑induced cell death

Strecker

Luger

et al. 2020

Int J Mol Med

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Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a major cellular energy sensor that is activated by an increase in the AMP/adenosine triphosphate (ATP) ratio. This causes the initiation of adaptive cellular programs, leading to the inhibition of anabolic pathways and increasing ATP synthesis. AMPK indirectly inhibits mammalian target of rapamycin (mTOR) complex 1 (mTORc1), a serine/threonine kinase and central regulator of cell growth and metabolism, which integrates various growth inhibitory signals, such as the depletion of glucose, amino acids, ATP and oxygen. While neuroprotective approaches by definition focus on neurons, that are more sensitive under cell stress conditions, astrocytes play an important role in the cerebral energy homeostasis during ischemia. Therefore, the protection of astrocytic cells or other glial cells may contribute to the preservation of neuronal integrity and function. In the present study, it was thus hypothesized that a preventive induction of energy deprivation-activated signaling pathways via AMPK may protect astrocytes from hypoxia and glucose deprivation. Hypoxia-induced cell death was measured in a paradigm of hypoxia and partial glucose deprivation in vitro in the immortalized human astrocytic cell line SVG. Both the glycolysis inhibitor 2-deoxy-d-glucose (2dG) and the AMPK activator A-769662 induced the phosphorylation of AMPK, resulting in mTORc1 inhibition, as evidenced by a decrease in the phosphorylation of the target ribosomal protein S6 (RPS6). Treatment with both 2dG and A-769662 also decreased glucose consumption and lactate production. Furthermore, A-769662, but not 2dG induced an increase in oxygen consumption, possibly indicating a more efficient glucose utilization through oxidative phosphorylation. Hypoxia-induced cell death was profoundly reduced by treatment with 2dG or A-769662. On the whole, the findings of the present study demonstrate, that AMPK activation via 2dG or A-769662 protects astrocytes under hypoxic and glucose-depleted conditions.

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Section: Measurement Of Glucose Lactate and Atp Concentrationsmentioning

confidence: 99%

Section: Inhibition Of Glycolysis and Activation Of Ampk Protects Svgmentioning

confidence: 99%

AMPK activation protects astrocytes from hypoxia‑induced cell death

Strecker

Luger

et al. 2020

Int J Mol Med

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“…LNT-229 cells were a kind gift of Dr. N de Tribolet (Lausanne, Switzerland) [37] and were cultured in high glucose Dulbecco’s modified eagle medium (DMEM) (4.5 g/L corresponding to 24.975 mM glucose) containing 10% foetal calf serum (FCS) (Biochrom KG, Berlin, Germany), 100 IU/mL penicillin, and 100 µg/mL streptomycin (Life Technologies, Karlsruhe, Germany) at 37 °C in a cell culture incubator (Binder, Tuttlingen, Germany) under a CO 2 atmosphere (5%). The experiments were performed in serum free DMEM, with 2 mM of glucose and an incubation time of 6 h.…”

Section: Methodsmentioning

confidence: 99%

“…The cell-free supernatant was collected and the glucose and lactate concentrations were measured using the biochemistry analyzer Hitachi 917 [37]. …”

Section: Methodsmentioning

confidence: 99%

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Rescue of 2-Deoxyglucose Side Effects by Ketogenic Diet

Voß

Lorenz

Luger

et al. 2018

IJMS

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Cancer metabolism is characterized by extensive glucose consumption through aerobic glycolysis. No effective therapy exploiting this cancer trait has emerged so far, in part, due to the substantial side effects of the investigated drugs. In this study, we examined the side effects of a combination of isocaloric ketogenic diet (KD) with the glycolysis inhibitor 2-deoxyglucose (2-DG). Two groups of eight athymic nude mice were either fed a standard diet (SD) or a caloric unrestricted KD with a ratio of 4 g fat to 1 g protein/carbohydrate. 2-DG was investigated in commonly employed doses of 0.5 to 4 g/kg and up to 8 g/kg. Ketosis was achieved under KD (ketone bodies: SD 0.5 ± 0.14 mmol/L, KD 1.38 ± 0.28 mmol/L, p < 0.01). The intraperitoneal application of 4 g/kg of 2-DG caused a significant increase in blood glucose, which was not prevented by KD. Sedation after the 2-DG treatment was observed and a behavioral test of spontaneous motion showed that KD reduced the sedation by 2-DG (p < 0.001). A 2-DG dose escalation to 8 g/kg was lethal for 50% of the mice in the SD and for 0% of the mice in the KD group (p < 0.01). A long-term combination of KD and an oral 1 or 2 g 2-DG/kg was well-tolerated. In conclusion, KD reduces the sedative effects of 2-DG and dramatically increases the maximum tolerated dose of 2-DG. A continued combination of KD and anti-glycolytic therapy is feasible. This is, to our knowledge, the first demonstration of increased tolerance to glycolysis inhibition by KD.

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An AMP‐activated protein kinase‐PGC‐1α axis mediates metabolic plasticity in glioblastoma

Sauer,

Kueckelhaus,

Lorenz

et al. 2024

Clinical & Translational Med

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Glioblastoma, the most frequent primary malignant brain tumour in adults, is characterised by profound yet dynamic hypoxia and nutrient depletion. To sustain survival and proliferation, tumour cells are compelled to acquire metabolic plasticity with the induction of adaptive metabolic programs. Here, we interrogated the pathways necessary to enable processing of nutrients other than glucose.We employed genetic approaches (stable/inducible overexpression, CRISPR/Cas9 knockout), pharmacological interventions with a novel inhibitor of AMP‐activated protein kinase (AMPK) in glioblastoma cell culture systems and a proteomic approach to investigate mechanisms of metabolic plasticity. Moreover, a spatially resolved multiomic analysis was employed to correlate the gene expression pattern of PGC‐1α with the local metabolic and genetic architecture in human glioblastoma tissue sections.A switch from glucose to alternative nutrients triggered an activation of AMPK, which in turn activated PGC‐1α‐dependent adaptive programs promoting mitochondrial metabolism. This sensor‐effector mechanism was essential for metabolic plasticity with both functional AMPK and PGC‐1α necessary for survival and growth of cells under nonglucose nutrient sources. In human glioblastoma tissue specimens, PGC‐1α‐expression correlated with nonhypoxic tumour niches defining a specific metabolic compartment.Our findings reveal a cell‐intrinsic nutrient sensing and switching mechanism. The exposure to alternative fuels triggers a starvation signal that subsequently is passed on via AMPK and PGC‐1α to induce adaptive programs necessary for broader spectrum nutrient metabolism. The integration of spatially resolved transcriptomic data confirms the relevance of PGC‐1α especially in nonhypoxic tumour regions. Thus, the AMPK‐PGC‐1α axis is a candidate for therapeutic inhibition in glioblastoma.Key Points/Highlights AMPK activation induces PGC‐1α expression in glioblastoma during nutrient scarcity. PGC‐1α enables metabolic plasticity by facilitating metabolism of alternative nutrients in glioblastoma. PGC‐1α expression is inversely correlated with hypoxic tumour regions in human glioblastomas.

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Mammalian target of rapamycin complex 1 activation sensitizes human glioma cells to hypoxia-induced cell death

Cited by 36 publications

References 55 publications

AMPK activation protects astrocytes from hypoxia‑induced cell death

AMPK activation protects astrocytes from hypoxia‑induced cell death

Rescue of 2-Deoxyglucose Side Effects by Ketogenic Diet

An AMP‐activated protein kinase‐PGC‐1α axis mediates metabolic plasticity in glioblastoma

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