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The weak acid sorbic acid is a common preservative used in soft drink beverages to control microbial spoilage. Consumers and industry are increasingly transitioning to low-sugar food formulations, but potential impacts of reduced sugar on sorbic acid efficacy are barely characterised. In this study, we report enhanced sorbic acid resistance of yeast in low-glucose conditions. We had anticipated that low glucose would induce respiratory metabolism, which was shown previously to be targeted by sorbic acid. However, a shift from respiratory to fermentative metabolism upon sorbic acid exposure of Saccharomyces cerevisiae was correlated with relative resistance to sorbic acid in low glucose. Fermentation-negative yeast species did not show the low-glucose resistance phenotype. Phenotypes observed for certain yeast deletion strains suggested roles for glucose signalling and repression pathways in the sorbic acid resistance at low glucose. This low-glucose induced sorbic acid resistance was reversed by supplementing yeast cultures with succinic acid, a metabolic intermediate of respiratory metabolism (and a food-safe additive) that promoted respiration. The results indicate that metabolic adaptation of yeast can promote sorbic acid resistance at low glucose, a consideration for the preservation of foodstuffs as both food producers and consumers move towards a reduced sugar landscape.

Yaks are often subject to long-term starvation and a high prevalence of respiratory diseases and mortality in the withered season, yet the mechanisms that cause this remain unclear. Research has demonstrated that β-hydroxybutyrate (BHB) plays a significant role in regulating the immune system. Hence, we hypothesize that the low glucose and high BHB condition induced by severe starvation might have an effect on the pro-inflammatory response of the alveolar macrophages (AMs) in yaks. To validate our hypothesis, we isolated and identified primary AMs from freshly slaughtered yaks and cultured them in a medium with 5.5 mM of glucose or 2.8 mM of glucose plus 1–4 mM of BHB. Utilizing a real-time quantitative polymerase chain reaction (RT-qPCR), immunoblot assay, and enzyme-linked immunosorbent assay (ELISA), we evaluated the gene and protein expression levels of GPR109A (G-protein-coupled receptor 109A), NF-κB p65, p38, and PPARγ and the concentrations of pro-inflammatory cytokines interleukin (IL)-1β and IL-6 and tumor necrosis factor (TNF)-α in the supernatant. The results demonstrated that AMs exposed to low glucose plus BHB had significantly higher levels of IL-1β, IL-6, and TNF-α (p < 0.05) and higher activity of the GPR109A/NF-κB signaling pathway. A pretreatment of either pertussis toxin (PTX, inhibitor of GPR109A) or pyrrolidinedithiocarbamic (PDTC, inhibitor of NF-κB p65) was effective in preventing the elevated secretion of pro-inflammatory cytokines induced by low glucose plus BHB (p < 0.05). These results indicated that the low glucose plus BHB condition would induce an enhanced pro-inflammatory response through the activation of the GPR109A/NF-κB signaling pathway in primary yak AMs, which is probably the reason why yaks experience a higher rate of respiratory diseases and mortality. This study will offer new insight into the prevention and treatment of bovine respiratory diseases. [ABSTRACT FROM AUTHOR]

Diabetes increases the risk of Alzheimer's disease (AD). We investigated the impact of glucose concentrations on the β-amyloid (Aβ)-induced alteration of mitochondrial/cellular energetics in primary human brain microvascular endothelial cells (HBMECs). HBMECs were grown and passaged in media containing 15 mmol/l glucose (normal) based on which the glucose levels in the media were designated as high (25 mmol/L) or low (5 mmol/L). HBMECs were treated with Aβ (1–42) (5 µmol/l) or a scrambled peptide for 24 h and mitochondrial respiratory parameters were measured using Seahorse Mito Stress Test. Aβ (1–42) decreased the mitochondrial ATP production at normal glucose levels and decreased spare respiratory capacity at high glucose levels. Aβ (1–42) diminished all mitochondrial respiratory parameters markedly at low glucose levels that were not completely recovered by restoring normal glucose levels in the media. The addition of mannitol (10 mmol/l) to low and normal glucose-containing media altered the Aβ (1–42)-induced bioenergetic defects. Even at normal glucose levels, pre-senescent HMBECs (passage 15) displayed greater Aβ (1–42)-induced mitochondrial respiratory impairments than young cells (passages 7–9). Thus, hypoglycemia, osmolarity changes, and senescence are stronger instigators of Aβ (1–42)-induced mitochondrial respiration and energetics in HBMECs and contributors to diabetes-related increased AD risk than hyperglycemia. [ABSTRACT FROM AUTHOR]

Yaks are often subject to long-term starvation and a high prevalence of respiratory diseases and mortality in the withered season, yet the mechanisms that cause this remain unclear. Research has demonstrated that β-hydroxybutyrate (BHB) plays a significant role in regulating the immune system. Hence, we hypothesize that the low glucose and high BHB condition induced by severe starvation might have an effect on the pro-inflammatory response of the alveolar macrophages (AMs) in yaks. To validate our hypothesis, we isolated and identified primary AMs from freshly slaughtered yaks and cultured them in a medium with 5.5 mM of glucose or 2.8 mM of glucose plus 1–4 mM of BHB. Utilizing a real-time quantitative polymerase chain reaction (RT-qPCR), immunoblot assay, and enzyme-linked immunosorbent assay (ELISA), we evaluated the gene and protein expression levels of GPR109A (G-protein-coupled receptor 109A), NF-κB p65, p38, and PPARγ and the concentrations of pro-inflammatory cytokines interleukin (IL)-1β and IL-6 and tumor necrosis factor (TNF)-α in the supernatant. The results demonstrated that AMs exposed to low glucose plus BHB had significantly higher levels of IL-1β, IL-6, and TNF-α (p < 0.05) and higher activity of the GPR109A/NF-κB signaling pathway. A pretreatment of either pertussis toxin (PTX, inhibitor of GPR109A) or pyrrolidinedithiocarbamic (PDTC, inhibitor of NF-κB p65) was effective in preventing the elevated secretion of pro-inflammatory cytokines induced by low glucose plus BHB (p < 0.05). These results indicated that the low glucose plus BHB condition would induce an enhanced pro-inflammatory response through the activation of the GPR109A/NF-κB signaling pathway in primary yak AMs, which is probably the reason why yaks experience a higher rate of respiratory diseases and mortality. This study will offer new insight into the prevention and treatment of bovine respiratory diseases.

Rubella virus (RuV) infections in pregnant women, especially first-trimester infections, can lead to congenital rubella syndrome (CRS). However, the mechanisms of fetal RuV infection are not completely understood, and it is not observed in every pregnant woman infected with RuV. As gestational diabetes mellitus is a risk factor for congenital viral infections, we investigated the possible roles of hypoglycemia-related endoplasmic reticulum (ER) stress as a key factor for vertical RuV infection using immortalized human first-trimester trophoblasts. Low-glucose stress was induced prior to RuV infection by culturing HTR-8/SVneo and Swan.71 cells in low-glucose (LG) medium for 24h or high-glucose medium for 6h and then LG medium for an additional 18h. Clinically isolated RuV was inoculated at a multiplicity of infection of 5 to 10. The intracellular localization of the RuV capsid protein was investigated 24 to 48h post-infection (pi) with flow cytometry (FCM) analysis and fluorescence microscopy. Viral progeny production was monitored by FCM analysis. Increases in RuV infection in LG-induced ER-stressed trophoblasts were observed. No significant increase in apoptosis of RuV-infected cells was noted at days 2 and 5 pi, and substantial viral progeny production was observed until day 5 pi. An approximate fivefold increase in viral binding was noted for the LG-stressed cells. Although the detailed mechanisms underlying viral entry into LG-stressed cells are not known and require further investigation, these findings suggest that a certain degree of LG stress in early pregnancy may facilitate infection and cause CRS. [ABSTRACT FROM AUTHOR]

Glucose is important for the maintenance of muscle function; however, it is still unclear how changes in glucose concentration affect muscle. Here, we analyzed the effect of glucose concentration on protein expression under different glucose concentration media in C2C12 myotubes. First, we performed proteome analysis in C2C12 myotubes cultured in Low (1.0 g/L), Medium (2.0 g/L), and High (4.5 g/L) glucose media. Proteome analysis revealed 113 proteins were significantly changed in group cultured in Low or Medium glucose media compared to group cultured in High glucose media. Furthermore, glycolysis, oxidative phosphorylation, and fatty acid metabolism were increased in the Medium and Low groups. Among these pathways, HK2, PFKP, NDUFA11, and FABP3 were especially upregulated proteins in Low and Medium groups. In this context, ATP production in C2C12 myotubes cultured in Low and Medium glucose media was increased. There was no significant change in myotubes morphology and myogenic differentiation factors in all groups. Finally, we examined the effect on glucose concentration in culture media on myosin isoforms expression by qRT-PCR. As a result, Myh2 and Myh4 were significantly increased in Low and Medium conditions. Altogether, Low and Medium glucose conditions induced Myh expression probably via enhancement glucose utilization. [ABSTRACT FROM AUTHOR]

Sodium glucose co-transporter 1 (SGLT1) triggers low glucose-induced glucagon-like peptide-1 (GLP-1) secretion. We reported that a two-week administration of 3-deoxyglucosone (3DG), an independent factor associated with the development of pre-diabetes, reduces basal GLP-1 secretion in rats. This study investigated the effects of 3DG on GLP-1 secretion and SGLT1 pathway under low-glucose conditions in STC-1 cells. STC-1 cells were incubated with phloridzin or 3DG at 5.6 mM glucose. SGLT1 expression (by western blotting), GLP-1 and cyclic adenosine monophosphate (cAMP) levels (by ELISA), and intracellular Ca2+ concentration (by Fluo-3/AM) were measured. Phloridzin inhibited GLP-1 secretion. SGLT1 protein expression in STC-1 cells cultured in 5.6 mM glucose is higher than that in 25 mM glucose. Exposure to 3DG for 6 h reduced GLP-1 secretion, SGLT1 protein expression, and intracellular concentrations of cAMP and Ca2+. 3DG reduces low glucose-induced GLP-1 secretion in part through reduction of SGLT1 expression. [ABSTRACT FROM AUTHOR]

Chronic meningoencephalitis is caused by Cryptococcus neoformans and is treated in many parts of the world with fluconazole (FLC) monotherapy, which is associated with treatment failure and poor outcome. In the host, C. neoformans propagates predominantly under low glucose growth conditions. We investigated whether low glucose, mimicked by growing in synthetic media (SM) with 0.05% glucose (SMlowglu), affects FLC-resistance. A > 4-fold increase in FLC tolerance was observed in seven C. neoformans strains when minimum inhibitory concentration (MIC) was determined in SMlowglu compared to MIC in SM with normal (2%) glucose (SMnlglu). In SMlowglu, C. neoformans cells exhibited upregulation of efflux pump genes AFR1 (8.7-fold) and AFR2 (2.5-fold), as well as decreased accumulation (2.6-fold) of Nile Red, an efflux pump substrate. Elevated intracellular ATP levels (3.2-fold and 3.4-fold), as well as decreased mitochondrial reactive oxygen species levels (12.8-fold and 17-fold), were found in the presence and absence of FLC, indicating that low glucose altered mitochondrial function. Fluorescence microscopy revealed that mitochondria of C. neoformans grown in SMlowglu were fragmented, whereas normal glucose promoted a reticular network of mitochondria. Although mitochondrial membrane potential (MMP) was not markedly affected in SMlowglu, it significantly decreased in the presence of FLC (12.5-fold) in SMnlglu, but remained stable in SMlowglu-growing C. neoformans cells. Our data demonstrate that increased FLC tolerance in low glucose-growing C. neoformans is the result of increased efflux pump activities and altered mitochondrial function, which is more preserved in SMlowglu. This mechanism of resistance is different from FLC heteroresistance, which is associated with aneuploidy of chromosome 1 (Chr1). [ABSTRACT FROM AUTHOR]

Understanding proteomic changes in the ischemic penumbra are crucial to rescue those salvageable cells and reduce the damage of an ischemic stroke. Since the penumbra region is dynamic with heterogeneous cells/tissues, tissue sampling from animal models of stroke for the molecular study is a challenge. In this study, cultured hippocampal HT22 cells under hypoxia treatment for 17.5 h with 0.69 mM low glucose (H+LG) could mimic ischemic penumbral cells since they had much higher cell viability and viable cell number compared to hypoxia without glucose (H−G) treatment. To validate established cell-based ischemic penumbral model and understand the beneficial effects of low glucose (LG), quantitative proteomics analysis was performed on H+LG, H−G, and normoxia with normal 22 mM glucose (N+G) treated cells. We identified 427 differentially abundant proteins (DAPs) between H−G and N+G and further identified 105 DAPs between H+LG and H−G. Analysis of 105 DAPs revealed that LG promotes cell survival by activating HIF1α to enhance glycolysis; preventing the dysregulations of extracellular matrix remodeling, cell cycle and division, and antioxidant and detoxification; as well as attenuating inflammatory reaction response, protein synthesis and neurotransmission activity. Our results demonstrated that this established cell-based system could mimic penumbral conditions and can be used for molecular studies.

Glucose is important for the maintenance of muscle function; however, it is still unclear how changes in glucose concentration affect muscle. Here, we analyzed the effect of glucose concentration on protein expression under different glucose concentration media in C2C12 myotubes. First, we performed proteome analysis in C2C12 myotubes cultured in Low (1.0 g/L), Medium (2.0 g/L), and High (4.5 g/L) glucose media. Proteome analysis revealed 113 proteins were significantly changed in group cultured in Low or Medium glucose media compared to group cultured in High glucose media. Furthermore, glycolysis, oxidative phosphorylation, and fatty acid metabolism were increased in the Medium and Low groups. Among these pathways, HK2, PFKP, NDUFA11, and FABP3 were especially upregulated proteins in Low and Medium groups. In this context, ATP production in C2C12 myotubes cultured in Low and Medium glucose media was increased. There was no significant change in myotubes morphology and myogenic differentiation factors in all groups. Finally, we examined the effect on glucose concentration in culture media on myosin isoforms expression by qRT-PCR. As a result, Myh2 and Myh4 were significantly increased in Low and Medium conditions. Altogether, Low and Medium glucose conditions induced Myh expression probably via enhancement glucose utilization.

Understanding proteomic changes in the ischemic penumbra are crucial to rescue those salvageable cells and reduce the damage of an ischemic stroke. Since the penumbra region is dynamic with heterogeneous cells/tissues, tissue sampling from animal models of stroke for the molecular study is a challenge. In this study, cultured hippocampal HT22 cells under hypoxia treatment for 17.5 h with 0.69 mM low glucose (H+LG) could mimic ischemic penumbral cells since they had much higher cell viability and viable cell number compared to hypoxia without glucose (H−G) treatment. To validate established cell-based ischemic penumbral model and understand the beneficial effects of low glucose (LG), quantitative proteomics analysis was performed on H+LG, H−G, and normoxia with normal 22 mM glucose (N+G) treated cells. We identified 427 differentially abundant proteins (DAPs) between H−G and N+G and further identified 105 DAPs between H+LG and H−G. Analysis of 105 DAPs revealed that LG promotes cell survival by activating HIF1α to enhance glycolysis; preventing the dysregulations of extracellular matrix remodeling, cell cycle and division, and antioxidant and detoxification; as well as attenuating inflammatory reaction response, protein synthesis and neurotransmission activity. Our results demonstrated that this established cell-based system could mimic penumbral conditions and can be used for molecular studies. [ABSTRACT FROM AUTHOR]

Summary: The focus of this report was to document the electroencephalogram (EEG) findings associated with nonislet cell tumour‐induced hypoglycaemia (NICTH) in a racing Thoroughbred mare subsequently diagnosed with renal carcinoma and carcinomatosis. We evaluated cortical cerebral activity and confirmed paroxysmal activity consistent with subclinical seizures by performing an EEG prior to onset of clinical signs of seizures. We showed that the electrical activity pattern progressed in a similar fashion as in humans with severe, progressive hypoglycaemia and presumed neuroglycopenia. The glycaemic threshold for abnormalities detected in EEG showed that abnormal electrical cortical activity appeared when blood glucose dropped to 44 mg/dL (2.4 mmol/L) and paroxysmal activity spread, becoming generalised when blood glucose dropped to 23 mg/dL (1.3 mmol/L). NICTH is an uncommon paraneoplastic phenomenon in several species. In horses, NICTH has been reported most frequently in primary renal tumours, followed by primary hepatic tumours. This report highlights the importance of investigating the possibility of hypoglycaemia in cases of horses that present altered state of consciousness with or without intermittent seizures. This case report also highlights that the diagnostic work‐up for horses presenting with episodic hypoglycaemia should comprise investigation of possible neoplasia, as paraneoplastic hypoglycaemia should be included in the list of differentials of horses with hypoglycaemia. [ABSTRACT FROM AUTHOR]

Chronic meningoencephalitis is caused by Cryptococcus neoformans and is treated in many parts of the world with fluconazole (FLC) monotherapy, which is associated with treatment failure and poor outcome. In the host, C. neoformans propagates predominantly under low glucose growth conditions. We investigated whether low glucose, mimicked by growing in synthetic media (SM) with 0.05% glucose (SMlowglu), affects FLC-resistance. A > 4-fold increase in FLC tolerance was observed in seven C. neoformans strains when minimum inhibitory concentration (MIC) was determined in SMlowglu compared to MIC in SM with normal (2%) glucose (SMnlglu). In SMlowglu, C. neoformans cells exhibited upregulation of efflux pump genes AFR1 (8.7-fold) and AFR2 (2.5-fold), as well as decreased accumulation (2.6-fold) of Nile Red, an efflux pump substrate. Elevated intracellular ATP levels (3.2-fold and 3.4-fold), as well as decreased mitochondrial reactive oxygen species levels (12.8-fold and 17-fold), were found in the presence and absence of FLC, indicating that low glucose altered mitochondrial function. Fluorescence microscopy revealed that mitochondria of C. neoformans grown in SMlowglu were fragmented, whereas normal glucose promoted a reticular network of mitochondria. Although mitochondrial membrane potential (MMP) was not markedly affected in SMlowglu, it significantly decreased in the presence of FLC (12.5-fold) in SMnlglu, but remained stable in SMlowglu-growing C. neoformans cells. Our data demonstrate that increased FLC tolerance in low glucose-growing C. neoformans is the result of increased efflux pump activities and altered mitochondrial function, which is more preserved in SMlowglu. This mechanism of resistance is different from FLC heteroresistance, which is associated with aneuploidy of chromosome 1 (Chr1).

Aims/hypothesis: Hypoglycaemia is a major barrier to good glucose control in type 1 diabetes. Frequent hypoglycaemic episodes impair awareness of subsequent hypoglycaemic bouts. Neural changes underpinning awareness of hypoglycaemia are poorly defined and molecular mechanisms by which glial cells contribute to hypoglycaemia sensing and glucose counterregulation require further investigation. The aim of the current study was to examine whether, and by what mechanism, human primary astrocyte (HPA) function was altered by acute and recurrent low glucose (RLG).Methods: To test whether glia, specifically astrocytes, could detect changes in glucose, we utilised HPA and U373 astrocytoma cells and exposed them to RLG in vitro. This allowed measurement, with high specificity and sensitivity, of RLG-associated changes in cellular metabolism. We examined changes in protein phosphorylation/expression using western blotting. Metabolic function was assessed using a Seahorse extracellular flux analyser. Immunofluorescent imaging was used to examine cell morphology and enzymatic assays were used to measure lactate release, glycogen content, intracellular ATP and nucleotide ratios.Results: AMP-activated protein kinase (AMPK) was activated over a pathophysiologically relevant glucose concentration range. RLG produced an increased dependency on fatty acid oxidation for basal mitochondrial metabolism and exhibited hallmarks of mitochondrial stress, including increased proton leak and reduced coupling efficiency. Relative to glucose availability, lactate release increased during low glucose but this was not modified by RLG. Basal glucose uptake was not modified by RLG and glycogen levels were similar in control and RLG-treated cells. Mitochondrial adaptations to RLG were partially recovered by maintaining euglycaemic levels of glucose following RLG exposure.Conclusions/interpretation: Taken together, these data indicate that HPA mitochondria are altered following RLG, with a metabolic switch towards increased fatty acid oxidation, suggesting glial adaptations to RLG involve altered mitochondrial metabolism that could contribute to defective glucose counterregulation to hypoglycaemia in diabetes. [ABSTRACT FROM AUTHOR]

The weak acid sorbic acid is a common preservative used in soft drink beverages to control microbial spoilage. Consumers and industry are increasingly transitioning to low-sugar food formulations, but potential impacts of reduced sugar on sorbic acid efficacy are barely characterised. In this study, we report enhanced sorbic acid resistance of yeast in low-glucose conditions. We had anticipated that low glucose would induce respiratory metabolism, which was shown previously to be targeted by sorbic acid. However, a shift from respiratory to fermentative metabolism upon sorbic acid exposure of Saccharomyces cerevisiae was correlated with relative resistance to sorbic acid in low glucose. Fermentation-negative yeast species did not show the low-glucose resistance phenotype. Phenotypes observed for certain yeast deletion strains suggested roles for glucose signalling and repression pathways in the sorbic acid resistance at low glucose. This low-glucose induced sorbic acid resistance was reversed by supplementing yeast cultures with succinic acid, a metabolic intermediate of respiratory metabolism (and a food-safe additive) that promoted respiration. The results indicate that metabolic adaptation of yeast can promote sorbic acid resistance at low glucose, a consideration for the preservation of foodstuffs as both food producers and consumers move towards a reduced sugar landscape., Competing Interests: None., (© 2023 The Authors.)

Objective To investigate the effect of low glucose microenvironment on the expression of clock genes(CLOCK, BMAL1, Per1, Per2, Per3 Cry1, and Cry2) in hepatocellular carcinoma(HCC) cells. Methods Immunohistochemistry was used to detect the expression of clock gene proteins(CLOCK, BMAL1, Per1, Per2, Per3, Cry1, and Cry2) in30 cases of hepatic carcinoma tissues and adjacent tissues. Hepatic carcinoma cell lines Huh7 and Bel-7404 cells were implanted into the high glucose and low glucose environment for 24 h respectively. The mRNA expression levels of the clock genes were detected by real-time PCR. Results Abnormal expression of biological clock genes was common in HCC tissues, and the protein levels of Per1, Per2, Per3, and Cry2 genes in the HCC tissues were significantly lower than those of the adjacent tissues. The positive rates in the adjacent tissues were 86. 7%(26/30), 90%(27/30), 86. 7%(26/30), and 77. 3%(22/30), and the positive rates in liver cancer tissues were 33. 3%(10/30), 36. 6%(11/30), 36. 6%(11/30), and40%(12/30), with significant difference(all P < 0. 05). The expression of Clock and Per2 mRNA in the Huh7 cells cultured in high glucose environment was 1. 01 ± 0. 01 and 1. 00 ± 0. 01 respectively, the expression of Clock and Per2 mRNA in the Huh7 cells cultured in low glucose environment was 0. 73 ± 0. 01 and 0. 71 ± 0. 01 respectively, all P < 0. 05. The expression of Cry1 mRNA in the Huh7 cells cultured in high glucose environment was 1. 00 ± 0. 01, and the expression of Cry1 mRNA in the Huh7 cells cultured in low glucose environment was 1. 35 ± 0. 02, P < 0. 05, and the other liver cancer cell line Bel-7404 also showed similar changes. Conclusion Abnormal expression of biological clock gene protein is common in HCC tissues(predominantly low expression); after the cuture in the low glucose microenvironment, the expression of part of the circadian clock gene mRNA is down-regulated; low glucose microenvironment may be one of causes attributing to the disturbance of circadian gene expression in HCC. [ABSTRACT FROM AUTHOR]

Cellular nutrient states control whether cells proliferate, or whether they enter or exit quiescence. Here, we report characterizations of fission yeast temperature-sensitive (ts) mutants of the evolutionarily conserved transmembrane protein Cwh43, and explore its relevance to utilization of glucose, nitrogen source and lipids. GFP-tagged Cwh43 localizes at ER associated with the nuclear envelope and the plasma membrane, as in budding yeast. We found that cwh43 mutants failed to divide in low glucose and lost viability during quiescence under nitrogen starvation. In cwh43 mutants, comprehensive metabolome analysis demonstrated dramatic changes in marker metabolites that altered under low glucose and/or nitrogen starvation, although cwh43 cells apparently consumed glucose in the culture medium. Furthermore, we found that cwh43 mutant cells had elevated levels of triacylglycerols (TGs) and coenzyme A, and that they accumulated lipid droplets. Notably, TG biosynthesis was required to maintain cell division in the cwh43 mutant. Thus, Cwh43 affects utilization of glucose and nitrogen sources, as well as storage lipid metabolism. These results may fit a notion developed in budding yeast stating that Cwh43 conjugates ceramide to glycosylphosphatidylinositol (GPI)-anchored proteins and maintains integrity of membrane organization. [ABSTRACT FROM AUTHOR]

There is a growing body of evidence about metformin being effective in cancer therapy. Despite controversies about the ways of its effectiveness, several ongoing clinical trials are evaluating the drug when used as an adjuvant or a neo-adjuvant agent. We aimed to investigate metformin’s effects on proliferation, metastasis, and hormone receptor expressions in breast cancer cell line MCF-7 incubated in two different glucose conditions. MCF-7 cells were incubated in high or low glucose media and treated with various doses of metformin. The cell viability was studied using MTT test. The Ki-67, estrogen and progesterone receptor expression were evaluated by ICC and galectin-3 expression was evaluated by ELISA or spectrophotometrically. The cell viability following consecutive metformin doses in either glucose condition for 24 and 48 h represented a significant decrease when compared to control. The proliferation detected in low glucose medium following metformin at doses < 20 mM was found significantly decreased when compared to high glucose medium at 48 h. In terms of galectin-3 levels, the increase in high glucose medium treated with metformin and the decrease in low glucose medium were found statistically significant when compared to control. Progesterone receptor staining demonstrated a significant increase in low glucose medium. Our findings represent better outcomes for cancer lines incubated in low glucose medium treated with metformin in terms of viability, receptor expression and metastatic activity, and highlight the potential benefit of metformin especially in restraining the cancer cell’s ability to cope energetic stress in low glucose conditions. [ABSTRACT FROM AUTHOR]

Aims/Introduction Overproduction of reactive oxygen species ( ROS) in endothelial cells ( ECs) plays a pivotal role in endothelial dysfunction. Mitochondrial ROS (mt ROS) is one of the key players in the pathogenesis of diabetic vascular complications. Hypoglycemia is linked to increased ROS production and vascular events; however, the underlying mechanisms remain unclear. In the present study, we aimed to determine whether and how low glucose ( LG) mediates mt ROS generation in ECs, and to examine the impact of LG-induced mt ROS on endothelial dysfunction. Materials and Methods Metabolomic profiling, cellular oxygen consumption rate, mt ROS, endothelial nitric oxide synthase phosphorylation, and the expression of vascular cell adhesion molecule-1 or intercellular adhesion molecule-1 were evaluated in bovine aortic ECs. Results We found that LG increased mt ROS generation in ECs; which was suppressed by overexpression of manganese superoxide dismutase. Comprehensive metabolic analysis using capillary electrophoresis-mass spectrometry and oxygen consumption rate assessment showed that the pathway from fatty acid to acetyl-CoA through fatty acid oxidation was upregulated in ECs under LG conditions. In addition, etomoxir, a specific inhibitor of the free fatty acid transporter, decreased LG-induced mt ROS production. These results suggested that LG increased mt ROS generation through activation of fatty acid oxidation. We further revealed that LG inhibited endothelial nitric oxide synthase phosphorylation, and increased the expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. These effects were suppressed either by overexpression of manganese superoxide dismutase or by treatment with etomoxir. Conclusions The activation of fatty acid oxidation followed by mt ROS production could be one of the causes for endothelial dysfunction during hypoglycemia. [ABSTRACT FROM AUTHOR]

P53 is a famous cancer suppressor and plays key roles in metabolism. Intervertebral disc (IVD) is the largest avascular cartilaginous structure in humans and its degeneration is a common cause of spine diseases initiated from damaged nucleus pulposus (NP) cells. The potential cause of disc degeneration has been attributed to aging, genetic factors, mechanical factors and nutrition. In this study, we found that p53 decreased and leaked to the cytoplasm in NP cells as the glucose level decreases, in contrast to cancer cells in which p53 increases and concentrates to the nuclei. Comparing with in p53 knockdown NP cells, relative high p53 expression in normal control NP cells inhibited autophagy and the pentose phosphate pathway. Furthermore, the expression of Sox 9 and type II collagen were higher in p53 normal control than p53 knockdown NP cells. Based on these results, we believe that relative high p53 facilitates NP cell viability and integrity. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) at low level promotes cell survival through lysosome induced autophagy induction. Glucose stress induced acidosis, hypoxia, ROS, upregulates markers related to cancer stemness and multidrug resistance. Also, lysosomal upregulation is proposed to be one of the important indicators of cell survival under ROS induced stress. Studies supported that, stimulation of Lysosome-TFEB-Ca2+ cascade has important role in induction of chemoresistance and survival of cancerous cells. To observe the effect of synergistic drug combination, Kaempferol and Verapamil on markers regulating chemoevasion, tumor stemness & acidosis as well as lysosome upregulation pathways, under low as well as high glucose conditions. Based on our earlier observation as well as previous reports, we hypothesized, our drug combination Kaempferol with Verapamil could attenuate markers related to chemoevasion, tumor stemness & acidosis as well as lysosome-TFEB-Ca2+ pathway, all of which have indispensable association and role in chemoresistance. RNA and protein expression of candidate genes, along with ROS production and Ca2+ concentrations were measured in ex vivo models in altered glucose conditions upon treatment with KV. Also, computational approaches were utilized to hypothesize the mechanism of action of the drug combination. PCR, IHC, western blotting and molecular docking approaches were used in this study. The overproduction of ROS by our candidate drugs KV, downregulated the chemoresistance and tumor acidosis markers along with ATP1B1 and resulted in lysosomal disruption with reduction of Ca2+ release, diminishing TFEB expression under low glucose condition. An anomalous outcome was observed in high glucose conditions. We also observed KV promoted the overproduction of ROS levels thereby inducing autophagy-mediated cell death through the upregulation of LC3-II and p62 in low glucose conditions. The ex vivo studies also corroborate with in silico study that exhibited the parallel outcome. Our ex-vivo and in-silico studies revealed that our candidate drug combination KV, could effectively target several pathways regulating chemoresistance, that were not hitherto studied in the same experimental setup and thus may be endorsed for therapeutic purposes. [Display omitted] [ABSTRACT FROM AUTHOR]

Diabetes increases the risk of Alzheimer's disease (AD). We investigated the impact of glucose concentrations on the β-amyloid (Aβ)-induced alteration of mitochondrial/cellular energetics in primary human brain microvascular endothelial cells (HBMECs). HBMECs were grown and passaged in media containing 15 mmol/l glucose (normal) based on which the glucose levels in the media were designated as high (25 mmol/L) or low (5 mmol/L). HBMECs were treated with Aβ (1-42) (5 µmol/l) or a scrambled peptide for 24 h and mitochondrial respiratory parameters were measured using Seahorse Mito Stress Test. Aβ (1-42) decreased the mitochondrial ATP production at normal glucose levels and decreased spare respiratory capacity at high glucose levels. Aβ (1-42) diminished all mitochondrial respiratory parameters markedly at low glucose levels that were not completely recovered by restoring normal glucose levels in the media. The addition of mannitol (10 mmol/l) to low and normal glucose-containing media altered the Aβ (1-42)-induced bioenergetic defects. Even at normal glucose levels, pre-senescent HMBECs (passage 15) displayed greater Aβ (1-42)-induced mitochondrial respiratory impairments than young cells (passages 7-9). Thus, hypoglycemia, osmolarity changes, and senescence are stronger instigators of Aβ (1-42)-induced mitochondrial respiration and energetics in HBMECs and contributors to diabetes-related increased AD risk than hyperglycemia., (© 2022. The Author(s), under exclusive licence to American Aging Association.)