Combination Treatment of Biochanin A and Atorvastatin Alters Mitochondrial Bioenergetics, Modulating Cell Metabolism and Inducing Cell Cycle Arrest in Pancreatic Cancer Cells.

BACKGROUND/AIM: Pancreatic cancer is an aggressive type of cancer, with a dismally low survival rate of <5%. FDA-approved drugs like gemcitabine have shown little therapeutic success, prolonging survival by a mere six months. Isoflavones, such as biochanin A and daidzein, are known to exhibit anti-cancer activity, whereas statins reportedly have anti-proliferative effects. This study investigated the effects of combination treatment of biochanin A and atorvastatin on pancreatic cancer cells. MATERIALS AND METHODS: Pancreatic cancer cells AsPC-1, PANC-1, and MIA PaCa-2 were procured from ATCC. The cell viability studies were carried out using MTT & cell count assays. Flow cytometry was used to study cell apoptosis whereas cell metabolism studies were carried out using the Seahorse Mito stress test and XF-PMP assay. The effects of treatment on cell signaling pathways & cell cycle associated proteins were investigated using western blot whereas invasiveness of cancer cells was evaluated using gelatin zymography. RESULTS: The combination treatment decreased the survival and enhanced pro-apoptotic responses compared to single treatments in the pancreatic cancer cells. In PANC-1 cells, the combination treatment decreased invasiveness, reduced expression of activated STAT3 and expression of critical mediators of cell cycle progression. Furthermore, the combination treatment induced a differential inhibition of respiratory complexes in the pancreatic cancer cells. CONCLUSION: The combination treatment of biochanin A and atorvastatin exerts enhanced anti-cancer effects, inducing apoptosis, down-regulating cell cycle associated proteins and invasiveness in pancreatic cancer cells and merits further investigation for new, improved treatments for pancreatic cancer.

Natural Products and Small Molecules Targeting Cellular Ceramide Metabolism to Enhance Apoptosis in Cancer Cells.

Molecular targeting strategies have been used for years in order to control cancer progression and are often based on targeting various enzymes involved in metabolic pathways. Keeping this in mind, it is essential to determine the role of each enzyme in a particular metabolic pathway. In this review, we provide in-depth information on various enzymes such as ceramidase, sphingosine kinase, sphingomyelin synthase, dihydroceramide desaturase, and ceramide synthase which are associated with various types of cancers. We also discuss the physicochemical properties of well-studied inhibitors with natural product origins and their related structures in terms of these enzymes. Targeting ceramide metabolism exhibited promising mono- and combination therapies at preclinical stages in preventing cancer progression and cemented the significance of sphingolipid metabolism in cancer treatments. Targeting ceramide-metabolizing enzymes will help medicinal chemists design potent and selective small molecules for treating cancer progression at various levels.

Co-Culturing Rat Dorsal Root Ganglion Neurons With Rat Schwann Cells Protects Them Against the Cytotoxic Effects of Silver and Gold Nanoparticles.

Previous studies using monotypic nerve cell cultures have shown that nanoparticles induced neurotoxic effects on nerve cells. Interactions between neurons and Schwann cells may protect against the neurotoxicity of nanoparticles. In this study, we developed a co-culture model consisting of immortalized rat dorsal root ganglion (DRG) neurons and rat Schwann cells and employed it to investigate our hypothesis that co-culturing DRG neurons with Schwann cells imparts protection on them against neurotoxicity induced by silver or gold nanoparticles. Our results indicated that neurons survived better in co-cultures when they were exposed to these nanoparticles at the higher concentrations compared to when they were exposed to these nanoparticles at the same concentrations in monotypic cultures. Synapsin I expression was increased in DRG neurons when they were co-cultured with Schwann cells and treated with or without nanoparticles. Glial fibrillary acidic protein (GFAP) expression was increased in Schwann cells when they were co-cultured with DRG neurons and treated with nanoparticles. Furthermore, we found co-culturing with Schwann cells stimulated neurofilament polymerization in DRG neurons and produced the morphological differentiation. Silver nanoparticles induced morphological disorganization in monotypic cultures. However, there were more cells displaying normal morphology in co-cultures than in monotypic cultures. All of these results suggested that co-culturing DRG neurons with Schwann cells imparted some protection on them against neurotoxicity induced by silver or gold nanoparticles, and altering the expression of neurofilament-L, synapsin I, and GFAP could account for the phenomenon of protection in co-cultures.

Pan HDACi Valproic Acid and Trichostatin A Show Apparently Contrasting Inflammatory Responses in Cultured J774A.1 Macrophages.

This study was initiated as an attempt to clarify some of the apparent conflicting data regarding the so-called anti-inflammatory versus proinflammatory properties of histone deacetylase inhibitors (HDACis). In cell culture, typically, chronic pretreatment with the HDACi valproic acid (VPA) and trichostatin A (TSA) exhibits an anti-inflammatory effect. However, the effect of acute treatment with VPA and TSA on the levels of inflammatory cytokines in J774A.1 macrophage cell line is unknown. Therefore, this study investigated the effect of acute treatment with VPA and TSA on levels of key inflammatory cytokines in maximally stimulated J774A.1 cells. J774A.1 macrophages were treated with either VPA or TSA for 1 h (acute treatment), followed by maximal stimulation with LPS + IFNγ for 24 h. ELISA was used to measure the levels of proinflammatory cytokines TNFα, NO and IL-1ß from the culture medium. Acute treatment with VPA showed a dose-dependent increase in levels of all three cytokines. Similar to VPA, TSA also showed a dose-dependent increase in levels of IL-1ß alone. This study sheds new light on the conflicting data in the literature that may partly be explained by acute or short-term exposure versus chronic or long-term exposure to HDACi.

Hydration and meal habits of physicians and medical learners: a literature review.

PURPOSE: Nutrition and hydration are important components of physician and medical learner well-being; meal-skipping and insufficient hydration are known to negatively impact cognition. Existing data on these phenomena are sparse and rarely considered together; furthermore, there is a lack of literature on interventions to address these problems. We therefore aimed to characterize existing literature on this topic. METHODS: We conducted a literature review of existing literature on the prevalence of and reasons for meal-skipping and insufficient hydration in physicians and medical learners. RESULTS: Reported prevalences varied widely, as did the ways in which the data were collected. Reasons for meal-skipping and insufficient hydration are less studied, but a lack of time is the most commonly reported reason, among a variety of other barriers. CONCLUSION: Further research is required to better characterize the prevalences and reasons for meal-skipping in physicians and medical learners. By consolidating the state of current knowledge on this topic in this work, we establish the groundwork for future studies and allow intervention studies to be based on a broader data set.

Music in Waiting Rooms: A Literature Review.

OBJECTIVE: We aim to review existing literature on the effects of background music in waiting rooms on patients. Furthermore, we examine existing neurobiological research for potential mechanisms by which music may affect patients. BACKGROUND: Music has been studied in healthcare in various forms, from formal interventions such as music therapy to passive listening as therapy. However, music is also present in the healthcare environment in the form of background music in waiting rooms. There has been interest in whether background music in such a setting may have beneficial effects on patient anxiety in order to potentially inform healthcare workers whether and what type of music may be suitable for waiting rooms. METHODS: We reviewed existing literature on music in healthcare waiting rooms and the neurobiological mechanisms by which music affects anxiety. RESULTS: We located several small studies performed in a range of settings, including physician office waiting rooms and preoperative waiting areas. The studies generally reported that most patients viewed music in these areas positively; some, but not all, studies showed positive effects on patient anxiety. A variety of theories by which music may impact patient anxiety was noted. CONCLUSIONS: We conclude that there exists some evidence to support an anxiety-reducing effect of background music on patients, though studies vary widely in methodology and music selection. A small amount of neurobiological research into the pertinent mechanisms has been conducted, but further research will be required to elucidate the exact mechanisms by which this intervention may reduce anxiety.

A review of astronaut mental health in manned missions: Potential interventions for cognitive and mental health challenges.

Space is an isolated, confined environment for humans. These conditions can have numerous effects on astronaut mental health and safety. Psychological and social issues affect space crew due to the isolation, confinement, and prolonged separation from family and friends. This area of research is particularly crucial given the space sector's plans for Martian colonies and space tourism, as well as to aid astronauts when under high stress. Therefore, this paper reviews the effects of isolation/confinement on psychological and cognitive health; impact of radiation and microgravity on cognitive health; and implications of disturbances to the circadian rhythm and sleep in space. Possible solutions to relevant mentioned cognitive and mental health challenges are also discussed.

SENSITIVITY AND SPECIFICITY OF DETECTING POLYPOIDAL CHOROIDAL VASCULOPATHY WITH EN FACE OPTICAL COHERENCE TOMOGRAPHY AND OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

PURPOSE: Determine sensitivity and specificity of polypoidal choroidal vasculopathy (PCV) diagnosis with structural en face optical coherence tomography (OCT) and OCT angiography (OCTA). METHODS: Retrospective review of the medical records of eyes diagnosed with PCV by indocyanine green angiography with review of diagnostic testing with structural en face OCT and OCTA by a trained reader. Structural en face OCT, cross-sectional OCT angiograms alone, and OCTA in its entirety were reviewed blinded to the findings of indocyanine green angiography and each other to determine if they could demonstrate the PCV complex. Sensitivity and specificity of PCV diagnosis was determined for each imaging technique using indocyanine green angiography as the ground truth. RESULTS: Sensitivity and specificity of structural en face OCT were 30.0% and 85.7%, of OCT angiograms alone were 26.8% and 96.8%, and of the entire OCTA were 43.9% and 87.1%, respectively. Sensitivity and specificity were improved for OCT angiograms and OCTA when looking at images taken within 1 month of PCV diagnosis. CONCLUSION: Sensitivity of detecting PCV was low using structural en face OCT and OCTA but specificity was high. Indocyanine green angiography remains the gold standard for PCV detection.

Combination of Biochanin A and Temozolomide Impairs Tumor Growth by Modulating Cell Metabolism in Glioblastoma Multiforme.

BACKGROUND/AIM: Several epidemiological studies have reported the chemopreventive potential of biochanin A, in cancer development and progression. We investigated the anticancer potential of combination of biochanin A and temozolomide against U-87 MG and T98 G [glioblastoma multiforme (GBM)] cells. MATERIALS AND METHODS: We evaluated the effect of biochanin A and temozolomide treatment on cell viability, expression of survival proteins, cell cycle, cell metabolism and mitochondrial function. RESULTS: Enhanced inhibitory effects of the combination treatment were observed on cell viability, expression of cell survival proteins EGFR, p-ERK, p-AKT, c-myc and MT-MMP1, and increased expression of the tumor suppressor, p-p53. Combination treatment also induced arrest in the G1 phase of the cell cycle. A shift in the metabolic phenotype of cells from glycolytic to oxidative phosphorylation was observed on combination treatment and the permeabilized cells showed a significant impairment in complex IV activity. CONCLUSION: Biochanin A significantly enhanced the anticancer efficacy of temozolomide in GBM cells.

Spectral-Domain Optical Coherence Tomography Angiography for the Diagnosis and Evaluation of Polypoidal Choroidal Vasculopathy.

PURPOSE: To compare the diagnostic ability of optical coherence tomography angiography (OCTA) with indocyanine green angiography (ICGA) in polypoidal choroidal vasculopathy (PCV). METHODS: Retrospective review of 47 eyes with PCV imaged with ICGA and OCTA. For each eye, it was determined which imaging modality better delineated the PCV complex. The presence of a branching vascular network (BVN) and polyp(s) were noted. RESULTS: PCV was better visualized with ICGA in 21 eyes (44.7%) and with OCTA in 9 eyes (19.2%). The results were comparable in 17 eyes (36.2%). Of the 44 eyes with BVN on ICGA, 41 eyes (93.2%) also showed BVN on OCTA. Of the 28 eyes with polyp(s) on ICGA, 22 eyes (78.6%) also showed polyp(s) on OCTA. Polyps were high-flow lesions or faint low-flow dilations on OCTA. CONCLUSION: OCTA readily detects BVNs and can detect most polyps, but in many cases ICGA is better able to detect the PCV complex.

Comparison of Glutamate Turnover in Nerve Terminals and Brain Tissue During [1,6-13C2]Glucose Metabolism in Anesthetized Rats.

The 13C turnover of neurotransmitter amino acids (glutamate, GABA and aspartate) were determined from extracts of forebrain nerve terminals and brain homogenate, and fronto-parietal cortex from anesthetized rats undergoing timed infusions of [1,6-13C2]glucose or [2-13C]acetate. Nerve terminal 13C fractional labeling of glutamate and aspartate was lower than those in whole cortical tissue at all times measured (up to 120 min), suggesting either the presence of a constant dilution flux from an unlabeled substrate or an unlabeled (effectively non-communicating on the measurement timescale) glutamate pool in the nerve terminals. Half times of 13C labeling from [1,6-13C2]glucose, as estimated by least squares exponential fitting to the time course data, were longer for nerve terminals (GluC4, 21.8 min; GABAC2 21.0 min) compared to cortical tissue (GluC4, 12.4 min; GABAC2, 14.5 min), except for AspC3, which was similar (26.5 vs. 27.0 min). The slower turnover of glutamate in the nerve terminals (but not GABA) compared to the cortex may reflect selective effects of anesthesia on activity-dependent glucose use, which might be more pronounced in the terminals. The 13C labeling ratio for glutamate-C4 from [2-13C]acetate over that of 13C-glucose was twice as large in nerve terminals compared to cortex, suggesting that astroglial glutamine under the 13C glucose infusion was the likely source of much of the nerve terminal dilution. The net replenishment of most of the nerve terminal amino acid pools occurs directly via trafficking of astroglial glutamine.

Prospective clinical trial of Intravitreal aflibercept treatment for PolypoIdal choroidal vasculopathy with hemorrhage or exudation (EPIC study): 6 month results.

BACKGROUND: Polypoidal choroidal vasculopathy is a variant of choroidal neovascularization and neovascular age related macular degeneration presenting with hemorrhagic and exudative changes within the macula and/or peripapillary region leading to vision loss. In contrast to neovascular age related macular degeneration, polypoidal choroidal vasculopathy has differing clinical manifestations and treatment strategies. Historically, polypoidal choroidal vasculopathy complexes are less responsive to anti-vascular endothelial growth factor therapy with no prospective clinical trials evaluating aflibercept in management of polypoidal choroidal vasculopathy. Herein we prospectively evaluate the efficacy and safety of intravitreal aflibercept in polypoidal choroidal vasculopathy. METHODS: A prospective, open-label, investigator-sponsored trial of intravitreal aflibercept for polypoidal choroidal vasculopathy in 21 eyes was conducted. Injections were administered monthly for 3 initial treatments, then every other month with monthly evaluations. The primary outcome measures were the mean change in best corrected visual acuity and adverse events. Secondary outcome measures included stabilization of vision, presence of subretinal hemorrhage, serous detachment, retinal pigment epithelial detachment, and regression of polypoidal complexes on indocyanine green angiography. RESULTS: At 6 months, the median visual acuity was 20/40 (range 20/25-20/200) with a mean Early Treatment Diabetic Retinopathy Study vision of 68.4 letters. There was a gain of 2.76 Early Treatment Diabetic Retinopathy Study letters at 6 months (p = 0.15). No patient developed severe vision loss (≤15 letters) and vision was stable or improved in 19/21 eyes (91 %). Subretinal fluid resolved in 13/18 eyes (72 %), and subretinal hemorrhage resolved in 6/8 eyes (75 %) respectively. The polyps regressed in 14/21 eyes (67 %) and the branching vascular network decreased in 1 eye and was stable in all other eyes. The retinal pigment epithelial detachment improved in 13/15 eyes (87 %). Bimonthly treatment occurred in 15/21 patients (71 %). There were no adverse events. CONCLUSIONS: Intravitreal aflibercept results in stabilization of vision, resolution of exudative and hemorrhagic complications with regression of polyps in polypoidal choroidal vasculopathy. Eyes with polypoidal choroidal vasculopathy previously treated with ranibizumab and bevacizumab can show marked improvement in the retinal pigment epithelial detachments and persistent polyps with aflibercept therapy. TRIAL REGISTRATION: Clinical trials.gov NCT01871376 , June 4(th) 2013.

Tyrosine phosphorylation of HSC70 and its interaction with RFC mediates methotrexate resistance in murine L1210 leukemia cells.

We previously identified and characterized a 66-68 kDa membrane-associated, tyrosine phosphorylated protein in murine leukemia L1210 cells as HSC70 which is a methotrexate (MTX)-binding protein. In order to further characterize the functional role of HSC70 in regulating MTX resistance in L1210 cells, we first showed that HSC70 colocalizes and interacts with reduced folate carrier (RFC) in L1210 cells by confocal laser scanning microscopy and Duolink in situ proximity ligation assay. The tyrosine phosphorylation status of HSC70 found in the membrane fraction was different from the parental L1210/0 and cisplatin (CDDP)-MTX cross resistant L1210/DDP cells. In MTX-binding assays, HSC70 from L1210/DDP cells showed less affinity for MTX-agarose beads than that of L1210/0 cells. In addition, genistein (a tyrosine phosphorylation inhibitor) significantly enhanced the resistance of L1210/0 cells to MTX. Moreover, site-directed mutation studies indicated the importance of tyrosine phosphorylation of HSC70 in regulating its binding to MTX. These findings suggest that tyrosine phosphorylation of HSC70 regulates the transportation of MTX into the cells via the HSC70-RFC system and contributes to MTX resistance in L1210 cells.

Biochanin A inhibits endothelial cell functions and proangiogenic pathways: implications in glioma therapy.

Malignant gliomas, such as glioblastoma multiforme, are highly vascularized tumors of the central nervous system. A rich network of angiogenic vessels supporting glioma growth is an important therapeutic target in glioma therapy. In the past few years, small molecules have gained interest as multitargeting therapies for cancer. Biochanin A is a small, natural dietary isoflavone known for its anticancer potential. Previously, we have found that biochanin A inhibits invasion in human glioblastoma cells. In this study, we elucidated the antiangiogenic mechanisms of biochanin A using rat brain tumor (C6) and murine brain endothelial (bEnd.3) cells and an ex-vivo chick chorioallantoic membrane model. Biochanin A inhibited endothelial cell functions such as cell viability, migration, and invasion, as analyzed using MTT, scratch wound, and gelatin zymography assays. Activation of proangiogenic proteins (ERK/AKT/mTOR) was inhibited. Biochanin A also inhibited chemical hypoxia-inducible factor-1α and vascular endothelial growth factor in C6 cells. Results of chick chorioallantoic membrane assay showed that biochanin A inhibited blood vessel formation ex vivo. As these results suggest that biochanin A directly targets different facets of angiogenesis in vitro and ex vivo, this study provides a rationale for future preclinical evaluation of its efficacy against angiogenic gliomas.

Direct evidence for activity-dependent glucose phosphorylation in neurons with implications for the astrocyte-to-neuron lactate shuttle.

Previous (13)C magnetic resonance spectroscopy experiments have shown that over a wide range of neuronal activity, approximately one molecule of glucose is oxidized for every molecule of glutamate released by neurons and recycled through astrocytic glutamine. The measured kinetics were shown to agree with the stoichiometry of a hypothetical astrocyte-to-neuron lactate shuttle model, which predicted negligible functional neuronal uptake of glucose. To test this model, we measured the uptake and phosphorylation of glucose in nerve terminals isolated from rats infused with the glucose analog, 2-fluoro-2-deoxy-D-glucose (FDG) in vivo. The concentrations of phosphorylated FDG (FDG6P), normalized with respect to known neuronal metabolites, were compared in nerve terminals, homogenate, and cortex of anesthetized rats with and without bicuculline-induced seizures. The increase in FDG6P in nerve terminals agreed well with the increase in cortical neuronal glucose oxidation measured previously under the same conditions in vivo, indicating that direct uptake and oxidation of glucose in nerve terminals is substantial under resting and activated conditions. These results suggest that neuronal glucose-derived pyruvate is the major oxidative fuel for activated neurons, not lactate-derived from astrocytes, contradicting predictions of the original astrocyte-to-neuron lactate shuttle model under the range of study conditions.

Biochanin A reduces pancreatic cancer survival and progression.

Pancreatic cancer has dismally low mean survival rates worldwide. Only a few chemotherapeutic agents including gemcitabine have been shown to improve the survival of pancreatic cancer patients. Biochanin A, an isoflavone, is known to exert an anticancer effect on various cancer types. In this study, we examined the anticancer properties of biochanin A on pancreatic cancer cells. The effect of biochanin A on cellular survival, apoptosis, and proliferation was analyzed using MTT, flow cytometry, and colony formation assay. The effect of biochanin A on pancreatic cancer's mitogenic signaling was determined using western blot analysis. Migration assay and zymography were used to determine biochanin A's effect on pancreatic cancer progression. Biochanin A induced dose-dependent toxicity on pancreatic cancer cells (Panc1 and AsPC-1). It reduced colony formation ability of Panc1 cells and induced dose-dependent apoptosis. Activation of Akt and MAPK was inhibited. Furthermore, the migratory and invasive potential of the cancer cells was also reduced. The results suggest that biochanin A is effective in reducing pancreatic cancer cell survival by inhibiting their proliferation and inducing apoptosis. It affects mitogenic, migratory, and invasive processes involved in cancer progression. These findings may lead to novel approaches to treat pancreatic cancer using isoflavones in combination with other therapeutic drugs.

Polypoidal choroidal vasculopathy exudation and hemorrhage: results of monthly ranibizumab therapy at one year.

PURPOSE: To evaluate the efficacy and safety of monthly intravitreal injections of ranibizumab in patients with polypoidal choroidal vasculopathy (PCV) and active exudation or hemorrhage. METHODS: A prospective, single practice, open label trial of monthly intravitreal ranibizumab (0.5 mg) injections for PCV in 13 eyes of 13 patients who completed the 1-year study. The primary outcome measure was stabilization of vision (loss of <15 ETDRS letters). Secondary outcome measures included incidence of ocular and systemic adverse events, changes in subretinal hemorrhage, central foveal thickness, and polypoidal complexes on indocyanine green angiography at 1 year. RESULTS: No patient lost ≥ 15 letters in visual acuity at 1 year. Three patients (23%) gained ≥ 15 letters at 12 months. Subretinal hemorrhage resolved in 9/9 eyes (100%). Macular edema improved in 5/5 eyes (100%). Subretinal fluid completely resolved in 4/9 eyes (44%), decreased in 2/9 eyes (22%), and increased in 3/9 eyes (33%). Polypoidal complexes decreased in 5/13 eyes (38%). CONCLUSION: Continuous monthly intravitreal ranibizumab decreases leakage and hemorrhage in eyes with exudative and hemorrhagic complications of PCV. Branching vascular networks persisted, and polypoidal complexes decreased in only 5/13 (38%) eyes with continuous antiangiogenic therapy at 1 year.

Interleukin-6 and JAK2/STAT3 signaling mediate the reversion of dexamethasone resistance after dexamethasone withdrawal in 7TD1 multiple myeloma cells.

We previously reported the establishment and characteristics of a DXM-resistant cell line (7TD1-DXM) generated from the IL6-dependent mouse B cell hybridoma, 7TD1 cell line. After withdrawing DXM from 7TD1-DXM cells over 90 days, DXM significantly inhibited the cell growth and induced apoptosis in the cells (7TD1-WD) compared with 7TD1-DXM cells. Additionally, IL-6 reversed while IL-6 antibody and AG490 enhanced the effects of growth inhibition and apoptosis induced by DXM in 7TD1-WD cells. Our study demonstrates that 7TD1-DXM cells become resensitized to DXM after DXM withdrawal, and IL-6 and JAK2/STAT3 pathways may regulate the phenomenon.

Regulation of astrocyte glutamine synthetase in epilepsy.

Astrocytes play a crucial role in regulating and maintaining the extracellular chemical milieu of the central nervous system under physiological conditions. Moreover, proliferation of phenotypically altered astrocytes (a.k.a. reactive astrogliosis) has been associated with many neurologic and psychiatric disorders, including mesial temporal lobe epilepsy (MTLE). Glutamine synthetase (GS), which is found in astrocytes, is the only enzyme known to date that is capable of converting glutamate and ammonia to glutamine in the mammalian brain. This reaction is important, because a continuous supply of glutamine is necessary for the synthesis of glutamate and GABA in neurons. The known stoichiometry of glutamate transport across the astrocyte plasma membrane also suggests that rapid metabolism of intracellular glutamate via GS is a prerequisite for efficient glutamate clearance from the extracellular space. Several studies have indicated that the activity of GS in astrocytes is diminished in several brain disorders, including MTLE. It has been hypothesized that the loss of GS activity in MTLE leads to increased extracellular glutamate concentrations and epileptic seizures. Understanding the mechanisms by which GS is regulated may lead to novel therapeutic approaches to MTLE, which is frequently refractory to antiepileptic drugs. This review discusses several known mechanisms by which GS expression and function are influenced, from transcriptional control to enzyme modification.

Neuroprotection against neuroblastoma cell death induced by depletion of mitochondrial glutathione.

Mitochondrial glutathione pool is vital in protecting cells against oxidative stress as the majority of the cellular reactive oxygen species are generated in mitochondria. Oxidative stress is implicated as a causative factor in neuronal death in neurodegenerative disorders. We hypothesized that depletion of mitochondrial glutathione leads to mitochondrial dysfunction and apoptotic death of SK-N-SH (human neuroblastoma) cells and investigated the neuroprotective strategies against GSH depletion. SK-N-SH cells were treated with two distinct inhibitors of glutathione metabolism: L-buthionine-(S, R)-sulfoximine (BSO) and ethacrynic acid (EA). EA treatment caused depletion of both the total and mitochondrial glutathione (while BSO had no effect on mitochondrial glutathione), enhanced rotenone-induced ROS production, and reduced the viability of SK-N-SH cells. Glutathione depletion by BSO or EA demonstrated positive features of mitochondria-mediated apoptosis in neuroblastoma cell death. Prevention of apoptosis by Bcl2 overexpression or use of antioxidant ebselen did not confer neuroprotection. Co-culture with U-87 (human glioblastoma) cells protected SK-N-SH cells from the cell death. Our data suggest that depletion of mitochondrial glutathione leads to mitochondrial dysfunction and apoptosis. The study indicates that preventing mitochondrial glutathione depletion could become a novel strategy for the development of neuroprotective therapeutics in neurodegenerative disorders.