Over-expression of facilitative glucose transporter genes in human cancer

Initial Standardized Uptake Value of Positron Emission Tomography Influences the Prognosis of Patients with Localized Gastric Adenocarcinoma Treated Preoperatively

BACKGROUND

In patients with localized gastric adenocarcinoma (LGAC) who receive preoperative therapy, tools to predict response or prognosticate outcome before therapy are lacking. We used initial standardized uptake value (iSUV) of positron emission tomography (PET) to evaluate its association with overall survival (OS).

METHODS

We identified 60 patients with confirmed LGAC who were treated with preoperative chemoradiation and had a baseline PET in addition to other routine staging. Fisher's exact test and Wilcoxon's rank sum test were used to determine the association between iSUV and other variables, and the log-rank test and Cox proportional hazards model were used for survival analysis.

RESULTS

The median iSUV was 6 (range, 0-28). The presence of signet ring cells in pretreatment biopsies correlated highly with low iSUV (≤ 6; p = 0.0017). Patients with a high iSUV (> 6) had a longer OS compared to those with a low iSUV (≤ 6; p = 0.0344). iSUV was not an independent predictor (p = 0.12); however, the risk of death was reduced for patients with an iSUV > 6 (hazard ratio = 0.26).

CONCLUSION

Our novel findings show that among LGAC patients treated with preoperative chemoradiation and surgery, those with a high iSUV have longer OS than patients with a low iSUV. iSUV appears to have a predictive role in patients with LGAC when treated with preoperative chemoradiation.

Inhibition of human GLUT1 and GLUT5 by plant carbohydrate products; insights into transport specificity

Glucose transporters GLUT1 (transports glucose) and GLUT5 (transports fructose), in addition to their functions in normal metabolism, have been implicated in several diseases including cancer and diabetes. While GLUT1 has several inhibitors, none have been described for GLUT5. By transport activity assays we found two plant products, rubusoside (from Rubus suavissimus) and astragalin-6-glucoside (a glycosylated derivative of astragalin, from Phytolacca americana) that inhibited human GLUT5. These plants are utilized in traditional medicine: R. suavissimus for weight loss and P. americana for cancer treatment, but the molecular interactions of these products are unknown. Rubusoside also inhibited human GLUT1, but astragalin-6-glucoside did not. In silico analysis of rubusoside:protein interactions pinpointed a major difference in substrate cavity between these transporters, a residue that is a tryptophan in GLUT1 but an alanine in GLUT5. Investigation of mutant proteins supported the importance of this position in ligand specificity. GLUT1W388A became susceptible to inhibition by astragalin-6-glucoside and resistant to rubusoside. GLUT5A396W transported fructose and also glucose, and maintained inhibition by rubusoside and astragalin-6-glucoside. Astragalin-6-glucoside can serve as a starting point in the design of specific inhibitors for GLUT5. The application of these studies to understanding glucose transporters and their interaction with substrates and ligands is discussed.

Both GLUT-1 and GLUT-14 are Independent Prognostic Factors in Gastric Adenocarcinoma

BACKGROUND

The role of glucose transporter 14 (GLUT-14/SLC2A14) in tumor biology is entirely unknown, and the significance of hypoxia inducible factor 1-alpha (HIF1-α) for gastric adenocarcinoma is controversial. The impact of GLUT-1/SLC2A1 has never been confirmed in a Caucasian cohort.

METHODS

Between 1996 and 2007, 124 patients underwent gastrectomy for gastric adenocarcinoma. Tumor sections were incubated with GLUT-1, GLUT-14, and HIF1-α antibodies. Expression was analyzed for correlations with histopathology, marker coexpression, and patient survival by uni- and multivariate analyses.

RESULTS

Expressions of GLUT-1, GLUT-14, and HIF1-α were detectable in 50, 77.4, and 27.1 %, respectively. Expression of GLUT-1 was associated with pT-category (p = 0.019), pN-category (p = 0.019), tubular (WHO, p = 0.008), and intestinal (Lauren classification; p = 0.002) histologic subtypes. Expression of GLUT-14 was correlated with pT category (p = 0.043), whereas HIF1-α did not show any correlation with histopathology or survival. The median survival period was 14 months (95 % confidence interval [CI] 9.2-18.8 months) for GLUT-1-positive patients and 55 months (95 % CI 25.8-84.2; p = 0.01) for GLUT-1-negative patients. An inferior prognosis also was seen for GLUT-14-positive cases compared with GLUT-14-negative cases (p = 0.004). Thus, worst survival was seen with both GLUT-1- and GLUT-14-positive expression followed by single-positive and then double-negative cases (p = 0.004). In multivariate analysis including International Union Against Cancer (UICC) stages, R category, Lauren classification, surgery alone versus neoadjuvant/perioperative chemotherapy, and marker expression as covariates, GLUT-1 (p = 0.011) and GLUT-14 (p = 0.025) kept their prognostic independence.

CONCLUSIONS

The study findings suggest that detection of GLUT-1 and GLUT-14 is of high prognostic value. It gives additional information to UICC stages and identifies patients with inferior prognosis. If confirmed in prospective studies, these markers need to be considered for future classification systems.

Glucosamine anchored cancer targeted nano-vesicular drug delivery system of doxorubicin

BACKGROUND

Efficacy of an anticancer drug is challenged by severe adverse effects persuaded by the drug itself; hence designing a tumour targeted delivery system is chosen as an objective of this research work.

PURPOSE

We propose, glucose transporter targeting ligand, i.e. synthesised N-lauryl glucosamine (NLG) anchored doxorubicin (DOX) in niosomal formulation.

METHODS

Synthesised NLG was incorporated into niosomal formulation of DOX using Span 60 as surfactant, cholesterol as membrane stabilizer and dicetyl phosphate (DCP) as stabilizer.

RESULTS

The formulation was stable with particle size of 110 ± 5 nm, zeta potential -30 ± 5 mV and entrapment efficiency approximately 95%. DSC and XRD pattern of freeze-dried formulation demonstrated encapsulation of DOX in niosomal formulation. Cytotoxicity of targeted niosomal formulation (IC50 = 0.830 ppm) was higher than non-targeted niosomal formulation (IC50 = 1.369 ppm) against B6F10 melanoma cell lines. In vitro cellular internalization revealed that targeted niosomal formulation was internalised more efficiently with higher cellular retention by cancer cells compared to the non-targeted niosomal formulation and free DOX. In vitro receptor binding and docking study of targeted niosomal formulation had shown the comparative association potential with glucose receptor.

CONCLUSION

NLG anchored niosomal formulation of DOX with enhanced cytotoxicity, internalization and receptor binding potential has implication in targeted cancer therapy.

Ghrelin promotes renal cell carcinoma metastasis via Snail activation and is associated with poor prognosis

Ghrelin is an appetite-regulating molecule that promotes growth hormone (GH) release and food intake through growth hormone secretagogue receptor (GHS-R). Recently, high ghrelin levels have been detected in various types of human cancer. Ghrelin expression is observed in proximal and distal renal tubules, where renal cell carcinoma (RCC) arises. However, whether ghrelin is up-regulated and promotes renal cell carcinogenesis remains obscure. In this study, we observed that ghrelin was highly expressed in renal tumours, especially in metastatic RCC. In addition, high ghrelin levels correlated with poor outcome, lymph node and distant metastasis. The addition of ghrelin promoted the migration ability of RCC cell lines 786-0, ACHN and A-498. Furthermore, knockdown of ghrelin expression reduced in vitro migration and in vivo metastasis, suggesting a requirement for ghrelin accumulation in the microenvironment for RCC metastasis. Analysis of microarray signatures using Ingenuity Pathway Analysis (IPA) and MetaCore pointed to the potential regulation by ghrelin of Snail, a transcriptional repressor of E-cadherin. We further observed that Ghrelin increased the expression, nuclear translocation and promoter-binding activity of Snail. Snail silencing blocked the ghrelin-mediated effects on E-cadherin repression and cell migration. Snail-E-cadherin regulation was mediated by GHS-R-triggered Akt phosphorylation at Ser473 and Thr308. Pretreatment with PI3K inhibitors, LY294002 and wortmannin, as well as Akt siRNA, decreased ghrelin-induced Akt phosphorylation, Snail promoter binding activity and migration. Taken together, our findings indicate that ghrelin can activate Snail function via the GHS-R-PI3K-Akt axis, which may contribute to RCC metastasis. The microarray raw data were retrieved from the Cancer Genome Atlas (TCGA) [KIRC gene expression (IlluminaHiSeq) dataset].

A Protein Kinase C Phosphorylation Motif in GLUT1 Affects Glucose Transport and is Mutated in GLUT1 Deficiency Syndrome

Protein kinase C has been implicated in the phosphorylation of the erythrocyte/brain glucose transporter, GLUT1, without a clear understanding of the site(s) of phosphorylation and the possible effects on glucose transport. Through in vitro kinase assays, mass spectrometry, and phosphospecific antibodies, we identify serine 226 in GLUT1 as a PKC phosphorylation site. Phosphorylation of S226 is required for the rapid increase in glucose uptake and enhanced cell surface localization of GLUT1 induced by the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Endogenous GLUT1 is phosphorylated on S226 in primary endothelial cells in response to TPA or VEGF. Several naturally occurring, pathogenic mutations that cause GLUT1 deficiency syndrome disrupt this PKC phosphomotif, impair the phosphorylation of S226 in vitro, and block TPA-mediated increases in glucose uptake. We demonstrate that the phosphorylation of GLUT1 on S226 regulates glucose transport and propose that this modification is important in the physiological regulation of glucose transport.

AMPK modulates Hippo pathway activity to regulate energy homeostasis

The Hippo pathway was discovered as a conserved tumour suppressor pathway restricting cell proliferation and apoptosis. However, the upstream signals that regulate the Hippo pathway in the context of organ size control and cancer prevention are largely unknown. Here, we report that glucose, the ubiquitous energy source used for ATP generation, regulates the Hippo pathway downstream effector YAP. We show that both the Hippo pathway and AMP-activated protein kinase (AMPK) were activated during glucose starvation, resulting in phosphorylation of YAP and contributing to its inactivation. We also identified glucose-transporter 3 (GLUT3) as a YAP-regulated gene involved in glucose metabolism. Together, these results demonstrate that glucose-mediated energy homeostasis is an upstream event involved in regulation of the Hippo pathway and, potentially, an oncogenic function of YAP in promoting glycolysis, thereby providing an exciting link between glucose metabolism and the Hippo pathway in tissue maintenance and cancer prevention.

Cancer stratification by molecular imaging

The lack of specificity of traditional cytotoxic drugs has triggered the development of anticancer agents that selectively address specific molecular targets. An intrinsic property of these specialized drugs is their limited applicability for specific patient subgroups. Consequently, the generation of information about tumor characteristics is the key to exploit the potential of these drugs. Currently, cancer stratification relies on three approaches: Gene expression analysis and cancer proteomics, immunohistochemistry and molecular imaging. In order to enable the precise localization of functionally expressed targets, molecular imaging combines highly selective biomarkers and intense signal sources. Thus, cancer stratification and localization are performed simultaneously. Many cancer types are characterized by altered receptor expression, such as somatostatin receptors, folate receptors or Her2 (human epidermal growth factor receptor 2). Similar correlations are also known for a multitude of transporters, such as glucose transporters, amino acid transporters or hNIS (human sodium iodide symporter), as well as cell specific proteins, such as the prostate specific membrane antigen, integrins, and CD20. This review provides a comprehensive description of the methods, targets and agents used in molecular imaging, to outline their application for cancer stratification. Emphasis is placed on radiotracers which are used to identify altered expression patterns of cancer associated markers.

Targeting metabolism with a ketogenic diet during the treatment of glioblastoma multiforme

Retrospective data suggests that low serum glucose levels during the treatment of glioblastoma multiforme (GBM) may improve clinical outcomes. As such, many patients are implementing a ketogenic diet (KD) in order to decrease serum glucose flux while simultaneously elevating circulating ketones during radiation therapy and chemotherapy for the treatment of GBM. With IRB approval, a retrospective review of patients with high-grade glioma treated with concurrent chemoradiotherapy and adjuvant chemotherapy was carried out from August 2010 to April 2013. Serum glucose and ketone levels, dexamethasone dose, and toxicity of patients undergoing a KD during treatment were also assessed. Blood glucose levels were compared between patients on an unspecified/standard diet and a KD. Toxicity was assessed by Common Terminology Criteria for Adverse Events version 4. In total, 53 patients were analyzed. Six underwent a KD during treatment. The diet was well tolerated with no grade III toxicity and one episode of grade II fatigue. No episodes of symptomatic hypoglycemia were experienced. Four patients are alive at a median follow-up of 14 months. The mean blood glucose of patients on a standard diet was 122 versus 84 mg/dl for those on a KD. Based on this retrospective study, a KD appears safe and well tolerated during the standard treatment of GBM. Dietary restriction of carbohydrates through a KD reduces serum glucose levels significantly, even in conjunction with high dose steroids, which may affect the response to standard treatment and prognosis. Larger prospective trials to confirm this relationship are warranted.

A 129-kb deletion on chromosome 12 confers substantial protection against rheumatoid arthritis, implicating the gene SLC2A3

We describe a copy-number variant (CNV) for which deletion alleles confer a protective affect against rheumatoid arthritis (RA). This CNV reflects net unit deletions and expansions to a normal two-unit tandem duplication located on human chr12p13.31, a region with conserved synteny to the rat RA susceptibility quantitative trait loci Oia2. Genotyping, using the paralogue ratio test and SNP intensity data, in Swedish samples (2,403 cases, 1,269 controls) showed that the frequency of deletion variants is significantly lower in cases (P = 0.0012, OR = 0.442 [95%CI 0.258–0.755]). Reduced frequencies of deletion variants were also seen in replication materials comprising 9,201 UK samples (1,846 cases, 7,355 controls) and 2,963 US samples (906 controls, 1,967 cases) (Mantel–Haenszel P = 0.036, OR = 0.559 [95%CI 0.323–0.966]). Combining the three datasets produces a Mantel–Haenszel OR of 0.497 (P < 0.0002). The deletion variant lacks 129-kb of DNA containing SLC2A3, NANOGP1, and SLC2A14. SLC2A3 encodes a high-affinity glucose transporter important in the immune response and chondrocyte metabolism, both key aspects of RA pathogenesis. The large effect size of this association, its potential relevance to other diseases in which SLC2A3 is implicated, and the possibility of targeting drugs to inhibit SLC2A3, argue for further examination of the genetics and the biology of this CNV.

Anti-cancer activity of anti-GLUT1 antibody-targeted polymeric micelles co-loaded with curcumin and doxorubicin

BACKGROUND

Treatment of late stage cancers has proven to be a very difficult task. Targeted therapy and combinatory drug administration may be the solution.

PURPOSE

The study was performed to evaluate the therapeutic efficacy of PEG-PE micelles, co-loaded with curcumin (CUR) and doxorubicin (DOX), and targeted with anti-GLUT1 antibody (GLUT1) against HCT-116 human colorectal adenocarcinoma cells both in vitro and in vivo.

METHODS

HCT-116 cells were treated with non-targeted and GLUT1-targeted CUR and DOX micelles as a single agent or in combination. Cells were inoculated in female nude mice. Established tumors were treated with the micellar formulations at a dose of 4 mg/kg CUR and 0.4 mg/kg DOX every 2 d for a total of 7 injections.

RESULTS

CUR + DOX-loaded micelles decorated with GLUT1 had a robust killing effect even at low doses of DOX in vitro. At the doses chosen, non-targeted CUR and CUR + DOX micelles did not exhibit any significant tumor inhibition versus control. However, GLUT1-CUR and GLUT1-CUR + DOX micelles showed a significant tumor inhibition effect with an improvement in survival.

CONCLUSION

We showed a dramatic improvement in efficacy between the non-targeted and GLUT1-targeted formulations both in vitro and in vivo. Hence, we confirmed that GLUT1-CUR + DOX micelles are effective and deserve further investigation.

Implications of the O-GlcNAc modification in the regulation of nuclear apoptosis in T cells

BACKGROUND

O-linked β-N-acetylglucosamine (O-GlcNAc) is a nutrient-/stress-sensitive post-translational modification that affects nucleocytoplasmic proteins. The enzyme O-N-acetylglucosamine transferase (OGT) catalyzes the addition of O-GlcNAc, whereas O-N-acetylglucosaminidase (OGA) removes it. O-GlcNAcylation plays a role in fundamental regulatory mechanisms through the modification of proteins involved in cell division, metabolism, transcription, cell signaling and apoptosis. The effects of O-GlcNAcylation on apoptosis appear to be cell-dependent, as elevated levels played a protective role in primary neonatal rat ventricular myocytes but had a cytotoxic effect in rat pancreatic β-cells. The aim of the current study was to determine the implications of the O-GlcNAc modification on T cell apoptosis.

METHODS

Human T lymphoblastic HPB-ALL cells were treated with the OGA inhibitor O-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino-N-phenylcarbamate (PUGNAc), or with glucosamine (GlcN), to increase O-GlcNAcylation. Apoptosis was induced in the presence of tributyltin (TBT). DNA fragmentation was observed by cell cycle analysis and corresponded to the sub G0/G1 population. O-GlcNAcylated proteins were detected by immunoblot using a specific antibody (ctd110.6) and were precipitated using succinylated wheat germ agglutinin (sWGA).

RESULTS

HPB-ALL cells treated with PUGNAc displayed a significant reduction in DNA fragmentation after TBT-induced apoptosis. DFF45, the protein that inhibits the endonuclease DFF40, was identified to be O-GlcNAc modified. O-GlcNAcylated DFF45 appeared to be more resistant to caspase cleavage during apoptosis. Our results suggest that a decrease in the O-GlcNAc modification on DFF45 occurs before its cleavage by caspase.

GENERAL SIGNIFICANCE

Our results indicate that the O-GlcNAcylation of DFF45 may represent a mechanism to control the accidental activation of DFF.

The SLC2 (GLUT) family of membrane transporters

GLUT proteins are encoded by the SLC2 genes and are members of the major facilitator superfamily of membrane transporters. Fourteen GLUT proteins are expressed in the human and they are categorized into three classes based on sequence similarity. All GLUTs appear to transport hexoses or polyols when expressed ectopically, but the primary physiological substrates for several of the GLUTs remain uncertain. GLUTs 1-5 are the most thoroughly studied and all have well established roles as glucose and/or fructose transporters in various tissues and cell types. The GLUT proteins are comprised of ∼500 amino acid residues, possess a single N-linked oligosaccharide, and have 12 membrane-spanning domains. In this review we briefly describe the major characteristics of the 14 GLUT family members.

The SLC2 (GLUT) family of membrane transporters

GLUT proteins are encoded by the SLC2 genes and are members of the major facilitator superfamily of membrane transporters. Fourteen GLUT proteins are expressed in the human and they are categorized into three classes based on sequence similarity. All GLUTs appear to transport hexoses or polyols when expressed ectopically, but the primary physiological substrates for several of the GLUTs remain uncertain. GLUTs 1-5 are the most thoroughly studied and all have well established roles as glucose and/or fructose transporters in various tissues and cell types. The GLUT proteins are comprised of ∼500 amino acid residues, possess a single N-linked oligosaccharide, and have 12 membrane-spanning domains. In this review we briefly describe the major characteristics of the 14 GLUT family members.

The SLC2 (GLUT) family of membrane transporters

GLUT proteins are encoded by the SLC2 genes and are members of the major facilitator superfamily of membrane transporters. Fourteen GLUT proteins are expressed in the human and they are categorized into three classes based on sequence similarity. All GLUTs appear to transport hexoses or polyols when expressed ectopically, but the primary physiological substrates for several of the GLUTs remain uncertain. GLUTs 1-5 are the most thoroughly studied and all have well established roles as glucose and/or fructose transporters in various tissues and cell types. The GLUT proteins are comprised of ∼500 amino acid residues, possess a single N-linked oligosaccharide, and have 12 membrane-spanning domains. In this review we briefly describe the major characteristics of the 14 GLUT family members.

Intermittent and continuous imatinib in a human GIST xenograft model carrying KIT exon 17 resistance mutation D816H

BACKGROUND

Acquired resistance to imatinib is frequently caused by secondary KIT mutations. We have investigated the effects of imatinib in mice with human gastrointestinal stromal tumour (GIST) xenograft which harbours a primary exon 11 deletion mutation and a secondary imatinib resistance mutation D816H in exon 17. Such mutations are commonly present in imatinib-resistant GIST in humans.

MATERIAL AND METHODS

The mice were randomly allocated to receive imatinib either continuously or intermittently. Dynamic (18)F-FDG PET was performed and blood volume fraction (vB), rate transfer constants (k1, k2, k3) and metabolic rate of (18)F-FDG (MRFDG) were computed using a three-compartment model. Tumours were evaluated for the mitotic rate and the expression of HIF-1α , caspase-3 and glucose transporters (GLUTs).

RESULTS

Both intermittent and continuous imatinib delayed tumour growth significantly compared to controls, significantly in favour of the latter. k1 (representing perfusion, vascular permeability and binding of (18)F-FDG to the GLUTs) was significantly higher in the intermittent group compared to the continuous group, as was tumour GLUT-3 expression. k3 (representing internalisation of (18)F-FDG to the cells) and MR(FDG) were significantly lower.

CONCLUSION

Imatinib delays GIST xenograft growth despite the presence of the D816H resistance mutation. The schedule of imatinib administration may influence tumour glucose uptake rate and metabolic rate.

Single step nanoplasmonic immunoassay for the measurement of protein biomarkers

A nanoplasmonic biosensor for highly-sensitive, single-step detection of protein biomarkers is presented. The principle is based on the utilization of the optical scattering properties of gold nanorods (GNRs) conjugated to bio-recognition molecules. The nanoplasmonic properties of the GNRs were utilized to detect proteins using near-infrared light interferometry. We show that the antibody-conjugated GNRs can specifically bind to our model analyte, Glucose Transporter-1 (Glut-1). The signal intensity of back-scattered light from the GNRs bound after incubation, correlated well to the Glut-1 concentration as per the calibration curve. The detection range using this nanoplasmonic immunoassay ranges from 10 ng/mL to 1 ug/mL for Glut-1. The minimal detectable concentration based on the lowest discernable concentration from zero is 10 ng/mL. This nanoplasmonic immunoassay can act as a simple, selective, sensitive strategy for effective disease diagnosis. It offers advantages such as wide detection range, increased speed of analysis (due to fewer incubation/washing steps), and no label development as compared to traditional immunoassay techniques. Our future goal is to incorporate this detection strategy onto a microfluidic platform to be used as a point-of-care diagnostic tool.

Multivalent glycoconjugate syntheses and applications using aromatic scaffolds

Glycan-protein interactions are of utmost importance in several biological phenomena. Although the variety of carbohydrate residues in mammalian cells is limited to less than a dozen different sugars, their spatial topographical presentation in what is now associated as the "glycocodes" provides the fundamental keys for specific and high affinity "lock-in" recognition events associated with a wide range of pathologies. Toward deciphering our understanding of these glycocodes, chemists have developed new creative tools that included dendrimer chemistry in order to provide monodisperse multivalent glycoconjugates. This review provides a survey of the numerous aromatic architectures generated for the multivalent presentation of relevant carbohydrates using covalent attachment or supramolecular self-assemblies. The basic concepts toward their controlled syntheses will be described using modern synthetic procedures with a particular emphasis on powerful organometallic methodologies. The large variety of dendritic aromatic scaffolds, together with a brief survey of their unique biophysical and biological properties will be critically reviewed. The distinctiveness of the resulting multivalent glycoarchitectures, encompassing glycoclusters, glycodendrimers and molecularly defined self-assemblies, in forming well organized cross-linked lattices with multivalent carbohydrate binding proteins (lectins) together with their photophysical, medical, and imaging properties will also be briefly highlighted. The topic will be presented in increasing order of aromatic backbone complexities and will end with fullerenes together with self-assembled nanostructures, thus complementing the various scaffolds described in this special thematic issue dedicated to multivalent glycoscience.

The histone deacetylase SIRT6 is a tumor suppressor that controls cancer metabolism

Reprogramming of cellular metabolism is a key event during tumorigenesis. Despite being known for decades (Warburg effect), the molecular mechanisms regulating this switch remained unexplored. Here, we identify SIRT6 as a tumor suppressor that regulates aerobic glycolysis in cancer cells. Importantly, loss of SIRT6 leads to tumor formation without activation of known oncogenes, whereas transformed SIRT6-deficient cells display increased glycolysis and tumor growth, suggesting that SIRT6 plays a role in both establishment and maintenance of cancer. By using a conditional SIRT6 allele, we show that SIRT6 deletion in vivo increases the number, size, and aggressiveness of tumors. SIRT6 also functions as a regulator of ribosome metabolism by corepressing MYC transcriptional activity. Lastly, Sirt6 is selectively downregulated in several human cancers, and expression levels of SIRT6 predict prognosis and tumor-free survival rates, highlighting SIRT6 as a critical modulator of cancer metabolism. Our studies reveal SIRT6 to be a potent tumor suppressor acting to suppress cancer metabolism.

Molecular histopathology using gold nanorods and optical coherence tomography

PURPOSE

To examine the novel application of a commercially available optical coherence tomography (OCT) system toward molecular histopathology using gold nanorod (GNR) linked antibodies as a functionalized contrast agent to evaluate ocular surface squamous neoplasia (OSSN).

METHODS

GNRs were synthesized and covalently attached to anti-glucose transporter-1 (GLUT-1) antibodies via carbodiimide chemistry. Three specimens from each of three distinct categories of human conjunctival tissue were selected for analysis, including conjunctiva without epithelial atypia (controls); conjunctival intraepithelial neoplasia, carcinoma in situ (CIS); and conjunctival squamous cell carcinoma (SCC). Tissue sections were incubated initially with GNR tagged anti-GLUT-1 antibodies and then with a fluorescent-tagged secondary antibody. Immunofluorescence and OCT imaging of the tissue was performed and the results were correlated to the light microscopic findings on traditional hemotoxyin and eosin stained sections.

RESULTS

No binding of the functionalized GNRs was observed within the epithelium of three normal conjunctiva controls. While immunofluorescence disclosed variable binding of the functionalized GNRs to atypical epithelial cells in all six cases of OSSN, the enhancement of the OCT signal in three cases of CIS was insufficient to distinguish these specimens from normal controls. In two of three cases of SCC, binding of functionalized GNRs was sufficient to produce an increased scattering effect on OCT in areas correlating to atypical epithelial cells which stained intensely on immunofluorescence imaging. Binding of functionalized GNRs was sufficient to produce an increased scattering effect on OCT in areas correlating to regions of erythrocytes and hemorrhage which stained intensely on immunofluorescence imaging within all nine tested samples.

CONCLUSIONS

We have demonstrated the use of OCT for molecular histopathology using functionalized gold nanorods in the setting of OSSN. Our results suggest a threshold concentration of functionalized GNRs within tissue is required to achieve a detectable enhancement in scattering of the OCT signal.

Starving tumors: inhibition of glycolysis reduces viability of human endometrial and ovarian cancer cells and enhances antitumor efficacy of GnRH receptor-targeted therapies

OBJECTIVE

Increased glycolysis for energy production is necessary for survival of tumor cells and thus represents a selective therapeutic target. We have analyzed in vitro whether inhibition of glycolysis can reduce the viability of human endometrial and ovarian cancer cells and whether it can enhance the antitumor efficacy of GnRH receptor-targeted therapies.

MATERIALS AND METHODS

Cell viability of ovarian and endometrial cancer cells treated without or with glycolysis inhibitor 2-Deoxy-D-Glucose (2DG) alone or in combination with GnRH-II antagonist [Ac-D2Nal(1), D-4Cpa(2), D-3Pal(3,6)(8),Leu, D-Ala(10)]GnRH-II or with cytotoxic GnRH-I agonist AEZS-108 (AN-152) was measured using alamar blue assay. Induction of apoptosis was analyzed using TUNEL assay and quantified by measurement of loss of mitochondrial membrane potential. Apoptotic signaling was measured by quantification of activated caspase-3 by using the Western blot technique.

RESULTS

Treatment of endometrial and ovarian cancer cells with glycolysis inhibitor 2DG resulted in a significant decrease of cell viability and a significant increase of apoptosis. Treatment with 2DG in combination with the GnRH-II antagonist or with AEZS-108 resulted in a significant reduced viability compared with single-agent treatments. The observed reduction in viability was due to induction of apoptosis. Also for apoptosis induction, a significant stronger effect in the case of cotreatments compared with single-agent treatments could be observed. These additive effects could be correlated to increased activation of caspase-3.

CONCLUSIONS

The glycolytic phenotype of human endometrial and ovarian cancer cells can be targeted for therapeutic intervention. In addition, cotreatment of a glycolysis inhibitor with GnRH receptor-targeted therapies might be a suitable therapy for GnRH receptor-positive human endometrial and ovarian cancers.

Smart gold nanoparticles enhance killing effect on cancer cells

The present study explored the cellular uptake dynamics, the subcellular location and the internalization mechanisms of gold nanoparticles (GNPs) and glucose-capped GNPs (Glu-GNPs). The cancer radiotherapy-enhancing effects of GNPs were also evaluated. We synthesized the GNPs and Glu-GNPs by the seeding technique. The effects on cellular uptake and the radiosensitizing effect induced by GNPs and Glu-GNPs at lower doses were investigated using two human cancer cell lines (HeLa and MCF-7). The intracellular location of the nanoparticles was analyzed by transmission electron microscopy (TEM). Analysis of cellular apoptosis following GNP-based radiotherapy was performed by flow cytometry and TUNEL assay. Cancer cells took up more Glu-GNPs than naked GNPs and the uptake curve showed size- and cell-dependent uptake. GNPs were mainly located in the cytoplasm and endocytosis is the mechanism behind the internalization of GNPs and Glu-GNPs. Lower doses of GNPs and Glu-GNPs still enhanced the killing effect using X-ray irradiation, although the apoptotic rate was not altered. The results presented in this study provide evidence that Glu-GNPs may have a bright future in tumor-targeted diagnosis and treatment.

Correlation of PET images of metabolism, proliferation and hypoxia to characterize tumor phenotype in patients with cancer of the oropharynx

Spatial organization of tumor phenotype is of great interest to radiotherapy target definition and outcome prediction. We characterized tumor phenotype in patients with cancers of the oropharynx through voxel-based correlation of PET images of metabolism, proliferation, and hypoxia.

METHODS

Patients with oropharyngeal cancer received (18)F-fluorodeoxyglucose (FDG) PET/CT, (18)F-fluorothymidine (FLT) PET/CT, and (61)Cu-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) PET/CT. Images were co-registered and standardized uptake values (SUV) were calculated for all modalities. Voxel-based correlation was evaluated with Pearson's correlation coefficient in tumor regions. Additionally, sensitivity studies were performed to quantify the effects of image segmentation, registration, noise, and segmentation on R.

RESULTS

On average, FDG PET and FLT PET images were most highly correlated (R(FDG:FLT) = 0.76, range 0.53-0.85), while Cu-ATSM PET showed greater heterogeneity in correlation to other tracers (R(FDG:Cu-ATSM) = 0.64, range 0.51-0.79; R(FLT:Cu-ATSM) = 0.61, range 0.21-0.80). Of the tested parameters, correlation was most sensitive to image registration. Misregistration of one voxel lead to ΔR(FDG) = 0.25, ΔR(FLT) = 0.39, and ΔR(Cu-ATSM) = 0.27. Image noise and reconstruction also had quantitative effects on correlation. No significant quantitative differences were found between GTV, expanded GTV, or CTV regions.

CONCLUSIONS

Voxel-based correlation represents a first step into understanding spatial organization of tumor phenotype. These results have implications for radiotherapy target definition and provide a framework to test outcome prediction based on pretherapy distribution of phenotype.

Early detection and longitudinal monitoring of experimental primary and disseminated melanoma using [¹⁰F]ICF01006, a highly promising melanoma PET tracer

PURPOSE

Here, we report a new and rapid radiosynthesis of (18)F-N-[2-(diethylamino)ethyl]-6-fluoro-pyridine-3-carboxamide ([(18)F]ICF01006), a molecule with a high specificity for melanotic tissue, and its evaluation in a murine model for early specific detection of pigmented primary and disseminated melanoma.

METHODS

[(18)F]ICF01006 was synthesized using a new one-step bromine-for-fluorine nucleophilic heteroaromatic substitution. Melanoma models were induced by subcutaneous (primary tumour) or intravenous (lung colonies) injection of B16BL6 melanoma cells in C57BL/6J mice. The relevance and sensitivity of positron emission tomography (PET) imaging using [(18)F]ICF01006 were evaluated at different stages of tumoural growth and compared to (18)F-fluorodeoxyglucose ([(18)F]FDG).

RESULTS

The fully automated radiosynthesis of [(18)F]ICF01006 led to a radiochemical yield of 61 % and a radiochemical purity >99 % (specific activity 70-80 GBq/μmol; total synthesis time 42 min). Tumours were visualized before they were palpable as early as 1 h post-injection with [(18)F]ICF01006 tumoural uptake of 1.64 ± 0.57, 3.40 ± 1.47 and 11.44 ± 2.67 percentage of injected dose per gram of tissue (%ID/g) at days 3, 5 and 14, respectively. [(18)F]ICF01006 PET imaging also allowed detection of melanoma pulmonary colonies from day 9 after tumour cell inoculation, with a lung radiotracer accumulation correlated with melanoma invasion. At day 21, radioactivity uptake in lungs reached a value of 5.23 ± 2.08 %ID/g (versus 0.41 ± 0.90 %ID/g in control mice). In the two models, comparison with [(18)F]FDG showed that both radiotracers were able to detect melanoma lesions, but [(18)F]ICF01006 was superior in terms of contrast and specificity.

CONCLUSION

Our promising results provide further preclinical data, reinforcing the excellent potential of [(18)F]ICF01006 PET imaging for early specific diagnosis and follow-up of melanin-positive disseminated melanoma.

Methyl 2-(5,5-dimethyl-1,3,2-dioxa-borinan-2-yl)-4-nitro-benzoate

The six-membered boronate ester ring of the title compound, C₁₃H₁₆BNO₆, adopts an envelope conformation with the C atom bearing the dimethyl substituents at the flap. The O—B—C—C torsion angles between the boronate group and the benzene ring are 72.5 (2) and 81.0 (2)°. The 4-nitro­benzoate unit adopts a slightly twisted conformation, with dihedral angles between the benzene ring and the nitrate and methyl ester groups of 17.5 (2) and 14.4 (3)°, respectively. In the crystal, inversion-related pairs of mol­ecules show weak π–π stacking inter­actions [centroid–centroid distance = 4.0585 (9) Å and inter­planar spacing = 3.6254 (7) Å].

Targeting insulin inhibition as a metabolic therapy in advanced cancer: a pilot safety and feasibility dietary trial in 10 patients

OBJECTIVE

Most aggressive cancers demonstrate a positive positron emission tomographic (PET) result using ¹⁸F-2-fluoro-2-deoxyglucose (FDG), reflecting a glycolytic phenotype. Inhibiting insulin secretion provides a method, consistent with published mechanisms, for limiting cancer growth.

METHODS

Eligible patients with advanced incurable cancers had a positive PET result, an Eastern Cooperative Oncology Group performance status of 0 to 2, normal organ function without diabetes or recent weight loss, and a body mass index of at least 20 kg/m². Insulin inhibition, effected by a supervised carbohydrate dietary restriction (5% of total kilocalories), was monitored for macronutrient intake, body weight, serum electrolytes, β-hydroxybutyrate, insulin, and insulin-like growth factors-1 and -2. An FDG-PET scan was obtained at study entry and exit.

RESULTS

Ten subjects completed 26 to 28 d of the study diet without associated unsafe adverse effects. Mean caloric intake decreased 35 ± 6% versus baseline, and weight decreased by a median of 4% (range 0.0-6.1%). In nine patients with prior rapid disease progression, five with stable disease or partial remission on PET scan after the diet exhibited a three-fold higher dietary ketosis than those with continued progressive disease (n = 4, P = 0.018). Caloric intake (P = 0.65) and weight loss (P = 0.45) did not differ in those with stable disease or partial remission versus progressive disease. Ketosis was associated inversely with serum insulin levels (P = 0.03).

CONCLUSION

Preliminary data demonstrate that an insulin-inhibiting diet is safe and feasible in selected patients with advanced cancer. The extent of ketosis, but not calorie deficit or weight loss, correlated with stable disease or partial remission. Further study is needed to assess insulin inhibition as complementary to standard cytotoxic and endocrine therapies.

Immunohistochemical expression of GLUT1 and its correlation with unfavorable histology and TP53 codon 72 polymorphism in Wilms tumors

Reprogramming of energy metabolism, such as increased glycolysis, is a hallmark of cancer cells. One mechanism by which cancer cells fuel glycolysis is through increased uptake of glucose across cell membranes via the glucose transporter GLUT1. One of the transcriptional repressors of GLUT1 is wild-type TP53, and cancer-associated loss of function mutations within the DNA-binding domain of TP53 impairs the repressive effect of TP53 on transcriptional activity of the GLUT1 gene promoter. Because TP53 mutations are associated with unfavorable histology (diffuse anaplasia) in Wilms tumors, we hypothesized increased expression of GLUT1 in these tumors. To evaluate this hypothesis, we performed tissue microarray-based immunohistochemistry for GLUT1 in a set of 50 Wilms tumors, including 5 with unfavorable histology. In a subset of 16 favorable histology Wilms tumors, we compared the GLUT1 immunoexpression with TP53 codon 72 polymorphism status. We found consistently stronger immunoexpression of GLUT1 in unfavorable histology Wilms tumors compared to favorable histology Wilms tumors (P  =  0.04). We noted that the favorable histology Wilms tumors with a proline residue at position 72 of TP53 tended to have higher immunoexpression of GLUT1, although this immunoexpression did not reach statistical significance in this small set of cases. In summary, our finding of strong GLUT1 immunoexpression in unfavorable histology Wilms tumors indicates that these tumors are likely to be 2-deoxy-2-((18)F)fluoro-d-glucose avid and that GLUT1 should be evaluated as a therapeutic target for these tumors that otherwise show resistance to conventional therapy.

Lentiviral vector-mediated shRNA against AIMP2-DX2 suppresses lung cancer cell growth through blocking glucose uptake

Aminoacyl-tRNA synthetases [ARS]-interacting multifunctional protein 2 (AIMP2) has been implicated in the control of cell fate and lung cell differentiation. A variant of AIMP2 lacking exon 2 (AIMP2-DX2) is expressed in different cancer cells. We previously studied the expression level of AIMP2-DX2 in several lung cell lines and reported elevated expression levels of AIMP2-DX2 in NCI-H460 and NCI-H520. Here, we report that the suppression of AIMP2-DX2 by lentivirus mediated short hairpin (sh)RNA (sh-DX2) decreased the rate of glucose uptake and glucose transporters (Gluts) in NCI-H460 cells. Down-regulation of AIMP2-DX2 reduced glycosyltransferase (GnT)-V in the Golgi apparatus, while inducing the GnT-V antagonist GnT-III. Down-regulation of AIMP2-DX2 also suppressed the epidermal growth factor receptor/mitogen activated protein kinase (EGFR/MAPK) signaling pathway, leading to the decrease of the proliferation marker Ki-67 expression in nuclei. Furthermore, dual luciferase activity reduced capdependent protein translation in cells infected with sh-DX2. These results suggest that AIMP2-DX2 may be a relevant therapeutic target for lung cancer, and that the sh-DX2 lentiviral system can be an appropriate method for lung cancer therapy.

The effect of clotrimazole on energy substrate uptake and carcinogenesis in intestinal epithelial cells

Clotrimazole has anticarcinogenic activity in several cell types. Our aims were to investigate the anticarcinogenic effect of clotrimazole in a tumoral intestinal epithelial (Caco-2) cell line, to compare it with the effect in a nontumoral intestinal epithelial cell line (IEC-6 cells), and to investigate inhibition of energy substrate uptake as a mechanism contributing to it. The effect of clotrimazole on cell proliferation, viability and differentiation, H-deoxyglucose (H-DG), H-O-methyl-glucose (H-OMG), and C-butyrate uptake, as well as mRNA expression levels of glucose transporters was assessed. In Caco-2 cells, clotrimazole decreased cellular viability and proliferation and increased cell differentiation. The effect on cell proliferation and viability was potentiated by rhodamine123. Clotrimazole also decreased cellular viability and proliferation in IEC-6 cells, but increased the cellular DNA synthesis rate and had no effect on cell differentiation. Exposure of Caco-2 cells to clotrimazole (10 µmol/l) for 1 and 7 days increased (by 20-30%) the uptake of H-DG and H-OMG, respectively, but had no effect on C-butyrate uptake. The effect on H-DG and H-OMG transport was maximal at 10 µmol/l, and the pharmacological characteristics of transport were not changed. However, clotrimazole changed the mRNA expression levels of the facilitative glucose transporter 2 and the Na-dependent glucose cotransporter. Clotrimazole exhibits comparable cytotoxic effects in tumoral and nontumoral intestinal epithelial cell lines. In Caco-2 cells, the cytotoxic effect of clotrimazole was strongly potentiated by the inhibition of oxidative phosphorylation. Moreover, stimulation of glucose uptake might be a compensation mechanism in response to the glycolysis inhibition caused by clotrimazole.

Cellular distribution of Glut-1 and Glut-5 in benign and malignant human prostate tissue

Over-expression of hexose transporters (Gluts), specifically Glut-1, is a common event in human malignancies. In prostate cancer (CaP), however, expression of Gluts has been characterized poorly. In this study, expression and distribution of Glut-1 and Glut-5 proteins were characterized using immunohistochemistry in 76 specimens of benign prostate, 10 specimens of high-grade intraepithelial neoplasia (HGPIN), and 28 specimens of CaP. In addition, mRNA expression of Glut-2, Glut-7, Glut-9, and Glut-11 was analyzed in a set of five specimens of benign prostate and CaP. In benign prostate, Glut-1 localized to the basal cells and to the basolateral membrane of secretory/luminal epithelial cells. Glut-5, however, localized to the apical membrane of secretory/luminal epithelial cells. In HGPIN, Glut-1 was immunohistochemically undetectable. Glut-5, however, localized to the apical membrane of the neoplastic epithelial cells. In CaP, Glut-1 and Glut-5, were immunohistochemically undetectable. However, over-expression of GLUT1 was observed in some specimens of highly proliferative intraductal CaP. Glut-7, Glut-9, and Glut-11 mRNAs were detected in benign prostate and CaP, however, only Glut-11 mRNA was consistently up-regulated in CaP compared to benign prostate. Low levels of expression of Glut-1 protein in the majority of CaP could explain, at least in part, the limited clinical applicability of positron emission tomography using 2-[18F]-fluoro-2-deoxy-D-glucose for imaging CaP. Moreover, expression of Glut-5 in HGPIN suggested that fructose could be utilized as potential metabolic substrate in HGPIN. Understanding the molecular mechanisms involved in regulation/dysregulation of Gluts in CaP could provide insight in the understanding of hexose metabolism in CaP.

Aerobic glycolysis: meeting the metabolic requirements of cell proliferation

Warburg's observation that cancer cells exhibit a high rate of glycolysis even in the presence of oxygen (aerobic glycolysis) sparked debate over the role of glycolysis in normal and cancer cells. Although it has been established that defects in mitochondrial respiration are not the cause of cancer or aerobic glycolysis, the advantages of enhanced glycolysis in cancer remain controversial. Many cells ranging from microbes to lymphocytes use aerobic glycolysis during rapid proliferation, which suggests it may play a fundamental role in supporting cell growth. Here, we review how glycolysis contributes to the metabolic processes of dividing cells. We provide a detailed accounting of the biosynthetic requirements to construct a new cell and illustrate the importance of glycolysis in providing carbons to generate biomass. We argue that the major function of aerobic glycolysis is to maintain high levels of glycolytic intermediates to support anabolic reactions in cells, thus providing an explanation for why increased glucose metabolism is selected for in proliferating cells throughout nature.

FDG-PET predicts survival in recurrent high-grade gliomas treated with bevacizumab and irinotecan

Prognosis of recurrent high-grade glioma (HGG) is poor, although bevacizumab has been documented in that context. This study aimed to determine the independent prognostic value of fluorodeoxyglucose (FDG)-PET on progression-free survival (PFS) and overall survival (OS) of recurrent HGG after combined treatment with bevacizumab and irinotecan, compared with other documented prognostic variables. Twenty-five adult patients with histologically proven HGG were included at recurrence. Brain FDG-PET imaging was performed within 6 weeks of starting chemotherapy with bevacizumab and irinotecan. Response based on MRI was assessed every 2 months according to revised assessment in Neuro-Oncology (RANO) criteria. Median PFS and OS were 4 months (range, 0.9-10.4 months) and 7.2 months (range, 1.2-41.7 months), respectively. At 6 months, PFS and OS rate were 16.0% and 72.0%. FDG uptake was the most powerful predictor of both PFS and OS, using either univariate or multivariate analysis, among all variables tested: histological grade, Karnofsky performance status, steroid intake, and number of previous treatments. Moreover, FDG uptake was also prognostic of response to bevacizumab-based therapy. This study provides the first evidence that pretreatment FDG-PET can serve as an imaging biomarker in recurrent HGG for predicting survival following anti-angiogenic therapy with bevacizumab.

Gluconjugates of 8-hydroxyquinolines as potential anti-cancer prodrugs

8-Hydroxyquinolines are systems of great interest in the field of inorganic and bioinorganic chemistry. They are metal-binding compounds and are known to exhibit a variety of biological activities, such as antibacterial and anticancer activities. Among these systems, clioquinol has been the focus of a renewed interest in recent years. In this scenario, we synthesized and characterized the new clioquinol glucoconjugate, 5-chloro-7-iodo-8-quinolinyl-β-D-glucopyranoside in order to compare this system to that of clioquinol. We also synthesized, 8-quinolinyl-β-D-glucopyranoside, an 8-hydroxyquinoline glucoconjugate. The reason for the development of glucoconjugates is the glucose avidity, and the over-expression of glucose transporters in cancer cells. Here we demonstrate that glycoconjugates are cleaved in vitro by β-glucosidase and these systems exhibit antiproliferative activity against different tumor cell lines in the presence of copper(II) ions.

Diabetes, cancer, and metformin: connections of metabolism and cell proliferation

Diabetes is associated with an increased risk of developing and dying from cancer. This increased risk may be due to hyperglycemia, hyperinsulinemia, and insulin resistance or other factors. Metformin has recently gained much attention as it appears to reduce cancer incidence and improve prognosis of patients with diabetes. In vitro data and animal studies support these findings from human epidemiological studies. Metformin has multiple potential mechanisms by which it inhibits cancer development and growth. For example, metaformin inhibits hepatic gluconeogenesis, thus decreasing circulating glucose levels, and it increases insulin sensitivity, thus reducing circulating insulin levels. Intracellularly, metformin activates AMPK, which decreases protein synthesis and cell proliferation. Metaformin also reduces aromatase activity in the stromal cells of the mammary gland. Finally, metformin may diminish the recurrence and aggressiveness of tumors by reducing the stem cell population and inhibiting epithelial to mesenchymal transition. Here, we discuss the metabolic abnormalities that occur in tumor development and some of the mechanisms through which metformin may alter these pathways and reduce tumor growth.

Functional regulation of HIF-1α under normoxia--is there more than post-translational regulation?

The hypoxia-inducible factor-1 (HIF-1) is an oxygen-regulated transcriptional activator playing a pivotal role in mammalian physiology and disease pathogenesis, e.g., HIF-1 is indispensable in a broad range of developmental stages in different tumors. Its post-translational regulation via PHDs under the influence of hypoxia is widely investigated and accepted. Different non-hypoxic stimuli such as lipopolysaccharides (LPS), thrombin, and angiotensin II (Ang II), have been proven to enhance HIF-1 levels through activation of regulative mechanisms distinct from protein stabilization. Some of these stimuli specifically regulate HIF-1α at the transcriptional, post-transcriptional, or translational level, whereas others additionally influence post-translational modifications. Thus, it is difficult for the investigators to discern the impact of the different mechanisms leading to functional HIF-1 protein. Nevertheless, profound knowledge of additional regulatory networks appears to depict new therapeutic opportunities and thus is an interesting and important field for further investigations.

¹⁸F-fluoro-2-deoxyglucose uptake on PET CT and glucose transporter 1 expression in colorectal adenocarcinoma

AIM

To evaluate the correlation between the level of (18)F-fluoro-2-deoxyglucose ((18)F-FDG) uptake and glucose transporter 1 (GLUT1) expression in colorectal adenocarcinoma (CRA).

METHODS

Forty four patients with resected CRA and preoperative (18)F-FDG positron emission tomography - computed tomography data were investigated in this study. Comparison of maximum standardized uptake value (SUVmax) of the lesion was made with GLUT1 expression by immunohistochemistry and various clinicopathologic factors including tumor volume, invasion depth, gross finding, and lymph node metastasis.

RESULTS

SUVmax was 14.45 ± 7.0 in negative GLUT1 expression cases, 15.51 ± 5.7 in weak GLUT1 expression cases, and 16.52 ± 6.8 in strong GLUT1 expression cases, and there was no correlation between between GLUT1 expression and SUVmax. SUVmax was significantly correlated with tumor volume (P < 0.001). However, there was no significant differences in SUVmax and GLUT1 expression among other clinicopathologic factors.

CONCLUSION

GLUT1 expression does not correlates significantly with (18)F-FDG uptake in CRA. (18)F-FDG uptake was increased with tumor volume, which is statistically significant.

Independent prognostic value of pre-treatment 18-FDG-PET in high-grade gliomas

The prognostic value of PET with (18F)-fluoro-2-deoxy-D: -glucose (FDG) has been shown in high-grade gliomas (HGG), but not compared with consensual prognostic factors. We sought to evaluate the independent predictive value of pre-treatment FDG-PET on overall (OS) and event-free survival (EFS). We retrospectively analyzed 41 patients with histologically-confirmed HGG (31 glioblastomas and 10 anaplastic gliomas). The pre-treatment uptake of FDG was assessed qualitatively by five-step visual metabolic grading, and quantitatively by the ratio between the tumor and contralateral maximal standardized uptake value (T/CL). EFS and OS following PET were compared with FDG uptake by univariate analysis, and by two multivariate analyses: one including main consensual prognostic factors (age, KPS, extent of surgery and histological grade), and the other including the classification system of the Radiation Therapy Oncology Group (Recursive Partitioning Analysis, RPA). Median OS and EFS were 13.8 and 7.4 months, respectively, for glioblastomas, and over 25.8 and 12 months, respectively, for anaplastic gliomas (P = 0.040 and P = 0.027). The T/CL ratio predicted OS in the entire group [P = 0.003; Hazard Ratio (HR) = 2.3] and in the glioblastoma subgroup (P = 0.018; HR = 2), independently of age, Karnofsky performance status, histological grade, and surgery, and independently of RPA classification. T/CL ratio tended to predict EFS in the whole group (P = 0.052). The prognostic value of visual metabolic grade on OS was less significant than T/CL ratio, both in the entire group and in the glioblastoma subgroup (P = 0.077 and P = 0.059). Quantitative evaluation of the ratio between the maximal tumor and contralateral uptake in pre-treatment FDG-PET provides significant additional prognostic information in newly-diagnosed HGG, independently of consensual prognostic factors.

Targeting cancer metabolism: a therapeutic window opens

Genetic events in cancer activate signalling pathways that alter cell metabolism. Clinical evidence has linked cell metabolism with cancer outcomes. Together, these observations have raised interest in targeting metabolic enzymes for cancer therapy, but they have also raised concerns that these therapies would have unacceptable effects on normal cells. However, some of the first cancer therapies that were developed target the specific metabolic needs of cancer cells and remain effective agents in the clinic today. Research into how changes in cell metabolism promote tumour growth has accelerated in recent years. This has refocused efforts to target metabolic dependencies of cancer cells as a selective anticancer strategy.

Expression of GLUT1 is associated with increasing grade of malignancy in non-invasive and invasive urothelial carcinomas of the bladder

Glucose Transporter 1 (GLUT1) belongs to the expanding mammalian facilitative glucose transporter family. Elevated GLUT1 protein expression has been observed in the majority of urothelial carcinomas, with various effects on clinicopathological parameters. Whereas malignant cells have an accelerated metabolism with increased energy requirements, the membranous expression of GLUTs is amplified. GLUT1 protein expression was evaluated in urothelial tumours of increasing grade of malignancy, supplemented by a tumour proliferation analysis. Particular attention was paid to non-invasive precursors of urothelial carcinoma. A total of 105 paraffin-embedded samples were classified (normal urothelium, low/high-grade papillary carcinoma, carcinoma in situ and invasive carcinoma). Grading and staging were conducted using the 1998 ISUP/2004 WHO criteria. The staining intensity of GLUT1 was assessed with a standard immunoreactive score (IRS). The Ki-67 index was assessed by counting positive nuclei in representative urothelial hot spots. Results showed that an increased GLUT1-IRS and mean count of Ki-67-positive cells were significantly associated with an increased grade of malignancy (p<0.0001), particularly in non-invasive tumours. GLUT1-IRS was significantly associated with a Ki-67-labelled proliferative fraction (p<0.0001). No significant association regarding tumour grade or stage was observed within the invasive carcinoma group. GLUT1 protein expression was found to be strongly correlated with increased malignant potential, particularly in non-invasive urothelial carcinomas. The increase of GLUT1 expression may reflect a preinvasive metabolic switch in terms of enhanced cell metabolism concomitant to known genetic alterations. A further increase in invasive carcinomas may be related to hypoxic conditions.