Advanced glycation end-products: a biological consequence of lifestyle contributing to cancer disparity

A comprehensive investigation on alleviating oxidative stress and inflammation in hyperglycaemic conditions through in vitro experiments and computational analysis

Protein glycation, hyper-inflammatory reactions, and oxidative stress play a crucial role in the pathophysiology of numerous diseases. The current work evaluated the protective ability of ethyl alcohol extract of leaves from holy basil (Ocimum sanctum Linn) against inflammation, oxidative stress, glycation and advanced glycation endproducts formation. Various in vitro assays assessed prementioned properties of holy basil. In addition, molecular docking was conducted. The highest hydrogen peroxide reduction activity (72.7 %) and maximum percentage of DPPH scavenging (71.3 %) depicted its vigorous antioxidant abilities. Furthermore, it showed the most excellent protection against proteinase activity (67.247 %), prevention of denaturation of egg albumin (65.29 %), and BSA (bovine serum albumin) (68.87 %) with 600 µg/ml. Percent aggregation index (57.528 %), browning intensity (56.61 %), and amyloid structure (57.0 %) were all reduced significantly using 600 μg/ml of extract. Additionally, the antimicrobial potential was also confirmed. According to a molecular docking study, active leaf extract ingredients were found to bind with superoxide dismutase, catalase, and carbonic anhydrase. As a conclusion, O. sanctum has a variety of health-promoting properties that may reduce the severity of many diseases in diabetic patients. However, in order to ascertain the mechanisms of action of the components of its leaves in disease prevention, more thorough research based on pharmacological aspects is needed.

Metabolites, Healthy Lifestyle, and Polygenic Risk Score Associated with Upper Gastrointestinal Cancer: Findings from the UK Biobank Study

Previous metabolomics studies have highlighted the predictive value of metabolites on upper gastrointestinal (UGI) cancer, while most of them ignored the potential effects of lifestyle and genetic risk on plasma metabolites. This study aimed to evaluate the role of lifestyle and genetic risk in the metabolic mechanism of UGI cancer. Differential metabolites of UGI cancer were identified using partial least-squares discriminant analysis and the Wilcoxon test. Then, we calculated the healthy lifestyle index (HLI) score and polygenic risk score (PRS) and divided them into three groups, respectively. A total of 15 metabolites were identified as UGI-cancer-related differential metabolites. The metabolite model (AUC = 0.699) exhibited superior discrimination ability compared to those of the HLI model (AUC = 0.615) and the PRS model (AUC = 0.593). Moreover, subgroup analysis revealed that the metabolite model showed higher discrimination ability for individuals with unhealthy lifestyles compared to that with healthy individuals (AUC = 0.783 vs 0.684). Furthermore, in the genetic risk subgroup analysis, individuals with a genetic predisposition to UGI cancer exhibited the best discriminative performance in the metabolite model (AUC = 0.770). These findings demonstrated the clinical significance of metabolic biomarkers in UGI cancer discrimination, especially in individuals with unhealthy lifestyles and a high genetic risk.

Associations of circulating advanced glycation end products and their soluble receptors with cancer risk: A systematic review and meta-analysis of observational studies

Advanced glycation end products (AGE) in complex with their receptors (RAGE) cause a chronic inflammatory state in the body, which is the major mechanism in cancer development. This study aimed to conduct a systematic review and meta-analysis on the observational studies investigating the association between AGEs / sRAGE and cancer incidence. The PubMed, Scopus, and Web of Science databases were comprehensively searched to identify papers focused on the associations of sRAGE and AGEs with cancer incidence up to May 2023. Eight studies with a total of 7690 participants were included in the analysis to evaluate the association between circulating sRAGE and cancer incidence. The results indicated that circulating sRAGE (per 100 ng/L) had a significant inverse association with cancer incidence (RR 0.977; 95% CI 0.956, 0.999; p = 0.036; I 2 = 73.3%). The association between AGEs and cancer incidence was evaluated in 8 studies with a total of 3718 individuals. Serum concentrations of AGEs (per 100 µg/L) were not associated with the risk of cancer incidence (RR 0.988; 95% CI 0.974, 1.002; p = 0.08; I2 = 78.8%). Our findings revealed that a higher circulating sRAGE may have a protective effect against cancer incidence.

Dietary and serum advanced glycation end-products and clinical outcomes in breast cancer

One in five women with breast cancer will relapse despite ideal treatment. Body weight and physical activity are strongly associated with recurrence risk, thus lifestyle modification is an attractive strategy to improve prognosis. Trials of dietary modification in breast cancer are promising but the role of specific diets is unclear, as is whether high-quality diet without weight loss can impact prognosis. Advanced glycation end-products (AGEs) are compounds produced in the body during sugar metabolism. Exogenous AGEs, such as those found in food, combined with endogenous AGEs, make up the total body AGE load. AGEs deposit in tissues over time impacting cell signaling pathways and altering protein functions. AGEs can be measured or estimated in the diet and measured in blood through their metabolites. Studies demonstrate an association between AGEs and breast cancer risk and prognosis. Here, we review the clinical data on dietary and serum AGEs in breast cancer.

Protein Advanced Glycation End Products and Their Implications in Pancreatic Cancer

Protein advanced glycation end products (AGE) formed by nonenzymatic glycation can disrupt the normal structure and function of proteins, and stimulate the receptor for AGEs (RAGE), triggering intricate mechanisms that are etiologically related to various chronic diseases, including pancreatic cancer. Many common risk factors of pancreatic cancer are the major sources for the formation of protein AGEs and glycative stress in the human body. Abnormal accumulation of protein AGEs can impair the cellular proteome and promote AGE-RAGE driven pro-inflammatory signaling cascades, leading to increased oxidative stress, protease resistance, protein dysregulation, transcription activity of STAT, NF-κB, and AP-1, aberrant status in ubiquitin-proteasome system and autophagy, as well as other molecular events that are susceptible for the carcinogenic transformation towards the development of neoplasms. Here, we review studies to highlight our understanding in the orchestrated molecular events in bridging the impaired proteome, dysregulated functional networks, and cancer hallmarks initiated upon protein AGE formation and accumulation in pancreatic cancer.

Pubertal exposure to dietary advanced glycation end products disrupts ductal morphogenesis and induces atypical hyperplasia in the mammary gland

BACKGROUND

Advanced glycation end products (AGEs) are reactive metabolites intrinsically linked with modern dietary patterns. Processed foods, and those high in sugar, protein and fat, often contain high levels of AGEs. Increased AGE levels are associated with increased breast cancer risk, however their significance has been largely overlooked due to a lack of direct cause-and-effect relationship.

METHODS

To address this knowledge gap, FVB/n mice were fed regular, low AGE, and high AGE diets from 3 weeks of age and mammary glands harvested during puberty (7 weeks) or adulthood (12 weeks and 7 months) to determine the effects upon mammary gland development. At endpoint mammary glands were harvested and assessed histologically (n ≥ 4). Immunohistochemistry and immunofluorescence were used to assess cellular proliferation and stromal fibroblast and macrophage recruitment. The Kruskal-Wallis test were used to compare continuous outcomes among groups. Mammary epithelial cell migration and invasion in response to AGE-mediated fibroblast activation was determined in two-compartment co-culture models. In vitro experiments were performed in triplicate. The nonparametric Wilcoxon rank sum test was used to compare differences between groups.

RESULTS

Histological analysis revealed the high AGE diet delayed ductal elongation, increased primary branching, as well as increased terminal end bud number and size. The high AGE diet also led to increased recruitment and proliferation of stromal cells to abnormal structures that persisted into adulthood. Atypical hyperplasia was observed in the high AGE fed mice. Ex vivo fibroblasts from mice fed dietary-AGEs retain an activated phenotype and promoted epithelial migration and invasion of non-transformed immortalized and tumor-derived mammary epithelial cells. Mechanistically, we found that the receptor for AGE (RAGE) is required for AGE-mediated increases in epithelial cell migration and invasion.

CONCLUSIONS

We observed a disruption in mammary gland development when mice were fed a diet high in AGEs. Further, both epithelial and stromal cell populations were impacted by the high AGE diet in the mammary gland. Educational, interventional, and pharmacological strategies to reduce AGEs associated with diet may be viewed as novel disease preventive and/or therapeutic initiatives during puberty.

Exploring the molecular interactions and binding affinity of resveratrol and calcitriol with RAGE and its intracellular proteins and kinases involved in colorectal cancer

Colorectal cancer (CRC) burden is progressively increasing in young population due to dietary and lifestyle pattern. Advanced glycation end products (AGEs), one of the dietary compounds, form complex aggregates with proteins, lipids, and nucleic acids distorting their structure and function. AGE's pro-tumorigenic role is mediated through the receptor for AGEs (RAGE) triggering an array of signaling pathways. The current study aimed to target AGE-RAGE axis signaling proteins and kinases at multiple levels with calcitriol (CAL) and trans-resveratrol (RES) through in silico analysis using molecular docking (MD), molecular dynamic simulation(MDS), MM-PBSA analysis, and in vitro study. In silico analysis of CAL and RES showed significant binding affinity toward RAGE and its signaling proteins such as NF-kB, PI3K/AKT, ERK1/2, and PKC compared to its reference inhibitors through better hydrogen, hydrophobic, pi-pi stacking interactions. MD and MDS studies have revealed stable and compact protein-ligand complexes. Binding free energies of protein-ligand complex were estimated using MM/PBSA analysis thatprovided an assessment of overall interacting free energies of complexes and revealed the presence of low binding energy within the active site. Furthermore, in the in vitro study, methylglyoxal (MG), an AGE-precursor showed a proliferative effect on HCT116, however, CAL and RES showed an inhibitory effect against MG induced effect with an IC50 value of 51 nM and 110 µM respectively. Thus, the study suggests the possible target binding sites of AGE-RAGE signaling proteins and kinases with CAL and RES, thereby exploiting it for developing CAL with RES as adjuvant therapy along with chemo drug for CRC.Communicated by Ramaswamy H. Sarma.

Inflammation level in type 2 diabetes is associated with dietary advanced glycation end products, Mediterranean diet adherence and oxidative balance score: A pathway analysis

AIMS

The aim of this study was to evaluate the effects of dietary advanced glycation end products (dAGE) intake, Mediterranean diet adherence screener (MEDAS), and oxidative balance score (OBS) on inflammation among individuals with type 2 diabetes.

METHODS

The study was conducted with 96 adults (aged between 32 and 64 years) with type 2 diabetes. The average daily dAGE intakes, energy and macronutrient intakes of the participants were taken with the three-day food consumption recording method. OBS and MEDAS score was used. At the same time, routine blood lipids, HbA1c, fasting blood glucose and inflammation marker C-reactive protein (CRP) were measured.

RESULTS

Dietary AGE intake was associated with fasting blood glucose, HbA1c, CRP and blood pressures (p < 0.01). The relationship between OBS and dAGE intake was significant (β = -0.36; 95 % Cl = -0.500, -0.220; p < 0.001). MEDAS has a negative and statistically significant effect on dAGE intake (β = -0.56; 95 % Cl = -0.696, -0.444; p < 0.001). There was a significant and positive effect of dAGE on CRP when other variables (MEDAS, OBS) affecting dAGE were also included in the analysis (β = 0.79; 95 % CI = 0.664, 0.917; p < 0.001).

CONCLUSIONS

Our findings may have important implications for explaining the development of inflammation in type 2 diabetes patients with high dAGE intake.

Genetically Modified Circulating Levels of Advanced Glycation End-Products and Their Soluble Receptor (AGEs-RAGE Axis) with Risk and Mortality of Breast Cancer

The interaction of advanced glycation end-products (AGEs) with their receptor (RAGE) elicits oxidative stress and inflammation, which is involved in the development of breast cancer. However, large-scale population-based evidence exploring genetically modified circulating levels of AGEs-RAGE axis with risk and mortality of breast cancer is scarce. We recruited 1051 pairs of age-matched breast cancers and controls and measured plasma AGEs and sRAGE concentrations by enzyme-linked immunosorbent assay (ELISA). Multivariate logistic regression and Cox proportional hazard model were used to calculate the effects of plasma levels and genetic variants of the AGEs-RAGE axis and their combined effects on breast cancer risk and prognosis, respectively. Furthermore, linear regression was performed to assess the modifications in plasma AGEs/sRAGE levels by genetic predisposition. Higher levels of AGEs and AGEs/sRAGE-ratio were associated with an increased risk of breast cancer, but sRAGE levels were negatively associated with breast cancer risk, especially in women <60 years. We also observed a positive association between AGEs and the bad prognosis of breast cancer. Although we did not observe a significant contribution of genetic variants to breast cancer risk, rs2070600 and rs1800624 in the AGER gene were dose-dependently correlated with sRAGE levels. Further, compared to the haplotype CT at the lowest quartile of AGEs, haplotypes TT and TA were prominently associated with breast cancer risk in the highest quartile of AGEs. This study depicted a significant association between circulating levels of AGEs-RAGE axis and breast cancer risk and mortality and revealed the potential of plasma AGEs, especially coupled with AGER polymorphism as biomarkers of breast cancer.

Receptor for Advanced Glycation End Products (RAGE): A Pivotal Hub in Immune Diseases

As a critical molecule in the onset and sustainment of inflammatory response, the receptor for advanced glycation end products (RAGE) has a variety of ligands, such as advanced glycation end products (AGEs), S100/calcium granule protein, and high-mobility group protein 1 (HMGB1). Recently, an increasing number studies have shown that RAGE ligand binding can initiate the intracellular signal cascade, affect intracellular signal transduction, stimulate the release of cytokines, and play a vital role in the occurrence and development of immune-related diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and Alzheimer’s disease. In addition, other RAGE signaling pathways can play crucial roles in life activities, such as inflammation, apoptosis, autophagy, and endoplasmic reticulum stress. Therefore, the strategy of targeted intervention in the RAGE signaling pathway may have significant therapeutic potential, attracting increasing attention. In this paper, through the systematic induction and analysis of RAGE-related signaling pathways and their regulatory mechanisms in immune-related diseases, we provide theoretical clues for the follow-up targeted intervention of RAGE-mediated diseases.

The Biological Role of Advanced Glycation End Products in the Development and Progression of Colorectal Cancer

“Colorectal cancer” (CRC) is one of the most prevalent cancers, posing a scientific challenge and serving as a model for investigating the molecular pathways underlying its development. “Advanced glycation end products” (AGEs) have drawn interest in this context. The buildup of these diverse, chemically complex groups, which are formed by a “non-enzymatic interaction” between reducing sugar and a range of macromolecules, significantly increases “inflammation and oxidative stress” in the body, which has long been associated to cancer formation. The traditional pathways that promote AGE formation, as well as the significance of AGEs’ interaction with the receptor for “advanced glycation end products” (RAGE) and other means involved in CRC initiation and progression, are discussed in this review.

Differential effects of glucose and N-acetylglucosamine on genome instability

Aberrant sugar metabolism is linked to an increased risk of pancreatic cancer. Previously, we found that high glucose induces genome instability and de novo oncogenic KRAS mutation preferentially in pancreatic cells through dysregulation of O-GlcNAcylation. Increasing O-GlcNAcylation by extrinsically supplying N-acetyl-D-glucosamine (GlcNAc) causes genome instability in all kinds of cell types regardless of pancreatic origin. Since many people consume excessive amount of sugar (glucose, fructose, and sucrose) in daily life, whether high sugar consumption directly causes genome instability in animals remains to be elucidated. In this communication, we show that excess sugar in the daily drink increases DNA damage and protein O-GlcNAcylation preferentially in pancreatic tissue but not in other kinds of tissue of mice. The effect of high sugar on the pancreatic tissue may be attributed to the intrinsic ratio of GFAT and PFK activity, a limiting factor that dictates UDP-GlcNAc levels. On the other hand, GlcNAc universally induces DNA damage in all six organs examined. Either inhibiting O-GlcNAcylation or supplementing dNTP pool diminishes the induced DNA damage in these organs, indicating that the mechanism of action is similar to that of high glucose treatment in pancreatic cells. Taken together, these results suggest the potential hazards of high sugar drinks and high glucosamine intake to genomic instability and possibly cancer initiation.

Targeting extracellular matrix glycation to attenuate fibroblast activation

The extracellular matrix (ECM) of the tumor microenvironment undergoes constant remodeling that alters its biochemical and mechano-physical properties. Non-enzymatic glycation can induce the formation of advanced glycation end-products (AGEs), which may cause abnormal ECM turnover with excessively cross-linked collagen fibers. However, the subsequent effects of AGE-mediated matrix remodeling on the characteristics of stromal cells in tumor microenvironments remain unclear. Here, we demonstrate that AGEs accumulated in the ECM alter the fibroblast phenotype within a three-dimensional collagen matrix. Both the AGE interaction with its receptor (RAGE) and integrin-mediated mechanotransduction signaling were up-regulated in glycated collagen matrix, leading to fibroblast activation to acquire a cancer-associated fibroblast (CAF)-like phenotype. These effects were blocked with neutralizing antibodies against RAGE or the inhibition of focal adhesion (FA) signaling. An AGE cross-link breaker, phenyl-4,5-dimethylthiazolium bromide (ALT 711), also reduced the transformation of fibroblasts into the CAF-like phenotype because of its dual inhibitory role in the AGE-modified matrix. Apart from targeting the AGE-RAGE interaction directly, the decreased matrix stiffness attenuated fibroblast activation by inhibiting the downstream cellular response to matrix stiffness. Our results suggest that indirect/direct targeting of accumulated AGEs in the ECM has potential for targeting the tumor stroma to improve cancer therapy. STATEMENT OF SIGNIFICANCE: Advanced glycated end-products (AGEs)-modified extracellular matrix (ECM) is closely associated with pathological states and is recognized as a critical factor that precedes tumorigenesis. While increased matrix stiffness is known to induce fibroblast activation, less is known about how both biochemical and mechano-physical changes in AGE-mediated matrix-remodeling cooperate to produce a myofibroblastic cancer-associated fibroblast (CAF)-like phenotype. For the first time, we found that both the AGE interaction with its receptor (RAGE) and integrin-mediated mechanotransduction were up-regulated in glycated collagen matrix, leading to fibroblast activation. We further demonstrated that an AGE cross-link breaker, ALT-711, reduced the CAF-like transformation because of its dual inhibitory role in the AGE-modified matrix. Our findings offer promising extracellular-reversion strategies targeting the non-enzymatic ECM glycation, to regulate fibroblast activation.

Fibrous stroma: Driver and passenger in cancer development

Cumulative evidence shows that fibrogenic stroma and stiff extracellular matrix (ECM) not only result from tumor growth but also play pivotal roles in cellular transformation and tumor initiation. This emerging concept may largely account for the increased cancer risk associated with environmental fibrogenic agents, such as asbestos and silica, and with chronic conditions that are fibrogenic, such as obesity and diabetes. It may also contribute to poor outcomes in patients treated with certain chemotherapeutics that can promote fibrosis, such as bleomycin and methotrexate. Although the mechanistic details of this phenomenon are still being unraveled, we provide an overview of the experimental evidence linking fibrogenic stroma and tumor initiation. In this Review, we will summarize the causes and consequences of fibrous stroma and how this stromal cue is transmitted to the nuclei of parenchymal cells through a physical continuum from the ECM to chromatin, as well as ECM-dependent biochemical signaling that contributes to cellular transformation.

Non-enzymatic glycoxidation linked with nutrition enhances the tumorigenic capacity of prostate cancer epithelia through AGE mediated activation of RAGE in cancer associated fibroblasts

The molecular implications of food consumption on cancer etiology are poorly defined. The rate of nutrition associated non-enzymatic glycoxidation, a reaction that occurs between reactive carbonyl groups on linear sugars and nucleophilic amino, lysyl and arginyl groups on fats and proteins, is rapidly increased by food cooking and manufacturing processes. In this study, we assign nutrition-associated glycoxidation with significant oncogenic potential, promoting prostate tumor growth, progression, and metastasis in vivo. Advanced glycation end products (AGEs) are the final irreversible product of non-enzymatic glycoxidation. Exogenous treatment of prostate tumor cells with a single AGE peptide replicated glycoxidation induced tumor growth in vivo. Mechanistically, receptor for AGE (RAGE) deficiency in the stroma inhibited AGE mediated tumor growth. Functionally, AGE treatment induced RAGE dimerization in activated fibroblasts which sustained and increased the migratory potential of tumor epithelial cells. These data identify a novel nutrition associated pathway that can promote a tissue microenvironment conducive for aggressive tumor growth. Targeted and/or interventional strategies aimed at reducing AGE bioavailability as a consequence of nutrition may be viewed as novel chemoprevention initiatives.

Dietary Advanced Glycation End-Products and Mortality after Breast Cancer in the Women's Health Initiative

BACKGROUND

Advanced glycation end-products (AGE) are formed through nonenzymatic glycation of free amino groups in proteins or lipid. They are associated with inflammation and oxidative stress, and their accumulation in the body is implicated in chronic disease morbidity and mortality. We examined the association between postdiagnosis dietary Nε-carboxymethyl-lysine (CML)-AGE intake and mortality among women diagnosed with breast cancer.

METHODS

Postmenopausal women aged 50 to 79 years were enrolled in the Women's Health Initiative (WHI) between 1993 and 1998 and followed up until death or censoring through March 2018. We included 2,023 women diagnosed with first primary invasive breast cancer during follow-up who completed a food frequency questionnaire (FFQ) after diagnosis. Cox proportional hazards (PH) regression models estimated adjusted hazard ratios (HR) and 95% confidence intervals (CI) of association between tertiles of postdiagnosis CML-AGE intake and mortality risk from all causes, breast cancer, and cardiovascular disease.

RESULTS

After a median 15.1 years of follow-up, 630 deaths from all causes were reported (193 were breast cancer-related, and 129 were cardiovascular disease-related). Postdiagnosis CML-AGE intake was associated with all-cause (HRT3vsT1, 1.37; 95% CI, 1.09-1.74), breast cancer (HRT3vsT1, 1.49; 95% CI, 0.98-2.24), and cardiovascular disease (HRT3vsT1, 1.91; 95% CI, 1.09-3.32) mortality.

CONCLUSIONS

Higher intake of AGEs was associated with higher risk of major causes of mortality among postmenopausal women diagnosed with breast cancer.

IMPACT

Our findings suggest that dietary AGEs may contribute to the risk of mortality after breast cancer diagnosis. Further prospective studies examining dietary AGEs in breast cancer outcomes and intervention studies targeting dietary AGE reduction are needed to confirm our findings.

Diabetes and Colorectal Cancer Risk: A New Look at Molecular Mechanisms and Potential Role of Novel Antidiabetic Agents

Epidemiological data have demonstrated a significant association between the presence of type 2 diabetes mellitus (T2DM) and the development of colorectal cancer (CRC). Chronic hyperglycemia, insulin resistance, oxidative stress, and inflammation, the processes inherent to T2DM, also play active roles in the onset and progression of CRC. Recently, small dense low-density lipoprotein (LDL) particles, a typical characteristic of diabetic dyslipidemia, emerged as another possible underlying link between T2DM and CRC. Growing evidence suggests that antidiabetic medications may have beneficial effects in CRC prevention. According to findings from a limited number of preclinical and clinical studies, glucagon-like peptide-1 receptor agonists (GLP-1RAs) could be a promising strategy in reducing the incidence of CRC in patients with diabetes. However, available findings are inconclusive, and further studies are required. In this review, novel evidence on molecular mechanisms linking T2DM with CRC development, progression, and survival will be discussed. In addition, the potential role of GLP-1RAs therapies in CRC prevention will also be evaluated.

Translating the advanced glycation end products (AGEs) knowledge into real-world nutrition strategies

Advanced glycation end products (AGEs) are glycated proteins or lipids derived from complex metabolic pathways involved in the pathophysiology of various diseases, especially diabetes and diabetes-related complications. These compounds are omnipresent in human life, with both endogenous and exogenous sources. Despite the well-elucidated disease mechanisms, little is known about the AGEs/nutrition nexus in the circles of clinical practice recommendations. This review seeks to translate the accumulated knowledge about the biochemistry and pathophysiology of AGEs into a nutritional intervention based on real-world prescriptions.

Experimental Animal Studies Support the Role of Dietary Advanced Glycation End Products in Health and Disease

The increased incidence of obesity, diabetes mellitus, aging, and associated comorbidities indicates the interplay between genetic and environmental influences. Several dietary components have been identified to play a role in the pathogenesis of the so-called "modern diseases", and their complications including advanced glycation end products (AGEs), which are generated during the food preparation and processing. Diet-derived advanced glycation end products (dAGEs) can be absorbed in the gastrointestinal system and contribute to the total body AGEs' homeostasis, partially excreted in the urine, while a significant amount accumulates to various tissues. Various in vitro, in vivo, and clinical studies support that dAGEs play an important role in health and disease, in a similar way to those endogenously formed. Animal studies using wild type, as well as experimental, animal models have shown that dAGEs contribute significantly to the pathogenesis of various diseases and their complications, and are involved in the changes related to the aging process. In addition, they support that dAGEs' restriction reduces insulin resistance, oxidative stress, and inflammation; restores immune alterations; and prevents or delays the progression of aging, obesity, diabetes mellitus, and their complications. These data can be extrapolated in humans and strongly support that dAGEs' restriction should be considered as an alternative therapeutic intervention.

Health Promoting Effect of Phyllanthus emblica and Azadiractha indica against Advanced Glycation End Products Formation

Oxidative stress is linked with inflammation, diabetic complications, and advanced glycation end products formation. Intake of flavonoid-rich foods has been reported to have a beneficial effect on human health. The aim of this study was to verify the therapeutic potential of Phyllanthusemblica and Azadiractha indica against glycation and other oxidative stress-induced complications such as inflammation using in vitro study. Ethanol extracts of Phyllanthus emblica fruit pulp and dried leaf of Azadiractha indica were prepared to investigate in vitro anti-inflammatory and anti-glycating potentials. In a DPPH assay, the EC50 value of extract of P. emblica and A. indica was found to be 1532.36 ± 0.17 and 1380.61 ± 0.27 µg/mL, respectively. The FRAP value of P. emblica and A. indica extract was 86.6 and 32.12 µg ascorbic acid/100 mg dry weight of the extract. The maximum percentage of H2O2 scavenging activity was 71.30% and 67.38%, respectively. Extracts of P. emblica and A. indica showed maximum inhibition of heat-induced BSA denaturation by 62.42% and 53.00%, heat-induced denaturation of egg albumin, by 50.84%% and 44.31%, and heat-induced hemolysis by 54.44% and 50.21%. Both extracts (600 µg/mL) significantly reduced the browning, structural changes, aggregation, and AGEs formation. Our biophysical studies confirmed the AGEs formation was inhibiting the potential of extracts. Thus, our findings confirm that these extracts are a rich source of antioxidants and may be utilized to prevent the oxidative stress-induced destruction of biomolecules, glycation, and in the therapy of a variety of health problems, including inflammation. Further, a combination of extracts of P. emblica and A. indica may be extremely useful in preventing and treating health problems.

Glycaemic index, glycaemic load and cancer risk: results from the prospective NutriNet-Santé cohort

BACKGROUND

Evidence is accumulating that high dietary glycaemic index (GI) and glycaemic load (GL) are potential risk factors for several metabolic disorders (e.g. type-2 diabetes, cardiovascular diseases), but remains limited concerning cancer risk. Although, mechanistic data suggest that consuming high-GI foods may contribute to carcinogenesis through elevated blood glucose levels, insulin resistance or obesity-related mechanisms. Our objective was to study the associations between dietary GI/GL and cancer.

METHODS

In total, 103 020 French adults (median age = 40.2 years) from the NutriNet-Santé cohort (2009-2020) with no cancer or diabetes at baseline were included (705 137 person-years, median follow-up time = 7.7 years). Repeated 24-h dietary records linked with a detailed food-composition table (>3500 food/beverage items). We computed the average dietary GI and GL at the individual level. Associations between GI, GL, contribution of low- and medium/high-GI foods to energy and carbohydrate intake and cancer risk (overall, breast, prostate and colorectal) were assessed using multivariable Cox proportional-hazard models.

RESULTS

Higher dietary GL was associated with higher overall cancer risk [n = 3131 cases, hazard ratios (HRs) for sex-specific quintile 5 vs 1 = 1.25, 95% confidence interval (CI) = 1.03-1.52; Ptrend = 0.008] and specifically postmenopausal breast cancer (n = 924, HRQ5vs.Q1 = 1.64, 95% CI = 1.06-2.55; Ptrend = 0.03). A higher contribution of low-GI food/beverages to energy intake was associated with lower cancer risk whereas a higher contribution of medium/high-GI items to energy intake was positively associated with higher risk of overall, breast and postmenopausal breast cancers (Ptrend ≤ 0.02).

CONCLUSIONS

These results support a possible impact of GI/GL on cancer risk. If confirmed in other populations and settings, dietary GI/GL could be considered as modifiable risk factors for primary cancer prevention.

TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT03335644.

Dietary N-epsilon-carboxymethyllysine as for a major glycotoxin in foods: A review

N-epsilon-carboxymethyllysine (CML), as a potential glycotoxin and general marker for dietary advanced glycation end products (dAGEs), exists in raw food and is formed via various formation routes in food processing such as Maillard reaction between the reducing sugars and amino acids. Although comprehensive cause-effect proof is not available yet, current research suggests a potential risk of chronic diseases such as diabetes is associated with exogenous CML. Thus, CML is causing public health concerns regarding its dietary exposure, but there is a lack of explicit guidance for understanding if it is detrimental to human health. In this review, inconsistent results of dietary CML contributed to chronic disease are discussed, available concentrations of CML in consumed foods are evaluated, measurements for dietary CML and relevant analytic procedures are listed, and the possible mitigation strategies for protecting against CML formation are presented. Finally, the main challenges and future efforts are highlighted. Further studies are needed to extend the dietary CML database in a wide category of foods, apply new identifying methods, elucidate the pathogenic mechanisms, assess its detrimental role in human health, and propose standard guidelines for processed food.

Network-Based Analysis of Fatal Comorbidities of COVID-19 and Potential Therapeutics

COVID-19 is a highly contagious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The case-fatality rate is significantly higher in older patients and those with diabetes, cancer or cardiovascular disorders. The human proteins, angiotensin-converting enzyme 2 (ACE2), transmembrane protease serine 2 (TMPRSS2) and basigin (BSG), are involved in high-confidence host-pathogen interactions with SARS-CoV-2 proteins. We considered these three proteins as seed nodes and applied the random walk with restart method on the human interactome to construct a protein-protein interaction sub-network, which captures the effects of viral invasion. We found that 'Insulin resistance', 'AGE-RAGE signaling in diabetic complications' and 'adipocytokine signaling' were the common pathways associated with diabetes, cancer and cardiovascular disorders. The association of these critical pathways with aging and its related diseases explains the molecular basis of COVID-19 fatality. We further identified drugs that have effects on these proteins/pathways based on gene expression studies. We particularly focused on drugs that significantly downregulate ACE2 along with other critical proteins identified by the network-based approach. Among them, COL-3 had earlier shown activity against acute lung injury and acute respiratory distress, while entinostat and mocetinostat have been investigated for non-small-cell lung cancer. We propose that these drugs can be repurposed for COVID-19.

Network-Based Analysis of Fatal Comorbidities of COVID-19 and Potential Therapeutics

COVID-19 is a highly contagious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The case-fatality rate is significantly higher in older patients and those with diabetes, cancer or cardiovascular disorders. The human proteins, angiotensin-converting enzyme 2 (ACE2), transmembrane protease serine 2 (TMPRSS2) and basigin (BSG), are involved in high-confidence host-pathogen interactions with SARS-CoV-2 proteins. We considered these three proteins as seed nodes and applied the random walk with restart method on the human interactome to construct a protein-protein interaction sub-network, which captures the effects of viral invasion. We found that 'Insulin resistance', 'AGE-RAGE signaling in diabetic complications' and 'adipocytokine signaling' were the common pathways associated with diabetes, cancer and cardiovascular disorders. The association of these critical pathways with aging and its related diseases explains the molecular basis of COVID-19 fatality. We further identified drugs that have effects on these proteins/pathways based on gene expression studies. We particularly focused on drugs that significantly downregulate ACE2 along with other critical proteins identified by the network-based approach. Among them, COL-3 had earlier shown activity against acute lung injury and acute respiratory distress, while entinostat and mocetinostat have been investigated for non-small-cell lung cancer. We propose that these drugs can be repurposed for COVID-19.

Examination of the Effectiveness of the Healthy Empowered Active Lifestyles (HEAL) Program on Advanced Glycation End Products

This pilot study investigated the effectiveness of the healthy empowered active lifestyles (HEAL) program to reduce circulatory levels of advanced glycation end products (AGEs) and assess its relationship to BMI, % body fat, fasting glucose, and A1C. The HEAL program was delivered at a local wellness center using a team-based approach and focused on physical activity and dietary education. A sample of twenty primarily European American (19 white, 1 black) participants (i.e., 10 males, 10 females) aged 26 to 71 (m = 48.75 ± 10.26) completed 12 weeks of the HEAL intervention. Pre to post changes in AGEs, BMI, % body fat, fasting glucose, and A1C were examined as primary outcomes. The findings showed participants had the following average reductions: AGEs 36.04 ± 18.48 ug/mL, BMI 2.0 ± 1.2 kg/m2, % body fat 3.18 ± 1.57%, fasting glucose 5.9 ± 17.21 mg/dL, and A1C 0.68 ± 1.11%. All twenty participants successfully completed the entire twelve weeks of the HEAL intervention. The results of this study show that the HEAL intervention provides beneficial reductions of AGEs, BMI, % body fat, fasting glucose, and A1C. In addition, the high adherence shows promise, and demonstrates the potential for HEAL as a behavioral intervention to improve pre-diabetic and other inflammatory related comorbidities. Further replication of results via additional randomized controlled trials is needed.

Proteomic Investigation of Glyceraldehyde-Derived Intracellular AGEs and Their Potential Influence on Pancreatic Ductal Cells

Glyceraldehyde-derived advanced glycation end products (AGEs) play an important role in the pathogenesis of many diseases including cancer. Accumulation of intracellular AGEs could stimulate cancer induction and facilitate cancer progression. We evaluated the toxic effect of glyceraldehyde-derived intracellular AGEs on normal and malignant pancreatic ductal cells by assessing the cell viability, toxicity, and oxidative stress, followed by proteomic analysis. Our functional studies showed that pancreatic cancer cells (PANC-1 and MIA PaCa-2) were more resistant to glyceraldehyde treatment compared to normal pancreatic ductal epithelial cells (HPDE), while cytotoxicity effects were observed in all cell types. Furthermore, using ¹³C isotopic labeled glyceraldehyde, the proteomic data revealed a dose-dependent increment of the number of glycation adducts in both these cell types. HPDE cells showed a higher number of intracellular AGEs compared to cancer cells. At a molecular level, the glycations in the lysine residues of proteins showed a concurrent increase with the concentration of the glyceraldehyde treatment, while the arginine glycations appeared to be less affected by the glyceraldehyde doses. Further pathway analysis of these glycated proteins suggested that the glycated proteins participate in important biological processes that are major hallmarks of cancer initiation and progression, including metabolic processes, immune response, oxidative stress, apoptosis, and S100 protein binding.

Skin autofluorescence predicts cancer in subjects with type 2 diabetes

INTRODUCTION

Subjects with type 2 diabetes have an excess risk of cancer. The potential role of advanced glycation end products (AGEs) accumulated during long-term hyperglycemia in cancer development has been suggested by biological studies but clinical data are missing. AGEs can be estimated by measuring the skin autofluorescence. We searched whether the skin autofluorescence could predict new cancers in persons with type 2 diabetes.

RESEARCH DESIGN AND METHODS

From 2009 to 2015, we measured the skin autofluorescence of 413 subjects hospitalized for uncontrolled or complicated type 2 diabetes, without any history of cancer. The participants were followed for at least 1 year and the occurrences of new cancers were compared according to their initial skin autofluorescences.

RESULTS

The participants were mainly men (57.9%), with poorly controlled (HbA1c 72±14 mmol/mol or 8.7%±1.8%) and/or complicated type 2 diabetes. Their median skin autofluorescence was 2.6 (2.2-3.0) arbitrary units. Forty-five new cancer cases (10.9%) were registered during 4.8±2.3 years of follow-up: 75.6% of these subjects had skin autofluorescence higher than the median (χ²: p=0.001). By Cox regression analysis adjusted for age, gender, body mass index, history of smoking and renal parameters, skin autofluorescence >2.6 predicted a 2.57-fold higher risk of cancer (95% CI 1.28 to 5.19, p=0.008). This association remained significant after excluding the eight cancers that occurred in the 4 years after inclusion (OR 2.95, 95% CI 1.36 to 6.38, p=0.006). As a continuous variable, skin autofluorescence was also related to new cancers (OR 1.05, 95% CI 1.01 to 1.10, p=0.045).

CONCLUSIONS

Skin autofluorescence, a potential marker of glycemic memory, predicts the occurrence of cancer in subjects with type 2 diabetes. This relation provides a new clinical argument for the role of AGEs in cancer. Their estimation by measuring the skin autofluorescence may help select subjects with diabetes in cancer screening programs.

Advanced glycation end products (AGEs) and other adducts in aging-related diseases and alcohol-mediated tissue injury

Advanced glycation end products (AGEs) are potentially harmful and heterogeneous molecules derived from nonenzymatic glycation. The pathological implications of AGEs are ascribed to their ability to promote oxidative stress, inflammation, and apoptosis. Recent studies in basic and translational research have revealed the contributing roles of AGEs in the development and progression of various aging-related pathological conditions, such as diabetes, cardiovascular complications, gut microbiome-associated illnesses, liver or neurodegenerative diseases, and cancer. Excessive chronic and/or acute binge consumption of alcohol (ethanol), a widely consumed addictive substance, is known to cause more than 200 diseases, including alcohol use disorder (addiction), alcoholic liver disease, and brain damage. However, despite the considerable amount of research in this area, the underlying molecular mechanisms by which alcohol abuse causes cellular toxicity and organ damage remain to be further characterized. In this review, we first briefly describe the properties of AGEs: their formation, accumulation, and receptor interactions. We then focus on the causative functions of AGEs that impact various aging-related diseases. We also highlight the biological connection of AGE-alcohol-adduct formations to alcohol-mediated tissue injury. Finally, we describe the potential translational research opportunities for treatment of various AGE- and/or alcohol-related adduct-associated disorders according to the mechanistic insights presented.

Recent Advances in Histone Glycation: Emerging role in Diabetes and Cancer

Ever increasing information on genome and proteome has offered fascinating details and new opportunities to understand the molecular biology. It is now known that histone proteins surrounding the DNA play a crucial role in the chromatin structure and function. Histones undergo a plethora of post-translational enzymatic modifications that influence nucleosome dynamics and affect DNA activity. Earlier research offered insights into the enzymatic modifications of histones; however attention has been diverted to histone modifications induced by by-products of metabolism without enzymatic engagement in the last decade. Non enzymatic modifications of histones are believed to be crucial for epigenetic landscape, cellular fate and for role in human diseases. Glycation of histone proteins constitutes the major non enzymatic modifications of nuclear proteins that have implications in diabetes and cancer. It has emerged that glycation damages nuclear proteins, modifies amino acids of histones at crucial locations, generates adducts affecting histone chromatin interaction, develops neo-epitopes inducing specific immune response and impacts cell function. Presence of circulating antibodies against glycated histone proteins in diabetes and cancer has shown immunological implications with diagnostic relevance. These crucial details make histone glycation an attractive focus for investigators. This review article, therefore, makes an attempt to exclusively summarize the recent researches in histone glycation, its impact on structural integrity of chromatin and elaborates on their role in diabetes and cancer. The work offers insights for future scientists who investigate the link between metabolism, bio-molecular structures, glycobiology, histone-DNA interactions in relation to diseases in humans.

The Taming of Nuclear Factor Erythroid-2-Related Factor-2 (Nrf2) Deglycation by Fructosamine-3-Kinase (FN3K)-Inhibitors-A Novel Strategy to Combat Cancers

Simple Summary

Aim of this review is to provide an overview on (a) Fructosamine-3-Kinase (FN3K) and its role in regulating Nuclear Factor Erythorid-2-Related Factor-2 (Nrf2); (b) the role of glycation and deglycation mechanisms in modulating the functional properties of proteins, in particular, the Nrf2; (c) the dual role of Nrf2 in the prevention and treatment of cancers. Since controlling the glycation of Nrf2 is one of the key mechanisms determining the fate of a cell; whether to get transformed into a cancerous one or to stay as a normal one, it is important to regulate Nrf2 and deglycating FN3K using pharmacological agents. Inhibitors of FN3K are being explored currently to modulate Nrf2 activity thereby control the cancers.

Abstract

Glycated stress is mediated by the advanced glycation end products (AGE) and the binding of AGEs to the receptors for advanced glycation end products (RAGEs) in cancer cells. RAGEs are involved in mediating tumorigenesis of multiple cancers through the modulation of several downstream signaling cascades. Glycated stress modulates various signaling pathways that include p38 mitogen-activated protein kinase (p38 MAPK), nuclear factor kappa–B (NF-κB), tumor necrosis factor (TNF)-α, etc., which further foster the uncontrolled proliferation, growth, metastasis, angiogenesis, drug resistance, and evasion of apoptosis in several cancers. In this review, a balanced overview on the role of glycation and deglycation in modulating several signaling cascades that are involved in the progression of cancers was discussed. Further, we have highlighted the functional role of deglycating enzyme fructosamine-3-kinase (FN3K) on Nrf2-driven cancers. The activity of FN3K is attributed to its ability to deglycate Nrf2, a master regulator of oxidative stress in cells. FN3K is a unique protein that mediates deglycation by phosphorylating basic amino acids lysine and arginine in various proteins such as Nrf2. Deglycated Nrf2 is stable and binds to small musculoaponeurotic fibrosarcoma (sMAF) proteins, thereby activating cellular antioxidant mechanisms to protect cells from oxidative stress. This cellular protection offered by Nrf2 activation, in one way, prevents the transformation of a normal cell into a cancer cell; however, in the other way, it helps a cancer cell not only to survive under hypoxic conditions but also, to stay protected from various chemo- and radio-therapeutic treatments. Therefore, the activation of Nrf2 is similar to a double-edged sword and, if not controlled properly, can lead to the development of many solid tumors. Hence, there is a need to develop novel small molecule modulators/phytochemicals that can regulate FN3K activity, thereby maintaining Nrf2 in a controlled activation state.

Soluble Receptor for Advanced Glycation End-products (sRAGE) and Colorectal Cancer Risk: A Case-Control Study Nested within a European Prospective Cohort

BACKGROUND

Overexpression of the receptor for advanced glycation end-product (RAGE) has been associated with chronic inflammation, which in turn has been associated with increased colorectal cancer risk. Soluble RAGE (sRAGE) competes with RAGE to bind its ligands, thus potentially preventing RAGE-induced inflammation.

METHODS

To investigate whether sRAGE and related genetic variants are associated with colorectal cancer risk, we conducted a nested case-control study in the European Prospective Investigation into Cancer and Nutrition (EPIC). Plasma sRAGE concentrations were measured by ELISA in 1,361 colorectal cancer matched case-control sets. Twenty-four SNPs encoded in the genes associated with sRAGE concentrations were available for 1,985 colorectal cancer cases and 2,220 controls. Multivariable adjusted ORs and 95% confidence intervals (CIs) were computed using conditional and unconditional logistic regression for colorectal cancer risk and circulating sRAGE and SNPs, respectively.

RESULTS

Higher sRAGE concentrations were inversely associated with colorectal cancer (ORQ5vs.Q1, 0.77; 95% CI, 0.59-1.00). Sex-specific analyses revealed that the observed inverse risk association was restricted to men (ORQ5vs.Q1, 0.63; 95% CI, 0.42-0.94), whereas no association was observed in women (ORQ5vs.Q1, 1.00; 95% CI, 0.68-1.48; P heterogeneity for sex = 0.006). Participants carrying minor allele of rs653765 (promoter region of ADAM10) had lower colorectal cancer risk (C vs. T, OR, 0.90; 95% CI, 0.82-0.99).

CONCLUSIONS

Prediagnostic sRAGE concentrations were inversely associated with colorectal cancer risk in men, but not in women. An SNP located within ADAM10 gene, pertaining to RAGE shedding, was associated with colorectal cancer risk.

IMPACT

Further studies are needed to confirm our observed sex difference in the association and better explore the potential involvement of genetic variants of sRAGE in colorectal cancer development.

Total and added sugar intakes, sugar types, and cancer risk: results from the prospective NutriNet-Santé cohort

BACKGROUND

Excessive sugar intake is now recognized as a key risk factor for obesity, type 2 diabetes, and cardiovascular diseases. In contrast, evidence on the sugar-cancer link is less consistent. Experimental data suggest that sugars could play a role in cancer etiology through obesity but also through inflammatory and oxidative mechanisms and insulin resistance, even in the absence of weight gain.

OBJECTIVE

The objective was to study the associations between total and added sugar intake and cancer risk (overall, breast, and prostate), taking into account sugar types and sources.

METHODS

In total, 101,279 participants aged >18 y (median age, 40.8 y) from the French NutriNet-Santé prospective cohort study (2009-2019) were included (median follow-up time, 5.9 y). Sugar intake was assessed using repeated and validated 24-h dietary records, designed to register participants' usual consumption for >3500 food and beverage items. Associations between sugar intake and cancer risk were assessed by Cox proportional hazard models adjusted for known risk factors (sociodemographic, anthropometric, lifestyle, medical history, and nutritional factors).

RESULTS

Total sugar intake was associated with higher overall cancer risk (n = 2503 cases; HR for quartile 4 compared with quartile 1: 1.17; 95% CI: 1.00, 1.37; Ptrend = 0.02). Breast cancer risks were increased (n = 783 cases; HRQ4vs.Q1 = 1.51; 95% CI: 1.14, 2.00; Ptrend = 0.0007). Results remained significant when weight gain during follow-up was adjusted for. In addition, significant associations with cancer risk were also observed for added sugars, free sugars, sucrose, sugars from milk-based desserts, dairy products, and sugary drinks (Ptrend ≤ 0.01).

CONCLUSIONS

These results suggest that sugars may represent a modifiable risk factor for cancer prevention (breast in particular), contributing to the current debate on the implementation of sugar taxation, marketing regulation, and other sugar-related policies. This trial was registered at clinicaltrials.gov as NCT03335644.

Glycation reaction and the role of the receptor for advanced glycation end-products in immunity and social behavior

The receptor for advanced glycation end-products (receptor for AGEs, RAGE) is a pattern recognition receptor. The interaction of RAGE with its ligands, such as AGEs, S100 proteins, high mobility group box-1 (HMGB1), and lipopolysaccharides (LPS), is known to play a pivotal role in the propagation of immune responses and inflammatory reactions. The ligand-RAGE interaction elicits cellular responses, for example, in myeloid and lymphoid cells, through distinct pathways by activating NF-κB and Rac1/cdc42, which lead to cytokine production, cell migration, phagocytosis, maturation, and polarization. Recently, oxytocin, a peptide hormone and neuropeptide, was identified as a novel binding molecule for the RAGE; however, it cannot compete with the interaction of RAGE with other ligands or induce RAGE intracellular signaling. The RAGE transports oxytocin from the blood into the brain and regulates brain functions. In this review, we summarize the current understanding of glycation reaction, AGEs, and the RAGE-mediated biological responses as well as the physiological role of RAGE in immunity and social behaviors, particularly, maternal bonding.

Colorimetric Urinalysis for On-Site Detection of Metabolic Biomarkers

Over the past few decades, colorimetric assays have been developed for cost-effective and rapid on-site urinalysis. Most of these assays were employed for detection of biomarkers such as glucose, uric acid, ions, and albumin that are abundant in urine at micromolar to millimolar levels. In contrast, direct assaying of urinary biomarkers such as glycated proteins, low-molecular-weight reactive oxygen species, and nucleic acids that are present at significantly lower levels (nanomolar to picomolar) remain challenging due to the interferences from the urine sample matrix. State-of-the-art assays for detection of trace amounts of urinary biomarkers typically utilize time-consuming and equipment-dependent sample pretreatment or clean-up protocols prior to assaying, which limits their applicability for on-site analysis. Herein, we report a colorimetric assay for on-site detection of trace amount of generic biomarkers in urine without involving tedious sample pretreatment protocols. The detection strategy is based on monitoring the changes in optical properties of poly(3-(4-methyl-3'-thienyloxy)propyltriethylammonium bromide) upon interacting with an aptamer or a peptide nucleic acid in the presence and absence of target biomarkers of relevance for the diagnosis of metabolic complications and diabetes. As a proof of concept, this study demonstrates facile assaying of advanced glycation end products, 8-hydroxy-2'-deoxyguanosine and hepatitis B virus DNA in urine samples at clinically relevant concentrations, with limits of detection of ∼850 pM, ∼650 pM, and ∼ 1 nM, respectively. These analytes represent three distinct classes of biomarkers: (i) glycated proteins, (ii) low-molecular-weight reactive oxygen species, and (iii) nucleic acids. Hence, the proposed methodology is applicable for rapid detection of generic biomarkers in urine, without involving sophisticated equipment and skilled personnel, thereby enabling on-site urinalysis. At the end of the contribution, we discuss the opportunity to translate the homogeneous assay into a paper-based format.

Pro-Oxidant Enzymes, Redox Balance and Oxidative Damage to Proteins, Lipids and DNA in Colorectal Cancer Tissue. Is Oxidative Stress Dependent on Tumour Budding and Inflammatory Infiltration?

This study is the first to assess redox homeostasis in patients with colorectal cancer (CRC) in respect to histopathological parameters associated with the tumour microenvironment such as tumour budding and inflammatory infiltration. Pro-oxidant enzymes (NADPH oxidase (NOX), xanthine oxidase (XO)), antioxidant barrier (Cu,Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), reduced glutathione (GSH)), redox status (total antioxidant (TAC)/oxidant status (TOS)) and oxidative damage products (advanced glycation end products (AGE), advanced oxidation protein products (AOPP), malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG)) were determined in both the normal and cancerous tissue of 29 CRC patients. The activity of NOX (p < 0.01) and XO (p = 0.01), as well as SOD (p < 0.0001), CAT (p < 0.0001) and TAC level (p < 0.01) were significantly higher in tumour tissue than in normal colon mucosa. Oxidative damage products (AGE-p < 0.01, AOPP-p < 0.001, MDA-p < 0.001, 8-OHdG-p < 0.0001) were also higher in cancerous colon tissue. Furthermore, we observed that CAT (p < 0.05) and XO (p < 0.05) activity depends on the intensity of inflammatory infiltration. Oxidative stress index (OSI) (p < 0.05) and MDA (p < 0.01) values were significantly higher in patients with tumour budding (TB) > 5 versus cases with TB < 5. However, OSI level did not differ significantly between cancer and normal tissue. Our results confirm that CRC is associated with enzymatic/non-enzymatic redox imbalance and increased oxidative damage to proteins, lipids and DNA. The determination of these biomarkers could be useful for the evaluation of the tumour progression.

Advanced glycation end products (AGEs), protein aggregation and their cross talk: new insight in tumorigenesis

Protein glycation and protein aggregation are two distinct phenomena being observed in cancer cells as factors promoting cancer cell viability. Protein aggregation is an abnormal interaction between proteins caused as a result of structural changes in them after any mutation or environmental assault. Protein aggregation is usually associated with neurodegenerative diseases like Alzheimer's and Parkinson's, but of late, research findings have shown its association with the development of different cancers like lung, breast and ovarian cancer. On the contrary, protein glycation is a cascade of irreversible nonenzymatic reaction of reducing sugar with the amino group of the protein resulting in the modification of protein structure and formation of advanced glycation end products (AGEs). These AGEs are reported to obstruct the normal function of proteins. Lately, it has been reported that protein aggregation occurs as a result of AGEs. This aggregation of protein promotes the transformation of healthy cells to neoplasia leading to tumorigenesis. In this review, we underline the current knowledge of protein aggregation and glycation along with the cross talk between the two, which may eventually lead to the development of cancer.

Dietary advanced glycation end products and the risk of postmenopausal breast cancer in the National Institutes of Health-AARP Diet and Health Study

BACKGROUND

Advanced glycation end products (AGEs) are reactive metabolites produced as a by-product of sugar metabolism and are consumed through the diet in high-fat and highly processed foods. They are associated with chronic inflammatory diseases, and evidence suggests that they play a role in carcinogenesis. The authors evaluated the association of dietary AGE intake and the risk of postmenopausal invasive breast cancer.

METHODS

This was a prospective cohort study of 183,548 postmenopausal women in the National Institutes of Health-AARP Diet and Health Study. The main outcome was incident invasive breast cancer. AGE intake was estimated from food-frequency questionnaires. Incident breast cancer cases were identified through state cancer registries. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals for developing breast cancer according to AGE intake quintiles. Multivariable regression models were adjusted for breast cancer risk factors.

RESULTS

The mean follow-up was 12.8 years, and 9851 breast cancers (1978 advanced stage) were identified. The median AGE daily intake was 5932 kilo units per 100 kilocalories (KU/1000 kcal). Women with higher intake tended to have lower education levels, higher body mass index, less physical activity, were current smokers, and had higher fat and meat intake. The highest quintile of AGE intake (compared with the lowest) was associated with an increased risk of breast cancer (HR, 1.09; 95% CI, 1.02-1.16; P = .03) after adjusting for breast cancer risk factors and particularly was associated with 37% of advanced-stage tumors (HR, 1.37; 95% CI, 1.09-1.74; P < .02) after adjusting for risk factors and fat and meat intake.

CONCLUSIONS

Dietary AGEs may play a role in the development of postmenopausal breast cancer.

Circulating free methylglyoxal as a metabolic tumor biomarker in a rat colon adenocarcinoma model

Since the 1956 hypothesis of Otto Warburg, aerobic glycolysis has been recognized as a metabolic hallmark of cancer. Because methylglyoxal (MG) is a naturally occurring waste metabolite of glycolysis, we measured blood levels of this molecule in colon cancer-bearing rats. To compare the blood levels of free MG in cancerous and healthy animals,the present study used a dedicated tumor graft model consisting of the subcutaneous administration in syngenic BD-IX rats of a tumorigenic cell clone (PROb) and another non-tumorigenic clone (REGb) derived from the same tumor. Rats grafted with the PROb growing tumor cell clone exhibited a statistically significant increase in free MG blood levels (P=0.003), whereas rats transplanted with the REGb non-growing tumor cell clone exhibited normal MG values. The present study (first of three parts) suggests that cancer cells can produce and release free MG at higher levels than normal cells, making MG a putative novel metabolic biomarker of cancer.

Non-enzymatic glycation of protein induces cancer cell proliferation and its inhibition by quercetin: Spectroscopic, cytotoxicity and molecular docking studies

Methylglyoxal (MG) is a potent glycating agent which reacts with proteins to form advanced glycation end products (AGEs). These chemically stable AGEs crosslink with proteins and could lead to amyloid formation that has the role in several diseases including Alzheimer's and Parkinson's. In this piece of work, glycation-induced conformational changes in HSA were observed with quenching of tryptophan fluorescence by 73.8% (41 nm red shift) and loss of hydrophobicity of HSA. CD spectroscopy result reaffirmed secondary structure changes in HSA. Moreover, MG-induced changes in HSA, proceeds to amyloid structure as characterized by an increase in thioflavin (ThT) fluorescence and transmission electron microscopy (TEM) images of HSA aggregates. Quercetin was found to inhibit both AGEs production and amyloid formation. Viability of MCF-7 cells was found to be increased with AGEs treatment, illustrating proliferation of cancer cells. Wound healing assay also revealed increased proliferation and migration of cells in the presence of AGEs. Additionally, molecular docking analyses were performed to demonstrate interactions involved in the stabilization of HSA-quercetin complex. The binding affinities of quercetin were found to be (K _d = 10⁵ M ^-1) much higher compared with MG (K _d = 10² M ^-1). From this study, it is quite clear that quercetin reverses the effect of MG by sterically inhibiting the interaction between HSA and MG. Communicated by Ramaswamy H. Sarma.

Redox Signaling and Advanced Glycation Endproducts (AGEs) in Diet-Related Diseases

Diets are currently characterized by elevated sugar intake, mainly due to the increased consumption of processed sweetened foods and drinks during the last 40 years. Diet is the main source of advanced glycation endproducts (AGEs). These are toxic compounds formed during the Maillard reaction, which takes place both in vivo, in tissues and fluids under physiological conditions, favored by sugar intake, and ex vivo during food preparation such as baking, cooking, frying or storage. Protein glycation occurs slowly and continuously through life, driving AGE accumulation in tissues during aging. For this reason, AGEs have been proposed as a risk factor in the pathogenesis of diet-related diseases such as diabetes, insulin resistance, cardiovascular diseases, kidney injury, and age-related and neurodegenerative diseases. AGEs are associated with an increase in oxidative stress since they mediate the production of reactive oxygen species (ROS), increasing the intracellular levels of hydrogen peroxide (H₂O₂), superoxide (O₂⁻), and nitric oxide (NO). The interaction of AGEs with the receptor for AGEs (RAGE) enhances oxidative stress through ROS production by NADPH oxidases inside the mitochondria. This affects mitochondrial function and ultimately influences cell metabolism under various pathological conditions. This short review will summarize all evidence that relates AGEs and ROS production, their relationship with diet-related diseases, as well as the latest research about the use of natural compounds with antioxidant properties to prevent the harmful effects of AGEs on health.

Role of Advanced Glycation End Products in Carcinogenesis and their Therapeutic Implications

Aging is one of the biggest risk factors for the major prevalent diseases such as cardiovascular diseases, neurodegeneration and cancer, but due to the complex and multifactorial nature of the aging process, the molecular mechanisms underlying age-related diseases are not yet fully understood. Research has been intensive in the last years aiming to characterize the pathophysiology of aging and develop therapies to fight age-related diseases. In this context advanced glycation end products (AGEs) have received attention. AGEs, when accumulated in tissues, significantly increase the level of inflammation in the body which has long been associated with the development of cancer. Here we discuss the classical settings promoting AGE formation, as well as reduction strategies, occurrence and relevance of AGEs in cancer tissues and the role of AGE-interaction with the receptor for advanced glycation end products (RAGE) in cancer initiation and progression.

Glycoxidative profile of cancer patient serum: A clinical result to associate glycation to cancer

The influence of advanced glycation end products (AGEs) in the biological processes contribute to the life-changing complications such as progression of cancer, diabetes and other chronic disorders. The receptor of AGEs while interacting with its ligands causes a never-ending irregularity in the cell-signaling communication. Hence, AGEs are considered as an important link between progression and contribution to cancer. This study focuses on the presence and/or absence of oxidative and glycative stress in the serum samples of various cancer patients. During analysis of the early and intermediate glycation product in cancer patient’s sera, our result indicates an increasing trend of both the adducts as compared to normal healthy subjects. Similarly, one of the AGEs i.e., carboxymethyllysine was found to be enhanced in cancer sera as compared to NHS. The binding characteristics of circulating auto-antibodies in cancer patient’s sera against human serum albumin (HSA)-AGEs were assessed through ELISA and furthermore, the maximum percent inhibition against HSA-AGEs was observed as 57–63%, 46–62% and 42–64% in prostate cancer, lung cancer and head and neck cancer. Hence, our result successfully assisted the presence of AGEs in all the cancer patient’s sera though it is not clear which specific cancer is more potent to AGEs.

Identification of Differential Patterns of Oxidative Biomarkers in Prostate Cancer Progression

INTRODUCTION

Oxidative stress has been found to be associated with the progression of prostate cancer (PCa); however, human studies which identify differential roles of each oxidation pathway in PCa progression are lacking. We aimed to identify which oxidative stress markers, specifically lipid and global oxidation and glycation, are associated with PCa progression.

PATIENTS AND METHODS

We recruited 3 groups of patients from a urologic clinic at the University of Cincinnati Medical Center: men with PCa who had undergone prostatectomy, men with PCa under watchful waiting, and men with benign prostatic hyperplasia (BPH). We used the most commonly used lipid oxidation marker, F2-isoprostanes; global oxidation markers, fluorescent oxidation products (FlOPs); and the commonly used marker for advanced glycation end products, carboxymethyllysine. These biomarkers were measured in plasma samples at baseline entry. Plasma prostate-specific antigen (PSA) was measured at enrollment and follow-up visits.

RESULTS

Compared with men with BPH, men with PCa who had undergone prostatectomy had 26% (P = .01) higher levels of F2-isoprostanes and 20% (P = .08) higher levels of carboxymethyllysine. All the oxidation markers were similar when comparing men under watchful waiting with men with BPH. When examining the associations between baseline oxidation markers and follow-up PSAs, we found that different oxidation markers had differential patterns associated with PSA elevation. F2-isoprostanes were positively associated with PSA elevation among men with PCa; FlOP_320 was positively associated with PSA elevation among both men with PCa and men with BPH, whereas among men with PCa under watchful waiting, FlOP_360 and FlOP_400 had opposite trends of associations with PSA elevation.

CONCLUSIONS

Our study suggested that high levels of lipid oxidation were associated with PCa progression, whereas different global oxidation markers had different patterns associated with PCa progression. Large-scale clinical studies are needed to confirm our associations. Our study provides a comprehensive view of the relationship between biomarkers and PCa progression.

Haem iron intake and risk of lung cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort

BACKGROUND

Epidemiological studies suggest that haem iron, which is found predominantly in red meat and increases endogenous formation of carcinogenic N-nitroso compounds, may be positively associated with lung cancer. The objective was to examine the relationship between haem iron intake and lung cancer risk using detailed smoking history data and serum cotinine to control for potential confounding.

METHODS

In the European Prospective Investigation into Cancer and Nutrition (EPIC), 416,746 individuals from 10 countries completed demographic and dietary questionnaires at recruitment. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident lung cancer (n = 3731) risk relative to haem iron, non-haem iron, and total dietary iron intake. A corresponding analysis was conducted among a nested subset of 800 lung cancer cases and 1489 matched controls for whom serum cotinine was available.

RESULTS

Haem iron was associated with lung cancer risk, including after adjustment for details of smoking history (time since quitting, number of cigarettes per day): as a continuous variable (HR per 0.3 mg/1000 kcal 1.03, 95% CI 1.00-1.07), and in the highest versus lowest quintile (HR 1.16, 95% CI 1.02-1.32; trend across quintiles: P = 0.035). In contrast, non-haem iron intake was related inversely with lung cancer risk; however, this association attenuated after adjustment for smoking history. Additional adjustment for serum cotinine did not considerably alter the associations detected in the nested case-control subset.

CONCLUSIONS

Greater haem iron intake may be modestly associated with lung cancer risk.

Inflammatory, oxidative stress and anti-oxidative markers in patients with endometrial carcinoma and diabetes

BACKGROUND

The role of chronic inflammation and oxidative stress in the development of diabetes and cancer has been established. In this study, we aimed to investigate inflammatory and oxidative stress markers in patients with diabetes (DM) and endometrial carcinoma (EC) separately and in combination.

METHODS

In a case-control study design, a total of 88 participants were enrolled including: 37 patients with EC (19 with DM and 18 without DM), 29 with type2 diabetes and 22 healthy controls. Cancer patients were sampled before treatment. Serum oxidative stress markers including: oxidized low density lipoprotein (ox-LDL,) nitric oxide (NO), advanced glycation end-products (AGEs) and advanced oxidation protein products (AOPP), malondialdehyde (MDA); ferric reducing ability of plasma (FRAP), as an antioxidant marker, and inflammatory markers including: Interleukin 6 (IL6), C reactive protein (CRP) and tumor necrosis factor alpha (TNFα) were measured.

RESULTS

Ox-LDL, NO, MDA, AOPP and AGE were increased in all patients either with endometrial carcinoma and/or diabetes compared to healthy controls (p < 0.05). Patients with both EC and DM had higher oxidative markers including: OX-LDL (17.47 ± 0.84 vs. 12.36 ± 0.91), NO (82.27 ± 5.75 vs. 76.34 ± 5.36), MDA (3.3 ± 0.1 vs. 2.75 ± 0.48) and AGE (73.89 ± 5.71 vs. 69.02 ± 3.14) compared to those with EC alone (ρ < 0.05). Levels of FRAP was lower in patients with both diabetes and cancer, cancer alone and diabetes alone compared to healthy controls (p < 0.05). Inflammatory markers, TNFα, IL6 and hs-CRP, were also significantly increased in patients with EC with and without DM compared to controls (ρ < 0.05). However, there were no significant differences between two groups of EC regarding to inflammatory markers (ρ > 0.05). Patients with DM had significantly higher levels of inflammatory markers compared to control group (all ρ < 0.05). In addition, significant subadditive interaction effect between EC and DM regarding levels of oxLDL, NO, AGE, AOPP and FRAP) was observed (p < 0.05).

CONCLUSION

Increased levels of chronic inflammatory and oxidative stress markers were observed in both endometrial carcinoma and diabetes. Additional effect of diabetes in patients with cancer was mediated more significantly via increase in oxidative stress rather than inflammatory markers.