Abstract 923: Interrelations between roles of phospholipase C-gamma 1 inhibition, mTOR and glycolytic enzymes in growth and survival of glioblastoma cells

Abstract Glioblastoma multiforme (GBM) is a deadly and a frequently occurring brain tumor in humans. Patients with this disease survive on an average for 12-14 months after diagnosis. Conventional approaches to treat the cancer are not effective in improving patient survival. Thus, it is imperative to seek new drug targets and therapies that could effectively treat brain tumors and enhance patient survival. Phospholipase C-gamma 1 (PLCα1) plays an important role in regulating intracellular calcium stores and acts as a point of convergence in several cell signaling cascades. Inhibition of PLCα1 is known to decrease cell differentiation, invasion and motility in several cancers. We previously demonstrated inhibition of PLCα1 blocks invasion of glioma cells. In this study, we investigated the effects of PLCα1 inhibition on cell viability, cell signaling and metabolism in brain tumor (U-87 MG) cells. We investigated the hypothesis that inhibition of PLCα1 blocks cellular progression of U-87 MG. U73122, an inhibitor of PLCα1, induced a dose-related decrease in survival of U-87 MG cells, with a maximal effect at 2 µM: this finding correlated with the U73122-induced decrease in expression of lactate dehydrogenase, a protein important in U-87 MG cell survival and metabolism. Moreover, U73122 was effective in enhancing the cytotoxic potential of temozolomide, a modestly effective drug used currently for the treatment of glioblastoma. Western blot analysis of U-87 MG cells treated with U73122 at concentrations between 0.5 and 2 µM showed biphasic effects on expression of phospho-ERK and mTOR, proteins involved in PLCα1 signaling as well as hexokinase II, an important glycolytic enzyme. Employing 1H-[13C]-NMR spectroscopy, we noted that treatment with 2 µM U73122 for 72 hours induced increased glycolytic flux in U-87 MG cells. Thus, our results suggest important mechanistic interrelations between PLCα1 signaling and roles of mTOR and glycolytic enzymes in regulating survival of brain tumor cells. Furthermore, our results also suggest that inhibition of PLCα1 may be exploited in combination with conventional therapies in treating patients with glioblastoma to improve their outcome. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 923. doi:1538-7445.AM2012-923</jats:p

Rates of pyruvate carboxylase, glutamate and GABA neurotransmitter cycling, and glucose oxidation in multiple brain regions of the awake rat using a combination of [2-¹³C]/[1-¹³C]glucose infusion and ¹H-[¹³C]NMR <i>ex vivo</i>

Anaplerosis occurs predominately in astroglia through the action of pyruvate carboxylase (PC). The rate of PC (Vpc) has been reported for cerebral cortex (or whole brain) of awake humans and anesthetized rodents, but regional brain rates remain largely unknown and, hence, were subjected to investigation in the current study. Awake male rats were infused with either [2-13C]glucose or [1-13C]glucose (n = 27/30) for 8, 15, 30, 60 or 120 min, followed by rapid euthanasia with focused-beam microwave irradiation to the brain. Blood plasma and extracts of cerebellum, hippocampus, striatum, and cerebral cortex were analyzed by 1H-[13C]-NMR to establish 13C-enrichment time courses for glutamate-C4,C3,C2, glutamine-C4,C3, GABA-C2,C3,C4 and aspartate-C2,C3. Metabolic rates were determined by fitting a three-compartment metabolic model (glutamatergic and GABAergic neurons and astroglia) to the eighteen time courses. Vpc varied by 44% across brain regions, being lowest in the cerebellum (0.087 ± 0.004 µmol/g/min) and highest in striatum (0.125 ± 0.009) with intermediate values in cerebral cortex (0.106 ± 0.005) and hippocampus (0.114 ± 0.005). Vpc constituted 13–19% of the oxidative glucose consumption rate. Combination of cerebral cortical data with literature values revealed a positive correlation between Vpc and the rates of glutamate/glutamine-cycling and oxidative glucose consumption, respectively, consistent with earlier observations. </jats:p

sj-xls-1-jcb-10.1177_0271678X221074211 - Supplemental material for Rates of pyruvate carboxylase, glutamate and GABA neurotransmitter cycling, and glucose oxidation in multiple brain regions of the awake rat using a combination of [2-¹³C]/[1-¹³C]glucose infusion and ¹H-[¹³C]NMR <i>ex vivo</i>

Supplemental material, sj-xls-1-jcb-10.1177_0271678X221074211 for Rates of pyruvate carboxylase, glutamate and GABA neurotransmitter cycling, and glucose oxidation in multiple brain regions of the awake rat using a combination of [2-13C]/[1-13C]glucose infusion and 1H-[13C]NMR ex vivo by Laura M McNair, Graeme F Mason, Golam MI Chowdhury, Lihong Jiang, Xiaoxian Ma, Douglas L Rothman, Helle S Waagepetersen and Kevin L Behar in Journal of Cerebral Blood Flow & Metabolism</p

sj-pdf-2-jcb-10.1177_0271678X221074211 - Supplemental material for Rates of pyruvate carboxylase, glutamate and GABA neurotransmitter cycling, and glucose oxidation in multiple brain regions of the awake rat using a combination of [2-¹³C]/[1-¹³C]glucose infusion and ¹H-[¹³C]NMR <i>ex vivo</i>

Supplemental material, sj-pdf-2-jcb-10.1177_0271678X221074211 for Rates of pyruvate carboxylase, glutamate and GABA neurotransmitter cycling, and glucose oxidation in multiple brain regions of the awake rat using a combination of [2-13C]/[1-13C]glucose infusion and 1H-[13C]NMR ex vivo by Laura M McNair, Graeme F Mason, Golam MI Chowdhury, Lihong Jiang, Xiaoxian Ma, Douglas L Rothman, Helle S Waagepetersen and Kevin L Behar in Journal of Cerebral Blood Flow & Metabolism</p

Long-range ordered vertical III-nitride nano-cylinder arrays via

In this work, we demonstrate vertical GaN, AlN, and InN hollow nano-cylindrical arrays (HNCs) grown on Si substrates using anodized aluminum oxide (AAO) membrane templated lowerature plasma-assisted atomic layer deposition (PA-ALD). III-Nitride HNCs have been characterized for their structural, chemical, surface, and optical properties. The material properties of nanostructured III-nitride materials have been compared with the thin-film counterparts which were also grown using PA-ALD. Our results revealed that long-range ordered arrays of III nitride HNCs were successfully integrated on Si substrates and possess hexagonal polycrystalline wurtzite crystalline structure. Such long-range ordered wafer-scale III-nitride nanostructures might be potentially used in piezotronic sensing, energy harvesting, resistive memory, flexible and wearable electronics, III-nitride photovoltaics, and (photo)catalysis