Upregulation Of Glucose Uptake Research Articles

Black raspberry extract stimulates glucose uptake via adenosine monophosphate‐activated protein kinase and phosphatidylinositol‐3 kinase pathways in skeletal muscle cells

AbstractBlack raspberry (Rubus occidentalis) shows beneficial health effects, such as antioxidant, anti‐inflammatory, chemopreventive, antiproliferative, and antihyperglycemic activities. The present study investigated the antihyperglycemic activity of black raspberry extract (BRE) and potential mechanisms in skeletal muscle cells. Differentiated C2C12 myotubes were treated with the BRE (1–1000 μg/mL) or metformin (1 mM). The protein levels of various insulin signaling targets were measured by western blot analysis. BRE significantly increased glucose uptake by upregulated insulin receptor and phosphatidylinositol‐3 kinase (PI3K) in C2C12 cells, leading to enhanced translocation of glucose transporter 4 (GLUT4) to the plasma membrane. The expression of phosphorylated (p)‐adenosine monophosphate‐activated protein kinase (AMPK) was also enhanced by treatment with BRE, this resulting in stimulation of GLUT4 translocation to the plasma membrane and hence glucose uptake in skeletal muscles. These results suggest that BRE has an antihyperglycemic effect by stimulating GLUT4 translocation to the plasma membrane via activating the PI3K and AMPK pathways in skeletal muscle cells, thereby upregulating glucose uptake. Black raspberry is a potential functional food and has important implications for preventing and treating type‐2 diabetes. In addition, our study found that the flavonoids fraction is the main contributor fraction to promote glucose uptake in C2C12 cells.

Biochemical Origin of the Warburg Effect in Light of 15 Years of Research Experience: A Novel Evidence-Based View (An Expert Opinion Article).

Cancer cells strongly upregulate glucose uptake and glycolysis to produce vital biomolecules for cancer cell survival, proliferation, and metastasis as ATP, lipids, proteins, nucleotides, and lactate. The Warburg effect is tumours' unique glucose oxidation to give lactate (not pyruvate) even in the presence of oxygen. Nicotinamide adenine dinucleotide (NAD/NADH.H) is used in glycolysis via glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase (LDH). Both catalyse reversible biochemical reactions to produce 1,3-diphosphoglycerate and lactate, respectively. In this expert opinion and based on published evidence, the author suggests that: "In transformed cells and hyperglycolytic cancer cells, the Warburg effect (permanent conversion of pyruvate to lactate) occurs secondary to a vicious cycle and a closed circuit between GAPDH and LDH (reaction of carcinogenesis) causing increased endogenous oxidative stress and subsequent carcinogenesis. Mitochondrial defects in cancer cells cause hyperglycolysis resulting in NADH.H accumulation (produced during GAPDH step) that obligatorily drives LDH to become an irreversible reaction in the direction of lactate formation (Warburg effect) but not pyruvate formation. Likewise, LDH oxidizes NADH.H producing excessive NAD+ that secondarily drives GAPDH reaction to be irreversible to produce NADH.H and so on. Pyruvate is an antioxidant while lactate is pro-oxidant, causing increased endogenous oxidative stress in cancer cells, tumour's hypoxia and obligatory hyperglycolysis with NADH.H overproduction (GAPDH step) to be consumed in the LDH step for lactate production and NAD+ generation (utilized by GAPDH) and so on". This confirms Warburg's origin of cancer cells. Best anticancer applications based on this hypothesis are: breaking this closed vicious circle using siRNA to target GAPDH and LDH, avoiding strong oxidants (as many cancer chemotherapeutics), and using strong antioxidants for causing antioxidant-oxidant antagonism or antioxidant-lactate antagonism to inhibit the Warburg effect. Strong natural antioxidants of prophetic medicine (related to Prophet Muhammad peace be upon him) such as Zamzam water, Nigella sativa, costus, Ajwa date fruit, olive oil, Al-hijamah and natural honey are strongly recommended to prevent and antagonize the Warburg effect.

ATPase Inhibitory Factor 1-A Novel Marker of Cellular Fitness and Exercise Capacity?

ATPase inhibitory factor 1 is a myokine inhibiting the hydrolytic activity of mitochondrial adenosine triphosphate synthase and ecto-F1-ATPase on the surface of many cells. IF1 affects ATP metabolism in mitochondria and the extracellular space and upregulates glucose uptake in myocytes; these processes are essential in physical activity. It is unknown whether the IF1 serum concentration is associated with exercise capacity. This study explored the association between resting IF1 serum concentration and exercise capacity indices in healthy people. IF1 serum concentration was measured in samples collected at rest in 97 healthy amateur cyclists. Exercise capacity was assessed on a bike ergometer at the successive stages of the progressive cardiopulmonary exercise test (CPET). IF1 serum concentration was negatively and significantly correlated with oxygen consumption, oxygen pulse, and load at various CPET stages. A better exercise capacity was associated with lower circulating IF1. IF1 may reflect better cellular/mitochondrial energetic fitness, but there is uncertainty regarding how IF1 is released into the intravascular space. We speculate that lower IF1 concentration may reflect a better cellular/mitochondrial integrity, as this protein is bound more strongly with ATPases in mitochondria and cellular surfaces in people with higher exercise capacity.

A ~24 kDa protein isolated from protein isolates of Hawaijar, popular fermented soy food of North-East India exhibited promising antidiabetic potential via stimulating PI3K/AKT/GLUT4 signaling pathway of muscle glucose metabolism

The present study investigated the antidiabetic potential of protein isolates from Hawaijar (HPI), a popular fermented soybean food of North-East India. Treatment with HPI significantly upregulated glucose uptake, glucose utilization, glucose-6-phosphate, and stimulated PI3K/AKT/GLUT4 pathway in high-glucose (HG)-treated myotubes. Signal silencing studies demonstrated that knockdown of insulin-dependent signaling molecule (IR) but not insulin-independent signaling molecule (AMPK) significantly inhibited HPI-induced activation of PI3K/AKT/GLUT4 pathway and glucose uptake in HG-treated myotubes. SDS-PAGE and immunoblotting analyses of HPI showed the reduction and/or absence of various subunits of 7S and 11S globulin protein and appearance of new proteins compared to respective non-fermented soy protein isolates. Using various chromatographic techniques, the present study further isolated a single protein (ISP, ~24 kDa) from HPI as one of the bioactive principles with promising glucose utilization potential via stimulating PI3K/AKT/GLUT4 pathway in HG-treated cells. ISP treatment along with insulin significantly stimulated PI3K/AKT/GLUT4 pathway and glucose uptake compared to either insulin or ISP alone treated cells against HG exposure suggesting the insulin sensitizing effect of ISP. Furthermore, ISP supplementation significantly reduced metabolic markers linked with diabetes in high-fructose high-fat diet-fed animal model of type 2 diabetes. This study demonstrated a novel molecular mechanism underlying the promising antidiabetic potential of HPI.

A popular fermented soybean food of Northeast India exerted promising antihyperglycemic potential via stimulating PI3K/AKT/AMPK/GLUT4 signaling pathways and regulating muscle glucose metabolism in type 2 diabetes.

This study examined the antidiabetic efficacy of popular fermented soybean foods (FSF) of Northeast (NE) India. Results showed that among different FSF, aqueous extract of Hawaijar (AEH), a traditional FSF of Manipur, NE India, significantly augmented glucose utilization in cultured myotubes treated with high glucose (HG, 25 mM). Furthermore, AEH also upregulated glucose uptake, glucose-6-phosphate level, and phopho-PI3K/phospho-AKT/phospho-AMPK/GLUT4 protein expression in HG-treated myotubes. In vivo studies demonstrated that AEH supplementation (50, 100, or 200 mg/kg body weight/day, oral gavaging, 16 weeks) reduced body weight, fasting blood glucose, glycated hemoglobin, insulin resistance, and glucose intolerance in rats fed with high-fat diet (HFD). AEH supplementation stimulated phopho-PI3K/phospho-AKT/phospho-AMPK/GLUT4 signaling cascades involved in glucose metabolism of muscle tissues in diabetic rats. Chemical profiling of AEH (SDS-PAGE, immunoblotting, and HRMS) suggests the possible role of bioactive proteins/peptides and isoflavones underlying the antihyperglycemic potential AEH. Results from this study will be helpful for developing food-based prophylactics/therapeutics in managing hyperglycemia. PRACTICAL APPLICATIONS: Fermented soybean foods are gaining acceptance due to multiple health benefits. This study for the first time reports the antidiabetic potential of Hawaijar, an indigenous fermented soybean food of North-East India. Higher abundance of bioactive compounds (isoflavones and proteins/peptides) in Hawaijar may be responsible for the alleviation of impaired glucose metabolism associated with diabetes. The findings may be helpful for the development of a novel therapeutic to achieve better control of hyperglycemia and improve the lives of the patient population with diabetes.

FC028: Characterization of Adipocyte Size and Glucose Uptake in Adipose Tissue with Focus on Different Perirenal Fat Depots

Abstract BACKGROUND AND AIMS Previous studies have suggested that the anatomical location of adipose tissue, and the characteristics of the adipocytes regulating adipose tissue function may be of importance for normal renal function and disease. However, in humans, the adipocyte size and metabolism of the fat depots surrounding the kidney have not been thoroughly characterized. The aim of this study was therefore to characterize adipocyte size and glucose uptake in human perirenal, renal sinus and paranephric adipose tissue. SUBJECTS AND METHODS A total of 25 healthy kidney donors [13 (50%) men, age 48 ± 11 years and BMI 25.7 ± 3.1 kg/m2] were included. Perirenal, renal sinus, paranephric, omental and subcutaneous adipose tissue were collected during laparoscopic unilateral nephrectomy. Adipocyte diameter, basal glucose uptake (no insulin) and insulin-stimulated glucose uptake (25 and 1000 µU/mL) were measured in isolated adipocytes from the different tissues. RESULTS The mean adipocyte cell diameters in the renal fat depots (perirenal, renal sinus and paranephric) were smaller than those in omental and subcutaneous tissue (mean ± sd; 69.3 ± 15.5, 65.5 ± 13.5 and 75.9 ± 16.5 versus 80.3 ± 20.5 and 85.5 ± 16.7 µm, respectively) with adipocytes from the renal sinus fat depot having the smallest cell diameter. Detailed data are displayed in Fig. 1. There were no significant gender differences in cell size and adipocyte size from the different depots did not correlate with body mass index (BMI). Insulin resistance index (HOMA-IR) correlated positively and significantly to adipocyte size in the omental (r = 0.607; P = 0.008), perirenal (r = 0.443; P = 0.027) and paranephric (r = 0.479; P = 0.015) depots. Insulin (both with 25 and 1000 µU/mL) significantly up-regulated glucose uptake in subcutaneous (1.6 and 1.9-fold; P < 0.05), perirenal (1.7 and 2.0-fold; P < 0.01) and paranephric (1.5 and 1.6-folds; P < 0.01) adipocytes, compared with basal (no insulin) as shown in Fig. 2. Interestingly, glucose uptake per cell surface was higher in renal sinus than omental adipocytes (basal (no insulin) 1.2-fold; P < 0.001, physiological (25 µU/mL) and supraphysiological (1000 µU/mL) both 1.3-fold higher; P < 0.001) than omental adipocytes (comparison not shown). CONCLUSION This study in healthy kidney donors indicate differences in different fat depots surrounding the kidney that may be of importance for renal function and disease. The fat depot in the renal sinus, with the smallest adipocytes and potentially a higher glucose uptake, is of specific interest. Detailed metabolic characterization of these fat depots is ongoing. Comparison of adipocyte diameter between the different adipose tissue depots: subcutaneous (n = 24), omental (n = 18), perirenal (n = 25), renal sinus (n = 21) and paranephric adipose tissue (n = 25); Values are mean with SEM as data were normally distributed. **P < 0.01 and ***P < 0.001. Physiological and supraphysiological effect of insulin (25 and 1000 µU/mL) on glucose uptake compared with basal (no insulin) by cell surface in adipocytes isolated from subcutaneous (n = 6), omental (n = 3), perirenal (n = 21), renal sinus (n = 4) and paranephric (n = 18) adipose tissue depots, respectively. Values are median and interquartile range as data were not normally distributed. *P < 0.05, **P < 0.01.

Ethyl Gallate Dual-Targeting PTPN6 and PPARγ Shows Anti-Diabetic and Anti-Obese Effects.

The emergence of the high correlation between type 2 diabetes and obesity with complicated conditions has led to the coinage of the term “diabesity”. AMP-activated protein kinase (AMPK) activators and peroxisome proliferator-activated receptor (PPARγ) antagonists have shown therapeutic activity for diabesity, respectively. Hence, the discovery of compounds that activate AMPK as well as antagonize PPARγ may lead to the discovery of novel therapeutic agents for diabesity. In this study, the knockdown of PTPN6 activated AMPK and suppressed adipogenesis in 3T3-L1 cells. By screening a library of 1033 natural products against PTPN6, we found ethyl gallate to be the most selective inhibitor of PTPN6 (Ki = 3.4 μM). Subsequent assay identified ethyl gallate as the best PPARγ antagonist (IC50 = 5.4 μM) among the hit compounds inhibiting PTPN6. Ethyl gallate upregulated glucose uptake and downregulated adipogenesis in 3T3-L1 cells as anticipated. These results strongly suggest that ethyl gallate, which targets both PTPN6 and PPARγ, is a potent therapeutic candidate to combat diabesity.

Fungal sensing enhances neutrophil metabolic fitness by regulating antifungal Glut1 activity

Combating fungal pathogens poses metabolic challenges for neutrophils, key innate cells in anti-Candida albicans immunity, yet how host-pathogen interactions cause remodeling of the neutrophil metabolism is unclear. We show that neutrophils mediate renal immunity to disseminated candidiasis by upregulating glucose uptake via selective expression of glucose transporter 1 (Glut1). Mechanistically, dectin-1-mediated recognition of β-glucan leads to activation of PKCδ, which triggers phosphorylation, localization, and early glucose transport by a pool of pre-formed Glut1 in neutrophils. These events are followed by increased Glut1 gene transcription, leading to more sustained Glut1 accumulation, which is also dependent on the β-glucan/dectin-1/CARD9 axis. Card9-deficient neutrophils show diminished glucose incorporation in candidiasis. Neutrophil-specific Glut1-ablated mice exhibit increased mortality in candidiasis caused by compromised neutrophil phagocytosis, reactive oxygen species (ROS), and neutrophil extracellular trap (NET) formation. In human neutrophils, β-glucan triggers metabolic remodeling and enhances candidacidal function. Our data show that the host-pathogen interface increases glycolytic activity in neutrophils by regulating Glut1 expression, localization, and function.

Regulation of Glucose Transport in Adipocytes by Interleukin-4.

Metabolic abnormalities such as obesity, insulin resistance, and type 2 diabetes mellitus are known to be associated with adipose tissue inflammation and impaired secretion of cytokines. Anti-inflammatory cytokine interleukin-4 (IL-4) was found to promote insulin sensitivity, glucose tolerance, and reduce lipid accumulation in vivo through multiple mechanisms, including direct regulation of lipolysis in adipocytes. However, little is known about its role in adipocyte glucose metabolism. This study reveals that IL-4 upregulates glucose uptake in adipocytes without additional activation of the insulin-dependent IRS1 (insulin receptor substrate 1)-Akt (protein kinase B) pathway. Moreover, the main transcription factor STAT6 (signal transducer and activator of transcription 6), regulated by IL-4, was not involved in adipocyte glucose uptake. The proteomic results showed that IL-4 upregulates expression of proteins involved in mitochondrial biogenesis, renewal, and glucose oxidation. Our study provides a new hypothesis, explaining protective effects of IL-4 against metabolic abnormalities through activation of adipocytes glucose utilization and maintenance of mitochondrial function under metabolic overload conditions.

Resolvin E3 ameliorates high-fat diet-induced insulin resistance via the phosphatidylinositol-3-kinase/Akt signaling pathway in adipocytes.

Obesity-associated type 2 diabetes mellitus is associated with the development of insulin resistance. Among several metabolites, resolvins that are metabolites of eicosapentaenoic acid have been shown to exert insulin-sensitizing effects; however, the role of resolvin E3 (RvE3) in glucose metabolism has not been studied. In this study, the effect of RvE3 on glucose metabolism in mice with high-fat diet-induced obesity and 3T3L1 adipocytes was studied. C57BL/6mice fed a high-fat diet were administered RvE3, for which insulin tolerance, oral glucose tolerance tests, and the homeostasis model assessment of insulin resistance, were performed. RvE3 treatment significantly improved insulin sensitivity and glucose tolerance and regulated protein kinase B (Akt) phosphorylation in the adipose tissue. Moreover, RvE3 treatment enhanced the insulin-stimulated glucose transporter 4 (Glut4) translocation, glucose uptake, phosphatidylinositol-3-kinase (PI3K) activity, and Akt phosphorylation in 3T3L1 adipocytes, whereas a PI3K inhibitor inhibited the enhanced insulin-stimulated glucose uptake induced by RvE3. These findings indicate that RvE3likely improves insulin sensitivity, resulting in the upregulation of glucose uptake in adipocytes by activating the PI3K/Akt signaling pathways. Collectively, the findings of this study show that RvE3may play a role in glucose homeostasis and could be used as a potential therapeutic target for developing treatments for obesity-associated diabetes.

Brown adipose tissue is the key depot for glucose clearance in microbiota depleted mice

Gut microbiota deficient mice demonstrate accelerated glucose clearance. However, which tissues are responsible for the upregulated glucose uptake remains unresolved, with different studies suggesting that browning of white adipose tissue, or modulated hepatic gluconeogenesis, may be related to enhanced glucose clearance when the gut microbiota is absent. Here, we investigate glucose uptake in 22 different tissues in 3 different mouse models. We find that gut microbiota depletion via treatment with antibiotic cocktails (ABX) promotes glucose uptake in brown adipose tissue (BAT) and cecum. Nevertheless, the adaptive thermogenesis and the expression of uncoupling protein 1 (UCP1) are dispensable for the increased glucose uptake and clearance. Deletion of Ucp1 expressing cells blunts the improvement of glucose clearance in ABX-treated mice. Our results indicate that BAT and cecum, but not white adipose tissue (WAT) or liver, contribute to the glucose uptake in the gut microbiota depleted mouse model and this response is dissociated from adaptive thermogenesis.

TRIM66 Overexpression Promotes Glioma Progression and Regulates Glucose Uptake Through cMyc/GLUT3 Signaling.

ObjectiveTripartite motif 66 (TRIM66) is reported to be closely associated with human cancers. However, the roles of TRIM66 in glioma remain unclear. The present study aimed to investigate the clinical significance and biological roles of TRIM66 in human glioma.MethodsTRIM66 expression in glioma tissues was examined by immunohistochemistry. TRIM66 overexpression and siRNA knockdown were performed in glioblastoma cell lines. CCK8, colony formation assay, transwell assay, Annexin V and JC1 staining, glucose uptake assay, and Western blotting were used to explore the biological roles and potential underlying mechanisms of TRIM66 in glioma progression.ResultsOur results showed that TRIM66 was overexpressed in 52/95 glioma cases. The rates of TRIM66 overexpression in Grade I, Grade II, Grade III, and Grade IV gliomas were 16.6%, 41.3%, 58.6%, and 70.9%, respectively. Oncomine data showed that TRIM66 was upregulated in glioblastoma and oligodendroglioma compared with normal brain tissues. TRIM66 expression was higher in glioblastoma cell lines compared with normal SVG p12 glial cell line. TRIM66 promoted in vitro and in vivo proliferation, invasion, and inhibited temozolomide (TMZ)-induced apoptosis. Notably, TRIM66 increased glucose metabolism by upregulating glucose uptake, glucose consumption, and ATP production. Western blotting showed that TRIM66 positively regulated cMyc and GLUT3. Depletion of cMyc by siRNA abolished the effect of TRIM66 on GLUT3. Chromatin immunoprecipitation (ChIP) assay showed that cMyc could bind to the promoter regions of GLUT3 in glioblastoma cells.ConclusionTRIM66 was upregulated in human gliomas, where it promoted cell growth and chemoresistance. Our data also identified novel roles of TRIM66 in glioma progression. TRIM66 upregulates glucose uptake and mitochondrial function through the cMyc/GLUT3 signaling, which makes it a potential therapeutic target.

Fatty acid oxidation is required for embryonic stem cell survival during metabolic stress.

Metabolic regulation is critical for the maintenance of pluripotency and the survival of embryonic stem cells (ESCs). The transcription factor Tfcp2l1 has emerged as a key factor for the naïve pluripotency of ESCs. Here, we report an unexpected role of Tfcp2l1 in metabolic regulation in ESCs-promoting the survival of ESCs through regulating fatty acid oxidation (FAO) under metabolic stress. Tfcp2l1 directly activates many metabolic genes in ESCs. Deletion of Tfcp2l1 leads to an FAO defect associated with upregulation of glucose uptake, the TCA cycle, and glutamine catabolism. Mechanistically, Tfcp2l1 activates FAO by inducing Cpt1a, a rate-limiting enzyme transporting free fatty acids into the mitochondria. ESCs with defective FAO are sensitive to cell death induced by glycolysis inhibition and glutamine deprivation. Moreover, the Tfcp2l1-Cpt1a-FAO axis promotes the survival of quiescent ESCs and diapause-like blastocysts induced by mTOR inhibition. Thus, our results reveal how ESCs orchestrate pluripotent and metabolic programs to ensure their survival in response to metabolic stress.

Potential Antidiabetic Effects of Seaweed Extracts by Upregulating Glucose Utilization and Alleviating Inflammation in C2C12 Myotubes

Seaweed is known to have various health-promoting effects. However, the mechanisms underlying seaweed’s antidiabetic effects remain unclear. We investigated the potential antidiabetic effects of seaweed water extracts and further examined their mechanism(s) using C2C12 mouse skeletal muscle cells. Briefly, we screened the physiochemical properties of seven seaweed extracts by comparing the antioxidant and α-glucosidase inhibitory effects. Among them, three seaweed extracts, Undaria pinnatifida sporophyll (UPS), Codium fragile (CF), and Gracilaria verrucosa (GV), were selected for further testing of their possible antidiabetic effects with underlying mechanisms using C2C12 myotubes. Consistent with the superior α-glucosidase inhibition of the three seaweed extracts, the extracts also enhanced glucose utilization in myotubes compared to the control. The upregulated glucose uptake by the seaweed extracts was reversed by an AMP-activated protein kinase (AMPK) inhibitor, compound C, in the UPS- and CF-treated groups. Furthermore, all three seaweed extracts significantly promoted the phosphorylation of AMPK which was completely blocked by pretreating with compound C. In addition, all three extracts reduced lipopolysaccharide-simulated TNF-α production in C2C12 cells. Our results demonstrated that all three seaweed extracts exhibited antidiabetic properties through not only the inhibition of glucose absorption but also the promotion of glucose utilization. Moreover, the regulation of inflammatory cytokine production by the extracts suggested their potential anti-inflammatory property which might play a critical role in protecting insulin sensitivity in a chronic inflammatory state. Taken together, UPS, CF, and GV are a promising source to modulate the glucose absorption and utilization in muscle cells partially via the AMPK pathway.

Lauric acid alleviates insulin resistance by improving mitochondrial biogenesis in THP-1 macrophages.

Mitochondrial dysfunction plays a crucial role in the central pathogenesis of insulin resistance and type 2 diabetes mellitus. Macrophages play important roles in the pathogenesis of insulin resistance. Lauric acid is a 12-carbon medium chain fatty acid (MCFA) found abundantly in coconut oil or palm kernel oil and it comes with multiple beneficial effects. This research objective was to uncover the effects of the lauric acid on glucose uptake, mitochondrial function and mitochondrial biogenesis in insulin-resistant macrophages. THP-1 monocytes were differentiated into macrophages and induce insulin resistance, before they were treated with increasing doses of lauric acid (5μM, 10μM, 20μM, and 50μM). Glucose uptake assay, cellular ROS and ATP production assays, mitochondrial content and membrane potential assay were carried out to analyse the effects of lauric acid on insulin resistance and mitochondrial biogenesis in the macrophages. Quantitative RT-PCR (qRT-PCR) and western blot analysis were also performed to determine the expression of the key regulators. Insulin-resistant macrophages showed lower glucose uptake, GLUT-1 and GLUT-3 expression, and increased hallmarks of mitochondrial dysfunction. Interestingly, lauric acid treatment upregulated glucose uptake, GLUT-1 and GLUT-3 expressions. The treatment also restored the mitochondrial biogenesis in the insulin-resistant macrophages by improving ATP production, oxygen consumption, mitochondrial content and potential, while it promoted the expression of mitochondrial biogenesis regulator genes such as TFAM, PGC-1α and PPAR-γ. We show here that lauric acid has the potential to improve insulin sensitivity and mitochondrial dysregulation in insulin-resistant macrophages.

Abstract 4191: Characterization of a novel anti-glucose transporter inhibitor as a pan-anticancer therapeutic in vitro and in vivo

Abstract Cancer has surpassed cardiovascular diseases as the top killer in many US counties. Opportunistic uptake of extracellular nutrients has recently been named as an emerging hallmark of cancer metabolism. Glucose is a key nutrient taken in by cancer cells for satisfying their high energy and biosynthesis needs. Drastic upregulation of glucose uptake and metabolism, a phenomenon called the Warburg effect, is prevalent among cancers. Cancer cells overexpress specific glucose transporters (GLUTS), particularly GLUT1, on their cell surface for uptaking glucose via facilitated diffusion. Considering the addiction of cancer cells to glucose and their sensitivity and vulnerability to changes in glucose supply, Gluts, have been recognized as an attractive anticancer target. Previously, our first-generation GLUT-inhibitor, WZB117, had been characterized in vitro and in vivo as an anticancer therapeutic. In this study, DRB18, a novel and proprietary lead inhibitor of glucose transporters, is characterized in vitro and in vivo by bioassays. DRB18 inhibits growth and proliferation in about 90% of the 60 different cancer cell lines in 9 major cancer types. It shows IC50 values in high nM range in some cell lines in several different cancer types. DRB18 treatment leads to significant changes in glucose-based metabolism in A549 lung cancer cells, including cell death via ER/oxidative stress and necrosis. The docking and Seahorse studies reveal the surprising contributions of macropinocytosis in DRB18 internalization, ultimately leading to better GLUT1 binding and increase in potency in killing cancer cells. DRB18 (10mg/kg) treatment thrice a week significantly reduces growth in Xenograft A549 tumors. Comprehensive in vitro and in vivo metabolomics analysis would be presented to better describe anti-glucose metabolism of activity of DRB18. Further, GLUT1-KO A549 (A549glut1ko) cell lines, in which Glut1 gene has been knocked out, were generated using CRISPR-Cas9 system for further studying GLUT1's roles in A549 cells. Immunoblotting analysis revealed the upregulation of other GLUTs after GLUT1 is knocked out, strongly suggesting the need for a pan-GLUT inhibitor for better inhibition of tumor growth. Citation Format: Pratik Shriwas, Stephen Bergmeier, Xiaozhuo Chen. Characterization of a novel anti-glucose transporter inhibitor as a pan-anticancer therapeutic in vitro and in vivo [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4191.

Activator of thyroid and retinoid receptor increases sorafenib resistance in hepatocellular carcinoma by facilitating the Warburg effect

Sorafenib resistance is a major challenge in the therapy for advanced hepatocellular carcinoma (HCC). However, the underlying molecular mechanisms of HCC resistance to sorafenib remain unclear. Activator of thyroid and retinoid receptor (ACTR, also known as SRC‐3), overexpressed in HCC patients, plays an important oncogenic role in HCC; however, the link between ACTR and sorafenib resistance in HCC is unknown. Our study demonstrated that ACTR was one of the most upregulated genes in sorafenib‐resistant HCC xenografts. ACTR increases sorafenib resistance through regulation of the Warburg effect. ACTR promotes glycolysis through upregulation of glucose uptake, ATP and lactate production, and reduction of the extracellular acidification and the oxygen consumption rates. Glycolysis regulated by ACTR is vital for the susceptibility of HCC to sorafenib in vitro and in vivo. Mechanistically, ACTR knockout or knockdown decreases the expression of glycolytic enzymes. In HCC patients, ACTR expression is positively correlated with glycolytic gene expression and is associated with poorer outcome. Furthermore, ACTR interacts with the central regulator of the Warburg effect, c‐Myc, and promotes its recruitment to glycolytic gene promoters. Our findings provide new clues regarding the role of ACTR as a prospective sensitizing target for sorafenib therapy in HCC.

Six1 Overexpression Promotes Glucose Metabolism and Invasion Through Regulation of GLUT3, MMP2 and Snail in Thyroid Cancer Cells.

IntroductionSineoculis homeobox homolog 1 (Six1) overexpression has been implicated in several human cancers. To date, its clinical significance and potential function in human thyroid cancer remain unclear.MethodsImmunohistochemistry was used to examine the protein expression of BCAT1 in 89 cases of thyroid cancer tissues. We overexpressed and knockdown Six1 in TPC-1 and B-CPAP thyroid cancer cell lines. Biological roles and potential mechanisms of Six1 were examined using CCK-8, colony formation assay, Matrigel invasion assay, Western blot, PCR, ATP assay, and 2-NBDG uptake assay.ResultsWe showed that Six1 protein was upregulated in thyroid cancers and was associated with tumor size and nodal metastasis. Analysis of TCGA dataset indicated that Six1 mRNA was higher in thyroid cancers compared with normal thyroid. CCK-8, colony formation and Matrigel invasion assays demonstrated that Six1 overexpression promoted proliferation, colony number and invasion while Six1 siRNA knockdown inhibited the growth rate, colony formation ability and invasive ability in both cell lines. Notably, Six1 upregulated glucose consumption, lactate production level and ATP level. 2-NBDG uptake analysis showed that Six1 overexpression upregulated glucose uptake while Six1 knockdown inhibited glucose uptake. Further analysis revealed that Six1 overexpression upregulated Snail, MMP2 and GLUT3 at both mRNA and protein levels. TCGA analysis demonstrated positive associations between Six1 and Snail, MMP2 and GLUT3 at the mRNA levels.ConclusionTaken together, our data demonstrated that Six1 was upregulated in human thyroid cancers and promoted cell proliferation and invasion. Our data also revealed new roles of Six1 in thyroid cancer development by modulating glucose metabolism and invasion, possibly through regulation of Snail, MMP2 and GLUT3.

Scopoletin increases glucose uptake through activation of PI3K and AMPK signaling pathway and improves insulin sensitivity in 3T3-L1 cells

Coumarins have been shown to reduce blood glucose levels and improve insulin sensitivity in other studies. The purpose of this study was to investigate the effects of scopoletin, which is a type of coumarin family, on glucose uptake in 3T3-L1 cells to test the hypothesis that scopoletin exerts an antidiabetic function on adipocytes. Scopoletin significantly increased glucose uptake, which was associated with increased expression of the plasma membrane glucose transporter type 4 (PM-GLUT4) in 3T3-L1 adipocytes. This increase in PM-GLUT4 expression was promoted by phosphorylation of protein kinase B, activation of phosphatidylinositol-3-kinase (PI3K), and enhanced intracellular glucose uptake. Scopoletin also promoted phosphorylation of adenosine monophosphate–activated protein kinase (AMPK) and enhanced PM-GLUT4 expression. Scopoletin-induced glucose uptake in 3T3-L1 adipocytes was inhibited by treatment with the PI3K inhibitor wortmannin and the AMPK inhibitor compound C. These results suggest that scopoletin has an antidiabetic effect by stimulating GLUT4 translocation to the PM through activation of the PI3K and AMPK pathways in 3T3-L1 adipocytes, thereby upregulating glucose uptake.

Long non-coding RNA mortal obligate RNA transcript suppresses tumor cell proliferation in prostate carcinoma by inhibiting glucose uptake.

A previous study reported the decreased expression of long non-coding RNA mortal obligate RNA transcript (lncRNA MORT) in 16 types of cancer, while the functionality of lncRNA MORT in cancer biology remains unknown. Therefore, the present study was conducted to characterize the functionality of lncRNA MORT in prostate carcinoma, a common cancer type worldwide. lncRNA MORT expression level was downregulated in tumor tissues compared with that in the adjacent healthy tissues of patients with prostate carcinoma. Expression of lncRNA MORT in tumor tissues was influenced by tumor size, but not by tumor metastasis. Overexpression of lncRNA MORT inhibited glucose uptake and glucose transporter 1 (GLUT-1) expression in prostate carcinoma cell lines; GLUT-1 overexpression upregulated glucose uptake and attenuated the effects of lncRNA MORT overexpression on glucose uptake, but did not significantly affect the expression of lncRNA MORT. Overexpression of lncRNA MORT inhibited, while GLUT-1 overexpression promoted the proliferation of prostate carcinoma cells. In addition, GLUT-1 overexpression attenuated the effects of lncRNA MORT on cell proliferation. Therefore, lncRNA MORT may inhibit cancer cell proliferation in prostate carcinoma by preventing glucose uptake.