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Background:The lipogenic transcription factor carbohydrate response element-binding protein (ChREBP) may play a key role in malignant progression of breast cancer by allowing metabolic adaptations to take place in response to changes in oxygenation.Methods:Immunohistochemical analysis of ChREBP was carried out in human breast tumour tissue microarrays representative of malignant progression from normal breast through to metastatic cancer. The ChREBP protein and mRNA expressions were then analysed in a series of breast cancers for correlative analysis with common and breast-specific hypoxia signatures, and survival.Results:In invasive ductal carcinoma, ChREBP correlated significantly with mean 'downregulated' hypoxia scores (r=0.3, P<0.015, n=67) and in two distinct breast progression arrays, ChREBP protein also increased with malignant progression (P<0.001). However, bioinformatic analysis of a large data set (2136 cases) revealed an apparent reversal in the relationship between ChREBP mRNA level and clinical outcome - not only being significantly correlated with increased survival (log rank P<0.001), but also downregulated in malignant tissue compared with adjacent normal tissue.Conclusion:The ChREBP expression may be reflective of an aerobic metabolic phenotype that may conflict with hypoxia-induced signalling but provide a mechanism for growth at the oxygenated edge of the tumours. [ABSTRACT FROM AUTHOR]

Background: Recent studies proposed GLUT12 to be a major glucose transporter involved in the glycolytic metabolism of cancer cells., Methods: GLUT12 expression was determined by immunohistochemistry in a selection of cancer cell lines and a tumour spheroid model., Results: GLUT12 expression was high in A549 and RH-36; low in HT29; and absent in NB-EB cancer cell lines. GLUT12 expression was located in the necrotic centre of HT29 spheroids, which is characterised by anaerobic metabolism., Conclusion: The data supports the involvement of GLUT12 in the glycolytic metabolism of cancer cells and therefore, its potential as a novel therapeutic target for cancer treatment.

The hypoxic tumor microenvironment is associated with malignant progression and poor treatment response. The glucose transporter Glut-1 is a prognostic factor and putative hypoxia marker. So far, studies of Glut-1 in cancer have utilized conventional immunohistochemical analysis in a series of individual biopsy or surgical specimens. Tissue microarrays, however, provide a rapid, inexpensive means of profiling biomarker expression. To evaluate hypoxia markers, tissue cores must show the architectural features of hypoxia; i.e. viable tissue surrounding necrotic regions. Glut-1 may be a useful biomarker to validate tissue microarrays for use in studies of hypoxia-regulated genes in cancer. In this study, we carried out immunohistochemical detection of Glut-1 protein in many tumor and normal tissue types in a range of tissue microarrays. Glut-1 was frequently found in peri-necrotic regions, occurring in 9/34 lymphomas, 6/12 melanomas, and 5/16 glioblastomas; and in 43/54 lung, 22/84 colon, and 23/60 ovarian tumors. Expression was rare in breast (6/40) and prostate (1/57) tumors, and in normal tissue, was restricted to spleen, tongue, and CNS endothelium. In conclusion, tissue microarrays enable the observation of Glut-1 expression in peri-necrotic regions, which may be linked to hypoxia, and reflect previous studies showing differential Glut-1 expression across tumor types and non-malignant tissue., (Copyright 2010 Elsevier GmbH. All rights reserved.)

The facilitative glucose transporter Glut-1 is overexpressed and confers poor prognosis in a wide range of solid tumours. The peri-necrotic pattern of expression often seen in human tumour samples is linked with its transcriptional control in hypoxic conditions by hypoxia-inducible factor HIF-1 or through a reduced rate of oxidative phosphorylation. Hypoxia-regulated genes offer promise as novel therapeutic targets as a means of preventing the proliferation and eventual metastatic spread of tissue originating from residual chemically and radio resistant hypoxic cells that have survived treatment. Inhibiting the expression or functionality of Glut-1 may be a way of specifically targeting hypoxic cells within the tumour that depend upon a high rate of glucose uptake for anaerobic glycolysis. We used an array of formalin-fixed, paraffin-embedded samples of the NCI-60 panel of cell lines to carry out immunohistochemical detection of Glut-1 and to select possible candidate lead compounds by COMPARE analysis with agents from the NCI diversity screen, which may work via inhibition of Glut-1 or Glut-1-dependent processes. "Positive" COMPARE hits were mostly conjugated Pseudomonas toxins binding the epidermal growth factor receptor (EGFR). However, correlations with standard anticancer agents were virtually all negative, indicating a link between Glut-1 and chemoresistance. MTT proliferation assays carried out using stable, Glut-1 overexpressing cell lines generated from the bladder EJ138, human fibrosarcoma HT 1080 and the hepatoma wild type Hepa and HIF-1B-deficient c4 tumour cell lines revealed a cell line-dependent increase in chemoresistance to dacarbazine, vincristine and the bioreductive agent EO9 in Glut-1 overexpressing EJ138 relative to WT and empty vector controls. Metabolomic analysis ((31)P-MRS and (1)H MRS) carried out using cell lysates and xenografts generated from Glut-1 overexpressing Hepa and c4 cell lines showed higher glucose levels in Glut-1 overxpressing c4 relative to parental tumour extracts occurred in the absence of an increase in lactate levels, which were in turn significantly higher in the Glut-1 overexpressing Hepa xenografts. This implies that Glut-1 over-expression without a co-ordinate increase in HIF-1-regulated glycolytic enzymes increases glucose uptake but not the rate of glycolysis. Glut-1 overexpressing xenografts also showed higher levels of phosphodiester (PDE), which relates to the metabolite turnover of phospholipids and is involved in membrane lipid degradation, indicating a mechanism by which Glut-1 may increase cell turnover.

Aquaporin 1 (AQP1) water channels are membrane proteins that control the permeability of endothelial and epithelial barriers by facilitating water movement across cell membranes. Recent studies suggest that AQP1 may be responsible for the high vascular permeability and interstitial fluid pressure in tumors of the brain, colon, breast and pancreas. AQP1 may also play a role in tumor angiogenesis and may be involved in development of effusions or edema fluid. The aim of the present study was to use immunohistochemistry and semi-quantitative histomorphometric analysis to compare the distribution and relative abundance of AQP1 on NCI TARP human multiple tumor tissue microarrays (TMAs) with normal tissues represented on the CHTN TMAs. Immunohistochemistry and semi-quantitative histomorphometric analysis were used to compare the distribution of AQP1 in tumors of the prostate, colon, lung, breast and ovary represented on TARP TMAs with their normal counterparts on CHTN TMAs. AQP1 was expressed in capillary endothelia of all normal tissues. In most tumors AQP1 was confined to endothelial barriers. AQP1 expression was marginally higher in microvascular structures in prostate and ovarian tumors and was higher in advanced mammary and colorectal carcinomas where AQP1 immunoreactivity was also seen in some neoplastic tumor cells. In conclusion, the AQP1 water channel is an excellent marker of microvasculature but it is heterogeneously expressed in different human tumors and not necessarily expressed in all neoplastic cells. Increased AQP1 expression in some human adenocarcinomas may be a consequence of angiogenesis and important for the formation or clearance of tumor edema.

Hypoxia in tumours of the oral cavity has not been extensively investigated with regard to clinical outcome and prognosis. The expression of the facilitative glucose transporter, Glut-1, has been shown to be related to hypoxia in tumours at other sites. The aim of the present study was to investigate the relationship between Glut-1 expression and clinical outcome in a series of oral squamous cell carcinomas. A retrospective series of 54 cases of oral squamous cell carcinomas with known clinical outcome and treated by one surgeon over a period of 6 years was used in the study. A representative section from each case was stained immunohistochemically with an antibody against Glut-1. The stained sections were then assessed independently by two observers using a semi-quantitative method. The relationship between these results and the clinical outcomes of local recurrence, regional lymph-node metastasis and disease-free survival were examined. Glut-1 staining was observed in most of the tissue specimens and all of the few sections with demonstrably necrotic areas histologically. Some showed more prominent staining in the epithelial islands of the tumour than others. However, the intensity of staining was variable. There was a significant relationship between those tumours which demonstrated intense staining and recurrence overall (chi(2)=6.18, P=0.032). This relationship was strongest in relation to regional lymph-node recurrence (chi(2)=10.19, P=0.005). A significant relationship between disease-related death and intense Glut-1 staining was also observed (chi(2)=11.67, P=0.002). In conclusion, the results of this study indicate a relationship between Glut-1 expression and disease progression of oral cancer and could indicate a need for neoadjuvant chemoradiotherapy for those tumours demonstrating intense Glut-1 expression.

Tissue microarrays (TMAs) are an ordered array of tissue cores on a glass slide. They permit immunohistochemical analysis of numerous tissue sections under identical experimental conditions. The arrays can contain samples of every organ in the human body, or a wide variety of common tumors and obscure clinical cases alongside normal controls. The arrays can also contain pellets of cultured tumor cell lines. These arrays may be used like any histological section for immunohistochemistry and in situ hybridization to detect protein and gene expression. This new technology will allow investigators to analyze numerous biomarkers over essentially identical samples, develop novel prognostic markers and validate potential drug targets. The ability to combine TMA technology with DNA microarrays and proteomics makes it a very attractive tool for analysis of gene expression in clinically stratified tumor specimens and relate expression of each particular protein with clinical outcome. Public domain software allows researchers to examine digital images of individual histological specimens from TMAs, evaluate and score them and store the quantitative data in a relational database. TMA technology may be specifically applied to the profiling of proteins of interest in other pathophysiological conditions such as congestive heart failure, renal disease, hypertension, diabetes, cystic fibrosis and neurodegenerative disorders. This review is intended to summarize the strengths and weaknesses of TMA technology which will have an increasingly important role in the laboratories of the post-genomic era.

Hypoxic tumors are known to be more malignant, to be more likely to metastasize, and to have a poor prognosis. They are also radio- and chemoresistant. For this reason, it is desirable that a clinically useful marker of hypoxia is found, so that treatment with radiotherapy and bioreductive chemotherapy can be rationally applied to individual patients. Glut-1 is a facilitative glucose transporter that is ubiquitously expressed in normal tissue and expressed at higher levels in a number of tumors. Its potential as an intrinsic hypoxia marker arises from its dual control in hypoxic conditions by reduced oxidative phosphorylation and the hypoxia-inducible factor (HIF-1) oxygen-sensing pathway. Eppendorf histography, by virtue of its proven predictive qualities, is a suitable gold standard used in our laboratory to validate new hypoxia markers. Using this technique, pretreatment pO(2) measurements were performed on 54 patients with locally advanced cervical carcinoma. Then, immunohistochemical staining was used to detect Glut-1 protein in individual tumor biopsy sections. Both measurements were made before initiation of treatment. By using a low-tech scoring system, pO(2) was found to correlate weakly with Glut-1 score (r = 0.28; P = 0.04). To extrapolate this correlation to the known adverse effects of tumor hypoxia on outcome, we examined the prognostic significance of Glut-1 staining in a retrospective series of 121 patients. An absence of Glut-1 significantly increased the likelihood of metastasis-free survival (P = 0.022) but did not significantly effect disease-free or recurrence-free survival. These findings suggest that Glut-1 be an intrinsic marker of hypoxia that can easily be applied in a clinical setting.