Fructose and metabolic diseases: too much to be good

GLUT5-overexpression-related tumorigenic implications

Glucose transporter 5 (GLUT5) overexpression has gained increasing attention due to its profound implications for tumorigenesis. This manuscript provides a comprehensive overview of the key findings and implications associated with GLUT5 overexpression in cancer. GLUT5 has been found to be upregulated in various cancer types, leading to alterations in fructose metabolism and enhanced glycolysis, even in the presence of oxygen, a hallmark of cancer cells. This metabolic shift provides cancer cells with an alternative energy source and contributes to their uncontrolled growth and survival. Beyond its metabolic roles, recent research has unveiled additional aspects of GLUT5 in cancer biology. GLUT5 overexpression appears to play a critical role in immune evasion mechanisms, which further worsens tumor progression and complicates therapeutic interventions. This dual role of GLUT5 in both metabolic reprogramming and immune modulation highlights its significance as a potential diagnostic marker and therapeutic target. Understanding the molecular mechanisms driving GLUT5 overexpression is crucial for developing targeted therapeutic strategies that can disrupt the unique vulnerabilities of GLUT5-overexpressing cancer cells. This review emphasizes the complexities surrounding GLUT5's involvement in cancer and underscores the pressing need for continued research to unlock its potential as a diagnostic biomarker and therapeutic target, ultimately improving cancer management and patient outcomes.

Host-diet-microbiota interplay in intestinal nutrition and health

The intestine is populated by a complex and dynamic assortment of microbes, collectively called gut microbiota, that interact with the host and contribute to its metabolism and physiology. Diet is considered a key regulator of intestinal microbiota, as ingested nutrients interact with and shape the resident microbiota composition. Furthermore, recent studies underscore the interplay of dietary and microbiota-derived nutrients, which directly impinge on intestinal stem cells regulating their turnover to ensure a healthy gut barrier. Although advanced sequencing methodologies have allowed the characterization of the human gut microbiome, mechanistic studies assessing diet-microbiota-host interactions depend on the use of genetically tractable models, such as Drosophila melanogaster. In this review, we first discuss the similarities between the human and fly intestines and then we focus on the effects of diet and microbiota on nutrient-sensing signaling cascades controlling intestinal stem cell self-renewal and differentiation, as well as disease. Finally, we underline the use of the Drosophila model in assessing the role of microbiota in gut-related pathologies and in understanding the mechanisms that mediate different whole-body manifestations of gut dysfunction.

Appearance quality, nutritional value, and aroma components of wild diguo (Ficus tikoua Bur.) fruit collected from southwest China

Diguo (Ficus tikoua Bur.), an ancient wild fruit, is widely spread in southwest China. However, there is little information on the phenotypic traits, quality characteristics, and aroma compounds available to diguo fruit. The present study is an investigation into the effects of geographical origin on the phenotypic traits and quality characteristics of wild diguo fruit collected from southwest China. The volatile compounds in the mixed fruit samples were also investigated using gas chromatography-mass spectrometry. Our results indicated that significant variation existed among the sampling materials in all the phenotypic parameters. Fruit fresh weight ranged between 2.06 and 4.59 g. Moreover, significant variation existed among the selected materials in all macronutrients (dry matter, total soluble solids, crude protein, crude fat, and ash) and some nutritional parameters (glutamate, arginine, total soluble solids, maltose, and mannose, etc.). Regardless of their geographical origin, diguo fruit is relatively low in fat and fructose and high in fiber and glutamate. A total of 95 volatile constituents were identified in the frozen diguo fruit. In conclusion, diguo fruit with rich nutritional attributes has a promising future for commercial-scale production. The variability of the observed morphological and nutritional features of diguo fruit provides important characteristics for improving the breeding of diguo as a modern fruit crop.

Detection of Biomarkers through Functionalized Polymers

Over the past decade, there has been a rising interest in utilizing functionalized porous polymers for sensor applications. By incorporating functional groups into nanostructured materials like hydrogels, nanosheets, and nanopores, exciting new opportunities have emerged for biomarker detection. The ability of functionalized polymers to undergo physical changes and deformations makes them perfect for modulating optical signals. This chemical mechanism enables the creation of biocompatible sensors for in situ biomarker measurement. Here a comprehensive overview of the current publication trends is provided in functionalized polymers, encompassing functional groups that can induce measurable physical deformations. It explores various materials categorized based on their detection targets, which include proteins, carbohydrates, ions, and deoxyribonucleic acid. As such, this work serves as a valuable reference for the development of functionalized polymer-based sensors.

Fructose-Induced mTORC1 Activation Promotes Pancreatic Cancer Progression through Inhibition of Autophagy

Excessive fructose intake is associated with the occurrence, progression, and poor prognosis of various tumors. A better understanding of the mechanisms underlying the functions of fructose in cancer could facilitate the development of better treatment and prevention strategies. In this study, we investigated the functional association between fructose utilization and pancreatic ductal adenocarcinoma (PDAC) progression. Fructose could be taken up and metabolized by PDAC cells and provided an adaptive survival mechanism for PDAC cells under glucose-deficient conditions. GLUT5-mediated fructose metabolism maintained the survival, proliferation, and invasion capacities of PDAC cells in vivo and in vitro. Fructose metabolism not only provided ATP and biomass to PDAC cells but also conferred metabolic plasticity to the cells, making them more adaptable to the tumor microenvironment. Mechanistically, fructose activated the AMP-activated protein kinase (AMPK)-mTORC1 signaling pathway to inhibit glucose deficiency-induced autophagic cell death. Moreover, the fructose-specific transporter GLUT5 was highly expressed in PDAC tissues and was an independent marker of disease progression in patients with PDAC. These findings provide mechanistic insights into the role of fructose in promoting PDAC progression and offer potential strategies for targeting metabolism to treat PDAC.

SIGNIFICANCE

Fructose activates AMPK-mTORC1 signaling to inhibit autophagy-mediated cell death in pancreatic cancer cells caused by glucose deficiency, facilitating metabolic adaptation to the tumor microenvironment and supporting tumor growth.

Fructose overconsumption impairs hepatic manganese homeostasis and ammonia disposal

Arginase, a manganese (Mn)-dependent enzyme, is indispensable for urea generation and ammonia disposal in the liver. The potential role of fructose in Mn and ammonia metabolism is undefined. Here we demonstrate that fructose overconsumption impairs hepatic Mn homeostasis and ammonia disposal in male mice. Fructose overexposure reduces liver Mn content as well as its activity of arginase and Mn-SOD, and impairs the clearance of blood ammonia under liver dysfunction. Mechanistically, fructose activates the Mn exporter Slc30a10 gene transcription in the liver in a ChREBP-dependent manner. Hepatic overexpression of Slc30a10 can mimic the effect of fructose on liver Mn content and ammonia disposal. Hepatocyte-specific deletion of Slc30a10 or ChREBP increases liver Mn contents and arginase activity, and abolishes their responsiveness to fructose. Collectively, our data establish a role of fructose in hepatic Mn and ammonia metabolism through ChREBP/Slc30a10 pathway, and postulate fructose dietary restriction for the prevention and treatment of hyperammonemia.

Diabetes and diabesity in the view of proteomics, drug, and plant-derived remedies

Diabetes and obesity are highly prevalent in the world. Proteomics is a promising approach to better understanding enzymes, proteins, and signaling molecules involved in diabetes processes which help recognize the basis of the disease better and find suitable new treatments. This study aimed to summarize the molecular mechanisms from the beginning of insulin secretion in response to stimuli to the pathology of the insulin signaling pathway and, finally, the mechanisms of drugs/chemicals remedies that affect this process. The titles and subtitles of this process were determined, and then for each of them, the articles searched in PubMed and ScienceDirect were used. This review article starts the discussion with the molecular basis of insulin biosynthesis, secretion, insulin's mechanism of action, and molecular aspect of diabetes and diabesity (a new term showing the relation between diabetes and obesity) and ends with the drug and plant-derived intervention for hyperglycemia.

PFKFB3 Inhibits Fructose Metabolism in Pulmonary Microvascular Endothelial Cells

Pulmonary microvascular endothelial cells contribute to the integrity of the lung gas exchange interface, and they are highly glycolytic. Although glucose and fructose represent discrete substrates available for glycolysis, pulmonary microvascular endothelial cells prefer glucose over fructose, and the mechanisms involved in this selection are unknown. 6-Phosphofructo-2-kinase/fructose-2, 6-bisphosphatase 3 (PFKFB3) is an important glycolytic enzyme that drives glycolytic flux against negative feedback and links glycolytic and fructolytic pathways. We hypothesized that PFKFB3 inhibits fructose metabolism in pulmonary microvascular endothelial cells. We found that PFKFB3 knockout cells survive better than wild-type cells in fructose-rich medium under hypoxia. Seahorse assays, lactate and glucose measurements, and stable isotope tracing showed that PFKFB3 inhibits fructose-hexokinase-mediated glycolysis and oxidative phosphorylation. Microarray analysis revealed that fructose upregulates PFKFB3, and PFKFB3 knockout cells increase fructose-specific GLUT5 (glucose transporter 5) expression. Using conditional endothelial-specific PFKFB3 knockout mice, we demonstrated that endothelial PFKFB3 knockout increases lung tissue lactate production after fructose gavage. Last, we showed that pneumonia increases fructose in BAL fluid in mechanically ventilated ICU patients. Thus, PFKFB3 knockout increases GLUT5 expression and the hexokinase-mediated fructose use in pulmonary microvascular endothelial cells that promotes their survival. Our findings indicate that PFKFB3 is a molecular switch that controls glucose versus fructose use in glycolysis and help better understand lung endothelial cell metabolism during respiratory failure.

Lipid peroxidation and neuroinflammation: A possible link between maternal fructose intake and delay of acquisition of neonatal reflexes in Wistar female rats

Fructose is a common sweetener found in the daily diet supplemented to many processed and ultra-processed foods and beverages. Consumption of fructose-sweetened beverages has drastically increased in the last decades and is widely associated with metabolic disease, systemic pro-inflammatory status, and adverse transgenerational effects. To date, the impact of maternal fructose intake in brain function of the offspring is less explored. Therefore, the aim of this study was first, to investigate adverse effects in developmental milestones of the progeny of mothers with metabolic syndrome (MetS), induced by ad libitum consumption of a 20% fructose solution, and second to identify possible molecular changes in the nervous system of the newborns associated with maternal fructose intake. Wistar rats were randomly separated into two groups with access to water or fructose (20% w/v in water) for 10 weeks. After MetS was confirmed, dams were mated with control males and continued drinking water or fructose solution during gestation. At postnatal day (PN) 1, a subgroup of offspring of each sex was sacrificed and brains were dissected for oxidative stress and inflammatory status analysis. Changes in the developmental milestones due to maternal fructose consumption were studied (PN3-PN21) in another subgroup of offspring. Sexually dimorphic effects were found on the progeny's acquisition of neurodevelopmental milestones, in brain lipid peroxidation, neuroinflammation, and antioxidative defensive response. Our results suggest that dams' MetS, induced by fructose intake, disrupts brain redox homeostasis in female offspring and affects sensorimotor brain circuitry which may have a translational value for studying neurodevelopmental diseases.

Hepatic but not Intestinal FBP1 Is Required for Fructose Metabolism and Tolerance

Fructose intolerance in mammals is caused by defects in fructose absorption and metabolism. Fructose-1,6-bisphosphatase 1 (FBP1) is a key enzyme in gluconeogenesis, and its deficiency results in hypoglycemia as well as intolerance to fructose. However, the mechanism about fructose intolerance caused by FBP1 deficiency has not been fully elucidated. Here, we demonstrate that hepatic but not intestinal FBP1 is required for fructose metabolism and tolerance. We generated inducible knockout mouse models specifically lacking FBP1 in adult intestine or liver. Intestine-specific deletion of Fbp1 in adult mice does not compromise fructose tolerance, as evidenced by no significant body weight loss, food intake reduction, or morphological changes of the small intestine during 4 weeks of exposure to a high-fructose diet. By contrast, liver-specific deletion of Fbp1 in adult mice leads to fructose intolerance, as manifested by substantial weight loss, hepatomegaly, and liver injury after exposure to a high-fructose diet. Notably, the fructose metabolite fructose-1-phosphate is accumulated in FBP1-deficient liver after fructose challenge, which indicates a defect of fructolysis, probably due to competitive inhibition by fructose-1,6-bisphosphate and may account for the fructose intolerance. In conclusion, these data have clarified the essential role of hepatic but not intestinal FBP1 in fructose metabolism and tolerance.

Diet-induced gut dysbiosis and inflammation: Key drivers of obesity-driven NASH

Sucrose, the primary circulating sugar in plants, contains equal amounts of fructose and glucose. The latter is the predominant circulating sugar in animals and thus the primary fuel source for various tissue and cell types in the body. Chronic excessive energy intake has, however, emerged as a major driver of obesity and associated pathologies including nonalcoholic fatty liver diseases (NAFLD) and the more severe nonalcoholic steatohepatitis (NASH). Consumption of a high-caloric, western-style diet induces gut dysbiosis and inflammation resulting in leaky gut. Translocation of gut-derived bacterial content promotes hepatic inflammation and ER stress, and when either or both of these are combined with steatosis, it can cause NASH. Here, we review the metabolic links between diet-induced changes in the gut and NASH. Furthermore, therapeutic interventions for the treatment of obesity and liver metabolic diseases are also discussed with a focus on restoring the gut-liver axis.

Hypercaloric Diet Promotes Metabolic Disorders and Impaired Kidney Function

Poor dietary habits such as overconsumption of hypercaloric diets characterized by a high content of fructose and fat are related to metabolic abnormalities development such as obesity, diabetes, and dyslipidemia. Accumulating evidence supports the hypothesis that if energy intake gradually exceeds the body's ability to store fat in adipose tissue, the prolonged metabolic imbalance of circulating lipids from endogenous and exogenous sources leads to ectopic fat distribution in the peripheral organs, especially in the heart, liver, and kidney. The kidney is easily affected by dyslipidemia, which induces lipid accumulation and reflects an imbalance between fatty acid supply and fatty acid utilization. This derives from tissue lipotoxicity, oxidative stress, fibrosis, and inflammation, resulting in structural and functional changes that lead to glomerular and tubule-interstitial damage. Some authors indicate that a lipid-lowering pharmacological approach combined with a substantial lifestyle change should be considered to treat chronic kidney disease (CKD). Also, the new therapeutic target identification and the development of new drugs targeting metabolic pathways involved with kidney lipotoxicity could constitute an additional alternative to combat the complex mechanisms involved in impaired kidney function. In this review article, we first provide the pathophysiological evidence regarding the impact of hypercaloric diets, such as high-fat diets and high-fructose diets, on the development of metabolic disorders associated with impaired renal function and the molecular mechanisms underlying tissue lipid deposition. In addition, we present the current progress regarding translational strategies to prevent and/or treat kidney injury related to the consumption of hypercaloric diets.

Dietary insulin index and insulin load in relation to hypertriglyceridemic waist phenotype and low brain derived neurotrophic factor in adults

Background

The evidence about the relation of the insulinemic potential of food with visceral obesity and brain-derived neurotrophic factor (BDNF) was limited. We aimed to investigate the relation of dietary insulin index (DII) and dietary insulin load (DIL) with hypertriglyceridemic waist phenotype (HTGW) and serum BDNF in Iranian adults.

Methods

This cross-sectional study included 528 middle-aged adults (45.6% women), using a multistage cluster random-sampling method. Dietary intakes were assessed using a validated semi-quantitative 168-item food frequency questionnaire. Blood samples were collected after 12 h of fasting for assessing the serum BDNF and triglyceride concentrations. HTGW was defined as triacylglycerol ≥ 150 mg/dL plus enlarged waist circumference. The values less than the first decile of serum BDNF were considered as the low level.

Results

Individuals in the top tertile of DIL, in comparison to those in the bottom tertile, had higher odds of HTGW in both crude (OR = 1.96, 95% CI: 1.14–3.37) and fully adjusted model (OR = 6.10, 95% CI: 1.58–23.53). However, the relation between DII and odds of HTGW was statistically insignificant in crude (OR = 1.30, 95% CI: 0.78–2.16) and maximally adjusted model (OR = 1.25, 95% CI: 0.65–2.40). After considering confounders, participants in the top tertile of DIL had marginally higher odds of having low BDNF values (OR = 2.00, 95% CI: 0.95–4.21). Nevertheless, the association between DII and odds of low BDNF values was statistically insignificant.

Conclusion

This population-based study demonstrated that adults with higher DIL had significantly higher chance of HTGW phenotype and slightly higher chance for low BDNF level. DII was not associated with HTGW phenotype or BDNF values.

Protective effects of green tea on blood and liver of rats fed with high fructose diet

This study was designed to investigate the effects of green tea on lipid profile, liver tissue damage, and oxidative stress in rats fed a diet including high fructose. Sprague-Dawley rats were randomly divided into four groups: Control (C), Fructose (F), Green Tea (GT), and F+GT. F and F+GT groups were given 20% fructose in the drinking water for eight weeks. Green tea (2 mg kg−1) was administrated to GT and F+GT groups by oral gavage for eight weeks. Biochemical parameters in serum and oxidative stress markers in the liver were analysed. The liver sections were stained with haematoxylin-eosin. As of the 3rd week of the experiment, the body weight of rats in the F group showed a statistically significant increase in comparison with the F+GT group. The serum glucose and triglyceride levels of the F+GT group significantly decreased when compared with the F group. The fructose-induced degenerative changes in the liver were reduced with green tea. Green tea may serve a protective role against hyperlipidaemia and liver injury in rats fed a high fructose diet.

Effects of High Dietary Carbohydrate and Lipid Intake on the Lifespan of C. elegans

Health and lifespan are influenced by dietary nutrients, whose balance is dependent on the supply or demand of each organism. Many studies have shown that an increased carbohydrate–lipid intake plays a critical role in metabolic dysregulation, which impacts longevity. Caenorhabditis elegans has been successfully used as an in vivo model to study the effects of several factors, such as genetic, environmental, diet, and lifestyle factors, on the molecular mechanisms that have been linked to healthspan, lifespan, and the aging process. There is evidence showing the causative effects of high glucose on lifespan in different diabetic models; however, the precise biological mechanisms affected by dietary nutrients, specifically carbohydrates and lipids, as well as their links with lifespan and longevity, remain unknown. Here, we provide an overview of the deleterious effects caused by high-carbohydrate and high-lipid diets, as well as the molecular signals that affect the lifespan of C. elegans; thus, understanding the detailed molecular mechanisms of high-glucose- and lipid-induced changes in whole organisms would allow the targeting of key regulatory factors to ameliorate metabolic disorders and age-related diseases.