Functional and Therapeutic Implications of Mitochondrial Network and Mitochondria-Associated Membranes: The Glioma’s Case

Even today, despite the surgery, radiotherapy, and chemotherapy, gliomas prognosis is still poor. There is a great need to develop new therapies. The understanding of the structural and functional characteristics of mitochondrial network (MN) and mitochondria-associated membranes (MAM) in gliomas is essential for the design of future therapeutic strategies. A huge range of ultrastructural findings is observed in MN and MAM in the human gliomas. These findings imply that a majority of glioma cells are incompetent to produce an adequate amount of energy by means of oxidative phosphorylation and compensatory increases in glycolytic ATP production. Regarding MAM, a “MAM-rich” cell (well-differentiated glioma cells) and “MAM-deficient” cells (glioma like-stem cells) exist. The quantity of MAM could be linked to the functional or metabolic state of the different glioma cells. MAM-resident mTORC2 is a major regulator tumor growth and drug resistance. If sufficient nutrients are present, glioblastoma cells maintain mTORC2 signaling to drive cell proliferation and survival. Consequently, the replacement of fermentable fuels like glucose with non-fermentable fuels like ketone bodies becomes a logical approach. The vision must be targeting the cellular signaling pathways and metabolic reprogramming. Whatever the modality, a holistic and feasible approach must be developed

Importance and repercussions of renal and cardiovascular pathology on stroke in young adults: an anatomopathologic study of 52 clinical necropsies

INTRODUCTION: Stroke in young adults has seldom been studied in a necropsy series. The objective of the present clinical necropsy-based investigation was to analyze stroke and its relationship with cardiovascular and renal pathology in young adults. MATERIALS AND METHODS:The protocols of 52 clinical necropsies with diagnoses of stroke in patients aged 18 - 49 years, performed between the years 1990-2006, were reviewed. RESULTS: Hemorrhagic stroke was diagnosed in 36 patients (69.3%), whereas the remaining 16 (30.7%) had ischemic stroke. Hypertensive cardiopathy was evident in 88.4% of the cases. Chronic renal pathology, directly or indirectly related to hypertension, was observed in 55.7% of the patients. Ischemic stroke as a result of occlusive atherosclerotic disease was seen in 50% of cases. Cardiogenic emboli were found in 25% of the cadavers. Hemorrhagic stroke was associated with hypertension in 43% of the cases, with ruptured vascular malformations in 29%, and coagulopathies in 17% of the cases. Hypertensive cardiopathy was present in patients with either ischemic or hemorrhagic stroke (81.2% and 91.6%, respectively). The most frequently observed renal ailments were chronic pyelonephritis (23%) and nephrosclerosis (21.1%). These were associated with ischemic stroke in 43.7%, and 12.5% of the cases, respectively, and with 13.8% and 25% of the hemorrhagic stroke cases. DISCUSSION: Hypertensive cardiopathy, occlusive atherosclerotic disease, chronic pyelonephritis and nephrosclerosis are among the pathophysiologycal mechanisms that apparently and eventually interact to induce a significant number of cases of stroke in young adults. A chronic systemic inflammatory state appears to be an important related condition because it possibly constitutes an accelerant of the pathophysiologycal process

Importance and repercussions of renal and cardiovascular pathology on stroke in young adults: an anatomopathologic study of 52 clinical necropsies

INTRODUCTION: Stroke in young adults has seldom been studied in a necropsy series. The objective of the present clinical necropsy-based investigation was to analyze stroke and its relationship with cardiovascular and renal pathology in young adults. MATERIALS AND METHODS:The protocols of 52 clinical necropsies with diagnoses of stroke in patients aged 18 - 49 years, performed between the years 1990-2006, were reviewed. RESULTS: Hemorrhagic stroke was diagnosed in 36 patients (69.3%), whereas the remaining 16 (30.7%) had ischemic stroke. Hypertensive cardiopathy was evident in 88.4% of the cases. Chronic renal pathology, directly or indirectly related to hypertension, was observed in 55.7% of the patients. Ischemic stroke as a result of occlusive atherosclerotic disease was seen in 50% of cases. Cardiogenic emboli were found in 25% of the cadavers. Hemorrhagic stroke was associated with hypertension in 43% of the cases, with ruptured vascular malformations in 29%, and coagulopathies in 17% of the cases. Hypertensive cardiopathy was present in patients with either ischemic or hemorrhagic stroke (81.2% and 91.6%, respectively). The most frequently observed renal ailments were chronic pyelonephritis (23%) and nephrosclerosis (21.1%). These were associated with ischemic stroke in 43.7%, and 12.5% of the cases, respectively, and with 13.8% and 25% of the hemorrhagic stroke cases. DISCUSSION: Hypertensive cardiopathy, occlusive atherosclerotic disease, chronic pyelonephritis and nephrosclerosis are among the pathophysiologycal mechanisms that apparently and eventually interact to induce a significant number of cases of stroke in young adults. A chronic systemic inflammatory state appears to be an important related condition because it possibly constitutes an accelerant of the pathophysiologycal process

Breaking up is hard to do: RalA, mitochondrial fission and cancer

The small GTPases RalA and RalB are activated downstream of oncogenic Ras. While activation of RalA is critically important for tumor initiation and growth of Ras-driven cancers, the highly similar small GTPase RalB is implicated in cell survival and metastasis. This difference in function between these two related proteins maps to the C-terminus, a 30 amino acid region that regulates subcellular localization and contains several potential phosphorylation sites. Here we discuss our recent evidence that phosphorylation by the mitotic kinase Aurora A promotes RalA relocalization to mitochondrial membranes, where it recruits the effector RalBP1 and the large dynamin-related GTPase Drp1 to promote mitochondrial fission. As upregulation of both RalA and Aurora A have been observed in human tumors, and phosphorylation of RalA at the site targeted by Aurora A promotes tumorigenesis, it is possible that regulation of mitochondrial fission is one mechanism by which RalA promotes cancer

The Quantum Mitochondrion and Optimal Health

A sufficiently complex set of molecules, if subject to perturbation, will self-organise and show emergent behaviour. If such a system can take on information it will become subject to natural selection. This could explain how self-replicating molecules evolved into life and how intelligence arose. A pivotal step in this evolutionary process was of course the emergence of the eukaryote and the advent of the mitochondrion, which both enhanced energy production per cell and increased the ability to process, store and utilise information. Recent research suggest that from its inception life embraced quantum effects such as “tunnelling” and “coherence” while competition and stressful conditions provided a constant driver for natural selection. We believe that the biphasic adaptive response to stress described by hormesis – a process that captures information to enable adaptability, is central to this whole process. Critically, hormesis could improve mitochondrial quantum efficiency, improving the ATP/ROS ratio, while inflammation, which is tightly associated with the aging process, might do the opposite. This all suggests that to achieve optimal health and healthy ageing, one has to sufficiently stress the system to ensure peak mitochondrial function, which itself could reflect selection of optimum efficiency at the quantum level

Differential utilization of ketone bodies by neurons and glioma cell lines: a rationale for ketogenic diet as experimental glioma therapy

Background: Even in the presence of oxygen, malignant cells often highly depend on glycolysis for energy generation, a phenomenon known as the Warburg effect. One strategy targeting this metabolic phenotype is glucose restriction by administration of a high-fat, low-carbohydrate (ketogenic) diet. Under these conditions, ketone bodies are generated serving as an important energy source at least for non-transformed cells. Methods: To investigate whether a ketogenic diet might selectively impair energy metabolism in tumor cells, we characterized in vitro effects of the principle ketone body 3-hydroxybutyrate in rat hippocampal neurons and five glioma cell lines. In vivo, a non-calorie-restricted ketogenic diet was examined in an orthotopic xenograft glioma mouse model. Results: The ketone body metabolizing enzymes 3-hydroxybutyrate dehydrogenase 1 and 2 (BDH1 and 2), 3-oxoacid-CoA transferase 1 (OXCT1) and acetyl-CoA acetyltransferase 1 (ACAT1) were expressed at the mRNA and protein level in all glioma cell lines. However, no activation of the hypoxia-inducible factor-1alpha (HIF-1alpha) pathway was observed in glioma cells, consistent with the absence of substantial 3-hydroxybutyrate metabolism and subsequent accumulation of succinate. Further, 3-hydroxybutyrate rescued hippocampal neurons from glucose withdrawal-induced cell death but did not protect glioma cell lines. In hypoxia, mRNA expression of OXCT1, ACAT1, BDH1 and 2 was downregulated. In vivo, the ketogenic diet led to a robust increase of blood 3-hydroxybutyrate, but did not alter blood glucose levels or improve survival. Conclusion: In summary, glioma cells are incapable of compensating for glucose restriction by metabolizing ketone bodies in vitro, suggesting a potential disadvantage of tumor cells compared to normal cells under a carbohydrate-restricted ketogenic diet. Further investigations are necessary to identify co-treatment modalities, e.g. glycolysis inhibitors or antiangiogenic agents that efficiently target non-oxidative pathways

Electron microscopy morphology of the mitochondrial network in gliomas and their vascular microenvironment

AbstractGliomas still represent a serious and discouraging brain tumor; despite of the diversity of therapeutic modalities, the prognosis for patients is still poor. Understanding the structural and functional characteristics of the vascular microenvironment in gliomas is essential for the design of future therapeutic strategies. This review describes and analyzes the electron microscopy morphology of the mitochondrial network in human gliomas and their vascular microenvironment. Heterogeneous mitochondrial network alterations in glioma cells and in microvascular environment are implicated directly and indirectly in the processes linked to hypoxia-tolerant and hypoxia-sensitive cells phenotype, effects of the hypoxia-inducible factor-1α, increased expression of several glycolytic protein isoforms as well as fatty acid synthase, and survivin. The prevalent existence of partial or total cristolysis observed suggests that oxidative phosphorylation is severely compromised. A mixed therapy emerged as the most appropriate. This article is part of a Special Issue entitled: Bioenergetics of Cancer