Nutritional and physiological consequences of tumour glycolysis

Cyclooxygenase-2, p53 and glucose transporter-1 as predictors of malignancy in the development of gallbladder carcinomas

Gallbladder carcinoma is the fifth most common malignancy of the gastrointestinal tract. The absolute characteristics of the disease are the high mortality rate due to the late discovery of a tumor and the low therapeutic possibilities except by surgical intervention. In oncology we can predict the outcome of the disease with a combination of classical standard clinico/pathological parameters (stage of the tumors, differentiation) and the intrinsic genetic and biochemical properties of the tumor. Such intrinzic properties of the tumors that are connected with the outcome of the disease are the denominators (markers). The author searched extensively for the expression and influence of 3 markers included in chronic inflammation and early carcinogenesis, cell cycle regulation and tissue hypoxia: cyclooxygenase-2 (COX-2), p53 gene and glucose transporter-1 protein (GLUT-1). The author discusses their possible role in the development as well as fighting this disease, if specific medications targeting them were available.

Troglitazone reduces glyoxalase I protein expression in glioma and potentiates the effects of chemotherapeutic agents

Despite resistance of most gliomas to chemotherapy, approximately 2/3 of oligodendrogliomas show sensitivity to such agents. This sensitivity has been associated with deletions on chromosome 1p alone or in combination with 19q. Higher expression of the enzyme glyoxalase I has been found in oligodendrogliomas with chromosome 1p intact compared to those with a deletion. Higher expression of this enzyme is also associated with tumor chemoresistance in other cancers. The present study tested whether the drug troglitazone would make a glioma cell line more sensitive to chemotherapeutic agents. This drug was chosen because it has been shown to decrease glyoxalase I enzyme activity in cells. Treatment with troglitazone decreased expression of glyoxalase I, and potentiated cell death when used in combination with chemotherapeutic agents. This decrease in glyoxalase I protein may be one mechanism by which this potentiation occurs, and troglitazone may be a candidate for use in glioma therapy.

Protein and nucleotide damage by glyoxal and methylglyoxal in physiological systems--role in ageing and disease

Glycation of proteins, nucleotides and basic phospholipids by glyoxal and methylglyoxal--physiological substrates of glyoxalase 1--is potentially damaging to the proteome, genome and lipidome. Glyoxalase 1 suppresses glycation by these alpha-oxoaldehyde metabolites and thereby represents part of the enzymatic defence against glycation. Albert Szent-Györgyi pioneered and struggled to understand the physiological function of methylglyoxal and the glyoxalase system. We now appreciate that glyoxalase 1 protects against dicarbonyl modifications of the proteome, genome and lipome. Latest research suggests there are functional modifications of this process--implying a role in cell signalling, ageing and disease.

Hepatic [2-13C]acetate metabolism by jirds infected with Echinococcus multilocularis

Carbon-13 decoupled 1H spin echo NMR spectroscopy, with and without population inversion, was used to study carbon flow between the host, Meriones unguiculatus, and the parasite, Echinococcus multilocularis. This was accomplished by monitoring [2-13C]acetate metabolism in the liver of jirds infected with metacestodes of this parasite. Thirty minutes after injection of labelled acetate solution into the portal vein, 13C enrichment was observed in hepatic acetate, β–hydroxybutyrate, succinate, alanine, lactate and glucose. For E. multilocularis cysts, at this time,13C enrichment was observed in the same metabolites as in livers and, in addition, citrate. At 120 min there was a significant decrease in the amount of label present in all hepatic metabolites whereas more label was found in the majority of the parasite metabolites. The results confirm that exogenous acetate, through randomization of the 13C in biochemical pathways of host liver, ends up in hepatic glucose. As this biosynthetic route is not available to the parasite, the presence of 13C enriched glucose in the cysts clearly indicates that the parasite is siphoning off glucose that is newly synthesized by the host. At 120 min some of this labelled glucose was stored in parasite glycogen whereas some of it had been catabolized to succinate, alanine, lactate and acetate, end products which are excreted back into the host.

Cancer cachexia demonstrates the energetic impact of gluconeogenesis in human metabolism

A review-based hypothesis is presented on the energy flow in cancer patients. This hypothesis centres on the hypoxic condition of tumours, the essential metabolic consequences, especially the gluconeogenesis, the adaptation of the body, and the pathogenesis of cancer cachexia. In growing tumours the O(2) concentration is critically low. Mammalian cells need O(2) for the efficient oxidative dissimilation of sugars and fatty acids, which gives 38 and 128 moles of ATP per mole glucose and palmitic acid, respectively. In the absence of sufficient O(2) they have to switch to anaerobic dissimilation, with only 2 moles of ATP and 2 moles of lactic acid from 1 mole of glucose. Since mammalian cells cannot ferment fatty acids, in vivo tumour cells completely depend on glucose fermentation. Therefore, growth of these tumour cells will require about 40 times more glucose than it should require in the presence of sufficient O(2). Since lactic acid lowers the intracellular pH, it decreases the activity of pyruvate dehydrogenase, stimulates fermentation, and thus amplifies its own fermentative production. Compensatory glucose is provided by hepatic gluconeogenesis from lactic acid. However, the liver must invest 3 times more energy to synthesize glucose than can be extracted by tumour cells in an anaerobic way. The liver extracts the required energy from amino acids and especially from fatty acids in an oxidative way. This may account for weight loss, even when food intake seems adequate. In the liver 6 moles of ATP are invested in the gluconeogenesis of one mole of glucose. The energy content of 4 out of these 6 moles of ATP is dissipated as heat. This may account for the elevated body temperature and sweating experience by cancer patients.

Medicine without drugs--a new direction for application of nanotechnology

A working model of direct computer-organism interaction is described. The model is based on the understanding of the ways/modes, by which information is transmitted in the living organism. Information is transmitted in an organism by different ways. Communication between (among) the streams of different modes of information is provided by particular natural mechanisms--transformers and interconnectors. The model suggests that the functions of the cells, organs and systems of an organism can be monitored, controlled and governed directly by means of nano-computers. The application of a computer enables one to provide early diagnostics and successful treatment using specifically designed computer programs instead of, or in conjunction with, medications or surgery. The computer-organism interaction is being achieved through an effective engagement and interaction of the streams of computer generated information with the streams of information naturally transmitted in the organism.

Glutathione conjugates and their synthetic derivatives as inhibitors of glutathione-dependent enzymes involved in cancer and drug resistance

Alterations in levels of glutathione (GSH) and glutathione-dependent enzymes have been implicated in cancer and multidrug resistance of tumor cells. The activity of a number of these, the multidrug resistance-associated protein 1, glutathione S-transferase, DNA-dependent protein kinase, glyoxalase I, and gamma-glutamyl transpeptidase, can be inhibited by GSH-conjugates and synthetic analogs thereof. In this review we focus on the function of these enzymes and carriers in cancer and anti-cancer drug resistance, in relation to their inhibition by GSH-conjugate analogs.

The relationship between the cancer cell and the oocyte

What causes cancer? To date, this question is left with no answer. The scientific community keeps defining cancer as a proliferation of cells in an uncontrolled and uncontrollable manner. The hypothesis developed here through an understanding of the cancer cell's behaviour led to its re-definition, providing answers to the questions arising from cancer. Through striking similarities in cell behaviour, I have concluded that the cancer cell is a reprogrammed cell with the launch of the egg cell's genetic program. The unique cell to express this program is the oocyte, therefore this oocyte cell should become the subject of significant study to understand the genesis of cancer. Above all, it will enable us to eradicate in a specific manner the cancer cell.

A theory of cellular-function pathology: further development of Virchow's theory of cellular pathology

A new theory of pathology is introduced. The human cell is an organism in itself. It fulfills both cell-oriented and organism-oriented functions. Impairment of either one of these functions may lead to disease. This means that a structural lesion of a cell is not a sole and necessary cause of the beginning of disease. When a cell-oriented function is impaired the cell suffers, but the overt symptoms at the organ-organism level might be absent for a very long time. This is how a chronic asymptomatic disease starts. Measures of prophylaxis, diagnosis, and treatment should be centered upon maintenance and restoration of a balance between the cell-oriented and organism-oriented cellular functions.

Signal transduction dynamics of the protein kinase-A/phosphofructokinase-2 system in Saccharomyces cerevisiae

This work focuses on the phosphofructokinase-2-system dynamics in Saccharomyces cerevisiae, in vivo. The investigations were dedicated to the development and implementation of appropriate theoretical and experimental methods toward evaluation of a quantitative strategy for the characterization of systemic mechanisms involved in the cAMP/protein kinase-A/phosphofructokinase-2 signal transduction cascade in yeast. Upon glucose pulse experiments, applied to glucose-limited continuous cultures of S. cerevisiae, the system response was determined with respect to alterations of intracellular metabolite concentrations or in vivo enzyme activities. Phosphofructokinase-2, in vivo, was found to be saturated with respect to both its substrates, F6P and ATP. This restriction results in an uncoupling of the enzyme activity and the signal transduction cascade from glycolytic flux, concluding that activation of phosphofructokinase-2 is exclusively a result of phosphorylation by protein kinase-A, which in turn is activated by increasing intracellular cAMP concentration after an extracellular glucose pulse. Signal processing from cAMP versus phosphofructokinase-2 also displays peculiar features implicated in a hysteresis behavior: when increasing cAMP concentration achieves a certain critical value, protein kinase-A switches into an active state. Posterior to this activation, the signal transform maintains autonomy and functional independence of further alterations of the intracellular cAMP concentration. Our observations, finally, allow the establishment of a representative model for the description of the signal transduction process via protein kinase-A in yeast.

Further evidence for the rejuvenating effects of the dipeptide L-carnosine on cultured human diploid fibroblasts

We have confirmed and extended previous results on the beneficial effects of L-carnosine on growth, morphology, and longevity of cultured human fibroblasts, strains MRC-5 and HFF-1. We have shown that late-passage HFF-1 cells retain a juvenile appearance in medium containing 50 mM carnosine, and revert to a senescent phenotype when carnosine is removed. Switching cells between medium with and without carnosine also switches their phenotype from senescent to juvenile, and the reverse. The exact calculation of fibroblast lifespans in population doublings (PDs) depends on the proportion of inoculated cells that attach to their substrate and the final yield of cells in each subculture. We have shown that carnosine does not affect cell attachment, but does increase longevity in PDs. However, the plating efficiency of MRC-5 cells seeded at low density is strongly increased in young and senescent cells by carnosine, as shown by the growth of individual colonies. We have also demonstrated that very late-passage MRC-5 cells (with weekly change of medium without subculture) remain attached to their substrate much longer in medium containing carnosine in comparison to control cultures, and also retain a much more normal phenotype. Carnosine is a naturally occurring dipeptide present at high concentration in a range of human tissues. We suggest it has an important role in cellular homeostasis and maintenance.

Increases in mRNA levels of glucose transporters types 1 and 3 in Ehrlich ascites tumor cells during tumor development

A common feature of many tumors is an increase in glucose catabolism during tumor growth. We studied the mechanism of this phenomenon by using Ehrlich ascites tumor bearing mice as the animal model. We found that Ehrlich ascites tumor cells possess only glucose transporter 1 (GLUT1) and GLUT3 but not GLUT2, GLUT4, or GLUT5. The mRNA levels of GLUT1 and GLUT3 increased progressively in the tumour during development; however, there were no changes observable in mRNA levels of glucose transporters of all types in brain, liver, and heart of the host mice. These findings suggest that Ehrlich ascites tumor augments its glucose transport mechanism relative to other tissues in response to its unique growth needs.

Pharmacology of methylglyoxal: formation, modification of proteins and nucleic acids, and enzymatic detoxification--a role in pathogenesis and antiproliferative chemotherapy

1. Methylglyoxal is a reactive alpha-oxoaldehyde and physiological metabolite formed by the fragmentation of triose-phosphates, and by the metabolism of acetone and aminoacetone. 2. Methylglyoxal modifies guanylate residues to form 6,7-dihydro-6,7-dihydroxy-6-methyl-imidazo[2,3-b]purine-9(8)one and N2-(1-carboxyethyl)guanylate residues and induces apoptosis. 3. Methylglyoxal modifies arginine residues in proteins to form N(delta)-(4,5-dihydroxy-4-methylimidazolidin-2-yl) ornithine, N(delta)-(5-hydro-5-methylimidazol-4-on-2-yl)ornithine and N(delta)-(5)methylimidazol-4-on-2-yl)ornithine residues. 4. Methylglyoxal-modified proteins undergo receptor-mediated endocytosis and lysosomal degradation in monocytes and macrophages, and induce cytokine synthesis and secretion. 5. Methylglyoxal is detoxified by the glyoxalase system. Decreased detoxification of methylglyoxal may be induced pharmacologically by glyoxalase I inhibitors which have anti-tumor and anti-malarial activities. 6. The modification of nucleic acids and protein by methylglyoxal is a signal for their degradation and may have a role in the development of diabetic complications, atherosclerosis, the immune response in starvation, aging and oxidative stress.

Implementing a ketogenic diet based on medium-chain triglyceride oil in pediatric patients with cancer

Traditionally, a ketogenic diet is given to drug-resistant children with epilepsy to improve seizure control. Inducing a ketogenic state in patients with cancer may be a useful adjunct to cancer treatment by affecting tumor glucose metabolism and growth while maintaining the patient's nutritional status. A ketogenic diet consisting of 60% medium-chain triglyceride (MCT) oil, 20% protein, 10% carbohydrate, and 10% other dietary fats was provided to a select group of pediatric patients with advanced-stage cancer to test the effects of dietary-induced ketosis on tumor glucose metabolism. Issues of tolerance and compliance for patients consuming an oral diet (consisting of normal table foods and daily MCT oil "shakes") and for patients receiving an enteral formula are reviewed. Preliminary use of the MCT oil-based diet suggests a potential in pediatric patients with cancer.

Effects of a ketogenic diet on tumor metabolism and nutritional status in pediatric oncology patients: two case reports

OBJECTIVE

Establish dietary-induced ketosis in pediatric oncology patients to determine if a ketogenic state would decrease glucose availability to certain tumors, thereby potentially impairing tumor metabolism without adversely affecting the patient's overall nutritional status.

DESIGN

Case report.

SETTING

University Hospitals of Cleveland.

SUBJECTS

Two female pediatric patients with advanced stage malignant Astrocytoma tumors.

INTERVENTIONS

Patients were followed as outpatients for 8 weeks. Ketosis was maintained by consuming a 60% medium chain triglyceride oil-based diet.

MAIN OUTCOME MEASURES

Tumor glucose metabolism was assessed by Positron Emission Tomography (PET), comparing [Fluorine-18] 2-deoxy-2-fluoro-D-glucose (FDG) uptake at the tumor site before and following the trial period.

RESULTS

Within 7 days of initiating the ketogenic diet, blood glucose levels declined to low-normal levels and blood ketones were elevated twenty to thirty fold. Results of PET scans indicated a 21.8% average decrease in glucose uptake at the tumor site in both subjects. One patient exhibited significant clinical improvements in mood and new skill development during the study. She continued the ketogenic diet for an additional twelve months, remaining free of disease progression.

CONCLUSION

While this diet does not replace conventional antineoplastic treatments, these preliminary results suggest a potential for clinical application which merits further research.