Expression Levels Of Glucose Transporter Research Articles

Role of glucose metabolism related gene GLUT1 in the occurrence and prognosis of colorectal cancer.

Colorectal cancer (CRC) ranks the third most commonly diagnosed cancer in males and the second in females worldwide. However, the functional and causal SNPs for CRC remain to be mined. Glucose transporter 1 (GLUT1), a pivotal rate-limiting element in the transport of glucose in malignancy cells, has been identified to be associated with many cancers. Here, we aim to explore the role of GLUT1 in the occurrence and prognosis of colorectal cancer in a Chinese population. We found that GLUT1 expression levels in CRC tumor tissues were significantly higher than those in the corresponding adjacent normal tissues, and Cox multivariate analysis demonstrated that the GLUT1 expression was an independent prognostic factor for CRC (HR = 2.11, 95% CI = 1.33–3.34, P=0.001). For a functional polymorphism of GLUT1 (rs710218), we found that individuals with TT genotype (OR = 1.68, 95% CI = 1.02-2.75, P = 0.041) or AT genotype (OR = 1.47, 95% CI = 1.09-1.99, P = 0.012) of rs710218 had a significantly increased risk of CRC compared to those with AA homozygote. These findings strongly suggest that glucose metabolism related gene GLUT1, and its functional SNP, rs710218 might contribute to CRC susceptibility and prognosis, and the exact biological mechanism awaits further research.

Geniposide promotes autophagy to inhibit insulin resistance in HepG2 cells via P62/NF‑κB/GLUT‑4.

Insulin resistance (IR) is known to be an important factor, which can lead to the onset of type 2 diabetes. Autophagy is a cellular process, which sequesters senescent or damaged proteins in autophagosomes for recycling of their products. Insulin and intracellular molecules, including mammalian target of rapamycin (mTOR), are well-known inhibitors of autophagy. In patients with type 2 diabetes, the expression levels of glucose transporter 4 (GLUT-4) in skeletal muscles are significantly decreased, indicating decreased glucose-processing ability. Geniposide is an iridoid compound isolated from Gardenia jasminoides Ellis. Previously, it was reported that geniposide significantly promoted glucose uptake. In the present study, a HepG2 cell model of IR was constructed to determine whether geniposide can promote autophagy to inhibit insulin resistance in HepG2 cells via P62/nuclear factor (NF)-κB/GLUT-4. Cell proliferation was analyzed by performing an MTT assay, and the mRNA expression levels of NF-κB and GLUT-4 were assessed using semi-quantitative polymerase chain reaction and immunohistochemical staining. In addition, the protein levels of GLUT-4, P62 and phosphorylated-P65 were assessed by western blotting. The expression of GLUT-4 was initially increased following geniposide treatment, decreasing in time to its lowest level at 8 h. The expression levels of NF-κB and GLUT-4 in the IR cells treated with and without geniposide were significantly different, compared with those in the control group. Geniposide promoted autophagy in the IR HepG2 cells and significantly improved IR in the HepG2 cells, which may be associated with the dynamic regulation of the P62/NF-κB/GLUT-4 pathway.

Puerariae Lobatae Radix elevated expression levels of OB-R, IRS2, GLUT1 and GLUT2 to regulate glucose metabolism in insulin-resistance HepG2 cells

To observe the anti-hyperglycemic effect of Puerariae Lobatae Radix in hepatocyte insulin resistance(IR) models, and investigate its preliminary molecular mechanism. IR-HepG2 cell model was stably established with 1×10-9 mol•L⁻¹ insulin plus 3.75×10-6 mol•L-1 dexamethasone treatment for 48 h according to optimized protocol in our research group. After IR-HepG2 cells were treated with different concentrations(5%,10% and 15%) of Puerariae Lobatae Radix-containing serum, cell viability was detected by CCK-8 assay; the glucose consumptions in IR-HepG2 cells were separately detected at different time points (12, 15, 18, 21, 24, 30, 36 h) by using glucose oxidase method; intracellular glycogen content was detected by anthrone method; and the protein expression levels of leptin receptor (Ob-R), insulin receptor substrate-2 (IRS2), glucose transporter 1(GLUT1) and GLUT2 were detected by Western blot assay. The results showed that Puerariae Lobatae Radix-containing serum (5%, 10% and 15%) had no significant effect on IR-HepG2 cell viability; 5% and 10% Puerariae Lobatae Radix-containing serum significantly increased glucose consumption of IR-HepG2 cells (P<0.01) at 18, 21 and 24 h; 15% Puerariae Lobatae Radix-containing serum elevated the glucose consumption of IR-HepG2 cells at 15 h (P<0.05), and significantly elevated the glucose consumption at 18, 21, 24 and 30 h (P<0.01) in a dose-dependent manner. The optimized time of anti-hyperglycemic effect was defined as 24 h, and further study showed that Puerariae Lobatae Radix-containing serum could increase intracellular glycogen content after 24 h treatment (P<0.01), and up-regulate IRS2, Ob-R, GLUT1 and GLUT2 protein expression levels. Our results indicated that Puerariae Lobatae Radix-containing serum could achieve the anti-hyperglycemic effect through important PI3K/PDK signaling pathway partially by up-regulating the expression levels of Ob-R and IRS2, GLUT1 and GLUT2 in IR-HepG2 cells, accelerating the glucose transport into hepatocytes and increasing hepatic glycogen synthesis to enhance the anti-hyperglycemic effect of IR-HepG2 cells.

Expression of hypoxia-inducible factor 1α, glucose transporter 1 and lactate dehydrogenase 5 in colorectal cancer and clinicopathologic significance

Objective: To investigate the expression and clinicopathological significance of hypoxia-inducible factor 1 alpha (HIF-1α), glucose transporter 1(GLUT-1) and lactate dehydrogenase(LDH)-5 in colorectal cancer. Methods: The expression levels of HIF-1α, GLUT-1 and LDH-5 were detected by immunohistochemical staining in 142 specimens of human carcinoma in comparison with adjacent normal tissues. Results: The expression levels of HIF-1α(78.2%, 111/142), GLUT-1(75.4%, 107/142) and LDH-5(68.3%, 97/142) were higher in tumor tissues than in adjacent normal tissues(14.8%, 21/142; 11.3%, 16/142; 7.0%, 10/142; P<0.01 for all three proteins), and such over-expression was significantly associated with lymphovascular invasion, tumor grade and pathological stages(all P<0.01). Additional studies showed that HIF-1α, GLUT-1 and LDH-5 were positively associated with each other(r<0.3, P<0.05 for all three proteins). Conclusion: The data suggest that HIF-1α, GLUT-1 and LDH-5 expression may serve as prognostic indicators for colorectal cancer patients.

Novel predictive biomarkers for cervical cancer prognosis

High hypoxic, glycolytic and acidosis metabolisms characterize cervical cancer tumors and have been described to be involved in chemoradioresistance mechanisms. Based on these observations, the present study assessed four selected novel biomarkers on the prognosis of locally advanced cervical carcinoma. A total of 66 patients with stage IIB/IIIB cervical cancer were retrospectively included. The protein expression levels of glucose transporter 1 (GLUT1), carbonic anhydrase 9 (CAIX) and hexokinase 1 (HKII) were investigated by immunohistochemistry on tumor biopsies, hemoglobin was measured and the disease outcome was monitored. A total of 53 patients (80.3%) presented a complete response. For these patients, the protein expression levels of GLUT1, CAIX and HKII were overexpressed. A significant difference was observed (P=0.0127) for hemoglobin levels (≤11 g/dl) in responsive compared with non-responsive patients. The expression of GLUT1 is associated with a lower rate of both overall and disease-free survival, with a trend of decreased risk of 1.1x and 1.5x, respectively. Co-expression of GLUT1 and HKII is associated with a decreased trend risk of 1.6x for overall survival. Patients with hemoglobin levels ≤11 g/dl had a 4.3-fold risk (P=0.02) in decreasing both to the rate of overall and disease-free survival. The presence of anemic hypoxia (hemoglobin ≤11 g/dl) and the expression of GLUT1 and/or HKII influence treatment response and are associated with a lower overall and disease-free survival. The present results demonstrated that these biomarkers may be used as predictive markers and suggested that these metabolic pathways can be used as potential novel therapeutic targets.

FOXM1 promotes reprogramming of glucose metabolism in epithelial ovarian cancer cells via activation of GLUT1 and HK2 transcription.

Cancer cells exhibit the reprogrammed metabolism mainly via aerobic glycolysis, a phenomenon known historically as the Warburg effect; however, the underlying mechanisms remain largely unknown. In this study, we characterized the critical role of transcription factor Forkhead box protein M1 (FOXM1) in aerobic glycolysis of human epithelial ovarian cancer (EOC) and its molecular mechanisms. Our data showed that aberrant expression of FOXM1 significantly contributed to the reprogramming of glucose metabolism in EOC cells. Aerobic glycolysis and cell proliferation were down-regulated in EOC cells when FOXM1 gene expression was suppressed by RNA interference. Moreover, knockdown of FOXM1 in EOC cells significantly reduced glucose transporter 1 (GLUT1) and hexokinase 2 (HK2) expression. FOXM1 bound directly to the GLUT1 and HK2 promoter regions and regulated the promoter activities and the expression of the genes at the transcriptional level. This reveals a novel mechanism by which glucose metabolism is regulated by FOXM1. Importantly, we further demonstrated that the expression levels of FOXM1, GLUT1 and HK2 were significantly increased in human EOC tissues relative to normal ovarian tissues, and that FOXM1 expression was positively correlated with GLUT1 and HK2 expression. Taken together, our results show that FOXM1 promotes reprogramming of glucose metabolism in EOC cells via activation of GLUT1 and HK2 transcription, suggesting that FOXM1 may be an important target in aerobic glycolysis pathway for developing novel anticancer agents.

Erythropoietin ameliorates hyperglycemia in type 1-like diabetic rats.

BackgroundErythropoietin (EPO) is widely used in diabetic patients receiving hemodialysis. The role of EPO in glucose homeostasis remains unclear. Therefore, we investigated the effect of EPO on hyperglycemia in rats with type 1-like diabetes.MethodsRats with streptozotocin-induced type 1-like diabetes (STZ rats) were used to estimate the blood glucose-lowering effects of EPO, and changes in the expression levels of glucose transporter 4 (GLUT4) and the hepatic enzyme phosphoenolpyruvate carboxykinase (PEPCK) were identified by Western blot analysis.ResultsEPO attenuated the hyperglycemia in the STZ rats in a dose-dependent manner without altering the hematopoietic parameters, including the hematocrit and number of red blood cells. The involvement of the EPO receptor (EPOR) was identified using EPOR-specific antibodies. In addition, injection of EPO enhanced the glucose utilization, which was assessed using an intravenous glucose tolerance test in rats. However, blood insulin was not changed by EPO in this assay, showing the insulinotropic action of EPO. Moreover, EPO treatment increased the insulin sensitivity. Western blots indicated that the phosphorylation of AMP-activated protein kinase was enhanced by EPO to support the signaling caused by EPOR activation. Furthermore, the decrease in the GLUT4 level in skeletal muscle was reversed by EPO, and the increase in the PEPCK expression in liver was reduced by EPO, as shown in STZ rats.ConclusionTaken together, the results show that EPO injection may reduce hyperglycemia in diabetic rats through activation of EPO receptors. Therefore, EPO is useful for managing diabetic disorders, particularly hyperglycemia-associated changes. In addition, EPO receptor will be a good target for the development of antihyperglycemic agent(s) in the future.

Glycolysis gene expression analysis and selective metabolic advantage in the clinical progression of colorectal cancer.

Production of lactate even in the presence of sufficient levels of oxygen (aerobic glycolysis) seems the prevalent energy metabolism pathway in cancer cells. The analysis of altered expression of effectors causing redirection of glucose metabolism would help to characterize this phenomenon with possible therapeutic implications. We analyzed mRNA expression of the key enzymes involved in aerobic glycolysis in normal mucosa (NM), primary tumor (PT) and liver metastasis (LM) of colorectal cancer (CRC) patients (pts) who underwent primary tumor surgery and liver metastasectomy. Tissues of 48 CRC pts were analyzed by RT-qPCR for mRNA expression of the following genes: hexokinase-1 (HK-1) and 2 (HK-2), embryonic pyruvate kinase (PKM-2), lactate dehydrogenase-A (LDH-A), glucose transporter-1 (GLUT-1), voltage-dependent anion-selective channel protein-1 (VDAC-1). Differences in the expression of the candidate genes between tissues and associations with clinical/pathologic features were studied. GLUT-1, LDH-A, HK-1, PKM-2 and VDAC-1 mRNA expression levels were significantly higher in PT/LM tissues compared with NM. There was a trend for higher expression of these genes in LM compared with PT tissues, but differences were statistically significant for LDH-A expression only. RAS mutation-positive disease was associated with high GLUT-1 mRNA expression levels only. Right-sided colon tumors showed significantly higher GLUT-1, PKM-2 and LDH-A mRNA expression levels. High glycolytic profile was significantly associated with poor prognosis in 20 metastatic, RAS-mutated pts treated with first-line chemotherapy plus Bevacizumab. Altered expression of effectors associated with upregulated glucose uptake and aerobic glycolysis occurs in CRC tissues. Additional analyses are warranted for addressing the role of these changes in anti-angiogenic resistance and for developing novel therapeutics.

Chlorogenic Acid Maintains Glucose Homeostasis through Modulating the Expression of SGLT-1, GLUT-2, and PLG in Different Intestinal Segments of Sprague-Dawley Rats Fed a High-Fat Diet

ObjectiveTo reveal the effects and related mechanisms of chlorogenic acid (CGA) on intestinal glucose homeostasis. MethodsForty male Sprague-Dawley rats were randomly and equally divided into four groups: normal chow (NC), high-fat diet (HFD), HFD with low-dose CGA (20 mg/kg, HFD-LC), and HFD with high-dose CGA (90 mg/kg, HFD-HC). The oral glucose tolerance test was performed, and fast serum insulin (FSI) was detected using an enzyme-linked immunosorbent assay. The mRNA expression levels of glucose transporters (Sglt-1 and Glut-2) and proglucagon (Plg) in different intestinal segments (the duodenum, jejunum, ileum, and colon) were analyzed using quantitative real-time polymerase chain reaction. SGLT-1 protein and the morphology of epithelial cells in the duodenum and jejunum was localized by using immunofluorescence. ResultsAt both doses, CGA ameliorated the HFD-induced body weight gain, maintained FSI, and increased postprandial 30-min glucagon-like peptide 1 secretion. High-dose CGA inhibited the HFD-induced elevation in Sglt-1 expression. Both CGA doses normalized the HFD-induced downregulation of Glut-2 and elevated the expression of Plg in all four intestinal segments. ConclusionAn HFD can cause a glucose metabolism disorder in the rat intestine and affect body glucose homeostasis. CGA can modify intestinal glucose metabolism by regulating the expression of intestinal glucose transporters and Plg, thereby controlling the levels of blood glucose and insulin to maintain glucose homeostasis.

Interruptin B induces brown adipocyte differentiation and glucose consumption in adipose-derived stem cells.

Interruptin B has been isolated from Cyclosorus terminans, however, its pharamcological effect has not been fully identified. In the present study, the effects of interruptin B, from C. terminans, on brown adipocyte differentiation and glucose uptake in adipose-derived stem cells (ASCs) were investigated. The results revealed that interruptin B dose-dependently enhanced the adipogenic differentiation of ASCs, with an induction in the mRNA expression levels of peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ. In addition, interruptin B efficiently increased the number and the membrane potential of mitochondria and upregulated the mRNA expression levels of uncoupling protein (UCP)-1 and cyclooxygenase (COX)-2, which are all predominantly expressed in brown adipocytes. Interruptin B increased glucose consumption in differentiated ASCs, accompanied by the upregulation in the mRNA expression levels of glucose transporter (GLUT)-1 and GLUT-4. The computational analysis of molecular docking, a luciferase reporter assay and surface plasmon resonance confirmed the marked binding affinity of interruptin B to PPAR-α and PPAR-γ (KD values of 5.32 and 0.10 µM, respectively). To the best of our knowledge, the present study is the first report to show the stimulatory effects of interruptin B on brown adipocyte differentiation and glucose uptake in ASCs, through its role as a dual PPAR-α and PPAR-γ ligand. Therefore, interruptin B could be further developed as a therapeutic agent for the treatment of diabetes.

Biological correlation between glucose transporters, Ki-67 and 2-deoxy-2-[18F]-fluoro-D-glucose uptake in diffuse large B-cell lymphoma and natural killer/T-cell lymphoma.

The purpose of this study was to investigate the association between cellular 2-deoxy-2-[18F]-fluoro-D-glucose ((18)F-FDG) uptake and the expression of several subtypes of glucose transporters (GLUT) and Ki-67 in diffuse large B-cell lymphoma (DLBCL) and natural killer (NK)/T-cell lymphoma (NKTCL). Cell lines were histologically determined to be DLBCL (Raji cells) and NKTCL (Daudi cells), and uptake after pretreatment with (18)F-FDG was determined. Real-time polymerase chain reaction was performed to detect the expression levels of GLUTs 1, 2, 3, 4, and 7 and Ki-67, and to evaluate their association with (18)F-FDG uptake in DLBCL and NKTCL cells. The uptake rates of (18)F-FDG ranged from 18 to 46% (average 30 ± 10.20%) in Raji cells and 25 to 48% (average 35.6 ± 7.57%) in Daudi cells. In DLBCL cells, the expression levels of GLUTs 1, 3, and 7 were significantly correlated with cellular (18)F-FDG uptake rates (Spearman's rank correlation coefficient of 0.667, 0.516, and 0.468, respectively; P < 0.05). In NKTCL cells, the expression levels of GLUTs 1 and 3 were observed to be significantly correlated with cellular (18)F-FDG uptake rates (Spearman's rho of 0.756 and 0.498, respectively; P < 0.05). Ki-67 played no role in (18)F-FDG uptake in Raji or Daudi cells. In conclusion, the data acquired through this preliminary study indicate that GLUT 1 and GLUT 3 contribute to 18F-FDG uptake in DLBCL and NKTCL.

Antcin K, a Triterpenoid Compound from Antrodia camphorata, Displays Antidiabetic and Antihyperlipidemic Effects via Glucose Transporter 4 and AMP-Activated Protein Kinase Phosphorylation in Muscles.

The purpose of this study was to screen firstly the potential effects of antcin K (AnK), the main constituent of the fruiting body of Antrodia camphorata, in vitro and further evaluate the activities and mechanisms in high-fat-diet- (HFD-) induced mice. Following 8-week HFD-induction, mice were treated with AnK, fenofibrate (Feno), metformin (Metf), or vehicle for 4 weeks afterward. In C2C12 myotube cells, the membrane GLUT4 and phospho-Akt expressions were higher in insulin and AnK-treated groups than in the control group. It was observed that AnK-treated mice significantly lowered blood glucose, triglyceride, total cholesterol, and leptin levels in AnK-treated groups. Of interest, AnK at 40 mg/kg/day dosage displayed both antihyperglycemic effect comparable to Metf (300 mg/kg/day) and antihypertriglyceridemic effect comparable to Feno (250 mg/kg/day). The combination of significantly increased skeletal muscular membrane expression levels of glucose transporter 4 (GLUT4) but decreased hepatic glucose-6-phosphatase (G6 Pase) mRNA levels by AnK thus contributed to a decrease in blood glucose levels. Furthermore, AnK enhanced phosphorylation of AMP-activated protein kinase (phospho-AMPK) expressions in the muscle and liver. Moreover, AnK treatment exhibited inhibition of hepatic fatty acid synthase (FAS) but enhancement of fatty acid oxidation peroxisome proliferator-activated receptor α (PPARα) expression coincident with reduced sterol response element binding protein-1c (SREBP-1c) mRNA levels in the liver may contribute to decreased plasma triglycerides, hepatic steatosis, and total cholesterol levels. The present findings indicate that AnK displays an advantageous therapeutic potential for the management of type 2 diabetes and hyperlipidemia.

Antidiabetic and Antihyperlipidemic Properties of a Triterpenoid Compound, Dehydroeburicoic Acid, from Antrodia camphorata in Vitro and in Streptozotocin-Induced Mice.

The aim of this study was to examine the effects of dehydroeburicoic acid (TT) on type 1 diabetes mellitus and dyslipidemia in streptozotocin (STZ)-induced diabetic mice. STZ-induced diabetic mice were randomly divided into six groups and given orally by gavage TT (at three dosages), metformin (Metf), fenfibrate (Feno), or vehicle for 4 weeks. STZ-induced diabetic mice showed elevations in blood glucose levels (P < 0.001). TT treatment markedly decreased blood glucose levels by 42.6-46.5%. Moreover, STZ-induced diabetic mice displayed an increase in circulating triglyceride (TG) and total cholesterol (TC) levels (P < 0.001 and P < 0.01, respectively) but a decrease in blood insulin and adiponectin levels (P < 0.01 and P < 0.05, respectively). These substances are also reversed by TT treatment, indicating TT ameliorated diabetes and dyslipidemia. Membrane skeletal muscular expression levels of glucose transporter 4 (GLUT4) and expression levels of AMPK phosphorylation (phospho-AMPK) in both liver and skeletal muscle were reduced in STZ-induced diabetic mice, which normalized upon TT treatment and correction of hyperglycemia accompanied with a decrease in mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6 Pase), which was related to the inhibition of hepatic glucose production and attenuating diabetic state. In addition, TT also showed hypolipidemic effect by increasing hepatic expression levels of peroxisome proliferator-activated receptor α (PPARα) and mRNA levels of carnitine palmitoyl transferase Ia (CPT-1a) but decreasing expression levels of fatty acid synthase (FAS), which further contributed to a decrease in circulating TG levels. TT-treated mice displayed decreased SREBP2 mRNA levels and reduced blood TC levels. These findings strongly support that TT prevents diabetic and dyslipidemic states in STZ-induced diabetic mice evidenced by regulation of GLUT4, PPARα, FAS, and phosphorylation of AMPK.

Clinicopathologic Features and Molecular Characteristics of Glucose Metabolism Contributing to ¹⁸F-fluorodeoxyglucose Uptake in Gastrointestinal Stromal Tumors.

Fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography–computed tomography (PET/CT) is useful in the preoperative diagnosis of gastrointestinal stromal tumors (GISTs); however, the molecular characteristics of glucose metabolism of GIST are unknown. We evaluated 18F-FDG uptake on preoperative PET/CT of 40 patients and analyzed the expression of glycolytic enzymes in resected GIST tissues by qRT-PCR, western blotting, and immunohistochemistry. Results of receiver operating characteristic curve analysis showed that the maximum standardized uptake value (SUVmax) cut-off value of 4.99 had a sensitivity of 89.5%, specificity was 76.2%, and accuracy of 82.5% for identifying tumors with a high risk of malignancy. We found that 18F-FDG uptake correlated positively with tumor size, risk grade, and expression levels of glucose transporter 1 (GLUT1), hexokinase 1 (HK1), and lactate dehydrogenase A (LDHA). Elevated HK and LDH activity was found in high-risk tumors. Among the isoforms of GLUT and HK, GLUT1 and HK1 expression increased with higher tumor risk grade. In addition, overexpression of glycolytic enzymes M2 isoform of pyruvate kinase (PKM2) and LDHA was observed in GISTs, especially in high-risk tumors. These results suggest that upregulation of GLUT1, HK1, PKM2, and LDHA may play an important role in GIST tumorigenesis and may be useful in the preoperative prediction of malignant potential.

Substance P enhances the activation of AMPK and cellular lipid accumulation in 3T3‑L1cells in response to high levels of glucose.

The rescue of glucose tolerance and insulin-sensitivity in peripheral tissues, including adipose tissue, is essential in therapeutic strategies for diabetes. The present study demonstrated that substance P (SP) increases the accumulation of lipids in 3T3-L1 cells during their differentiation into adipocytes in response to a high concentration of glucose. SP reciprocally regulated the activities of AMP-activated protein kinase (AMPK) and Akt: SP enhanced the activation of AMPK, although the activity of Akt was downregulated. Notably, SP induced an increase in the expression level of glucose transporter 4 in the 3T3-L1 adipocytes. Therefore, it is possible that SP leads to an increase in glucose uptake and the accumulation of lipids in adipocytes, and may contribute towards the rescue of insulin-sensitivity in diabetes.

C/EBPβ is required in pregnancy-induced cardiac hypertrophy

AimPregnancy is a physiological model of adaptive and reversible heart enlargement, but the molecular mechanisms determining this kind of physiologic cardiac hypertrophy are poorly known. Here, we analyzed the role of the transcription factor C/EBPβ in the development of pregnancy-induced cardiac hypertrophy. ResultsC/EBPβ+/− mice at day 18 of gestation were used as happloinsufficiency model of late pregnancy. We found that C/EBPβ expression was specifically increased in hearts from Wt pregnant mice whereas expression of other C/EBP subtypes (α and δ) was not affected by gestation. Pregnancy-induced changes in systemic metabolic and hormonal profiles were not essentially different in Wt versus C/EBPβ+/− mice. However, C/EBPβ+/− mice developed pregnancy-induced heart hypertrophy to a lower extent relative to Wt mice. Furthermore, hearts from C/EBPβ+/− mice have alterations in fatty acid oxidation genes and reductions in the expression levels of glucose transporters that may compromise metabolic cardiac function during pregnancy. Among marker genes of inflammation, interleukin-6 (Il-6) showed a marked differential behavior in C/EBPβ+/− pregnant mice: pregnancy strongly induced cardiac Il-6 expression in wt, a phenomenon that did not occur in C/EBPβ+/− mice. Moreover, marker genes for M2 macrophages were decreased in C/EBPβ+/− pregnant mice and in C/EBPβ−/− mice subjected to LPS stimulus. ConclusionsHere we found that normal levels of C/EBPβ are required for hypertrophy development during pregnancy. Events such as the increase in IL-6 in the heart of pregnant mice are prevented in C/EBPβ+/− animals. Moreover, C/EBPβ controls M2-macrophage gene expression in the heart. Thus, C/EBPβ appears as a transcription factor required for cardiac hypertrophy response to gestation.

Evaluation of Glucose Uptake in Normal and Cancer Cell Lines by Positron Emission Tomography

To date, there is no definitive demonstration of the utility of positron emission tomography (PET) in studying glucose metabolism in cultured cell lines. Thus, this study was designed to compare PET to more standardized methods for the quantitative assessment of glucose uptake in nontransformed and transformed living cells and to validate PET for metabolic studies in vitro. Human colon and breast carcinoma cell lines and mouse embryo fibroblasts were evaluated for [(18)F]fluorodeoxyglucose ([(18)F]FDG) uptake by PET and autoradiography and 2-deoxyglucose (2-DG) incorporation by colorimetric assay and analyzed for the radiotoxic effects of [(18)F]FDG and the expression levels of glucose transporters. Indeed, [(18)F]FDG incorporation on PET was comparable to [(18)F]FDG uptake by autoradiography and 2-DG incorporation by colorimetric assay, although radiotracer-based methods exhibited more pronounced differences between individual cell lines. As expected, these data correlated with glucose transporters 1 to 4 and hexokinase II expression in tumor cell lines and mouse fibroblasts. Notably, [(18)F]FDG incorporation resulted in low apoptotic rates, with fibroblasts being slightly more sensitive to radiotracer-induced cell death. The quantitative analysis of [(18)F]FDG uptake in living cells by PET represents a valuable and reproducible method to study tumor cell metabolism in vitro, being representative of the differences in the molecular profile of normal and tumor cell lines.

MRNA expression levels of hypoxia-induced and stem cell-associated genes in human glioblastoma.

The roles of hypoxia-induced and stem cell-associated genes in the development of malignancy and tumour progression are well known. However, there are a limited number of studies analysing the impact of mRNA expression levels of hypoxia-induced and stem cell-associated genes in the tissues of brain tumours and glioblastoma patients. In this study, tumour tissues from patients with glioblastoma multiforme and tumour adjacent tissues were analysed. We investigated mRNA expression levels of hypoxia-inducible factor-1α (HIF-1α), hypoxia-inducible factor-2α (HIF-2α), carbonic anhydrase 9 (CA9), vascular endothelial growth factor (VEGF), glucose transporter-1 (GLUT-1) and osteopontin (OPN), and stem cell-associated genes survivin, epidermal growth factor receptor (EGFR), human telomerase reverse transcriptase (hTERT), Nanog and octamer binding transcription factor 4 (OCT4) using quantitative real-time polymerase chain reaction (qRT-PCR). Our data revealed higher mRNA expression levels of hypoxia-induced and stem cell-associated genes in tumour tissue than levels in the tumour adjacent tissues in patients with glioblastoma multiforme. A strong positive correlation between the mRNA expression levels of HIF-2α, CA9, VEGF, GLUT-1 and OPN suggests a specific hypoxia-associated profile of mRNA expression in glioblastoma multiforme. Additionally, the results indicate the role of stem-cell-related genes in tumour hypoxia. Kaplan-Maier analysis revealed that high mRNA expression levels of hypoxia-induced markers showed a trend towards shorter overall survival in glioblastoma patients (P=0.061). Our data suggest that mRNA expression levels of hypoxia-induced genes are important tumour markers in patients with glioblastoma multiforme.

The progression from a lower to a higher invasive stage of bladder cancer is associated with severe alterations in glucose and pyruvate metabolism

Cancer cells present a particular metabolic behavior. We hypothesized that the progression of bladder cancer could be accompanied by changes in cells glycolytic profile. We studied two human bladder cancer cells, RT4 and TCCSUP, in which the latter represents a more invasive stage. The levels of glucose, pyruvate, alanine and lactate in the extracellular media were measured by Proton Nuclear Magnetic Resonance. The protein expression levels of glucose transporters 1 (GLUT1) and 3 (GLUT3), monocarboxylate transporter 4 (MCT4), phosphofructokinase-1 (PFK1), glutamic-pyruvate transaminase (GPT) and lactate dehydrogenase (LDH) were determined. Our data showed that glucose consumption and GLUT3 levels were similar in both cell lines, but TCCSUP cells displayed lower levels of GLUT1 and PFK expression. An increase in pyruvate consumption, concordant with the higher levels of lactate and alanine production, was also detected in TCCSUP cells. Moreover, TCCSUP cells presented lower protein expression levels of GPT and LDH. These results illustrate that bladder cancer progression is associated with alterations in cells glycolytic profile, namely the switch from glucose to pyruvate consumption in the more aggressive stage. This may be useful to develop new therapies and to identify biomarkers for cancer progression.

High Glucose Induces Aerobic Glycolysis and Vascular Endothelial Growth Factor‐C through LPA Signals in Human Prostate Cancer PC‐3 Cells

Prostate cancer is one of the most commonly diagnosed cancers in males and frequently metastasizes to lymph nodes. Clinical evidences suggested that type II diabetes mellitus were closely associated with the prognosis of prostate cancer. Furthermore, hyperglycemia increases aerobic glycolysis and promote cancer growth. However, the effects of hyperglycemia in prostate cancer remain elusive. Lysophosphatidic acid (LPA) is a small lipid growth factor with multiple functions by activating G‐protein coupled LPA receptors. We demonstrated that LPA enhance VEGF‐C expression through activating LPA receptor 1 and 3 in prostate cancer cells. Furthermore, high glucose treatment has also been shown to enhance VEGF‐C expression in human synovial fibroblasts. In this study, we used PC‐3 cell to investigate whether high glucose induces VEGF‐C expression and aerobic glycolysis through LPA signals to enhance cancer progression. Our preliminary results demonstrated that the mRNA expression level of autotaxin (ATX), an enzyme responsible for LPA synthesis, was increased in PC‐3 cell by 0.02 M glucose treatments. Protein levels of VEGF‐C were also increased after high glucose treatments. Furthermore, the enhancement of VEGF‐C was mediated through ROS‐ and LEDGF‐dependent pathways. On the other hand, high glucose treatments also enhanced aerobic glycolysis rate and affected mRNA expression levels of glucose transporter and hexokinase. Taken together, these results suggested that unregulated glucose metabolism might lead to LPA synthesis and therefore subsequent pathological conditions of prostate cancer.