Lower Lactate Levels and Lower Intracellular pH in Patients with IDH-Mutant versus Wild-Type Gliomas.

BACKGROUND AND PURPOSE: Preclinical evidence points toward a metabolic reprogramming in isocitrate dehydrogenase (IDH) mutated tumor cells with down-regulation of the expression of genes that encode for glycolytic metabolism. We noninvasively investigated lactate and Cr concentrations, as well as intracellular pH using 1H/phosphorus 31 (31P) MR spectroscopy in a cohort of patients with gliomas. MATERIALS AND METHODS: Thirty prospectively enrolled, mostly untreated patients with gliomas met the spectral quality criteria (World Health Organization II [n = 7], III [n = 16], IV [n = 7]; IDH-mutant [n = 23]; IDH wild-type [n = 7]; 1p/19q codeletion [n = 9]). MR imaging protocol included 3D 31P chemical shift imaging and 1H single-voxel spectroscopy (point-resolved spectroscopy sequence at TE = 30 ms and TE = 97 ms with optimized echo spacing for detection of 2-hydroxyglutarate) from the tumor area. Values for absolute metabolite concentrations were calculated (phantom replacement method). Intracellular pH was determined from 31P chemical shift imaging. RESULTS: At TE = 97 ms, lactate peaks can be fitted with little impact of lipid/macromolecule contamination. We found a significant difference in lactate concentrations, lactate/Cr ratios, and intracellular pH when comparing tumor voxels of patients with IDH-mutant with those of patients with IDH wild-type gliomas, with reduced lactate levels and near-normal intracellular pH in patients with IDH-mutant gliomas. We additionally found evidence for codependent effects of 1p/19q codeletion and IDH mutations with regard to lactate concentrations for World Health Organization tumor grades II and III, with lower lactate levels in patients exhibiting the codeletion. There was no statistical significance when comparing lactate concentrations between IDH-mutant World Health Organization II and III gliomas. CONCLUSIONS: We found indirect evidence for metabolic reprogramming in IDH-mutant tumors with significantly lower lactate concentrations compared with IDH wild-type tumors and a near-normal intracellular pH.

BCL-xL: time-dependent dissociation between modulation of apoptosis and invasiveness in human malignant glioma cells.

Conditionally BCL-xL-overexpressing LNT-229 Tet-On glioma cell clones were generated to investigate whether the 'antiapoptosis phenotype' and the 'motility phenotype' mediated by BCL-2 family proteins in glioma cells could be separated. BCL-xL induction led to an immediate and concentration-dependent protection of LNT-229 cells from apoptosis. BCL-xL induction for up to 3 days did not result in altered invasiveness. In contrast, long-term BCL-xL induction for 21 days resulted in increased transforming growth factor-beta2 expression, and in metalloproteinase-2 and -14 dependent, but integrin independent, increased invasiveness. Withdrawal of doxycycline (Dox) abolished the protection from apoptosis whereas the 'invasion phenotype' remained stable. Dox stimulation of BCL-xL-inducible LNT-229 cells conferred infiltrative growth to BCL-xL-positive glioma cells in vivo and reduced the survival of tumor-bearing mice. These data allow to dissect a direct antiapoptotic action of BCL-xL from an indirect effect, presumably mediated by altered gene expression, which modifies tumor cell invasiveness in vitro and in vivo.

Adult onset glutaric aciduria type I presenting with a leukoencephalopathy.

Glutaric aciduria type I usually presents with an acute metabolic crisis during infancy. The authors report a previously healthy 19-year-old woman who presented with recurrent headaches, oculomotor symptoms, and a severe leukoencephalopathy on MRI. The diagnosis was made by urinary organic acid analysis and confirmed by enzyme studies. Genetic analysis revealed compound heterozygosity with a deletion c.219delC in exon 3 and a novel missense mutation R132G in exon 5 of the glutaryl CoA dehydrogenase (GCDH) gene.

Synthesis of cytochrome C oxidase 2: a p53-dependent metabolic regulator that promotes respiratory function and protects glioma and colon cancer cells from hypoxia-induced cell death.

P53 has an important role in the processing of starvation signals. P53-dependent molecular mediators of the Warburg effect reduce glucose consumption and promote mitochondrial function. We therefore hypothesized that the retention of wild-type p53 characteristic of primary glioblastomas limits metabolic demands induced by deregulated signal transduction in the presence of hypoxia and nutrient depletion. Here we report that short hairpin RNA-mediated gene suppression of wild-type p53 or ectopic expression of mutant temperature-sensitive dominant-negative p53(V135A) increased glucose consumption and lactate production, decreased oxygen consumption and enhanced hypoxia-induced cell death in p53 wild-type human glioblastoma cells. Similarly, genetic knockout of p53 in HCT116 colon carcinoma cells resulted in reduced respiration and hypersensitivity towards hypoxia-induced cell death. Further, wild-type p53 gene silencing reduced the expression of synthesis of cytochrome c oxidase 2 (SCO2), an effector necessary for respiratory chain function. An SCO2 transgene reverted the metabolic phenotype and restored resistance towards hypoxia in p53-depleted and p53 mutant glioma cells in a rotenone-sensitive manner, demonstrating that this effect was dependent on intact oxidative phosphorylation. Supplementation with methyl-pyruvate, a mitochondrial substrate, rescued p53 wild-type but not p53 mutant cells from hypoxic cell death, demonstrating a p53-mediated selective aptitude to metabolize mitochondrial substrates. Further, SCO2 gene silencing in p53 wild-type glioma cells sensitized these cells towards hypoxia. Finally, lentiviral gene suppression of SCO2 significantly enhanced tumor necrosis in a subcutaneous HCT116 xenograft tumor model, compatible with impaired energy metabolism in these cells. These findings demonstrate that glioma and colon cancer cells with p53 wild-type status can skew the Warburg effect and thereby reduce their vulnerability towards tumor hypoxia in an SCO2-dependent manner. Targeting SCO2 may therefore represent a valuable strategy to enhance sensitivity towards hypoxia and may complement strategies targeting glucose metabolism.

Complementary therapy use in patients with glioma: an observational study.

OBJECTIVE: Despite novel multimodal therapeutic approaches, the vast majority of glial tumors are not curable. Patients may search for complementary therapies in order to contribute to the fight against their disease or to relieve symptoms induced by their brain tumor. The extent of the use of complementary or alternative therapies, the patients' rationale behind it, and the cost of complementary therapy for gliomas are not known. We used a questionnaire and the database of the German Glioma Network to evaluate these questions. METHODS: A total of 621 questionnaires were available for evaluation from patients with glial tumors of WHO grades II to grade IV. The patients were recruited from 6 neuro-oncologic centers in Germany. Complementary therapy was defined as methods or compounds not used in routine clinical practice and not scientifically evaluated. RESULTS: Forty percent of the responding patients reported the use of complementary therapies. Significant differences between the group of complementary therapy users and nonusers were seen with respect to age (younger > older), gender (female > male), and education (high education level > low education level). The motivation for complementary therapy use was not driven by unsatisfactory clinical care by the neuro-oncologists, but by the wish to add something beneficial to the standard of care. CONCLUSIONS: In clinical practice, patients' use of complementary therapies may be largely overseen and underestimated. The major motivation is not distrust in conventional therapies. Neuro-oncologists should be aware of this phenomenon and encourage an open but critical dialogue with their patients.

Adenoviral expression of XIAP antisense RNA induces apoptosis in glioma cells and suppresses the growth of xenografts in nude mice.

The expression of inhibitor of apoptosis (IAP) family members contributes to the resistance of human cancers to apoptosis induced by radiotherapy and chemotherapy. We report that the infection of malignant glioma cells and several other tumor cell lines with adenoviruses encoding antisense RNA to X-linked IAP (XIAP) depletes endogenous XIAP levels and promotes global caspase activation and apoptosis. In contrast, non-neoplastic SV-FHAS human astrocytes and other non-neoplastic cells express XIAP at very low levels and resist these effects of adenovirus-expressing XIAP antisense RNA (Ad-XIAP-as). Caspase inhibitors such as z-Val-Ala-DL-Asp(OMe)-fluoromethylketone (zVAD-fmk) delay caspase processing and XIAP depletion, suggesting that XIAP depletion results both from antisense-mediated interference with protein synthesis and proteolytic cleavage by activated caspases. However, zVAD-fmk neither prevents nor delays cell death, indicating a caspase-independent pathway to cell death triggered by IAP depletion. Similarly, B-cell lymphoma-X(L) (BCL-X(L)) inhibits caspase activity, but fails to rescue from apoptosis. Loss of p65/nuclear factor-kappaB (NF-kappaB) protein and NF-kappaB activity is an early event triggered by Ad-XIAP-as and probably involved in Ad-XIAP-as-induced apoptosis. Finally, Ad-XIAP-as gene therapy induces cell death in intracranial glioma xenografts, prolongs survival in nude mice and may reduce tumorigenicity in synergy with Apo2L/TNF-related apoptosis-inducing ligand (TRAIL) in vivo. Altogether, these data define a powerful survival function for XIAP and reinforce its possible role as a therapeutic target in human glioma cells.

Selective potentiation of drug cytotoxicity by NSAID in human glioma cells: the role of COX-1 and MRP.

Here, we report that nonsteroidal anti-inflammatory drugs (NSAID) enhance the cytotoxic effects of doxorubicin and vincristine in T98G human malignant glioma cells. The cytotoxicity of BCNU, cisplatin, VM26, camptothecin, and cytarabine is unaffected by NSAID. No free radical formation is induced by doxorubicin or vincristine in the absence or presence of NSAID. Doxorubicin and vincristine cytotoxicity in the absence or presence of NSAID are unaffected by free radical scavengers. Functional inhibitors of phospholipase A2 (PLA2), such as dexamethasone and quinacrine, do not mimick the effects of NSAID. T98G cells, but not LN-18, LN-229, LN-308, or A172 glioma cells, express cyclooxygenase (COX-1) and NSAID do not modulate drug cytotoxicity in the other cell lines, except T98G. Thus, augmentation of doxorubicin and vincristine cytotoxicity by NSAID correlates with COX-1 expression. However, ectopic expression of COX-1 in LN-229 cells does not induce the phenotype of T98G cells, indicating that COX-1 inhibition does not mediate the effects of NSAID on drug cytotoxicity. In contrast, a multidrug resistance (MDR) phenotype due to expression of the multidrug resistance-associated protein (MRP) is most prominent in T98G cells and is amenable to modulation by indomethacin, suggesting that inhibition of MRP is at least in partly responsible for the potentiation of doxorubicin and vincristine cytotoxicity by NSAID.