Tolerance of Human Fibroblasts to Benfo-Oxythiamine In Vitro.

OBJECTIVES: To explore the potential application of B-OT in the aspiration tract. MATERIALS AND METHODS: We conceived and optimized an in vitro model simulating the mouth-washing process to assess tolerance to B-OT on primary human gingival fibroblasts. Cells derived from 4 unrelated donors were flushed with medium containing drugs of various concentration for one minute twice daily for 3 days. RESULTS: No effect was seen on the cells up to 1000 µM B-OT. In addition, we treated the cells with B-OT permanently in medium, corresponding to a systemic treatment. No effect was seen by 10 µM B-OT and only a slight reduction (approximately 10%) was seen by 100 µM B-OT. CONCLUSIONS: Our results suggest good tolerance of oral cells for B-OT, favoring the further development of this antiviral reagent as a mouth-washing solution and nasal spray.

EDIM-TKTL1/Apo10 Blood Test: An Innate Immune System Based Liquid Biopsy for the Early Detection, Characterization and Targeted Treatment of Cancer.

Epitope detection in monocytes (EDIM) represents a liquid biopsy exploiting the innate immune system. Activated monocytes (macrophages) phagocytose unwanted cells/cell fragments from the whole body including solid tissues. As they return to the blood, macrophages can be used for a non-invasive detection of biomarkers, thereby providing high sensitivity and specificity, because the intracellular presence of biomarkers is due to an innate immune response. Flow cytometry analysis of blood enables the detection of macrophages and phagocytosed intracellular biomarkers. In order to establish a pan-cancer test, biomarkers for two fundamental biophysical mechanisms have been exploited. The DNaseX/Apo10 protein epitope is a characteristic of tumor cells with abnormal apoptosis and proliferation. Transketolase-like 1 (TKTL1) is a marker for an anaerobic glucose metabolism (Warburg effect), which is concomitant with invasive growth/metastasis and resistant to radical and apoptosis inducing therapies. The detection of Apo10 and TKTL1 in blood macrophages allowed a sensitive (95.8%) and specific (97.3%) detection of prostate, breast and oral squamous cell carcinomas. Since TKTL1 represents a drugable target, the EDIM based detection of TKTL1 enables a targeted cancer therapy using the vitamin derivatives oxythiamine or benfo-oxythiamine.

A key role for transketolase-like 1 in tumor metabolic reprogramming.

Metabolic reprogramming, a crucial cancer hallmark, shifts metabolic pathways such as glycolysis, tricarboxylic acid cycle or lipogenesis, to enable the growth characteristics of cancer cells. Here, we provide evidence that transketolase-like 1 (TKTL1) orchestrates aerobic glycolysis, fatty acid and nucleic acid synthesis, glutamine metabolism, protection against oxidative stress and cell proliferation. Furthermore, silencing of TKTL1 reduced the levels of sphingolipids such as lactosylceramide (a sphingolipid regulating cell survival, proliferation and angiogenesis) and phosphatidylinositol (which activates PI3K/Akt/mTOR signaling). Thus, in addition to its well-known roles in glucose and amino acid metabolism, TKTL1 also regulates lipid metabolism. In conclusion, our study provides unprecedented evidence that TKTL1 plays central roles in major metabolic processes subject to reprogramming in cancer cells and thus identifies TKTL1 as a promising target for new anti-cancer therapies.

Analysis of circulating CD14+/CD16+ monocyte-derived macrophages (MDMs) in the peripheral blood of patients with oral squamous cell carcinoma.

OBJECTIVES: Monocytes/macrophages are regarded as the first line of defense in tumors. Therefore, analyzing monocyte subtypes in oral squamous cell carcinoma (OSCC) may be of value in disease monitoring and to explore immunotherapeutic strategies for cancer patients. STUDY DESIGN: Circulating peripheral blood CD14+/CD16+ monocyte-derived macrophages (MDMs) were evaluated in OSCC patients with oral squamous cell carcinoma (n = 44) compared with controls (n = 85). Moreover, epitope detection in monocytes (EDIM) technology was used to detect biomarkers Apo10 and transketolase-like-1 in CD14+/CD16+ MDMs. RESULTS: Compared with controls, no significant (P = .3646) difference (control group 9.8%, OSCC group 8.8%) in CD14+/CD16+ MDM were noted in OSCC. However, EDIM-Apo10 and EDIM-TKTL1 scores detected in the CD14+/CD16+ MDMs were increased in OSCC compared with controls (P < .0001). CONCLUSIONS: Analyzing CD14+/CD16+ MDMs represents a stable cell population for detecting biomarkers in cancer disease monitoring.

Cancer cell-autonomous TRAIL-R signaling promotes KRAS-driven cancer progression, invasion, and metastasis.

Many cancers harbor oncogenic mutations of KRAS. Effectors mediating cancer progression, invasion, and metastasis in KRAS-mutated cancers are only incompletely understood. Here we identify cancer cell-expressed murine TRAIL-R, whose main function ascribed so far has been the induction of apoptosis as a crucial mediator of KRAS-driven cancer progression, invasion, and metastasis and in vivo Rac-1 activation. Cancer cell-restricted genetic ablation of murine TRAIL-R in autochthonous KRAS-driven models of non-small-cell lung cancer (NSCLC) and pancreatic ductal adenocarcinoma (PDAC) reduces tumor growth, blunts metastasis, and prolongs survival by inhibiting cancer cell-autonomous migration, proliferation, and invasion. Consistent with this, high TRAIL-R2 expression correlates with invasion of human PDAC into lymph vessels and with shortened metastasis-free survival of KRAS-mutated colorectal cancer patients.

ERGO: a pilot study of ketogenic diet in recurrent glioblastoma.

Limiting dietary carbohydrates inhibits glioma growth in preclinical models. Therefore, the ERGO trial (NCT00575146) examined feasibility of a ketogenic diet in 20 patients with recurrent glioblastoma. Patients were put on a low-carbohydrate, ketogenic diet containing plant oils. Feasibility was the primary endpoint, secondary endpoints included the percentage of patients reaching urinary ketosis, progression-free survival (PFS) and overall survival. The effects of a ketogenic diet alone or in combination with bevacizumab was also explored in an orthotopic U87MG glioblastoma model in nude mice. Three patients (15%) discontinued the diet for poor tolerability. No serious adverse events attributed to the diet were observed. Urine ketosis was achieved at least once in 12 of 13 (92%) evaluable patients. One patient achieved a minor response and two patients had stable disease after 6 weeks. Median PFS of all patients was 5 (range, 3-13) weeks, median survival from enrollment was 32 weeks. The trial allowed to continue the diet beyond progression. Six of 7 (86%) patients treated with bevacizumab and diet experienced an objective response, and median PFS on bevacizumab was 20.1 (range, 12-124) weeks, for a PFS at 6 months of 43%. In the mouse glioma model, ketogenic diet alone had no effect on median survival, but increased that of bevacizumab-treated mice from 52 to 58 days (p<0.05). In conclusion, a ketogenic diet is feasible and safe but probably has no significant clinical activity when used as single agent in recurrent glioma. Further clinical trials are necessary to clarify whether calorie restriction or the combination with other therapeutic modalities, such as radiotherapy or anti-angiogenic treatments, could enhance the efficacy of the ketogenic diet.

Reproducibility studies for experimental epitope detection in macrophages (EDIM).

INTRODUCTION: We have recently described epitope detection in macrophages (EDIM) by flow cytometry. This is a promising tool for the diagnosis and follow-up of malignancies. However, biological and technical validation is warranted before clinical applicability can be explored. METHODS: The pre-analytic and analytic phases were investigated. Five different aspects were assessed: blood sample stability, intra-individual variability in healthy persons, intra-assay variation, inter-assay variation and assay transferability. The post-analytic phase was already partly standardized and described in an earlier study. RESULTS: The outcomes in the pre-analytic phase showed that samples are stable for 24h after venipuncture. Biological variation over time was similar to that of serum tumor marker assays; each patient has a baseline value. Intra-assay variation showed good reproducibility, while inter-assay variation showed reproducibility similar to that of to established serum tumor marker assays. Furthermore, the assay showed excellent transferability between analyzers. CONCLUSION: Under optimal analytic conditions the EDIM method is technically stable, reproducible and transferable. Biological variation over time needs further assessment in future work.

A biomarker based detection and characterization of carcinomas exploiting two fundamental biophysical mechanisms in mammalian cells.

BACKGROUND: Biomarkers allowing the characterization of malignancy and therapy response of oral squamous cell carcinomas (OSCC) or other types of carcinomas are still outstanding. The biochemical suicide molecule endonuclease DNaseX (DNaseI-like 1) has been used to identify the Apo10 protein epitope that marks tumor cells with abnormal apoptosis and proliferation. The transketolase-like protein 1 (TKTL1) represents the enzymatic basis for an anaerobic glucose metabolism even in the presence of oxygen (aerobic glycolysis/Warburg effect), which is concomitant with a more malignant phenotype due to invasive growth/metastasis and resistance to radical and apoptosis inducing therapies. METHODS: Expression of Apo10 and TKTL1 was analysed retrospectively in OSCC specimen (n = 161) by immunohistochemistry. Both markers represent independent markers for poor survival. Furthermore Apo10 and TKTL1 have been used prospectively for epitope detection in monocytes (EDIM)-blood test in patients with OSCC (n = 50), breast cancer (n = 48), prostate cancer (n = 115), and blood donors/controls (n = 74). RESULTS: Positive Apo10 and TKTL1 expression were associated with recurrence of the tumor. Multivariate analysis demonstrated Apo10 and TKTL1 expression as an independent prognostic factor for reduced tumor-specific survival. Apo10+/TKTL1+ subgroup showed the worst disease-free survival rate in OSCC.EDIM-Apo10 and EDIM-TKTL1 blood tests allowed a sensitive and specific detection of patients with OSCC, breast cancer and prostate cancer before surgery and in after care. A combined score of Apo10+/TKTL1+ led to a sensitivity of 95.8% and a specificity of 97.3% for the detection of carcinomas independent of the tumor entity. CONCLUSIONS: The combined detection of two independent fundamental biophysical processes by the two biomarkers Apo10 and TKTL1 allows a sensitive and specific detection of neoplasia in a noninvasive and cost-effective way. Further prospective trials are warranted to validate this new concept for the diagnosis of neoplasia and tumor recurrence.

Ehrlichia chaffeensis uses its surface protein EtpE to bind GPI-anchored protein DNase X and trigger entry into mammalian cells.

Ehrlichia chaffeensis, an obligatory intracellular rickettsial pathogen, enters and replicates in monocytes/macrophages and several non-phagocytic cells. E. chaffeensis entry into mammalian cells is essential not only for causing the emerging zoonosis, human monocytic ehrlichiosis, but also for its survival. It remains unclear if E. chaffeensis has evolved a specific surface protein that functions as an 'invasin' to mediate its entry. We report a novel entry triggering protein of Ehrlichia, EtpE that functions as an invasin. EtpE is an outer membrane protein and an antibody against EtpE (the C-terminal fragment, EtpE-C) greatly inhibited E. chaffeensis binding, entry and infection of both phagocytes and non-phagocytes. EtpE-C-immunization of mice significantly inhibited E. chaffeensis infection. EtpE-C-coated latex beads, used to investigate whether EtpE-C can mediate cell invasion, entered both phagocytes and non-phagocytes and the entry was blocked by compounds that block E. chaffeensis entry. None of these compounds blocked uptake of non-coated beads by phagocytes. Yeast two-hybrid screening revealed that DNase X, a glycosylphosphatidyl inositol-anchored mammalian cell-surface protein binds EtpE-C. This was confirmed by far-Western blotting, affinity pull-down, co-immunoprecipitation, immunofluorescence labeling, and live-cell image analysis. EtpE-C-coated beads entered bone marrow-derived macrophages (BMDMs) from wild-type mice, whereas they neither bound nor entered BMDMs from DNase X(-/-) mice. Antibody against DNase X or DNase X knock-down by small interfering RNA impaired E. chaffeensis binding, entry, and infection. E. chaffeensis entry and infection rates of BMDMs from DNase X(-/-) mice and bacterial load in the peripheral blood in experimentally infected DNase X(-/-) mice, were significantly lower than those from wild-type mice. Thus this obligatory intracellular pathogen evolved a unique protein EtpE that binds DNase X to enter and infect eukaryotic cells. This study is the first to demonstrate the invasin and its mammalian receptor, and their in vivo relevance in any ehrlichial species.

Diagnostic use of epitope detection in monocytes blood test for early detection of colon cancer metastasis.

A follow-up strategy in cancer aftercare can result in early detection of metastasis and/or recurrence. Therefore, sensitive and reliable diagnostic tests that are easy to perform are needed. Here, the authors present the combined use of the epitope detection in monocytes (EDIM)-TKTL1 and EDIM-Apo10 blood test in aftercare monitoring of a patient with colon carcinoma. Whereas the established tumor markers CEA and CA19-9 did not indicate metastasis even at a timepoint where clinical signs and imaging techniques already demonstrated metastasis, the combined application of the EDIM-TKTL1 and the EDIM-Apo10 blood tests was positive 9 months before detection of metastasis. These findings - taken together with recently published evaluation data of the EDIM-TKTL1 blood test - suggest that the combined application of the EDIM-TKTL1 and the EDIM-Apo10 blood tests might indicate metastasis earlier than established tumor markers and could serve as sensitive and noninvasive methods that might be used for early detection of colon cancer metastasis.

EDIM-TKTL1 blood test: a noninvasive method to detect upregulated glucose metabolism in patients with malignancies.

AIM: To determine whether the TKTL1 protein epitope detection in monocytes (EDIM) test allows detection of upregulated glucose metabolism in malignancies. MATERIALS & METHODS: The EDIM-TKTL1 blood test was conducted in 240 patients with 17 different confirmed or suspected malignancies. Test scores were compared with (18)F-fluoro-2-deoxy-D-glucose (FDG)-PET/computed tomography (CT) results. RESULTS: EDIM-TKTL1 score and FDG-PET results showed a concordance of 90% with a sensitivity of 94% and specificity of 81%. Including CT data, all values were enhanced. A subgroup analysis of non-small-cell lung cancer patients showed a significant correlation between the EDIM-TKTL1 score and the primary tumor size determined by FDG-PET/CT. CONCLUSION: EDIM-TKTL1 blood test revealed good concordance with FDG-PET/CT results in patients with malignancies demonstrating its efficacy to detect upregulation of glucose metabolism in primary tumors or metastases.

TKTL-1 expression in lung cancer.

Study of the physiological changes associated with the development of malignancy demonstrates a metabolic signature for the different stages of tumorigenesis. Increased glucose uptake and lactate production have been detected during malignant transformation. Based on energy production, malignancies can be divided into two subclasses: (a) tumor cells which use the mitochondrial machinery for ATP synthesis, and (b) tumor cells which generate ATP by glucose fermentation and lactate production even in the presence of oxygen (aerobic glycolysis). Recently, transketolase-like protein 1 (TKTL1) gene expression has been shown to contribute to carcinogenesis through increased aerobic glycolysis and hypoxia-inducible factor alpha stabilization. In the present study, 197 patients suffering from lung cancer were investigated by immunohistochemistry for the presence of TKTL1 protein expression. We detected: (1) moderate to strong TKTL1 expression (immune reactive score>100) in 39.1% of the investigated lung cancer patients; (2) a complete lack of TKTL1 by immunohistochemistry in 12.7% of lung cancer cases, with small cell lung cancer (SCLC) being most frequent in this subgroup; (3) no correlation of TKTL1 with overall survival, disease-free survival, any of the established variables of the TNM system, grading, stage, smoking status, or gender. Based on this data, we conclude that TKTL1 could be a target protein for improved therapeutic strategies in some cases of lung cancer.

Lack of transketolase-like (TKTL) 1 aggravates murine experimental colitis.

Transketolase-like (TKTL) 1 indirectly replenishes NADPH preventing damage induced by reactive oxygen species (ROS) formed upon intestinal inflammation. We investigated the function of TKTL1 during murine colitis and ROS detoxification for prevention of tissue damage. Mucosal damage in TKTL1(-/-) and wild-type (WT) mice was assessed by miniendoscopy and histology during dextran sodium sulfate (DSS) colitis. mRNA levels of interferon (IFN)-γ, inducible nitric oxide synthase (iNOS), interleukin (IL)-6, tumor necrosis factor (TNF), transketolase (TKT), and TKTL2 were determined by PCR and/or Western blotting. To assess oxidative and nitrosative stress nitrosylation, carbonylation and antioxidative enzymes catalase (Cat), superoxide dismutase 1 and 2, as well as glutathione (GSH) were determined. Myeloperoxidase (MPO) was determined for assessment of tissue neutrophils. TKTL1 knockout or DSS treatment did not influence TKT and TKTL2 mRNA or protein expression. Mucosal damage was significantly increased in TKTL1(-/-) mice indicated by miniendoscopy as well as a significantly shorter colon and more severe histological scores compared with WT mice during DSS colitis. This was associated with higher mRNA levels of IFN-γ, iNOS, IL-6, and TNF. In addition, iNOS protein expression was significantly enhanced in TKTL1(-/-) mice as well as MPO activity. Protein modification by nitric oxide (nitrotyrosine) was induced in TKTL1(-/-) mice. However, introduction of carbonyl groups by ROS was not induced in these mice. The expression of SOD1, SOD2, Cat, as well as GSH content was not significantly changed in TKTL1(-/-) mice. We conclude that induced colitis in TKTL1(-/-) mice was more severe compared with WT. This indicates a role of TKTL1 during mucosal repair and restoration.

Cancer proliferation and therapy: the Warburg effect and quantum metabolism.

BACKGROUND: Most cancer cells, in contrast to normal differentiated cells, rely on aerobic glycolysis instead of oxidative phosphorylation to generate metabolic energy, a phenomenon called the Warburg effect. MODEL: Quantum metabolism is an analytic theory of metabolic regulation which exploits the methodology of quantum mechanics to derive allometric rules relating cellular metabolic rate and cell size. This theory explains differences in the metabolic rates of cells utilizing OxPhos and cells utilizing glycolysis. This article appeals to an analytic relation between metabolic rate and evolutionary entropy - a demographic measure of Darwinian fitness - in order to: (a) provide an evolutionary rationale for the Warburg effect, and (b) propose methods based on entropic principles of natural selection for regulating the incidence of OxPhos and glycolysis in cancer cells. CONCLUSION: The regulatory interventions proposed on the basis of quantum metabolism have applications in therapeutic strategies to combat cancer. These procedures, based on metabolic regulation, are non-invasive, and complement the standard therapeutic methods involving radiation and chemotherapy.

Transketolase-like protein 1 (TKTL1) is required for rapid cell growth and full viability of human tumor cells.

Cancer cells display high rates of aerobic glycolysis, a phenomenon known as the Warburg effect. Lactate and pyruvate, the end products of glycolysis, are overproduced by cancer cells even in the presence of oxygen. The pentose phosphate pathway (PPP) allows glucose conversion to ribose for nucleic acid synthesis, glucose degradation to lactate, and regeneration of redox equivalents. The nonoxidative part of the PPP is controlled by transketolase (TKT) enzymes. One TKT isoform, the transketolase-like protein 1 (TKTL1) is specifically upregulated in different human cancers and its overexpression predicts a poor patient's survival. This finding implicates that an increased TKTL1 expression may activate the PPP leading to enhanced cancer cell growth and survival. To analyze the functional role of TKTL1 in malignant progression, we inhibited TKTL1 by RNAi technologies in human HCT116 colon carcinoma cells. TKTL1 suppression resulted in a significantly slowed cell growth, glucose consumption and lactate production. In TKTL1 knockdown-cells, the intracellular reactive oxygen species levels were not significantly increased, whereas the sensitivity towards oxidative stress-induced apoptosis was clearly enhanced. These data provide new clues on the importance of TKTL1 dys-regulation in tumor cells and indicate that TKTL1 overexpression may be considered not only as a new tumor marker but also as a good target for anticancer therapy.

Increased expression of transketolase-like-1 in papillary thyroid carcinomas smaller than 1.5 cm in diameter is associated with lymph-node metastases.

BACKGROUND: Patients with small papillary thyroid carcinoma (PTC) may have a high incidence of regional lymph-node (LN) metastases at presentation, and these are considered to be an independent risk factor for tumor recurrence. A mutated transketolase transcript (TKTL1) has been found up-regulated in different human malignancies, and strong TKTL1 protein expression has been associated with aggressiveness and poor patient survival in several epithelial cancers. METHODS: TKTL1 protein expression was analyzed in 256 consecutive cases of PTCs

Growth of human gastric cancer cells in nude mice is delayed by a ketogenic diet supplemented with omega-3 fatty acids and medium-chain triglycerides.

BACKGROUND: Among the most prominent metabolic alterations in cancer cells are the increase in glucose consumption and the conversion of glucose to lactic acid via the reduction of pyruvate even in the presence of oxygen. This phenomenon, known as aerobic glycolysis or the Warburg effect, may provide a rationale for therapeutic strategies that inhibit tumour growth by administration of a ketogenic diet with average protein but low in carbohydrates and high in fat enriched with omega-3 fatty acids and medium-chain triglycerides (MCT). METHODS: Twenty-four female NMRI nude mice were injected subcutaneously with tumour cells of the gastric adenocarcinoma cell line 23132/87. The animals were then randomly split into two feeding groups and fed either a ketogenic diet (KD group; n = 12) or a standard diet (SD group; n = 12) ad libitum. Experiments were ended upon attainment of the target tumor volume of 600 mm3 to 700 mm3. The two diets were compared based on tumour growth and survival time (interval between tumour cell injection and attainment of target tumour volume). RESULTS: The ketogenic diet was well accepted by the KD mice. The tumour growth in the KD group was significantly delayed compared to that in the SD group. Tumours in the KD group reached the target tumour volume at 34.2 +/- 8.5 days versus only 23.3 +/- 3.9 days in the SD group. After day 20, tumours in the KD group grew faster although the differences in mean tumour growth continued significantly. Importantly, they revealed significantly larger necrotic areas than tumours of the SD group and the areas with vital tumour cells appear to have had fewer vessels than tumours of the SD group. Viable tumour cells in the border zone surrounding the necrotic areas of tumours of both groups exhibited a glycolytic phenotype with expression of glucose transporter-1 and transketolase-like 1 enzyme. CONCLUSION: Application of an unrestricted ketogenic diet enriched with omega-3 fatty acids and MCT delayed tumour growth in a mouse xenograft model. Further studies are needed to address the impact of this diet on other tumour-relevant functions such as invasive growth and metastasis.

Metastasis is promoted by a bioenergetic switch: new targets for progressive renal cell cancer.

Targeted therapies have demonstrated clinical benefit with limited impact on long-term disease specific survival in the treatment of renal cell cancer (RCC). New opportunities for the treatment of tumors that are resistant or have relapsed, are needed. Increased anaerobic glucose fermentation to lactate (aerobic glycolysis), leading to oxygen- and mitochondria-independent ATP generation is a hallmark of aggressive cancer growth. This metabolic shift results in increased lactate production via cycling through the pentose phosphate pathway (PPP), and plays an important role in tumor immune escape, progression and resistance to immune-, radiation- and chemo-therapy. This study explored the activity and impact of the oxidative and nonoxidative branches of the PPP on RCC to evaluate new therapeutic options. Activity was determined in the oxidative branch by glucose-6-phosphate-dehydrogenase (G6PD) activity, and in the nonoxidative branch by the total transketolase activity and the specific expression of the transketolase-like-1 (TKTL1) protein. Transketolase and G6PD activity were intensely elevated in tumor tissues. Transketolase, but not G6PD activity, was more elevated in metastasizing tumors and TKTL1 protein was significantly overexpressed in progressing tumors (p = 0.03). Lethal tumors, where surrogate parameters such as grading and staging had failed to predict progression, showed intensive TKTL1 protein expression. RCC was found to have activated oxidative and nonoxidative glucose metabolism through the PPP, displaying a bioenergetic shift toward nonoxidative glucose fermentation in progressing tumors. The coexistence of cancer cells with differentially regulated energy supplies provides new insights in carcinogenesis and novel anticancer targets.

The role of glucose metabolism and glucose-associated signalling in cancer.

Aggressive carcinomas ferment glucose to lactate even in the presence of oxygen. This particular metabolism, termed aerobic glycolysis, the glycolytic phenotype, or the Warburg effect, was discovered by Nobel laureate Otto Warburg in the 1920s. Since these times, controversial discussions about the relevance of the fermentation of glucose by tumours took place; however, a majority of cancer researchers considered the Warburg effect as a non-causative epiphenomenon. Recent research demonstrated, that several common oncogenic events favour the expression of the glycolytic phenotype. Moreover, a suppression of the phenotypic features by either substrate limitation, pharmacological intervention, or genetic manipulation was found to mediate potent tumour-suppressive effects. The discovery of the transketolase-like 1 (TKTL1) enzyme in aggressive cancers may deliver a missing link in the interpretation of the Warburg effect. TKTL1-activity could be the basis for a rapid fermentation of glucose in aggressive carcinoma cells via the pentose phosphate pathway, which leads to matrix acidification, invasive growth, and ultimately metastasis. TKTL1 expression in certain non-cancerous tissues correlates with aerobic formation of lactate and rapid fermentation of glucose, which may be required for the prevention of advanced glycation end products and the suppression of reactive oxygen species. There is evidence, that the activity of this enzyme and the Warburg effect can be both protective or destructive for the organism. These results place glucose metabolism to the centre of pathogenesis of several civilisation related diseases and raise concerns about the high glycaemic index of various food components commonly consumed in western diets.

Expression of an endogenous retroviral sequence from the HERV-H group in gastrointestinal cancers.

Human endogenous retroviruses (HERVs) account for approximately 8% of the human genome. Since the majority of HERV elements have accumulated inactivating mutations in the viral genes, only few expressed viral open reading frames (ORFs) have been described. In this study, we have analyzed the expression of a HERV-H copy located on Xp22.3 encompassing a potential ORF immediately downstream of the viral promoter. Conventional and real time RT-PCR based expression analysis of this specific HERV-H sequence showed overexpression in 16 of 34 (47%) colorectal, 25 of 63 (40%) gastric and 2 of 12 (17%) pancreatic cancers, whereas no overexpression was detected in bronchial and cervical cancers. Normal human testis, placenta and breast tissue did not show expression of this sequence. CpG methylation analysis of the viral promoter revealed a loss of methylation in cell lines expressing the HERV-H sequence as compared to nonexpressing cell lines and lymphocyte DNA derived from healthy individuals. Further investigations of the HERV-H long terminal repeat and the HERV-H RNA are necessary to assess the functional relevance of the HERV-H expression.