2-Deoxy-d-Glucose and Its Analogs: From Diagnostic to Therapeutic Agents.

The ability of 2-deoxy-d-glucose (2-DG) to interfere with d-glucose metabolism demonstrates that nutrient and energy deprivation is an efficient tool to suppress cancer cell growth and survival. Acting as a d-glucose mimic, 2-DG inhibits glycolysis due to formation and intracellular accumulation of 2-deoxy-d-glucose-6-phosphate (2-DG6P), inhibiting the function of hexokinase and glucose-6-phosphate isomerase, and inducing cell death. In addition to glycolysis inhibition, other molecular processes are also affected by 2-DG. Attempts to improve 2-DG's drug-like properties, its role as a potential adjuvant for other chemotherapeutics, and novel 2-DG analogs as promising new anticancer agents are discussed in this review.

Addition of iron and zinc complexes to Eagle's Minimal Essential Medium is sufficient to induce and support the proliferation of B16 melanoma cells.

It was observed that the addition of zinc and iron tartrate complexes to the Eagle's Minimal Essential Medium was sufficient to support the proliferation of murine B16 melanoma cells in this simple extracellular protein-free medium. The addition of these trace elements to the serum-depleted EMEM induced growth of B16 cells as did the addition of serum. This implicates that this test, often used in the search for mitogenic factors, does not discriminate between the real mitogens and the nutrients necessary for cell growth.

Reversible inhibition of growth of B16 melanoma cells by decreased amino acid nutrition.

The effect of limited amino acid nutrition upon the growth of B16 melanoma cells was investigated. It was observed that the cells in Basal Medium Eagle do not proliferate and are inhibited predominantly in the G1 phase of cell cycle. The cells which were inhibited in growth for 7 or 12 days in Basal Medium Eagle were able to commence proliferation when transferred to Eagle's Minimal Essential Medium containing higher concentration of amino acids. The proliferating cells were found to be more evenly distributed throughout all phases of the cell cycle. The reversible inhibition of growth of B16 melanoma cells was caused by decreased concentrations of amino acids and not by their depletion in the culture medium. The B16 melanoma cells which are known to be capable of highly autonomous growth in the absence of extracellular hormones and growth factors have appeared to be sensitive to nutritional inadequacy.

Restricted amino acid nutrition induces attachment to glass and spreading of Ehrlich ascites tumour cells.

Ehrlich ascites tumour (EAT) cells were cultured in vitro in Eagle's MEM and Medium 199 with a lowered amino-acid content. Under these conditions EAT cells lose their rounded shape typical of highly malignant cancer cells, and begin to spread on the substratum. The changes in EAT cell morphology are preceded by a decrease in the rate of protein synthesis. These changes were maintained for three days after returning the cells to Eagle's MEM with a normal amino-acid content, but the return to control media did not cause reasumption of growth in the once spread cells. The increase in glucose content (up to five-fold) or the presence of inhibitors of DNA synthesis did not prevent the attachment and flattening of EAT cells in media with a lowered amino acid content. Several possible mechanisms of the influence of restricted amino-acid availability on the changes in EAT cell surface properties are pointed out and the need for study of cancer cell responses to restricted nutrition is discussed.

Density-dependent survival of Ehrlich ascites tumour cells in the presence of various substrates for energy metabolism.

We have found that Ehrlich ascites tumour (EAT) cells, deprived of any carbon source, and suspended at a density of 2 X 10(5) cells/cm3, begin to die only after 12 h of starvation, though it is known that under these conditions they lose over 80% of their ATP within 30 min. Moreover, we have found that the viability of the cells incubated in the absence of any substrate for energy metabolism is strongly dependent on the density of the cell suspension, and can be significantly improved simply by increasing the suspension density. This prompted us to investigate the density dependence of the maintenance of EAT cell viability in the presence of various substrates for energy metabolism and metabolic intermediates. It was found that: Glucose ensures 48 h viability of EAT cells irrespective of suspension density. Fatty acids and pyruvate as sole carbon source do not improve EAT cell survival. In the presence of glutamine as sole carbon source the EAT cell survival shows dependence on cell-suspension density. At densities of 1.6 X 10(6) to 3.2 X 10(6) cells/cm3 the cell viability is maintained at least as well as in the presence of glucose, but at low cell-suspension densities glutamine does not support cell viability. In the presence of glutamine, addition of 1 mM-inosine and 1 mM-uridine ensures high cell survival irrespective of the cell-suspension density. In the presence of inosine or uridine (10 mM) as sole carbon source, the EAT cell survival is the same as in the presence of glucose and does not depend upon cell-suspension density. Guanosine is less effective, whereas adenosine has no effect at all on the maintenance of EAT cell viability for 48 h. There is no correlation at all between EAT cell survival and the rate of lactic acid production. At a cell-suspension density of 1.6 X 10(6) cells/cm3 the cell survival is of the same order in the presence of glutamine as in the presence of glucose, in spite of the fact that in the first case the rate of lactic acid production is more than 20 times lower. There is no correlation between the capacity of particular nucleosides to support EAT cell survival and their effects on glycolysis and oxygen consumption.