ENO1
Alpha-enolase (EC 4.2.1.11) (2-phospho-D-glycerate hydro-lyase) (C-myc promoter-binding protein) (Enolase 1) (MBP-1) (MPB-1) (Non-neural enolase) (NNE) (Phosphopyruvate hydratase) (Plasminogen-binding protein) [ENO1L1] [MBPB1] [MPB1]
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Despite good responses to first-line treatment with platinum-based combination chemotherapy, most ovarian cancer patients will relapse and eventually develop a platinum-resistant disease with a poor overall prognosis. The molecular events leading to the cisplatin resistance of ovarian cancer cells are not fully understood. Here, we performed a proteomic analysis to identify protein candidates deregulated in a cisplatin-resistant ovarian cancer cell line (A2780CP20) in comparison to their sensitive counterpart (A2780). Forty-eight proteins were differentially abundant in A2780CP20, as compared with A2780, cells. Enolase-1 (ENO1) was significantly decreased in cisplatin-resistant ovarian cancer cells. Western blots and RT-PCR confirmed our findings. Ectopic ENO1 expression increased the sensitivity of ovarian cancer cells to cisplatin treatment. In contrast, small-interfering (siRNA)-based ENO1 silencing in A2780 cells reduced the sensitivity of these cells to cisplatin treatment. Whereas glucose consumption was lower, intracellular levels were higher in cisplatin-resistant ovarian cancer cells as compared with their cisplatin-sensitive counterparts. Senescence-associated β-galactosidase (β-Gal) levels were higher in cisplatin-resistant ovarian cancer cells as compared with cisplatin-sensitive ovarian cancer cells. β-Gal levels were decreased in ENO1 overexpressed clones. Protein levels of the cell cycle regulators and senescence markers p21 and p53 showed opposite expression patterns in cisplatin-resistant compared with cisplatin sensitive cells. Our studies suggest that decreased expression of ENO1 promotes glucose accumulation, induces senescence, and leads to cisplatin resistance of ovarian cancer cells.
Keywords
- ENO1
- Enolase
- beta-Gal
- cisplatin resistance
- glucose
- ovarian cancer
- p21
- p53
- senescence
Alzheimer's disease (AD) is a progressive neurodegenerative disorder that represents the most common cause of dementia in the United States. Although the link between alcohol use and AD has been studied, preclinical research has potential to elucidate neurobiological mechanisms that underlie this interaction. This study was designed to test the hypothesis that nondependent alcohol drinking exacerbates the onset and magnitude of AD-like neural and behavioral pathology. We first evaluated the impact of voluntary 24-h, two-bottle choice home-cage alcohol drinking on the prefrontal cortex and amygdala neuroproteome in C57BL/6J mice and found a striking association between alcohol drinking and AD-like pathology. Bioinformatics identified the AD-associated proteins MAPT (Tau), amyloid beta precursor protein (APP), and presenilin-1 (PSEN-1) as the main modulators of alcohol-sensitive protein networks that included AD-related proteins that regulate energy metabolism (ATP5D, HK1, AK1, PGAM1, CKB), cytoskeletal development (BASP1, CAP1, DPYSL2 [CRMP2], ALDOA, TUBA1A, CFL2, ACTG1), cellular/oxidative stress (HSPA5, HSPA8, ENO1, ENO2), and DNA regulation (PURA, YWHAZ). To address the impact of alcohol drinking on AD, studies were conducted using 3xTg-AD mice that express human MAPT, APP, and PSEN-1 transgenes and develop AD-like brain and behavioral pathology. 3xTg-AD and wild-type mice consumed alcohol or saccharin for 4 months. Behavioral tests were administered during a 1-month alcohol-free period. Alcohol intake induced AD-like behavioral pathologies in 3xTg-AD mice including impaired spatial memory in the Morris Water Maze, diminished sensorimotor gating as measured by prepulse inhibition, and exacerbated conditioned fear. Multiplex immunoassay conducted on brain lysates showed that alcohol drinking upregulated primary markers of AD pathology in 3xTg-AD mice: Aβ 42/40 ratio in the lateral entorhinal and prefrontal cortex and total Tau expression in the lateral entorhinal cortex, medial prefrontal cortex, and amygdala at 1-month post alcohol exposure. Immunocytochemistry showed that alcohol use upregulated expression of pTau (Ser199/Ser202) in the hippocampus, which is consistent with late-stage AD. According to the NIA-AA Research Framework, these results suggest that alcohol use is associated with Alzheimer's pathology. Results also showed that alcohol use was associated with a general reduction in Akt/mTOR signaling via several phosphoproteins (IR, IRS1, IGF1R, PTEN, ERK, mTOR, p70S6K, RPS6) in multiple brain regions including hippocampus and entorhinal cortex. Dysregulation of Akt/mTOR phosphoproteins suggests alcohol may target this pathway in AD progression. These results suggest that nondependent alcohol drinking increases the onset and magnitude of AD-like neural and behavioral pathology in 3xTg-AD mice.
MeSH Terms
- Alcohol Drinking
- Alzheimer Disease
- Amyloid beta-Protein Precursor
- Animals
- Behavior, Animal
- Brain
- Disease Models, Animal
- Mice, Transgenic
- tau Proteins
Keywords
- Aging
- Amyloid beta
- Ethanol
- GSK
- Immunohistochemistry
- Morris Water Maze
- Prepulse inhibition
- Self-administration
- Tau pathology
- Transgenic mouse model
In the last 5 years, novel knowledge on tumor metabolism has been revealed with the identification of critical factors that fuel tumors. Alpha-enolase (ENO1) is commonly over-expressed in tumors and is a clinically relevant candidate molecular target for immunotherapy. Here, we silenced ENO1 in human cancer cell lines and evaluated its impact through proteomic, biochemical and functional approaches. ENO1 silencing increased reactive oxygen species that were mainly generated through the sorbitol and NADPH oxidase pathways, as well as autophagy and catabolic pathway adaptations, which together affect cancer cell growth and induce senescence. These findings represent the first comprehensive metabolic analysis following ENO1 silencing. Inhibition of ENO1, either alone, or in combination with other pathways which were perturbed by ENO1 silencing, opens novel avenues for future therapeutic approaches.
MeSH Terms
- Animals
- Apoptosis
- Autophagy
- Biomarkers, Tumor
- Blotting, Western
- Breast Neoplasms
- Cell Cycle
- Cell Proliferation
- Cellular Reprogramming
- DNA-Binding Proteins
- Female
- Humans
- Mice
- Mice, SCID
- Oxidative Phosphorylation
- Pancreatic Neoplasms
- Phosphopyruvate Hydratase
- Proteomics
- RNA, Messenger
- RNA, Small Interfering
- Reactive Oxygen Species
- Real-Time Polymerase Chain Reaction
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction
- Tandem Mass Spectrometry
- Tumor Cells, Cultured
- Tumor Suppressor Proteins
- Xenograft Model Antitumor Assays
Keywords
- Warburg effect
- alpha-enolase
- cancer metabolism
- cellular senescence
Age-related impairment of functionality of the central nervous system (CNS) is associated with increased susceptibility to develop many neurodegenerative diseases. Increased oxidative stress in the CNS of aged animals is manifested by increased protein oxidation, which is believed to contribute to the age-related learning and memory deficits. Glutamate dysregulation, mitochondrial dysfunction and impaired protein synthesis are observed in aged brains, along with increased protein oxidation. Interestingly, all of these age-related cellular alterations can be improved by caloric restriction (CR), which can also improve the plasticity and recovery of the CNS. Although the beneficial effects of CR on brains are well established, the mechanism(s) of its action remains unclear. In order to gain insight into the mechanism of CR in the brain, we located the brain regions that are benefited the most from reduced oxidative stress by CR. Along with other brain regions, striatum (ST) showed significantly decreased bulk protein carbonyl levels and hippocampus (HP) showed decreased bulk protein 3-nitrotyrosine (3-NT) levels in CR aged rats when compared to those of age matched controls. To determine which proteins were oxidatively modified in these brain regions, we used parallel proteomics approach to identify the proteins that are altered in oxidation and expression. The specific carbonyl levels of pyruvate kinase M2 (PKM2), alpha-enolase (ENO1), inositol monophosphatase (INSP1), and F1-ATPase Chain B (ATP-F1B) were significantly decreased in ST of aged CR rats. In contrast, the expression levels of phosphoglycerate kinase 1 (PKG1), inosine monophosphate cyclohydrolase (IMPCH) and F1-ATPase Chain A (ATP-F1A) were significantly increased in the ST of CR rats. In the hippocampus of CR rats, the specific 3-NT levels of malate dehydrogenase (MDH), phosphoglycerate kinase 1 (PKG1) and 14-3-3 zeta protein were significantly decreased and expression levels of DLP1 splice variant 1 (DLP1), mitochondrial aconitase (ACO2), dihydrolipoamide dehydrogenase (DLDH), neuroprotective peptide H3 (NPH3), and eukaryotic translation initiation factor 5A (eIF-5A) are increased. Moreover, an unnamed protein product (UNP1) with similar sequence to initiation factor 2 (IF-2) was decreased in the HP of CR rats. Our data support the hypothesis that CR induces a mild metabolic stress response by increasing the production of neurotrophic proteins, therefore, priming neurons against apoptosis. Moreover, our study shows that the improvement of glutamate dysregulation, mitochondrial dysfunction and protein synthesis by CR is, at least partially, due to the CR-mediated alteration of the oxidation or the expression of PKM2, ENO1, INSP1, ATP-F1B, PKG1, IMPCH, ATP-F1A MDH, PKG1 and 14-3-3 zeta protein, DLP1, ACO2, DLDH, NPH3, eIF-5A and UNP1. This study provides valuable insights into the mechanisms of the beneficial factors on brain aging by CR.
MeSH Terms
- Aging
- Animals
- Brain
- Caloric Restriction
- Down-Regulation
- Energy Metabolism
- Enzyme Activation
- Enzymes
- Glutamic Acid
- Male
- Mitochondria
- Nerve Growth Factors
- Nerve Tissue Proteins
- Neurodegenerative Diseases
- Oxidative Stress
- Proteomics
- Rats
- Rats, Wistar
- Up-Regulation