Glucose Concentration in Cell Culture Medium Influences the BRCA1-Mediated Regulation of the Lipogenic Action of IGF-I in Breast Cancer Cells

Transcriptional upregulation of MMP-9 gene under hyperglycemic conditions in AGS cells: Role of AP-1 transcription factor

Gastric cancer and diabetes are two complex and interrelated diseases having significant impact on global health. Hyperglycemic condition notably exacerbates cancer by promoting inflammation, angiogenesis, and metastasis. Elevated glucose levels can also upregulate the expression of specific matrix metalloproteinases (MMPs), especially MMP-9, which is associated with cancer cell migration and invasion. However, the molecular mechanism behind such upregulation remains unexplored. In the present study, we have identified the mechanism for hyperglycemia-induced transcriptional activation of MMP-9, in gastric adenocarcinoma (AGS) cells. Using various tools like luciferase-reporter assays with promoter deletion constructs, siRNAs, pharmacological inhibitors, and nuclear translocation experiments, we have identified that the transcriptional activation of MMP-9 under hyperglycemic conditions is predominantly governed by the MAPK pathway, via formation of the AP-1 heterodimer. The p65 NF-κB signaling pathway, although activated, plays no significant role in regulating hyperglycemia-induced MMP-9 expression. Chromatin immunoprecipitation studies indicate that the distal AP-1 binding site is responsible for hyperglycemia-induced MMP-9 transcription; whereas the proximal one accounts for both hyperglycemia-induced and basal MMP-9 transcription. Therefore, binding of AP-1 at both the proximal and distal binding sites on the MMP-9 promoter region is required for hyperglycemia-induced MMP-9 expression. Overall, our study unveils a novel mechanism of MMP-9 transcription under hyperglycemic conditions and also suggests that inhibiting the binding of the AP-1 heterodimer with its distal binding site can potentially reduce the complications developed during gastric cancer-hyperglycemia co-morbidity. A drug designed specifically to inhibit this interaction may prevent hyperglycemia-induced tumor aggressiveness to a considerable extent by impeding MMP-9 transcription.

Effect of type of anticoagulant, transportation time, and glucose in the culture media on neutrophil viability and function test results in dairy cattle

In dairy cattle research, in vitro assessment of innate immune function is commonly evaluated by flow cytometry via the quantitative analysis of circulating polymorphonuclear leukocytes (PMN) functionalities specifically focusing on the capacities for phagocytosis (PC) and oxidative burst (OB). Variations in these PMN functions, however, may not only be influenced by the health status of the animals but also by technical, non-animal related factors. Our objectives were to assess the PMN viability, PC and OB capacities from blood samples collected in tubes coated with different anticoagulants (acid citrate dextrose (ACD) and ethylenediaminetetraacetic acid (EDTA)) and stored for 0, 3, 6, 9, and 12 h at 4°C (to mimic transportation timeframe). Furthermore, we evaluated the PMN functionalities (PC and OB) in samples incubated in culture medium with glucose (7.2 mM) versus no glucose. Over five replicates, coccygeal blood samples were collected from three nulliparous Holstein heifers (5 ACD and 5 EDTA per heifer) and allocated in a refrigerated container (4°C) for 0, 3, 6, 9, and 12 h. At each time point, PMN were isolated using gradient centrifugation. Immunolabeled PMN (CH138A) were subjected to a tricolor fluorescent staining to evaluate their viability (viable, apoptotic, and necrotic PMN). Phagocytosis and OB were assessed by incubating PMN with fluorescent beads and by phorbol 12-myristate 13-acetate stimulation, respectively. The effects of anticoagulant type, storage time, and presence of glucose in the culture medium on PMN viability and function parameters were fitted in mixed linear regression models. The proportion of viable PMN at 0 h was similar for ACD and EDTA (92 ± 4.6% and 93 ± 4.6%, respectively) but it decreased to 78 ± 4.6% for ACD and 79 ± 4.6% for EDTA after 6 h of storage. The proportion of viable PMN was not different between ACD and EDTA at any time point. The proportion of PMN that engulfed beads (PC percentage) and the PC median fluorescence intensity (MFI) reached their highest value after 3 h of storage compared with the other time points. However, the anticoagulant type (ACD versus EDTA) and the presence of glucose in the culture medium did not influence these PC parameters. Oxidative burst MFI was higher in PMN incubated in glucose-supplemented culture medium versus no glucose. We demonstrated that technical factors interfere with the evaluation of PMN viability and functionality, which can potentially lead to bias in the findings of a research hypothesis. To conclude, the present study showed that the optimal timeframe for performing PMN function analyses is within 3 hours after blood sampling. Furthermore, the presence of 7.2 mM glucose in the culture medium, a common concentration in formulation of cell culture medium, increases the in vitro OB capacity, potentially masking any impairments in in vivo PMN dysfunctionality.

Tobacco-induced hyperglycemia promotes lung cancer progression via cancer cell-macrophage interaction through paracrine IGF2/IR/NPM1-driven PD-L1 expression

Tobacco smoking (TS) is implicated in lung cancer (LC) progression through the development of metabolic syndrome. However, direct evidence linking metabolic syndrome to TS-mediated LC progression remains to be established. Our findings demonstrate that 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo[a]pyrene (NNK and BaP; NB), components of tobacco smoke, induce metabolic syndrome characteristics, particularly hyperglycemia, promoting lung cancer progression in male C57BL/6 J mice. NB enhances glucose uptake in tumor-associated macrophages by increasing the expression and surface localization of glucose transporter (GLUT) 1 and 3, thereby leading to transcriptional upregulation of insulin-like growth factor 2 (IGF2), which subsequently activates insulin receptor (IR) in LC cells in a paracrine manner, promoting its nuclear import. Nuclear IR binds to nucleophosmin (NPM1), resulting in IR/NPM1-mediated activation of the CD274 promoter and expression of programmed death ligand-1 (PD-L1). Restricting glycolysis, depleting macrophages, or blocking PD-L1 inhibits NB-mediated LC progression. Analysis of patient tissues and public databases reveals elevated levels of IGF2 and GLUT1 in tumor-associated macrophages, as well as tumoral PD-L1 and phosphorylated insulin-like growth factor 1 receptor/insulin receptor (pIGF-1R/IR) expression, suggesting potential poor prognostic biomarkers for LC patients. Our data indicate that paracrine IGF2/IR/NPM1/PD-L1 signaling, facilitated by NB-induced dysregulation of glucose levels and metabolic reprogramming of macrophages, contributes to TS-mediated LC progression.

Melatonin Inhibits AGS Cell Proliferation by Binding to the ATP Binding Site of CDK2 Under Hyperglycemic Conditions

Cancer cells utilize glucose as their primary energy source. The aggressive nature of cancer cells is therefore enhanced in hyperglycemic conditions. This study has been adopted to investigate the therapeutic potential of melatonin against such aggressive proliferation of AGS cells-a human gastric cancer cell line, under hyperglycemic conditions. AGS cells were incubated with high glucose-containing media, and the effects of melatonin have been evaluated, therein. Cell proliferation, ROS generation, flow-cytometric analysis for cell cycle and apoptosis, wound healing, immunoblotting, zymography, reverse zymography assays, in-silico analysis, and kinase activity assays were performed to evaluate the effects of melatonin. We observed that melatonin inhibited the hyperglycemia-induced cell proliferation in a dose-dependent manner. It further altered the expression and activity of MMP-9 and TIMP-1. Moreover, melatonin inhibited AGS cell proliferation by arresting AGS cells in the G0/G1 phase after binding in the ATP binding site of CDK-2, thereby inhibiting its kinase activity. In association, a significant decrease in the expression of cyclin D1, cyclin E, CDK-4, and CDK-2 were observed. In conclusion, these findings suggest that melatonin has anti-gastric cancer potential. Melatonin could therefore be included in future drug designs for gastric cancer-hyperglycemia co-morbidity treatment.

Increased Brucella abortus asRNA_0067 expression under intraphagocytic stressors is associated with enhanced virB2 transcription

Intracellular pathogens like Brucella face challenges during the intraphagocytic adaptation phase, where the modulation of gene expression plays an essential role in taking advantage of stressors to persist inside the host cell. This study aims to explore the expression of antisense virB2 RNA strand and related genes under intracellular simulation media. Sense and antisense virB2 RNA strands increased expression when nutrient deprivation and acidification were higher, being starvation more determinative. Meanwhile, bspB, one of the T4SS effector genes, exhibited the highest expression during the exposition to pH 4.5 and nutrient abundance. Based on RNA-seq analysis and RACE data, we constructed a regional map depicting the 5' and 3' ends of virB2 and the cis-encoded asRNA_0067. Without affecting the CDS or a possible autonomous RBS, we generate the deletion mutant ΔasRNA_0067, significantly reducing virB2 mRNA expression and survival rate. These results suggest that the antisense asRNA_0067 expression is promoted under exposure to the intraphagocytic adaptation phase stressors, and its deletion is associated with a lower transcription of the virB2 gene. Our findings illuminate the significance of these RNA strands in modulating the survival strategy of Brucella within the host and emphasize the role of nutrient deprivation in gene expression.

Lipid profile in breast cancer: From signaling pathways to treatment strategies

Breast cancer is the most prevalent cancer in women. Metabolic abnormalities, particularly increased lipid synthesis and uptake, impact the onset and progression of the disease. However, the influence of lipid metabolism in breast cancer varies according to the disease stage and patient's hormone status. In postmenopausal patients, obesity is associated with a higher risk and poor prognosis of luminal tumors, while in premenopausal individuals, it is correlated to BRCA mutated tumors. In fact, the tumor's lipid profile may be used to distinguish between HER2+, luminal and BRCA-mutated tumors. Moreover, drug resistance was associated with increased fatty acid synthesis and alterations in membrane composition, impacting its fluidity and spatial subdomains such as lipid rafts. Here, we discuss the subtype-specific lipid metabolism alterations found in breast cancer and the potentiality of its modulation in a clinical setting.

An evaluation of photobiomodulation effects on human gingival fibroblast cells under hyperglycemic condition: an in vitro study

An in vitro study was designed to evaluate the effects of photobiomodulation (PBM) with 915-nm diode laser on human gingival fibroblast (HGF) cells under hyperglycemic condition. The HGF cells were cultured in Dulbecco's modified eagle medium (DMEM) medium containing 30 mM glucose concentration for 48 h to mimic the hyperglycemic condition. Subsequently, the cells received three sessions of PBM (915 nm, continuous emission mode, 200 mW, energy density values of 3.2, 6, and 9.2 J/cm2). Twenty-four hours post-irradiation, cell proliferation, expression of interleukin 6 (IL-6), and vascular endothelial growth factor (VEGF) were assessed with MTT and real-time polymerase chain reaction (PCR) tests, respectively. Also, reactive oxygen species (ROS) production was measured using CM-H2DCFDA fluorimetry. No changes were detected in the cell proliferation rate between the high glucose control group and laser-treated cells, while VEGF and IL-6 gene expression levels increased significantly after PBM in the high glucose-treated cells group. ROS level was significantly decreased in the irradiated cells in high-glucose medium compared with the high glucose control group. Our study revealed the inductive role of 915-nm-mediated PBM on VEGF and the inflammatory response while concurrently reducing reactive oxygen species production in HGF cells in hyperglycemic conditions.

Inhibition of DNMT1 methyltransferase activity via glucose-regulated O-GlcNAcylation alters the epigenome

The DNA methyltransferase activity of DNMT1 is vital for genomic maintenance of DNA methylation. We report here that DNMT1 function is regulated by O-GlcNAcylation, a protein modification that is sensitive to glucose levels, and that elevated O-GlcNAcylation of DNMT1 from high glucose environment leads to alterations to the epigenome. Using mass spectrometry and complementary alanine mutation experiments, we identified S878 as the major residue that is O-GlcNAcylated on human DNMT1. Functional studies in human and mouse cells further revealed that O-GlcNAcylation of DNMT1-S878 results in an inhibition of methyltransferase activity, resulting in a general loss of DNA methylation that preferentially occurs at partially methylated domains (PMDs). This loss of methylation corresponds with an increase in DNA damage and apoptosis. These results establish O-GlcNAcylation of DNMT1 as a mechanism through which the epigenome is regulated by glucose metabolism and implicates a role for glycosylation of DNMT1 in metabolic diseases characterized by hyperglycemia.

Cytotoxic mixed-ligand complexes of Cu(II): A combined experimental and computational study

Herein, we report the synthesis of mixed-ligand Cu(II) complexes of metformin and ciprofloxacin drugs together with 1,10-phenanthroline as a co-ligand. The synthesized complexes were characterized using different spectroscopic and spectrometric techniques. In vitro cytotoxic activity against human breast adenocarcinoma cancer cell line (MCF-7) as well as antibacterial activity against two gram-negative and two gram-positive bacterial strains were also investigated. The analyses of the experimental results were supported using quantum chemical calculations and molecular docking studies against estrogen receptor alpha (ERα; PDB: 5GS4). The cytotoxicity of the [Cu(II) (metformin) (1,10-phenanthroline)] complex (1), with IC₅₀ of 4.29 µM, and the [Cu(II) (ciprofloxacin) (1,10-phenanthroline)] complex (2), with IC₅₀ of 7.58 µM, were found to be more effective than the referenced drug, cisplatin which has IC₅₀ of 18.62 µM against MCF-7 cell line. The molecular docking analysis is also in good agreement with the experimental results, with binding affinities of –7.35, –8.76 and –6.32 kcal/mol, respectively, for complexes 1, 2 and cisplatin against ERα. Moreover, complex 2 showed significant antibacterial activity against E. coli (inhibition diameter zone, IDZ, = 17.3 mm), P. aeruginosa (IDZ = 17.08 mm), and S. pyogen (IDZ = 17.33 mm), at 25 μg/ml compared to ciprofloxacin (IDZ = 20.0, 20.3, and 21.3 mm), respectively. Our BOILED-egg model indicated that the synthesized metal complexes have potentially minimal neurotoxicity than that of cisplatin.

AMPK-ChREBP axis mediates de novo milk fatty acid synthesis promoted by glucose in the mammary gland of lactating goats

To investigate the role of glucose in regulating milk fatty acid synthesis, 6 lactating Guanzhong dairy goats were infused with 0, 60, or 100 g/d glucose via the external pubic artery in a 3 × 3 repeated Latin square experiment. A concomitant in vitro experiment was conducted to investigate possible mechanisms whereby glucose regulates milk fatty acid synthesis. RNA sequencing was used for cellular transcriptome analysis. Drugs, MK-2206, rapamycin, and dorsomorphin were used to block cellular mammalian AMP-activated protein kinase (AMPK), AKT serine/threonine kinase 1, and mechanistic target of rapamycin kinase signaling pathways, respectively. Carbohydrate response element binding protein (ChREBP) was knockdown and overexpressed to investigate its role in regulating milk fatty acid synthesis in mammary epithelial cells. Glucose infusion linearly elevated the concentration of C8:0 (P = 0.039) and C10:0 (P = 0.041) in milk fat while it linearly decreased (P = 0.049) that of C16:0. This result was in agreement with the upregulation of genes related to de novo synthesis of fatty acids and lipid droplet formation, including adipose differentiation-related protein, butyrophilin subfamily 1 member A1, fatty acid synthase (FASN) and ChREBP. Their expression increased (P < 0.05) linearly in the lactating goat mammary gland. In vitro, glucose linearly stimulated the expression of genes related to de novo synthesis of fatty acids and cellular triacylglycerol in cultured mammary epithelial cells. RNA sequencing and inhibition studies revealed that glucose induced transcriptomic changes increasing lipogenic pathways, with AMPK responding to glucose by controlling ChREBP and FASN. Knockdown and overexpression of ChREBP highlighted its essential role in lipogenesis. The knockdown and overexpression of ChREBP protein also revealed an essential role in regulating the de novo synthesis of fatty acids. Collectively, our data highlight that glucose supplementation promotes de novo fatty acid synthesis via the AMPK-ChREBP axis, hence increasing milk fat yield in the goat mammary gland. Results from the current study provide possible strategies to manipulate the fatty acid composition as well as improve ruminant milk quality.

Inhibition of ASGR1 decreases lipid levels by promoting cholesterol excretion

High cholesterol is a major risk factor for cardiovascular disease¹. Currently, no drug lowers cholesterol through directly promoting cholesterol excretion. Human genetic studies have identified that the loss-of-function Asialoglycoprotein receptor 1 (ASGR1) variants associate with low cholesterol and a reduced risk of cardiovascular disease². ASGR1 is exclusively expressed in liver and mediates internalization and lysosomal degradation of blood asialoglycoproteins³. The mechanism by which ASGR1 affects cholesterol metabolism is unknown. Here, we find that Asgr1 deficiency decreases lipid levels in serum and liver by stabilizing LXRα. LXRα upregulates ABCA1 and ABCG5/G8, which promotes cholesterol transport to high-density lipoprotein and excretion to bile and faeces⁴, respectively. ASGR1 deficiency blocks endocytosis and lysosomal degradation of glycoproteins, reduces amino-acid levels in lysosomes, and thereby inhibits mTORC1 and activates AMPK. On one hand, AMPK increases LXRα by decreasing its ubiquitin ligases BRCA1/BARD1. On the other hand, AMPK suppresses SREBP1 that controls lipogenesis. Anti-ASGR1 neutralizing antibody lowers lipid levels by increasing cholesterol excretion, and shows synergistic beneficial effects with atorvastatin or ezetimibe, two widely used hypocholesterolaemic drugs. In summary, this study demonstrates that targeting ASGR1 upregulates LXRα, ABCA1 and ABCG5/G8, inhibits SREBP1 and lipogenesis, and therefore promotes cholesterol excretion and decreases lipid levels.

Glucose deprivation reduces proliferation and motility, and enhances the anti-proliferative effects of paclitaxel and doxorubicin in breast cell lines in vitro

Background

Breast cancer chemotherapy with high dose alkylating agents is severely limited by their collateral toxicity to crucial normal tissues such as immune and gut cells. Taking advantage of the selective dependence of cancer cells on high glucose and combining glucose deprivation with these agents could produce therapeutic synergy.

Methods

In this study we examined the effect of glucose as well as its deprivation, and antagonism using the non-metabolized analogue 2-deoxy glucose, on the proliferation of several breast cancer cell lines MCF7, MDA-MB-231, YS1.2 and pII and one normal breast cell line, using the MTT assay. Motility was quantitatively assessed using the wound healing assay. Lactate, as the end product of anaerobic glucose metabolism, secreted into culture medium was measured by a biochemical assay. The effect of paclitaxel and doxorubicin on cell proliferation was tested in the absence and presence of low concentrations of glucose using MTT assay.

Results

In all cell lines, glucose supplementation enhanced while glucose deprivation reduced both their proliferation and motility. Lactate added to the medium could substitute for glucose. The inhibitory effects of paclitaxel and doxorubicin were significantly enhanced when glucose concentration was decreased in the culture medium, requiring 1000-fold lesser concentration to achieve a similar degree of inhibition to that seen in glucose-containing medium.

Conclusion

Our data show that a synergy was obtained by combining paclitaxel and doxorubicin with glucose reduction to inhibit cancer cell growth, which in vivo, might be achieved by applying a carbohydrate-restricted diet during the limited phase of application of chemotherapy; this could permit a dose reduction of the cytotoxic agents, resulting in greater tolerance and lesser side effects.

BRCA1: An Endocrine and Metabolic Regulator

The breast and ovarian cancer susceptibility gene (BRCA1) is a tumor suppressor whose mutation has been associated with the development of breast, ovarian and, probably, other malignancies at young ages. The BRCA1 gene product participates in multiple biological pathways including the DNA damage response, transcriptional control, cell growth and apoptosis. Inactivating germline mutations of the BRCA1 gene can be detected in a substantial portion of families with inherited breast and/or ovarian cancer. While the genomic and cancer-related actions of BRCA1 have been extensively investigated, not much information exists regarding the cellular and circulating factors involved in regulation of BRCA1 expression and action. The present review article dissects the emerging role of BRCA1 as an important regulator of various endocrine and metabolic axes. Experimental and clinical evidence links BRCA1 with a number of peptide and steroid hormones. Furthermore, comprehensive analyses identified complex interactions between the insulin/insulin-like growth factor-1 (IGF1) signaling axis and BRCA1. The correlation between metabolic disorders, including diabetes and the metabolic syndrome, and BRCA1 mutations, are discussed in this article.