Glycolysis

About: Glycolysis is a(n) research topic. Over the lifetime, 10593 publication(s) have been published within this topic receiving 507460 citation(s). The topic is also known as: GO:0006096 & glycolysis.

Understanding the Warburg Effect: The Metabolic Requirements of Cell Proliferation

Abstract: In contrast to normal differentiated cells, which rely primarily on mitochondrial oxidative phosphorylation to generate the energy needed for cellular processes, most cancer cells instead rely on aerobic glycolysis, a phenomenon termed “the Warburg effect.” Aerobic glycolysis is an inefficient way to generate adenosine 5′-triphosphate (ATP), however, and the advantage it confers to cancer cells has been unclear. Here we propose that the metabolism of cancer cells, and indeed all proliferating cells, is adapted to facilitate the uptake and incorporation of nutrients into the biomass (e.g., nucleotides, amino acids, and lipids) needed to produce a new cell. Supporting this idea are recent studies showing that (i) several signaling pathways implicated in cell proliferation also regulate metabolic pathways that incorporate nutrients into biomass; and that (ii) certain cancer-associated mutations enable cancer cells to acquire and metabolize nutrients in a manner conducive to proliferation rather than efficient ATP production. A better understanding of the mechanistic links between cellular metabolism and growth control may ultimately lead to better treatments for human cancer.

Why do cancers have high aerobic glycolysis

Abstract: If carcinogenesis occurs by somatic evolution, then common components of the cancer phenotype result from active selection and must, therefore, confer a significant growth advantage. A near-universal property of primary and metastatic cancers is upregulation of glycolysis, resulting in increased glucose consumption, which can be observed with clinical tumour imaging. We propose that persistent metabolism of glucose to lactate even in aerobic conditions is an adaptation to intermittent hypoxia in pre-malignant lesions. However, upregulation of glycolysis leads to microenvironmental acidosis requiring evolution to phenotypes resistant to acid-induced cell toxicity. Subsequent cell populations with upregulated glycolysis and acid resistance have a powerful growth advantage, which promotes unconstrained proliferation and invasion.

Nutrient control of glucose homeostasis through a complex of PGC-1alpha and SIRT1.

Abstract: Homeostatic mechanisms in mammals respond to hormones and nutrients to maintain blood glucose levels within a narrow range. Caloric restriction causes many changes in glucose metabolism and extends lifespan; however, how this metabolism is connected to the ageing process is largely unknown. We show here that the Sir2 homologue, SIRT1--which modulates ageing in several species--controls the gluconeogenic/glycolytic pathways in liver in response to fasting signals through the transcriptional coactivator PGC-1alpha. A nutrient signalling response that is mediated by pyruvate induces SIRT1 protein in liver during fasting. We find that once SIRT1 is induced, it interacts with and deacetylates PGC-1alpha at specific lysine residues in an NAD(+)-dependent manner. SIRT1 induces gluconeogenic genes and hepatic glucose output through PGC-1alpha, but does not regulate the effects of PGC-1alpha on mitochondrial genes. In addition, SIRT1 modulates the effects of PGC-1alpha repression of glycolytic genes in response to fasting and pyruvate. Thus, we have identified a molecular mechanism whereby SIRT1 functions in glucose homeostasis as a modulator of PGC-1alpha. These findings have strong implications for the basic pathways of energy homeostasis, diabetes and lifespan.

The M2 splice isoform of pyruvate kinase is important for cancer metabolism and tumour growth

Abstract: Many tumour cells express the M2 form of pyruvate kinase rather than the usual M1 form. PKM2 is now shown to promote tumorigenesis and switch the cellular metabolism to increased lactate production and reduced oxygen consumption, recapitulating key aspects of the Warburg effect.

Beyond aerobic glycolysis : Transformed cells can engage in glutamine metabolism that exceeds the requirement for protein and nucleotide synthesis

Abstract: Tumor cell proliferation requires rapid synthesis of macromolecules including lipids, proteins, and nucleotides. Many tumor cells exhibit rapid glucose consumption, with most of the glucose-derived carbon being secreted as lactate despite abundant oxygen availability (the Warburg effect). Here, we used 13C NMR spectroscopy to examine the metabolism of glioblastoma cells exhibiting aerobic glycolysis. In these cells, the tricarboxylic acid (TCA) cycle was active but was characterized by an efflux of substrates for use in biosynthetic pathways, particularly fatty acid synthesis. The success of this synthetic activity depends on activation of pathways to generate reductive power (NADPH) and to restore oxaloacetate for continued TCA cycle function (anaplerosis). Surprisingly, both these needs were met by a high rate of glutamine metabolism. First, conversion of glutamine to lactate (glutaminolysis) was rapid enough to produce sufficient NADPH to support fatty acid synthesis. Second, despite substantial mitochondrial pyruvate metabolism, pyruvate carboxylation was suppressed, and anaplerotic oxaloacetate was derived from glutamine. Glutamine catabolism was accompanied by secretion of alanine and ammonia, such that most of the amino groups from glutamine were lost from the cell rather than incorporated into other molecules. These data demonstrate that transformed cells exhibit a high rate of glutamine consumption that cannot be explained by the nitrogen demand imposed by nucleotide synthesis or maintenance of nonessential amino acid pools. Rather, glutamine metabolism provides a carbon source that facilitates the cell's ability to use glucose-derived carbon and TCA cycle intermediates as biosynthetic precursors.