Rationale Neurogenic hypertension is characterized by an increase in sympathetic activity and often resistance to drug treatments. We previously reported that it is also associated with a reduction of Angiotensin Converting Enzyme 2 (ACE2) and an increase in A Disintegrin And Metalloprotease 17 (ADAM17) activity in experimental hypertension. In addition, while multiple cells within the central nervous system have been involved in the development of neurogenic hypertension, the contribution of ADAM17 has not been investigated. Objective To assess the clinical relevance of this ADAM17-mediated ACE2 shedding in hypertensive patients and further identify the cell types and signaling pathways involved in this process. Methods and Results Using a mass spectrometry-based assay, we identified ACE2 as the main enzyme converting Ang II into Ang-(1–7) in human cerebrospinal fluid (CSF). We also observed an increase in ACE2 activity in the CSF of hypertensive patients, which was correlated with systolic blood pressure. Moreover, the increased level of tumor necrosis factor (TNF)-α in those CSF samples confirmed that ADAM17 was up-regulated in the hypertensive patients’ brain. To further assess the interaction between brain renin-angiotensin system and ADAM17, we generated mice lacking Angiotensin II type 1 receptors (AT1R) specifically on neurons. Our data reveal that despite expression on astrocytes and other cells types in the brain, ADAM17 up-regulation during DOCA-salt hypertension occurs selectively on neurons and neuronal AT1R are indispensable to this process. Mechanistically, reactive oxygen species (ROS) and extracellular signal-regulated kinase (ERK) were found to mediate ADAM17 activation. Conclusions Our data demonstrate that AT1R promote ADAM17-mediated ACE2 shedding in the brain of hypertensive patients, leading to a loss in compensatory activity during neurogenic hypertension.

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e Fenofibrate (FF) is a common lipid-lowering drug and a potent agonist of the peroxisome proliferator-activated receptor alpha (PPAR␣). FF and several other agonists of PPAR␣ have interesting anticancer properties, and our recent studies demonstrate that FF is very effective against tumor cells of neuroectodermal origin. In spite of these promising anticancer effects, the molecular mechanism(s) of FF-induced tumor cell toxicity remains to be elucidated. Here we report a novel PPAR␣-independent mechanism explaining FF's cytotoxicity in vitro and in an intracranial mouse model of glioblastoma. The mechanism involves accumulation of FF in the mitochondrial fraction, followed by immediate impairment of mitochondrial respiration at the level of complex I of the electron transport chain. This mitochondrial action sensitizes tested glioblastoma cells to the PPAR␣-dependent metabolic switch from glycolysis to fatty acid ␤-oxidation. As a consequence, prolonged exposure to FF depletes intracellular ATP, activates the AMP-activated protein kinase-mammalian target of rapamycin-autophagy pathway, and results in extensive tumor cell death. Interestingly, autophagy activators attenuate and autophagy inhibitors enhance FF-induced glioblastoma cytotoxicity. Our results explain the molecular basis of FF-induced glioblastoma cytotoxicity and reveal a new supplemental therapeutic approach in which intracranial infusion of FF could selectively trigger metabolic catastrophe in glioblastoma cells. F enofibrate (FF) is a common lipid-lowering drug and a potent agonist of peroxisome proliferator-activated receptor alpha (PPAR␣). Multiple reports indicate a beneficial role for lipid-lowering drugs, including fibrates and statins, as anticancer agents (1-7). For example, a 10-year, all-cause mortality study involving 7,722 patients treated with different fibrates revealed that the use of these drugs is associated with a significantly lower total mortality rate and a reduced probability of death from cancer (8). In cell culture and animal studies, various members of the fibrate family, which are all agonists of PPAR␣, demonstrate interesting anticancer effects, which are not fully understood. FF inhibited tumor growth by reducing both inflammation and angiogenesis in host tissue (5). Clofibrate attenuated ovarian cancer cell proliferation (9, 10), and gemfibrozil (GEM) inhibited the invasiveness of glioblastoma cells (11). In our previous work, FF synergized with staurosporine to reduce melanoma lung metastases (3, 12), significantly reduced glioblastoma invasiveness (13), and triggered apoptotic death in medulloblastoma (14) and human glioblastoma cell lines by inducing the FOXO3A-Bim apoptotic pathway (15). All of these studies encouraged the use of FF as a supplemental anticancer drug, a concept supported by recent clinical trials in which chronic administration of FF along with chemotherapeutic agents used at relatively low doses minimizes the toxicity and acute side effects of chemotherapy while maintaining efficacy for patients wit...

High density micro-RNA (miRNA) arrays, fluorescent-reporter miRNA assay and Northern miRNA dot-blot analysis show that a brain-enriched miRNA-128 is significantly down-regulated in glioblastoma multiforme (GBM) and in GBM cell lines when compared to age-matched controls. The down-regulation of miRNA-128 was found to inversely correlate with WHO tumor grade. Three bioinformatics-verified miRNA-128 targets, angiopoietin-related growth factor protein 5 (ARP5; ANGPTL6), a transcription suppressor that promotes stem cell renewal and inhibits the expression of known tumor suppressor genes involved in senescence and differentiation, Bmi-1, and a transcription factor critical for the control of cell-cycle progression, E2F-3a, were found to be up-regulated. Addition of exogenous miRNA-128 to CRL-1690 and CRL-2610 GBM cell lines (a) restored 'homeostatic' ARP5 (ANGPTL6), Bmi-1 and E2F-3a expression, and (b) significantly decreased the proliferation of CRL-1690 and CRL-2610 cell lines. Our data suggests that down-regulation of miRNA-128 may contribute to glioma and GBM, in part, by coordinately up-regulating ARP5 (ANGPTL6), Bmi-1 and E2F-3a, resulting in the proliferation of undifferentiated GBM cells.